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Zinc nanoparticles were electro-deposited along the fibres of carbon paper (CP) substrate uniformly in a salt-induced pre-phase separation region solution. The as-prepared Zn/CP electrode was used for electro-reduction of CO 2 and exhibited a Faradaic efficiency towards CO of 97.6% with a current density of 340 mA cm−2 in an H-type cell, which is the best result to date. [Display omitted] Efficient electrode design is crucial for the electrochemical reduction of CO 2 to produce valuable chemicals. The solution used for the preparation of electrodes can affect their overall properties, which in turn determine the reaction efficiency. In this work, we report that transition metal salts could induce the change of two-phase ionic liquid/ethanol mixture into miscible one phase. Pre-phase separation region near the phase boundary of the ternary system was observed. Zinc nanoparticles were electro-deposited along the fibres of carbon paper (CP) substrate uniformly in the salt-induced pre-phase separation region solution. The as-prepared Zn(1)/CP electrode exhibits super-wettability to the electrolyte, rendering very high catalytic performance for CO 2 electro-reduction, and the Faradaic efficiency towards CO is 97.6% with a current density of 340 mA cm −2, which is the best result to date in an H-type cell. [ABSTRACT FROM AUTHOR]

A free-standing cathode without any binder, conductor, and current collector is attractive due to its reduced weight and cost. This study introduces nitrogen-rich and hierarchical porous carbon fibers in the form of a free-standing carbon paper synthesized by NaBH 4 -aided electrospinning and subsequent CO 2 annealing. This modified process leads to a large mesopore volume of 1.007 cm3 g−1 and exposes the nitrogen inside the polymer to the surface of the fiber, resulting in the outstanding surface nitrogen content of 19.38 wt% with abundant pyridinic-N and pyrrolic-N of 16.24 wt% in total surface atoms, while eliminating any further treatment for increasing porosity or coating the polar active sites. The resultant material impregnated by sulfur and filtered by a graphene solution is directly employed as a cathode without any additives. As a result, the capacity is maintained at 696 mAh g−1 up to the 500th cycle at 0.2 C, and 645 mAh g−1 at a high current density of 5.0 C. Even with a high sulfur loading of 6.11 mg cm−2, a remarkable areal capacity of 3.09 mAh cm−2 is recorded after 500 cycles at 0.2 C with the free-standing form preserved. Image 1 • NaBH 4 -added electrospinning and subsequent heat treatment under CO 2 atmosphere. • High meso pore volume of 1.007 cm3 g−1, and surface nitrogen contents of 19.38 wt%. • Employed as a cathode without any additives due to a free-standing paper form. • High sulfur amount of 6.11 mg cm−2, and capacity of 3.09 mAh cm−2 for 500 cycles. [ABSTRACT FROM AUTHOR]

For the electro-reduction of CO 2 to syngas, the fabrication of electrodes with excellent and adjustable catalytic performance is a critical step. In this work, Ni particles encapsulated in N-doped carbon nanotubes on carbon paper (Ni@N-CNTs/CP) composites were designed and prepared via an in-situ chemical vapor deposition method. As confirmed by different characterization techniques, the Ni@N-CNTs are successfully synthesized, and the surface of the CP is evenly covered by the Ni@N-CNTs. The effects of Ni content and treating temperature on the textural properties of composites are carefully investigated. The Ni@N-CNTs/CP composites are directly employed as the electrode for electro-reduction of CO 2 , and the action mechanisms of the N species, Ni particles, and N-CNTs structure are explored as well. The electrode exhibits excellent catalytic activity and high stability, reaching a specific current of 10 mA cm−2. The H 2 /CO ratio in the achieved syngas can be tuned in the range of 5/1 to 1/1.5. Image 1 • A in-situ CVD method was employed to fabricate an electrode for electro-reduction of CO 2. • The as-synthesized Ni@N-CNTs evenly cover on the whole surface of CP. • The Ni@N-CNTs/CP electrode exhibits high CO 2 reduction activity and stability. • The ratio of H 2 /CO can be adjusted in the range of 5/1 to 1/1.5. • The action mechanism of different components are detailedly investigated. [ABSTRACT FROM AUTHOR]

A scalable papermaking process was employed herein to manufacture cellulosic papers from native and phosphorylated cellulose microfibers (referred to as CMF and PCMF, respectively) impregnated with polyethyleneimine (PEI) for Direct Air Capture (DAC) applications. These papers were analyzed in terms of their physico-chemical properties using several techniques. The impact of PEI content on desorbing the co-adsorbed H 2 O and CO 2 from the air, as well as on the anisotropic microporous network, was explicitly analyzed. The results indicated that phosphorylation promotes the uptake of both CO 2 and H 2 O in the corresponding neat and PEI-loaded papers, reaching a superior CO 2 adsorption capacity of ∼0.7–0.9 mmol.g−1 for PCMF papers versus 0.07–0.3 mmol.g−1 for CMF papers. Furthermore, the CMF and PCMF papers exhibited H 2 O adsorption capacities in the range of 1.5–1.8 mmol.g−1 and 2.2–3.8 mmol.g−1, respectively. This work further highlights the combined role of phosphorylation and favorable PEI impregnation in tuning the cellulose CO 2 adsorption properties under humid conditions, facilitating the rapid release of the adsorbed CO 2 under mid conditions. [Display omitted] • Manufacturing of scalable solid cellulosic papers with amine functionalities and enhanced carbon capture. • Microstructural and chemical characterization of amine functionalized paper with various amine ratios. • Valorization of Alfa biomass in Carbon capture applications. • The combined role of phosphorylation and PEI impregnation in tuning the H 2 O and CO 2 co-adsorption properties. [ABSTRACT FROM AUTHOR]

A recent commentary by Santhosh and Ravindran on our paper (Int. J. Hydrogen Energy 2014, 39:10,606) demonstrated that the interaction between H 2 and MXene (Sc 2 C and Ti 2 C) phases are not Kubas-type and should be of weak physisorption, and thus made a conclusion that 2D Sc 2 C and Ti 2 C are not suitable for practical hydrogen storage applications. In this responses, we recalculated hydrogen adsorption on 2D Sc 2 C and Ti 2 C by using different exchange-correlation functionals. And based on the calculated results, bare MXenes (especially the Ti 2 C) are suitable as hydrogen storage materials at temperatures of several tens degrees lower than room temperature. And the hydrogen adsorptions on the MXenes terminated with oxygen group were also investigated. Among the Ti 2 C, Sc 2 C and their oxygen-functional counterparts, the binding energy of H 2 on Sc 2 CO 2 surface is the closest to the ideal range of 0.16–0.42 eV/H 2 at ambient conditions, and thus the Sc 2 C with oxygen group is expected to be more suitable as hydrogen storage materials. [ABSTRACT FROM AUTHOR]

A completely lab-made paper/graphene-based 3D pop-up device (3D-PP) for the analysis of carbaryl (CBR), a pesticide widely used in crop production, is proposed. The device is composed of a nitrocellulose sensor equipped with reduced graphene oxide (rGO) and a foldable 3D paper pop-up. The rationale of the device is based on 3D and 2D configurations to allow the whole analytical procedure. In the 3D arrangement sample pre-concentration and hydrolysis occur; after folding (2D), contact with the complementary nitrocellulose-based sensor is ensured. The sensor, constituted by nanostructured graphene film, allows to obtain the necessary electroanalytical performance. 3D-PP has been shaped and nanostructured using a CO 2 -laser plotter and finished using low-cost benchtop instruments, ensuring in-series manufacturing of the device modules. 3D-PP includes the main steps required for CBR determination, i.e. (i) pre-concentration/purification, (ii) hydrolysis, (iii) medium neutralization, and (iv) electrochemical detection. 3D-PP was challenged for CBR quantification in model solutions and different grain samples. The response linearity (1.5–33 μM) and LOD (0.4 μM) obtained ensures CBR determination at the European-law admitted maximum residue levels (MRL). As proof of applicability, to simulate contaminates samples, different grains (i.e. soft and durum wheat, kamut, and barley) were spiked, before extraction, with CBR at three concentration levels corresponding to 0.5x, 1x, and 1.5x MRL; in all cases, quantitative and reproducible recoveries were obtained (93–109%; RSD ≤ 6%, n = 3). 3D-PP is produced using cellulosic components and solvent-free approaches, includes all CBR analysis steps, and returns reliable results in 15 min, resulting portable and usable with a smartphone [Display omitted] • A paper/graphene-based device for integrated carbaryl (CBR) analysis is proposed. • CO 2 -laser was used to shape and nanostructure the paper-based platform. • Complete CBR analysis is strategically enclosed in a 3D foldable paper pop-up (3D-PP). • 3D-PP design and sensing ability allow CBR residues analysis at EU-law limits. • 3D-PP analysis ability was proven in soft and durum wheat, kamut, and barley. [ABSTRACT FROM AUTHOR]

