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Synthesis of affordable electrocatalysts with high efficiency at low cost is crucial for large-scale water splitting. Molybdenum carbide (Mo 2 C) has been suggested to be a promising alternative to noble metal based electrocatalysts for water splitting. In this paper, we fabricated a nanotextured coating of wrinkled Ni-doped Mo 2 C on carbon fiber paper (CFP) from Ni, Mo and carbon black (CB) via a molten salt method. Such a novel electrocatalyst, denoted as Ni-Mo 2 C CB /CFP, shows an overpotential of 121.4, 209.3 and 426.4 mV to achieve a current density of 10, 20 and 50 mA cm−2 respectively in acidic medium. The hydrogen evolution reaction (HER) performance of other as-prepared CFP based electrodes (bare CFP, Mo 2 C/CFP, Mo 2 C CB /CFP, Ni-Mo 2 C/CFP and NiC x /CFP) also tested. We found that the addition of carbon black and the doping of Ni could significantly improve the electrocatalytic performance of Mo 2 C/CFP in terms of overpotential, Tafel slope and exchange current density. This work demonstrates a facile and scalable route using molten salt method for the synthesis of high-performance electrocatalysts from non-precious compounds on carbon materials. Image 1 • Carbon fiber paper (CFP) was employed as a carbon source and substrate of Mo 2 C. • The addition of carbon black (CB) contributes to the refinement of Mo 2 C particles. • Ni-Mo 2 C/CFP composite was prepared from Ni, Mo, CFP and CB by a molten salt method. • The Ni-Mo 2 C/CFP electrocatalyst exhibits excellent catalytic performance for HER. [ABSTRACT FROM AUTHOR]

Photocatalytic oxidation (PCO) is a promising technology for purification of biological pretreated wastewater or destruction of non-biodegradable compounds. For this reason PCO has been investigated as a last step of purification of biologically pre-treated paper-mill effluents. The influence of the parameters pH, TiO2-modification, TiO2-concentration, catalyst re-use, concentration of substances to be oxidised (wastewater quality) has been determined. The TOC of the biologically pretreated wasterwater was up to 55 mg L-1. This wastewater was treated with a previously presented aerated cascade photoreactor which was modified for batch experiments. A high specific oxidation rate of up to 0.76 g TOC m-2 h-1 as well as a complete TOC mineralization has been achieved after the optimisation of the process parameters. The complete destruction of recalcitrant compounds will offer the opportunity to reuse the wastewater in the production process. The increase of the BOD5/TOC ratio after a short irradiation period indicates the transformation of recalcitrant organic compounds to better biodegradable intermediates. The use of PCO as a pre-treatment step for the enhancement of the biodegradability of wastewater, containing recalcitrant or inhibitory compounds is an alternative to a long and energy-intensive total pollutant mineralization. [ABSTRACT FROM AUTHOR]

Abstract: Present study was envisaged for fast bioremediation of toxic paper mill sludge into a soil ameliorating agent. Although a rich source of organic carbon this sludge cannot be directly applied in fields and is recycled very slowly in landfills as it is deficient in other nutrients. Therefore it was mixed with cattle dung in various proportions and subjected to aerobic cocomposting (without worms) and vermicocomposting (with Eisenia fetida). It was observed that mixing cattle dung with the sludge improved physico–chemical characteristics (with transition metals in the permissible range for manures) of the products of both the processes and enhanced its acceptability for worms. Higher decline in organic carbon and higher content of nitrogen and phosphorous along with lower electrical conductivity and higher pH of the products of vermicomposting indicated that E. fetida helped in fast conversion of toxic paper mill sludge into a soil conditioner in 100days. [Copyright &y& Elsevier]

This work addresses the development of a compact paper-based enzymatic microfluidic glucose/O 2 fuel cell that can operate using a very limited sample volume (≈35 µl) and explores the energy generated by glucose at concentrations typically found in blood samples at physiological conditions (pH 7.4). Carbon paper electrodes combined with a paper sample absorption substrate all contained within a plastic microfluidic casing are used to construct the paper-based fuel cell. The anode catalysts consist of glucose dehydrogenase and [Os(4,4′-dimethoxy-2,2′-bipyridine) 2 (poly-vinylimidazole) 10 Cl] + as mediator, while the cathode catalysts were bilirubin oxidase and [Os(2,2′-bipyridine) 2 (poly-vinylimidazole) 10 Cl] + as mediator. The fuel cell delivered a linear power output response to glucose over the range of 2.5–30 mM, with power densities ranging from 20 to 90 µW cm −2 . The quantification of the available electrical power as well as the energy density extracted from small synthetic samples allows planning potential uses of this energy to power different sensors and analysis devices in a wide variety of in-vitro applications. [ABSTRACT FROM AUTHOR]

Hydrazine is often regarded as one of the most appealing fuels for fuel cells due to its high energy content, and also because it gives off only environmentally benign byproducts when it is used in fuel cells ( cf. many other fuels produce the greenhouse gas CO 2 ). However, current electrocatalysts for the hydrazine oxidation reaction (HOR) in direct hydrazine fuel cells involve the expensive, unsustainable noble metals such as Pt. Herein, using cellulose filter paper both as a precursor and a self-template, we show the synthesis of nanoporous carbon electrocatalysts that can efficiently electrocatalyze HOR. To make the electrocatalysts, first cellulose filter paper is modified with metal-amine complexes and then with silica shells. After carbonization of the resulting composite material at different temperatures, followed by removal of the silica shells, nanoporous carbon-based electrocatalysts are obtained. Notably, the intertwined structure of the cellulose matrix in the filter paper is taken advantage of to serve as a self-template, allowing the formation of the desired fibrous, nanoporous carbon electrocatalysts. The materials show a good electrocatalytic activity toward HOR, giving a low overpotential and a high current density. Thus, such nanoporous carbons can be good candidate materials to replace conventional metal-based catalysts commonly used in HOR and other related reactions. [ABSTRACT FROM AUTHOR]

Carbon-coated titanium dioxide (TiO 2 –C) has received much attention as a catalyst support in proton exchange membrane fuel cells. In this study, TiO 2 nanorod arrays (NRs) are hydrothermally grown on carbon paper and converted into TiO 2 –C NRs by heat treatment at 900 °C under methane atmosphere. Then, platinum nanoparticles are sputtered onto the TiO 2 NRs by physical vapor deposition to produce Pt–TiO 2 –C. The as-prepared Pt–TiO 2 –C exhibits high stability during accelerated durability tests. As compared with the commercial gas diffusion electrode (GDE, 34.4% decrease), a minor reduction in the electrochemically active surface area of the Pt–TiO 2 –C electrode after 1500 cycles (10.6% decrease) is observed. When the as-prepared electrode with ultra-low platinum content (Pt loading: 28.67 μg cm −2 ) is employed as the cathode of a single cell, the electrode generates power that is 4.84 × that of the commercial GDE (Pt loading: 400 μg cm −2 ). An electrode that generates power of 11.9 kW g Pt −1 (as the cathode) is proposed. The fabricated Pt–TiO 2 –C electrode can be used in proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

Abstract: The work presented in this paper addresses the issues of fault detection and isolation properties of the partial PCA method and the isolation-enhanced PCA method. In order to increase the sensitivity of the residuals with respect to various faults, the structured residuals generated from both partial PCA and isolation-enhanced PCA are optimized. For the residual evaluation, the bootstrap technique is combined with the CUSUM method to achieve fast and robust detection. Three sensor faults and three actuator faults were studied using simulations employing a rigorous, first principles based, paper machine simulator. All the faults were correctly detected and isolated with both studied methods, and the results are compared with the classical T 2 and SPE contribution plot methods. [Copyright &y& Elsevier]

Discharge waters from activated sludge processes in the pulp and paper industry and from a municipal wastewater treatment plant were filtered with various nanofiltration (NF) and low pressure reverse osmosis (RO) membranes. The purpose was to study flux, retention, and permeate quality after membrane filtration by using a high shear (CR-250/2) filter. The suitability of the achieved permeates for reuse at the industrial site is also discussed. The NF permeate was practically free from colour and organic compounds but contained significant amount of inorganic compounds e.g. chloride ions, especially when a high amount of sulphate containing discharge waters were filtered, in which case a low pressure RO membrane was needed to successfully remove monovalent anions. Organic compounds were almost completely retained by NF and RO membranes and organic carbon in the permeate was less than 10 rag/dm³ on average. The achieved permeate can easily be reused in paper production. Nanofiltration has a significantly higher flux and also a lower fouling tendency than reverse osmosis but it passes through monovalent ions when there is a high sulphate concentration in the water. Therefore, RO might be needed in such cases to produce excellent process water. [ABSTRACT FROM AUTHOR]