The present study investigated the fresh, hardened, and physicochemical properties of CO 2 -cured belite-rich cement (BRC) paste incorporating hygiene tissue paper (HTP) as an additive. HTP was added at 0.5% and 1.0% by wt. of BRC paste. The BRC paste was prepared at a water-to-cement ratio of 0.4 and cured under water and carbonation. The results demonstrated that upon carbonation, the incorporation of HTP at 1.0% increases the CO 2 uptake and compressive strength of specimens by 18.60% and 22.29%, respectively. A pore structure analysis shows a decrease in the threshold pore size diameter with an increase in the HTP content for CO 2 -cured samples. An SEM analysis revealed precipitation and impregnation of calcites in and around the HTP microfiber particles. The incorporation of HTP under water curing on the other hand did not significantly influence the strength or the physicochemical properties. It was observed that HTP contributes to improving the properties of CO 2 -cured BRC paste in two ways; the porous structure of HTP provides pathways for the deep permeation of CO 2 into the matrix, and the surface of HTP offers an additional area for calcite precipitation. [ABSTRACT FROM AUTHOR]

This work presents an unconventional use of capacitively coupled contactless conductivity detector (C4D) for detection of gas absorption by moist paper with potential application for chemical analysis. To be suitable for measuring conductivity of moist paper absorbent, the C4D sensor was therefore designed in planar configuration. A layer of dry filter paper, only 20 mm × 25 mm in size, was placed on the C4D sensor and the device installed inside a specifically designed vaporization chamber. A vial (16 mm i.d., 8 mm high) containing a 150-μL solution of sodium bicarbonate was placed alongside. The filter paper was loaded with 110 μL of deionized water through an injection hole in the cover lid. A 100-μL aliquot of 2 M hydrochloric acid solution was directly dispensed into the vial through a second hole in the lid to generate CO 2 gas from the bicarbonate solution. It was observed that the C4D sensor gave real-time response that corresponded to the absorption of the gas and subsequent production of H+ and HCO 3 − in the moist paper. The monitored signal reached a constant value at 160 s after the addition of the acid. Chemistry of the absorption process and equivalent circuit for the C4D are proposed. Direct measurement of cement powder was chosen to demonstrate the potential use of this device for quantifying the CaCO 3 content of the cement. The calibration curve for 0.5–3 mg CaCO 3 was linear for signals recorded at 160 s: V dc = (0.172 ± 0.005) · (mg CaCO 3) + (0.016 ± 0.009), with coefficient of determination of 0.9965. Linear calibrations were also observed when the signals were monitored at various time less than 160 s. The limit of quantitation (3 SD of intercept/slope) was 0.17 mg CaCO 3. The method provided acceptable precision with %RSD of 4.6 (2 mg CaCO 3 , n = 10). Image 1 • Unconventional use of planar contactless conductivity detector is presented. • Real-time in-situ detection of CO 2 absorption by moist paper was demonstrated. • The absorption chemistry by moist paper and C4D equivalent circuit are proposed. • Potential application in direct measurement of cement powder is demonstrated. [ABSTRACT FROM AUTHOR]

Pulp and paper mill sludge (PPMS) is applied on agricultural soils as an organic fertilizer. Although it is well accepted that land application of PPMS has benefits for soils and crops, information on PPMS-induced soil N 2 O emissions is still limited. We assessed the effect of substituting mineral N fertilizer for PPMS on soil N 2 O emissions after a single application at planting on a clay loam cropped to wheat ( Triticum aestivum L.) over two snow-free seasons in eastern Canada. Fertilization treatments consisted of 0, 25, 50, 75, and 100% of crop N requirements derived from N supplied by PPMS, the remaining N being supplied as urea-N. Soil CO 2 and CH 4 emissions were also measured and not affected by the fertilizer addition; a slight CH 4 oxidation occurred. Area-based N 2 O emissions from PPMS fertilization (4.4 to 12.1 kg N 2 O-N ha −1 ) were similar or higher than from urea alone (3.4 and 6.2 kg N 2 O-N ha −1 ). Although crop yields were not affected by the type of fertilizer, yield-based N 2 O emissions, N uptake efficiency and N surplus (applied N minus aboveground N uptake in crop biomass) indicated that N availability from the mineral fertilizer was higher than from PPMS for the wheat crop. However, treatments with PPMS had fertilizer-induced N 2 O emission factors (FIEF, applied N lost as N 2 O-N; 0.8 to 3.1%) similar to urea alone (−0.3 and 4.5%). Although substituting urea-N with PPMS in agricultural fields might reduce N 2 O emissions under moderate soil moisture conditions, PPMS land application produced greater N 2 O emissions under high soil moisture conditions. Further research on a variety of agricultural practices is needed before concluding that including PPMS in the fertilization plan could result in a global GHG abatement as compared to mineral fertilizers under the cool climate of eastern Canada. [ABSTRACT FROM AUTHOR]

Utilization of the quality-upgraded waste paper in the manufacture of paper and board will reduce the wood consumption and pulping energy. While the optical property of the fibers from recycled old newspaper is very poor, in-situ calcium carbonate formation on those fibers by injecting carbon dioxide to the mixed slurry of those pulp and calcium oxide improved their brightness. Upgrading recycled old newspaper to substitute more expensive wood furnish, such as recycled old magazine, was successfully demonstrated in the present study. This study showed that the in-situ calcium carbonate formation process improved the optical quality of the recycled old newspaper by covering colored impurities with newly formed calcium carbonate, and improved calcium carbonate retention in papermaking process by attaching them to fibers. The strength reduction by the presence of newly formed calcium carbonate in the paper was recovered by adding strength agent. High ash retention at high ash content under the strong turbulence in the modern paper mill was achieved by the application of the in-situ calcium carbonate formation method. The quality-upgrade of recycled fibers and cost saving in the manufacture of duplex paperboard were demonstrated in the mill trial. [ABSTRACT FROM AUTHOR]

Pyrolysis of paper mill sludge (PMS) was conducted to produce syngas (H 2 and CO) and fabricate magnetic biochar (PMS biochar) for use as an adsorbent for As(V). The enhanced generation of CO was observed in the CO 2 atmosphere due to reactions triggered by CO 2 . Particularly, the generation of syngas from pyrolysis of PMS in CO 2 (9.6 mol% at 720 °C) was superior to the cases of pyrolysis of acid-washed PMS ( i.e. , minerals-eliminated PMS) in CO 2 (2.9 mol% at 720 °C), which evidences catalytic effects attributed by Fe and Ca species contained in PMS. Based on the results of X-ray diffraction (XRD), pyrolysis of PMS in CO 2 led to the conversion of Fe species into magnetite (Fe 3 O 4 ) solid phase that imparted the magnetic property to the biochar (saturation magnetization: 28.4 emu g −1 ). The PMS biochar exhibited high As(V) adsorption capacity of 34.1 mg g −1 in a given condition, which could be attributed to the great adsorption affinity of Fe 3 O 4 /CaCO 3 mixture toward As(V). The integrated approach for the utilization of PMS could satisfy growing demand for renewable energy and environmental sustainability. [ABSTRACT FROM AUTHOR]

Highlights: [•] Carbon monoxide is one of the key toxic components in cigarette mainstream smoke. [•] Carbon dioxide delivery can be discouraged by engineering of cigarette paper. [•] The relevant concepts on engineering of cigarette paper are reviewed. [ABSTRACT FROM AUTHOR]

The combustion of biomass and waste paper sludge in a fluidized bed is ecologically profitable. However, a large amount of by-product with high hydraulic reactivity is produced and is considered as wastes. Most of the time the waste paper fly ash (WPFA) goes to landfills, therefore new utilization methods are necessary. In some countries, the high content of metallic and metalloids trace elements (MMTE) in WPFA, more specifically Barium (Ba) and Lead (Pb) makes its valorization difficult. In this paper, the Lightweight Aggregates (LWA) was produced from WPFA by granulating with water in high-intensity granulator. Since WPFA is rich in CaO, the addition of water promotes rapid setting and hydration compared to other types of ash. In this study, different granulation parameters were investigated, such as the rotation modes between the steel pan and the impeller, the rotation speed of the steel pan, the granulation time, in order to improve the mass percentage of the targeted LWA (2–16 mm). In order to evolve the immobilization potential of Ba and Pb, a carbonation process was performed, exposing the manufactured LWA to pure carbon dioxide (CO 2) gas at laboratory scale. The physical, morphological, thermal and mechanical characterizations were performed on LWA for use in mortars, concretes or civil engineering constructions. Results have demonstrated the influence of the rotation mode between the steel pan and the on the distribution of WPFA inside the steel pan and the change in the growth rate of the granules can be observed. Increased density and improved compressive strength with low porosity and water absorption were also found in LWA after carbonation. This was due to the occurrence of both a carbonation reaction and a hydration reaction. Furthermore, the results of thermogravimetry and SEM-EDS confirmed the formation of hydrated phases (ettringite, carboaluminates), also the formation of calcite in the pores and the external surface of the LWA. Regarding environmental aspects, the results have revealed that Ba and Pb were well immobilized in the solid matrix after carbonation. [Display omitted] • LWA was manufactured from WPA without any agglomerating agents. • The physical-chemical properties of LWA were improved after carbonation. • The resulted LWA meet the requirements of NF EN -13,055-1. • The microstructure of LWA was studied before and after carbonation. • Influence of time, mode and rotation speed on the size of the manufactured LWA. [ABSTRACT FROM AUTHOR]

Currently, developing highly active and low-cost electrocatalytic materials for oxygen evolution reaction (OER) is an enormously grand challenge. Herein, we developed a novel and highly active Mn doped Co 2 Fe layer double hydroxide (LDH) electrocatalyst for OER. We discovered that these electrocatalytic materials can be directly grown on carbon papers to construct high-specific-surface-area electrode, which shows the lowest overpotential of 266 mV at 10 mA cm−2. Furthermore, after introducing Mn element, DFT + U calculation found that the ∗OOH of Fe-site on Co 2 Fe 0.67 Mn 0.33 LDH could draw more electrons than Co 2 Fe LDH due to the electronegativity differences between Fe-site on Co 2 Fe 0.67 Mn 0.33 LDH and Fe-site on Co 2 Fe LDH, which is reason that the energy level of Fe 3d (e g) was obviously downshifted by d-d repulsion of Mn 3d and Fe 3d in the neighboring sites of Co 2 Fe 0.67 Mn 0.33 LDH after doped Mn element, which leads to reduce charge-transfer energy from O 2p to Fe 3d (e g) to promote oxygen evolution processes for OER. Meanwhile, the band gap is also decreased after doped Mn element in Co 2 Fe LDH due to the downshifted e g orbital energy of Fe 3d. This study gives a general avenue to design and developing efficiently active LDH electrocatalysts for OER in the future. • Both bimetallic CoFe LDH and Mn doped CoFe LDHs directly grown on carbon paper are successfully synthesized. • The Co 2 Fe 0.67 Mn 0.33 LDH@NFs exhibits a small overpotential of 236 mV at 10 mA cm−1 for OER. • DFT + U studies reveal that the observed superb OER activity could be attributed to d-d repulsion of Mn 3d and Fe 3d. [ABSTRACT FROM AUTHOR]

Highlights • Synthetic CaO-based CO 2 sorbent was prepared using paper fibre as a biotemplate. • Synthetic sorbent is mainly composed of CaO and Ca 12 Al 14 O 33. • Synthetic sorbents possess microtube-like structure with superior CO 2 uptake. • Synthetic sorbent has improved sintering resistance in severe calcination condition. Abstract Calcium looping is regarded as an effective and viable way to address CO 2 emissions. To overcome the loss-in-capacity problems of calcium-based sorbents with the number of calcium looping cycles, a novel CaO/Ca 12 Al 14 O 33 sorbent with a microtube-like structure was prepared from carbide slag and Al(NO 3) 3 ·9H 2 O using paper fibre as a biotemplate. The CO 2 capture performance and microstructure of the novel synthetic sorbent under calcium looping conditions were investigated. The results show that the utilization of the biotemplate is good to retain the high cyclic CO 2 capture reactivity of the synthetic sorbent. Due to the unique hollow porous structure, the CO 2 capture capacity of the synthetic sorbent containing 7.5 wt% Al 2 O 3 retains 0.56 and 0.33 g/g after 30 cycles under mild and severe calcination conditions, respectively, which are 2.56 and 2.11 times higher than those of carbide slag under the same respective calcination conditions. With the presence of 10% steam in the carbonation atmosphere, the CO 2 capture capacity of the synthetic sorbent retains 0.55 g/g under the severe calcination conditions after 10 cycles. The native hierarchical biostructure of paper fibre is preserved in the synthetic sorbent. CaO and Ca 12 Al 14 O 33 are uniformly distributed in the synthetic sorbent, resulting in a high sintering resistance during multiple CO 2 capture cycles. CO 2 can penetrate through the microtube-like structure of the synthetic sorbent from two directions, i.e., from the outer surface and inner surface. This phenomenon effectively enlarges the contact area between CO 2 and CaO. The CaO/Ca 12 Al 14 O 33 sorbent with a hollow porous structure by means of a biotemplate appears promising in the calcium looping technology for CO 2 capture. [ABSTRACT FROM AUTHOR]

The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. [Display omitted] • Flower-like Co 2 FeO 4 showed the best catalytic performance. • The "D-band center" and "valence -band center" of Co 2 MO 4 were studied. • Composition and electronic control improve the catalytic performance of Co 2 MO 4. • The adsorption configuration of H 2 O on the Co 2 MO 4 (311) surface was studied. [ABSTRACT FROM AUTHOR]

Activated carbon fiber paper (ACFP) has the potential for adsorption due to their high surface area and low through resistance. In this work, free-standing ACFP was developed from fibrillated polyacrylonitrile (PAN) fiber through wet forming process combined with subsequent pre-oxidation, carbonization and CO 2 activation. A PFI refiner was used to prepare fibrillated PAN fibers with a beating degree of 7, 11, 25 and 60 oSR, respectively. As expected, PAN fibers with high beating degree improved surface area and fine fiber content, which resulted in the dense structure and low porosity of paper, thus influencing later stabilization and pyrolysis, as well as final properties of ACFP. With the increase of beating degree, the oxygen content of pre-oxidized PAN paper increased, but the cyclization index first decreased and then increased. ACFP with higher beating degree possessed higher BET surface area, pore volume and CO 2 uptake capacity. ACFP, prepared from freeze-dried PAN paper, performed better in physicochemical properties than that from plate-press drier under the same beating degree. This study exhibited that ACFP can be a special material featured by scale production, lightweight, and high microporosity of chemical adsorption and separation. [Display omitted] • ACFPs were prepared from fibrillated PAN fiber through wet forming process. • Effects of pore structure of PAN papers on physicochemical properties of ACFPs • CO 2 adsorption on ACFPs was a combined effects of physisorption and chemisorption. [ABSTRACT FROM AUTHOR]

Abstract: The pulp and paper industry both uses and produces large amounts of energy and rising fuel prices bring along significant challenges to the sector. Several strategies can be applied in order to remain competitive e.g. an increase in energy efficiency, a switch in fuel and/or a novel energy conversion technology. In this study, we investigate if improved energy conversion strategies can reduce energy costs, primary energy use and CO2 emissions of paper mills within different European countries (The Netherlands, Poland and Sweden). Our results show that differences in history and availability of resources has led to different conversion strategies in the three countries. We found that a natural gas combined cycle, which is largely implemented in The Netherlands due to long term domestic availability of natural gas, has the lowest primary energy demand. Due to a long history of low electricity prices, CHP has not been common in Sweden. Many Swedish mills use biomass as an energy source and due to low CO2 emissions of the national grid the CO2 emission profile of the Swedish paper industry is very low. Our results imply that future conversion routes for the Swedish paper and board industry are again wood based; in case of increasing electricity prices these would be biomass gasification based CHP solutions. With a reduction of 800kg CO2/ton paper on average, a switch from coal to biomass would reduce CO2 emissions in the Polish pulp and paper industry with approximately 0.6Mton/year. A carbon price of 20–25€/ton would, according to our results, be enough to provoke this switch. Due to the high share of natural gas, the CO2 emission reduction potential of the Dutch paper industry (1.5Mton/year) is even larger than in Poland. Due to high biomass prices and relative low CO2 emission profile of natural gas, a carbon prices of more than 60€/ton CO2 would be needed to provoke a switch in The Netherlands. Provided with few alternatives, the most effective strategy in The Netherlands would be an increase in energy efficiency. [Copyright &y& Elsevier]

[Display omitted] • Filter paper is used as carbon source to prepare highly porous N-doped carbon. • KHCO 3 is chosen as the activator because it is safe and non-corrosive. • Addition of urea at the activation step significantly improves the surface area. • At 0 °C and 20 bar, the carbon shows high CO 2 uptake of 19.65 mmol/g. Herein, we presented the preparation of N-doped porous carbon from lab used filter paper. Filter paper was first carbonized at 500 °C. The obtained carbon was then pyrolyzed with KHCO 3 and urea. Effects of KHCO 3 activation on the carbons' physicochemical properties were thoroughly investigated. The derived carbon materials were also tested for CO 2 adsorption with pressure up to 20 bar. The carbons exhibited very high CO 2 uptake of 19.65 mmol/g at 0 °C and 20 bar. The correlations between adsorption performances and the carbons' physicochemical properties at 1/20 bar were analyzed and discussed. [ABSTRACT FROM AUTHOR]

In this paper an approach for analysing the potential for implementation of different technology pathways for the European pulp and paper industry (PPI) is presented. The approach is based on detailed technical research and aggregates the knowledge from previous studies to incorporate the whole European PPI. Thus, the potential for different technology pathways can be estimated on a European level whilst still considering important characteristics of individual mills. The usefulness of the approach was exemplified by applying it to a case study of the potential for introduction of carbon capture and storage (CCS) within the European PPI. The results from the case study show that for the European PPI, CCS has an up-hill road in order to be a viable, large scale alternative for reduction of CO2 emissions. If CCS is to be introduced in large scale within the European PPI, large biomass-based point sources of CO2 emissions need to be included when planning for CCS infrastructure and also the infrastructure needs to be built out for clusters emitting <20 MtCO2/yr. [ABSTRACT FROM AUTHOR]

Abstract: Lime mud (LM), a solid waste that results from the causticization reaction in alkali recycling process of paper manufacture industry, was utilized as CO2 sorbent in calcium looping process in this study. The carbonation behavior of LM in the calcination/carbonation cycles was investigated in a dual fixed-bed reactor and a thermo-gravimetric analyzer. The results show that the carbonation conversions of LM are lower than those of limestone at the same reaction conditions. It attributes to the high chlorine content in LM which leads to more pronounced sintering and decreases the CO2 capture performance of LM. A pre-wash process was employed to decrease the chlorine content in LM. Based on an overall consideration of various factors, the pre-wash process is effective enough if the Cl/Ca molar ratio in LM is smaller than 1:100. Pre-washed lime mud (PLM) achieves higher carbonation rates and carbonation conversions, compared with LM. When calcined at 850°C and carbonated at 700°C, the carbonation conversion of PLM maintains at 36% after 100cycles, which is 1.8 and 4.8 times as high as LM and limestone after the same number of cycles, respectively. The pore volume and surface area of calcined PLM were greater than those of calcined LM after the same number of cycles, especially the volume of the pores in the range of 10–100nm in diameter. That is the reason why PLM exhibits higher CO2 capture capacity than LM in the multiple calcination/carbonation cycles. The carbonation conversions of LM and PLM are further enhanced by hydration of their calcines. [Copyright &y& Elsevier]

Abstract: Superhydrophobic alkyl ketene dimer (AKD) layers were successfully produced on top of untreated paper surfaces by a rapid expansion of supercritical CO2 solution (RESS) process. The new method resulted in a degree of hydrophobicity, as measured by contact angles of water droplets on AKD surfaces, dramatically higher, up to 173°, compared to a conventional method consisting in melting AKD granules directly on the paper substrate, giving contact angles of around 109°. Experiments were conducted to investigate the effects of varying pre-expansion pressure (100–300bar), pre-expansion temperature (40 and 60°C) and spraying distance (10 and 50mm) on the properties of the treated surfaces. The surfaces were analyzed regarding AKD particle size, surface morphology and hydrophobicity with the aid of scanning electron microscopy (SEM) and contact angle measurements. The average AKD particle size after RESS processing was between 1 and 2μm depending upon the experimental conditions used, being slightly smaller when using higher pre-expansion pressure and temperature as well as shorter spraying distance. [Copyright &y& Elsevier]

Highlights: [•] 9–12h adsorption of CO2 in the 1st cycle increases cyclic CO2 adsorption of APMW. [•] Repeated prolonged adsorptions in cycles are feasible to capture CO2 using APMW. [•] Prolonged adsorption increases pores in 10–100nm of APMW after desorption of CO2. [Copyright &y& Elsevier]

This paper explores green hydrogen-based carbon dioxide (CO 2) hydrogenation for the production of oxygenates, presenting it as a pivotal strategy for mitigating carbon emissions and advancing sustainable energy solutions. The conversion of CO 2 into oxygenates through hydrogenation emerges as a promising avenue, particularly in the context of transportation applications where the storage of hydrogen poses challenges. The substitution of fossil diesel and gasoline fuels with green hydrogen-derived dimethyl ether, or methanol/ethanol, is advantageous from a life cycle analysis (LCA) CO 2 emission perspective even without the capture of the CO 2. However, the greatest sustainability appeal is contingent on the crucial aspect of capturing CO 2 when utilizing these fuels, which is an aspect currently absent in the literature. This narrative review comprehensively explores catalytic processes, mechanisms, sustainability perspectives, and the current state of research in this evolving area. It encompasses both the production of oxygenates through CO 2 hydrogenation and the subsequent utilization of these oxygenates in fuel cells or combustion systems, emphasizing the integration of CO 2 capture technologies. The paper contributes to the discourse surrounding the environmental and technological dimensions of energy storage ecosystems, providing a holistic view of their potential to foster sustainable energy solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compared to N 2 , the pyrolysis of MSW and PS was more complete under CO 2 atmosphere. • The evolution of six typical pyrolysis products were illustrated by TG-FTIR. • MgO could act as a catalyst to promote the pyrolysis reaction of blends. • Through DAEM, the activation energy in two stages were about 170 and 300 kJ/mol. In order to explore a harmless and resource-based way to treat municipal solid waste (MSW) and paper sludge (PS), the co-pyrolysis MSW and PS was studied in this paper. Firstly, MSW and PS had the lower residue mass, and MSW had higher pyrolysis index under CO 2 atmosphere, compared with the one under N 2 atmosphere. Hence, the CO 2 was used as the carrier gas in the following study. Secondly, under CO 2 atmosphere, the co-pyrolysis of MSW and PS with and without MgO were researched. With the increasing of PS ratio, the pyrolysis performance of the blends decreased constantly. MgO act as catalyst could improve the pyrolysis characteristic index of the blends. However, MgO was an inorganic salt and it would affect the synergistic effect of MSW and PS. The curves of online evolutions of all the gas products and the functional groups had an obvious peak at around 500 ℃. The activation energy of the blends in the first step (<600 ℃) were around 170 kJ/mol and reached more than 300 kJ/mol of the second step (600−1000 ℃). In addition, the adding of MgO could decrease the activation energy of MSW, 50M50P and PS. Finally, 50M50P-M was suitable for treating more sludge. And these results could offer some referential information for designing and optimizing the co-pyrolysis technology for MSW and PS. [ABSTRACT FROM AUTHOR]

• The CMC from office waste paper was synthesized completely within 30 min at ambient temperature by ultrasonic-assisted technique. • The degree of substitution of obtained CMC product was 0.75. This report demonstrates the fastest technique to successfully achieve carboxymethyl cellulose (CMC) from office paper waste, within 30 min at ambient temperature using ultrasonic-assisted method as a source of energy. The obtained CMC was characterized using FTIR, TGA, and NMR techniques to confirm its structure. The FTIR spectrum showed characteristic peaks of carboxymethyl groups and its salt at the wavenumbers of 1585 (C=O) and 1412 (C-O) cm−1. The TGA results of CMC exhibited the loss of carbon dioxide at ca. 260 – 300 °C. Moreover, a higher ash yield of the obtained CMC indicated the substitution of carboxymethyl in the structure. The CMC product structure was confirmed using 13C- and HMBC 2D-NMR. The HMBC 2D-NMR results indicated a correlation between carbonyl and methylene carbons of carboxymethyl groups and protons of pyranose ring, implying that pyranose ring was substituted successfully by monocholoroacetic acid (MCA). The optimal conditions were obtained by using 4.11 ml of 30%w/v NaOH and 1.4 g of MCA in 40 ml of isopropanol at ambient temperature. The resulting CMC showed 0.75 degree of substitution at 18.75 W/ml ultrasonic intensity. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract: The possibility of changing waste paper sludge into valuable carbonaceous adsorbent was tested. The performance of three types of samples obtained from this waste was studied: chars (PK), activated chars (PKA) and activated initial material (PA). Pyrolysis of the initial material was carried out at 550, 600 and 700°C, while the activation of the initial material and chars obtained with CO2 at 550, 600 and 700°C. The sorption capacity of carbonaceous adsorbents obtained was evaluated on the basis of NO2 adsorption in dry and wet conditions. The NO2 sorption properties of the activates decrease with increasing temperature of activation and the maximum sorption capacity was noted for the samples activated at 550°C. On the basis of measurements in dry and wet conditions, the presence of water was found to increase the NO2 breakthrough capacity. The NO2 sorption capacity of the adsorbents obtained depended on the type and temperature of modification process and acid–base properties of the materials obtained. [Copyright &y& Elsevier]

Pulp and paper is considered to be the fourth most energy-intensive industry (EII) worldwide. However, as most of the CO 2 emissions are of biomass origin, this sector has the potential to become a carbon-negative industry. This study proposes a new concept for conversion of the pulp and paper industry to carbon negative that relies on the inherent CO 2 capture capability of the Kraft process. The techno-economic performance of the proposed carbon-negative system, based on calcium looping (CaL) retrofitted to a pulp and paper plant, was evaluated. The effect of CaL design specifications and cost assumptions on the thermodynamic and economic performance were evaluated. Under the initial design assumptions, the reference pulp and paper plant was shown to turn from electricity importer to electricity exporter with the cost of CO 2 avoided equal to 39.0 €/tCO 2. The parametric study showed that an increase in the fresh limestone make-up rate resulted in a linear increase of the specific primary energy consumption for CO 2 avoided (SPECCA) and a reduction in the amount of electricity exported to the electric grid. This translates into an increase in the price of pulp and newsprint, and the cost of CO 2 avoided. This study has also demonstrated that the pulp and paper industry has high potential to become carbon negative. It has been shown that carbon capture and storage would become economically viable in this industry if the negative CO 2 emissions are recognised and a negative CO 2 emissions credit of at least 41.8 €/tCO 2 is implemented. • Concept of the Kraft process with inherent CO 2 capture. • Calcium looping for CO 2 capture is integrated in the lime cycle. • Reference pulp and paper plant turns from importer to exporter of electricity. • Pulp and paper industry has a high potential to become carbon negative. • Economic feasibility needs the inclusion of biogenic emissions in emission trading. [ABSTRACT FROM AUTHOR]

Abstract: Evolutionary behavior of syngas chemical composition and yield have been examined for paper and cardboard at three different temperatures of 800, 900 and 1000°C using CO2 as the gasifying agent at constant flow rate. Specifically the evolution of syngas chemical composition with time has been investigated. Pyrolysis of the sample was dominant at the beginning of the gasification process as observed from the high initial devolatilization of the sample followed by char gasification of material to form syngas for a long period of time. Results provided the role of gasification temperature on kinetics of the CO2 gasification process. Increase in gasification temperature provided increased conversion of the sample material to syngas. Thus the sample conversion to syngas was low at the low temperature of 800°C while at elevated temperatures of 900 and 1000°C substantial enhancement of the kinetics process occurred. The evolution of extensive reaction rate of carbon-monoxide was calculated. Results show that increase in temperature increased the extensive reaction rate of carbon-monoxide. The global behavior of syngas chemical composition examined at three different temperatures revealed a peak in concentration of H2 to exhibit after few minutes into the gasification that changed with gasification temperature. At 800°C gasification temperature peak in H2 was displayed at 3min into gasification while it decreased to only 2min, approximately, at gasification temperatures of 900 and 1000°C. The effect of reactor temperature on CO mole fraction has also been examined. Increase in the gasification temperature enhances the mole fraction of CO yields. This is attributed to the increase in forward reaction rate of the Boudouard reaction (). The results show important role of CO2 gas for the gasification of wastes and low grade fuels to clean syngas. [Copyright &y& Elsevier]

• Freestanding carbon paper confined with ultrafine lithiophilic TiO 2 is in-situ synthesized from MXene and CO 2. • Freestanding C/TiO 2 paper is firstly employed as dendrite-free Li metal anodic host. • The growth behaviors of metallic Li on C/TiO 2 is systematically probed. • Lithiophilic TiO 2 seeds and conductive 3D carbon synergistically induce dendrite-free Li deposition. • C/TiO 2 @Li paper enables full cell with improved electrochemical performance. Lithium (Li) metal anode is deemed as one of the most fascinating anodes due to its high energy density. Nonetheless, low Coulombic efficiency and safety issues caused by detrimental Li dendrites growth severely hamper its practical application. Herein, we construct an ultrafine TiO 2 confined in 3D freestanding carbon paper by one-step green in-situ oxidation of Ti 3 C 2 T x MXene film with greenhouse gas CO 2. The lithiophilic TiO 2 seeds and freestanding 3D carbon matrix can synergistically induce uniform Li deposition and buffer the volume changes during lithium striping and deposition, which ensure improved electrochemical performance with high Coulombic efficiency and low overpotential, etc. The growth process of metallic Li on C/TiO 2 is also systematically investigated. Moreover, the C/TiO 2 @Li||LiFePO 4 full batteries present a stable cycling performance over 250cycles at 1.0C and superior rate performance. Additionally, this work proposes an alternative way to utilize CO 2 , which may alleviate greenhouse effect and boost sustainable development. These results may be useful for both the design of dendrite-free lithium metal batteries and the sustainable utilizing of CO 2. [ABSTRACT FROM AUTHOR]

Coal-based chemical looping gasification (CCLG) has been proposed as an emergent type of coal gasification technology that produces high-quality syngas by using lattice oxygen from oxygen carrier instead of molecular oxygen. In this paper, the Fe–Ni composite oxygen carrier was synthetized using sol-gel method and the gasification performance of the prepared sample was analyzed by a fixed-bed reactor. The results indicated that the Fe–Ni composite oxygen carrier presented a high carbon conversion of fuel and syngas selectivity during the CCLG process. Additionally, the cycle stability test showed that the carbon conversion of fuel and syngas selectivity did not change significantly with the increase of cyclic frequency. To further study the influence of volatiles released from coal on the gasification performance of oxygen carrier, the interactions between the oxygen carrier samples and char obtained at different pyrolysis temperatures were investigated by a fixed-bed reactor and TG-MS, respectively. The results suggested that the gas products (H 2 , CO, CO 2 and CH 4) yields of char-oxygen carrier were significantly lower than those of coal-oxygen carrier. Besides, the pyrolysis temperature for preparing char had a great effect on the carbon conversion of fuel and syngas selectivity due to the distinction of volatiles released from solid fuel. • Efficient Fe–Ni composite oxygen carrier was crafted via sol-gel method. • Fe–Ni composite oxygen carrier showed good performance with desirable reactivity and cyclic stability. • Interaction between oxygen carrier and volatiles released from coal was investigated. • Char gasification was demonstrated to be the rate determining step during the CCLG process. [ABSTRACT FROM AUTHOR]

The sintering temperature of an oxide/oxide composite, comprising a barium aluminosilicate (BaAl 2 Si 2 O 8 or BAS) matrix reinforced with alumina fibers, is constrained to avoid a decrease in the mechanical properties of the fibers. This paper highlights the potential of sintering additives in lowering the sintering temperature of the hexagonal BAS (hexacelsian), thereby safeguarding the integrity of the fibers. Consequently, the role of sintering additives, MgO, TiO 2 , and B 2 O 3 , is investigated to determine their impact on the BAS matrix sintering. The addition of 1 wt% of these additives successfully achieved this objective, as confirmed through thermal and microstructural analyses. MgO and TiO 2 facilitated sintering kinetics through a solid-phase mechanism. Concerning the addition of B 2 O 3 , its effect on BAS sintering accelerated densification through a transient liquid-phase mechanism. Another consequence of incorporating these sintering additives is the destabilization of the hexagonal BAS. To limit this phenomenon, the addition of 1 wt% Rb 2 CO 3 served as a stabilizer through steric hindrance, partially substituting the Ba element in the BAS matrix with Rb. [ABSTRACT FROM AUTHOR]

Rising levels of carbon dioxide (CO 2) emissions due to human activities exert a substantial adverse effect on the environment. The conversion of CO 2 into methanol (CH 3 OH) through hydrogenation is a promising way to utilize this greenhouse gas, thus maintaining carbon in the cycle. In terms of sustainability, methanol is of particular interest because of its dual utilization potential as a fuel or base material to produce different chemicals. The versatility of the latter allows it to be used directly as a precursor to produce numerous compounds, including dimethyl ether (DME), olefins, formaldehydes, and hydrocarbon fuels. This paper first reviews the latest developments in catalyst design, focusing on the relationship between catalyst structure and performance. In addition, recent advances in understanding the reaction mechanisms, optimizing catalyst architectures, innovating membrane reactors, and reaction conditions have been discussed. This summarizes the strategies for increasing the efficiency of sustainable methanol production with the help of membranes. This study provides an outlook for future research in this field. [Display omitted] • Developing efficient hydrogen conversion is essential for addressing climate change. • Technological improvements in the synthesis of water selective zeolite membranes. • Latest developments in CO 2 hydrogenation using Cu-based catalysts. • Adapting zeolite membranes in catalytic membrane reactors to increase methanol yield. • Challenges and perspectives of CO 2 hydrogenation in the presence of a membrane. [ABSTRACT FROM AUTHOR]

Decarbonizing the building sector to achieve sustainable development goals (SDGs) is a complex issue that poses significant challenges to the scientific community. In this context, the current paper aims to assess the viability of employing incinerated by-products as a sustainable mineral resource to produce sustainable geopolymers. To this end, the study focuses on the formulation of geopolymer binders using fly ash with various proportions (ranging from 0 % to 50 %) of metakaolin (MK), investigating their physico-mechanical, microstructural analysis as well as their sealing capacity. The results indicate that incorporating 30 % MK not only preserves good workability but also significantly improves mechanical strength, ensuring long-term durability by increasing bulk density and concurrently reducing water absorption and harmful porosity. Moreover, the results of the Toxicity Characteristic Leaching Procedure (TCLP) demonstrated that the released contaminants remained within the regulatory limits established by the USEPA. The geopolymer binder developed exhibited a significant reduction of 77.23 % and 57.92 % in terms of carbon dioxide equivalent (CO 2 -e) emissions and energy demand compared to conventional cement. This study introduces a novel approach to promoting a circular economy within the building sector. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to guide the operation of the actual cascade system, this paper takes the cascade system as the research object and compares the use of six refrigerant pairs. Unlike the previous single-objective optimization of refrigeration system carbon emissions and other indicators, this research uses a multi-objective optimization algorithm, that is, we consider the cascade system's exergy efficiency and carbon emissions at the same time. We reduce carbon emissions while improving the system's exergy efficiency, and finally find out the specific operating conditions under which the system can realize low-carbon and high-efficiency operation, which further promotes the process of achieving energy saving and emission reduction in factories. The optimization results show that among the six refrigerant pairs, the use of R744-R134a and R744-R290 refrigerant pairs can make the system operate better, but considering the high global warming potential (GWP) of R134a refrigerant, the use of R744-R290 combination is more recommended. [Display omitted] [ABSTRACT FROM AUTHOR]

To reveal the deflagration hazard and propagation law of hydrogen-enriched natural gas (H 2 NG) in closed spaces, this paper studied the deflagration characteristic parameters under different H 2 blended ratio (λ) and inert gas dilution fraction (X dilution) in slender closed pipelines with steel circular hole obstacles. The results indicate that the positive feedback mechanism's sustained effect, failure, and re-action leads to a "three-zone" distribution of H 2 NG explosion overpressure along the pipeline, namely the acceleration, attenuation, and rebound zones. The maximum explosion overpressure (P max), maximum pressure rise rate ((dP/dt) max), and peak shock wave propagation velocity (V p) all increase with the increase of λ. The rise of λ has the most significant enhancement effect on (dP/dt) max , while the enhancement effect on V p is the smallest. This is because the main reasons affecting their increase are different. P max , (dP/dt) max , and V p exhibit exponential decay with increased N 2 and CO 2. However, CO 2 has a more significant inhibitory effect on the H 2 NG deflagration process. When X CO2 = 25% and X CO2 = 30%, the deflagration process of H 2 NG with λ = 20% and λ = 80% can be inhibited entirely, respectively, which has important guiding significance for the safe application of H 2 NG. • The evolution law of deflagration shock waves in slender closed pipelines by H 2 NG was researched. • Effects of H 2 blended ratio and N 2 /CO 2 dilution fraction on H 2 NG deflagration characteristics were revealed. • The effects of N 2 /CO 2 dilution fraction on the P max , (dP/dt) max , and V p were predicted by an exponential model. [ABSTRACT FROM AUTHOR]

This paper presents and analyzes a finite volume scheme for a fully degenerate parabolic system modeling the compressible two-phase flow, such as water-gas, problem in porous media considering the effects of temperature. The problem is written in terms of the phase formulation, i.e. the saturation of one phase, the pressure of the second phase and the temperature are primary unknowns. We use a first-order time implicit Euler scheme. The spatial discretization uses a fully coupled fully implicit cell-centered two-point flux approximation scheme where upwinding of the flux across an interface between two control volumes is performed for each fluid phase. Under physically relevant assumptions on the data, we prove the maximum principle for both saturation and temperature. We obtain a priori estimates and we show that the discrete problem is well posed. Also, we exploit various a priori estimates as well as compactness arguments to establish the convergence of the numerical scheme toward the weak solution. The open-source platform DuMu X was employed for the implementation of the developed algorithm based on the above scheme. Numerical result are presented to demonstrate the efficiency of this scheme. The test addresses the evolution in 2D of CO 2 injection into a layered aquifer. The algorithm's convergence with first order is validated by our numerical results, which support the theoretical results. To our best knowledge, this is the first convergence result of a finite volume scheme in the case of nonisothermal immiscible compressible two-phase flow in porous media. [ABSTRACT FROM AUTHOR]

Chemical equilibrium represents the highest efficiency achievable by a thermochemical cycle under specific operational conditions. This study delves into two-step thermochemical water splitting cycles, which dissociate water into hydrogen (H 2) and oxygen (O 2) via sequential thermal reduction and re-oxidation processes. Building on the thermal reduction analysis presented in Part 1, this paper zeroes in on the re-oxidation reaction within the optimal reactor framework – the counter-current reactor. It elucidates the equilibrium pathway, delineating the progression of chemical equilibrium at each incremental stage of re-oxidation. Using ceria (CeO 2) as a model redox-active metal oxide, the investigation analyzes the influence of operational parameters on the re-oxidation reaction. Findings reveal the theoretical feasibility of maintaining near constant temperature (±2.5 °C) during re-oxidation, achieving a total extent of reduction of 0.038 and a hydrogen conversion yield of 32%. While near adiabatic operation is also achievable, practicality is constrained by a maximum total extent of reduction of 6.5·10−3. The study also explores the economic implications of thermochemical water splitting, particularly focusing on the steam-to-hydrogen output ratio. It highlights the severe economic hurdles associated with hydrogen yields below approximately 1%. Furthermore, the investigation reveals that the addition of inert gas to the re-oxidation step offers no significant advantages. Concluding the analysis, a comparative assessment exposes negligible differences in outcomes when substituting carbon dioxide (CO 2) for water (H 2 O) as the oxidant in low-temperature scenarios (800 °C). This comprehensive study not only advances the understanding of re-oxidation dynamics in thermochemical water splitting but also informs practical and economic considerations crucial for the advancement of this technology. • Reversible/equilibrium re-oxidation pathway defined for water splitting cycles. • Reversible quasi-constant temperature and quasi-adiabatic re-oxidation is feasible. • Limited impact of gas purity on re-oxidation at fixed flow/minimum temperature. • Inert gas addition offers no thermodynamic advantage in re-oxidation. • Low re-oxidation temperatures expand the solution space for high cycle efficiency. [ABSTRACT FROM AUTHOR]

Syngas, which is used as both a fuel and a raw material, presents numerous safety risks during its utilization. In this paper, the effects of H 2 /CO ratio (R = 0%, 30%, 50%, 70% and 100%) and CO 2 dilution ([CO 2 ] = 0%–20%) on the explosion behaviors of syngas/air mixtures with different equivalence ratios (φ = 0.8, 1.0, 1.6, and 2.5) are examined via experiments and numerical calculations. The results show that the peaks of explosion pressure and OH* spectral intensity are significantly influenced by the H 2 percentage in the syngas. The introduction of CO 2 notably decreases these parameters in oxygen-rich and severe oxygen-poor states. Additionally, the flame propagation speed noticeably increases with increasing H 2 proportion in the syngas. The influence of CO 2 on the buoyancy instability of the spherical flame of syngas is considered negligible when compared to that of other combustible gases, such as CH 4. Nevertheless, the presence of CO 2 decreases the density ratio between the unburned gas and burned gas and increases the flame thickness of syngas/air mixtures. This trend reduces the cellular instability of the spherical flame, particularly in severe oxygen-poor states. Notably, there is a definite correlation between the formation of cellular flames and the rise rate of explosion pressure. The cellular structure on the flame surface becomes more pronounced when the rise rate of explosion pressure increases. Conversely, it develops later or is noticeably inhibited. Furthermore, the main reaction pathways are H 2 → ∙OH → H 2 O 2 → H 2 O and H 2 → ∙OH → CO → CO 2 during the syngas explosion process. ∙OH is critical in the entire chain reaction because it promotes the conversion of H 2 to H 2 O and acts as a vital connection between the reactants H 2 and CO in the explosion process. • The P max and I max were investigated with H 2 addition and CO 2 dilution. • The cellular instability of the spherical flame was analyzed. • The interaction of flame development and explosion pressure was revealed. • The main reaction pathways during the syngas explosion process were examined. [ABSTRACT FROM AUTHOR]

Legislation regulating the sustainability requirements for hydrogen technologies relies more and more on life cycle assessments (LCAs). Due to different scopes and development processes, different pieces of EU legislation refer to different LCA methodologies, with differences in the way multifunctional processes (i.e., co-productions, recycling, and energy recovery) are treated. These inconsistencies arise because incentive mechanisms are not standardized across sectors, even though the end product, hydrogen, remains the same. The goal of this paper is to compare the life-cycle greenhouse gas (GHG) emissions of hydrogen from four production pathways depending on the multifunctional approach prescribed by the different EU policies (e.g., using substitution or allocation). The study reveals a large variation in the LCA results. For instance, the life-cycle GHG emissions of hydrogen co-produced with methanol is found to vary from 1 kg CO 2 -equivalent/kg H 2 (when mass allocation is considered) to 11 kg CO 2 -equivalent/kg H 2 (when economic allocation is used). These inconsistencies could affect the market (e.g., hydrogen from a certain pathway could be considered sustainable or unsustainable depending on the approach) and the environment (e.g., pathways that do not lead to a global emission reduction could be promoted). To mitigate these potential negative effects, we urge for harmonized and strict guidelines to assess the life-cycle GHG emissions of hydrogen technologies in an EU policy context. Harmonization should cover international policies too, to avoid the same risks when hydrogen will be traded based on its GHG emissions. The appropriate methodological approach for each production pathway should be chosen by policymakers in collaboration with the LCA community and stakeholders from the industry based on the potential market and environmental consequences of such choice. • LCA methodologies for hydrogen-related policies are currently not fully harmonized. • Four hydrogen production pathways involving multifunctionality were analysed. • GHG emissions of hydrogen vary significantly with the LCA methodology adopted. • Inconsistencies can lead to market distortions, inefficiencies, and confusion. • There is an urgent need for harmonized and strict LCA guidelines for H2 production. [ABSTRACT FROM AUTHOR]

Global shale oil is abundant in geological reserves, but there are widespread problems of difficult exploitation and unsatisfactory oil recovery. CO 2 injection in shale reservoirs can achieve effective exploitation of shale reservoirs and alleviate the current energy shortage. In this paper, investigations on shale oil in recent years were summarized and analyzed. Firstly, the reservoir characteristics and fluid properties of several shale reservoirs and their effects on CO 2 -enhanced oil recovery (CO 2 -EOR) were analyzed, including porosity, permeability, mineral composition, pore structure, geomechanical characteristics and organic matter properties of shale reservoirs, as well as the density, viscosity, gas-oil ratio and composition of shale oil. Subsequently, multiple mechanisms of CO 2 -EOR in shale reservoirs were revealed, including swelling, diffusion, viscosity reduction, extraction, miscibility, and competitive adsorption. The effects of temperature, pressure, CO 2 injection amount, oil composition and reservoir heterogeneity on different mechanisms were analyzed. The effects of nanopore confinement and CO 2 injection on the fluid phase were also analyzed. Then, the CO 2 storage forms of structural space, bound space, dissolution, and mineralization were introduced. And the effects of temperature, pressure, reservoir heterogeneity and formation water salinity on various forms of CO 2 storage were summarized. Furthermore, the research methods of CO 2 injection technique through molecular simulation, physical simulation, mathematical model, and reservoir numerical simulation were introduced. Finally, the reasonable prospect of CO 2 injection technique for shale oil reservoirs was proposed based on the current technical problems. The purpose of this paper is to provide a theoretical basis for EOR and carbon geological storage of shale reservoirs by using the CO 2 injection technique. [Display omitted] • Reservoir and fluid properties of major shale oil reservoirs were summarized. • EOR mechanisms of CO2 injection in shale reservoirs were reviewed systematically. • Research methods of CO2 injection techniques in shale reservoirs were introduced. • Future perspectives of CO 2 injection techniques in shale reservoirs were analyzed. [ABSTRACT FROM AUTHOR]

Strategies for changing the conductivity of Li 2 CO 3 is introduced into the fabrication of Li-CO 2 battery. Benefitting from the favorable hierarchical architecture constructed (CPM-MnO 2), facile charge transfer occurs between catalytic surface and Li 2 CO 3 by –OH⋯O hydrogen bonds improves the metallicity of Li 2 CO 3 , facilitating the formation/decomposition of Li 2 CO 3 and bestowing an ultra-long-term stability of 1087 cycles (4348 h). Taking into account its simplicity, scalable character and outstanding performance, this hierarchical composite electrode paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [Display omitted] • Excellent hierarchical structure of MXene and MnO 2 on carbon paper was fabricated. • Enriched charge transfer occurred on MXene and the MnO 2 by OH⋯O hydrogen bonding. • The prepared batteries showed an ultra-long cycle lifetime and low overpotential. • The optimized electronic structure can improve the metallicity of Li 2 CO 3. • The accelerated decomposition of discharge products promoted CRR and CER kinetics. Lithium-CO 2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li 2 CO 3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO 2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO 2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li 2 CO 3 , springing from the –OH functional group (in MXene) to MnO 2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li 2 CO 3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [ABSTRACT FROM AUTHOR]

Abstract: The objective of the present work was to understand how the structural, surface, water vapour and gas barrier properties of wheat gluten (WG) coated paper could be influenced by the features of paper. For this purpose, a surface treated paper (TP) and an untreated paper (UTP) were compared. Penetration of WG-coating into the bulk of paper was more pronounced in UTP than TP. This led to the formation of a significant junction zone resulting in an interpenetrated structure for WG–UTP, suggesting a composite-like structure, while a bi-layer one was obtained for WG–TP. Differences in WG penetration were related to the hydrophilicity, roughness and porosity of the paper used. Even though the extent of penetration did not greatly affect the surface properties (water and oil resistance), the transfer properties (water vapour, O2 and CO2) of WG-coated papers were significantly improved when WG-coating highly penetrated: while the WG–TP behaved as a micro-perforated material, the WG–UTP behaved as WG-film. [Copyright &y& Elsevier]

This work proposes to utilize supercritical CO 2 as a reaction medium for the acetylation of Hanji, a traditional Korean cellulose textile, to enhance its water repellency while retaining the other properties. We first examined the phase behavior of acetic anhydride and CO 2 mixtures, then a series of experiments were performed and statistically analyzed to find optimal operating conditions. Good surface hydrophobicity was attained in the optimized process within 4 h, shorter than classical non-catalytic liquid and gaseous processes. Hanji's tensile strength was also enhanced in the proposed process by a factor of 1.1, while it was aggravated in classical liquid processes. Hanji samples were slightly discolored in the proposed method, but the degree of discoloration was below the perception level. These results suggest that the proposed method has great potential to be used for the functionalization of cellulose-based textiles with a wide range of industrial applications. [Display omitted] • ScCO 2 -mediated acetylation was optimized to enhance Hanji's surface hydrophobicity. • Surface hydrophobicity is improved in scCO 2 -mediated acetylation within 4 h. • Tensile index increases by 11% in scCO 2 -mediated acetylation. • Tensile index decreases by 20% in classical acetylation methods. • Cellulose discoloration in scCO 2 -mediated acetylation is mild. [ABSTRACT FROM AUTHOR]

• CaCl 2 is an additive suitable for pyrometallurgical recovery of spent LIBs. • CaCl 2 has good chlorination ability and slag optimization ability. • SiO 2 and CO 2 in the system contribute to the increase in HCl yield. The difficulty of separating Li during pyrometallurgical smelting of spent lithium-ion batteries (LIBs) has limited the development of pyrometallurgical processes. Chlorination enables the conversion of Li from spent LIBs to the gas phase during the smelting process. In this paper, the effects of four solid chlorinating agents (KCl, NaCl, CaCl 2 and MgCl 2) on Li volatilization and metal (Co, Cu, Ni and Fe) recovery were investigated. The four solid chlorinating agents were systematically compared in terms of the direct chlorination capacities, indirect chlorination capacities, alloy physical losses and chemical losses in the slag. CaCl 2 was better suited for use as a solid chlorinating agent to promote Li volatilization due to its excellent results in these indexes. The temperature required for the release of HCl from MgCl 2 , facilitated by CO 2 and SiO 2 , was lower than 500 °C. The prematurely released HCl failed to participate in the chlorination reaction. This resulted in approximately 12 % less Li volatilization when MgCl 2 was used as a chlorinating agent compared to when CaCl 2 was used. In addition, the use of KCl as a chlorinating agent decreased the chemical dissolution loss of alloys in the slag. The performance of NaCl was mediocre. Finally, based on evaluations of the four indexes, recommendations for the selection and optimization of solid chlorinating agents were provided. [ABSTRACT FROM AUTHOR]

• An enhanced ejector-subcooler CO 2 transcritical refrigeration cycle is presented. • A parametric analysis and optimization of the enhanced cycle and the baseline cycle are carried out. • The results suggest the integration of the proposed cycle could achieve more compact and reliable systems. • The maximum COP improvements are computed as 11.7%-17.5% when the gas cooler outlet temperature ranges from 35 °C to 50 °C and the evaporating temperature is -40 °C. The main drawback associated with CO 2 refrigeration systems is related to their performance reduction during transcritical operation at warm climate conditions, which may be compensated by better cycle architectures such as the split-cycle with subcooling or the flash-tank configuration, among others. Specifically, the use of standard gas-ejectors together with parallel compressors provides even better efficiency improvements, not being able to use them with low-temperature evaporators to prevent the triple point inside the ejector. This paper proposes an enhanced cycle with a gas ejector for two-stage compressor architectures with vapor injection from the flash-tank, which is able to operate at low evaporating temperatures and that provides a greater performance improvement the more severe the climate conditions are. The methodology conducted is based on a thermodynamic analysis that includes parametric evaluation and cycle optimization, comparing the results to a conventional CO 2 transcritical cycle with flash-tank and dynamic vapor injection architecture. The main results show that a maximum Coefficient of Performance improvement of 17.5% is achievable for transcritical operation at -40 °C evaporating temperature. The compressor displacement capacity required with the enhanced cycle is up to 9% lower for the same refrigeration demand, reducing the electrical consumption as well as the compressor expenditure. Moreover, greater vapor injection mass flow rates are obtained by the gas-ejector injection with discharge temperature reductions up to 18%, enhancing the system reliability. [ABSTRACT FROM AUTHOR]

• The zoning simulation method was developed for CO 2 ejector. • Comparison of different numerical models for each section. • The zoning simulation can predict entrainment ratio more accurately. • Effects of geometries on performances of ejector were analyzed. In this paper, a novel simulation method (zoning simulation) for the CO 2 ejector containing lubricant oil is established. Firstly, the feasibility of the zoning simulation method is verified. Subsequently, the phase change model and turbulence model are selected for each section when using the zoning simulation method. The average relative discrepancy of entrainment ratio using zoning simulation is 8.696%, and the average relative discrepancy of entrainment ratio using overall simulation is 14.118%. The results demonstrate that the predicted entrainment ratio using zoning simulation outperforms entrainment ratio using overall simulation. Introducing the concepts of relative temperature and relative pressure, the average relative discrepancy of entrainment ratio using zoning simulation is reduced to 4.620 %, when both relative temperature and relative pressure greater than 1. [ABSTRACT FROM AUTHOR]

A R744 (CO 2) refrigeration system has been designed to cool down the Large Hadron Collider (LHC) silicon detectors ATLAS and CMS, located at CERN, Switzerland. The silicon detectors are subjected to high radiation levels. The system is composed of a pri- mary CO 2 trans-critical booster vapor compression loop operated with piston compressors, and an oil-free liquid pumped loop on the evaporation side, to preserve the detectors. To ensure the system's reliability, the cooling facility is designed to operate under a parallel operation mode of several modular 70 kW plant units providing evaporation temperature as low as -53 °C. This layout, is also useful in case of components failure and maintenance. A numerical model is developed using a dynamic simulation software Dymola that is based on the open source Modelica modelling language. The simulation results are proven on a first demonstration plant (System A) experimentally to explore the systems control logic and to validate the reliability of the system before it is built on the detectors side. In this paper the models development is explained and the results of the experimental validation of the numerical model are shown. [ABSTRACT FROM AUTHOR]