The plate-like graphene shells (GS) produced by an original methane pyrolysis method and their derivatives graphene oxide (GO) and graphene oxide paper (GO-P) were evaluated with luminescent Escherichia coli biotests and additional bacterial-based assays which together revealed the graphene-family nanomaterials’ toxicity and bioactivity mechanisms. Bioluminescence inhibition assay, fluorescent two-component staining to evaluate cell membrane permeability, and atomic force microscopy data showed GO expressed bioactivity in aqueous suspension, whereas GS suspensions and the GO-P surface were assessed as nontoxic materials. The mechanism of toxicity of GO was shown not to be associated with oxidative stress in the targeted soxS::lux and katG::lux reporter cells; also, GO did not lead to significant mechanical disruption of treated bacteria with the release of intracellular DNA contents into the environment. The well-coordinated time- and dose-dependent surface charge neutralization and transport and energetic disorders in the Escherichia coli cells suggest direct membrane interaction, internalization, and perturbation (i.e., “membrane stress”) as a clue to graphene oxide’s mechanism of toxicity. [ABSTRACT FROM AUTHOR]

Flexible non-metal oxygen electrodes fabricated from phosphorus-doped graphitic carbon nitride nano-flowers directly grown on carbon-fiber paper exhibit high activity and stability in reversibly catalyzing oxygen reduction and evolution reactions, which is a result of N, P dual action, enhanced mass/charge transfer, and high active surface area. The performance is comparable to that of the state-of-the-art transition-metal, noble-metal, and non-metal catalysts. Remarkably, the flexible nature of these oxygen electrodes allows their use in folded and rolled-up forms, and directly as cathodes in Zn-air batteries, featuring low charge/discharge overpotential and long lifetime. [ABSTRACT FROM AUTHOR]

Abstract: Carbon molecular sieve membranes (CMSM) were successfully prepared from cellophane paper by one single pyrolysis step. The influence of pyrolysis parameters on the membranes’ structure, morphology and performance was examined through scanning electron microscopy, X-ray microanalysis, X-ray diffraction and monocomponent permeation experiments towards He, H2, Ar, N2, CO2, O2, CH4 and water vapor at 29.5°C. The permeabilities reached a maximum for CMSM heated up to 550°C, without significantly compromising selectivities. The soaking time at this temperature led to pore closing and, consequently, decrease in permeability and an enhancement in selectivity. These membranes were also considerably permeable to water vapor (1000barrer), and very selective concerning H2O/CH4 (α =921–7518) and H2O/N2 (α =364–9936) separations. No aging effects were observed due to oxygen or water vapor exposure. The permselectivity of CMSM prepared up to 550°C overtook the Robeson bound for polymeric membranes, especially regarding ideal selectivities of pairs O2/N2 (α =13–18), H2/N2, H2/O2, H2/CH4 and H2/CO2. Therefore, they might be considered in relevant industrial applications such as separation of nitrogen from air and recovery of hydrogen from synthesis gas. [Copyright &y& Elsevier]

Abstract: Pulp and paper mill wastewater was characterizated, before (influent) and after (effluent) biological wastewater treatment based on an activated sludge process, by microfiltration (8, 3, 0.45 and 0.22μm) and ultrafiltration (100, 50, 30 and 3kDa) of the wastewater samples into different size fractions. Various parameters were measured on each fraction: molecular weight distribution (MWD) using high performance size exclusion chromatography (HPSEC), total organic carbon (TOC), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (Tot-P), phosphate phosphorus (PO4-P), electrical conductivity, pH, turbidity, charge quantity and zeta potential. The MWD, TOC and CODCr results indicated that the majority of the material present in both the influent and effluent was in the medium molecular weight (MW) range (i.e. MW<10kDa) with three main MW sub-fractions. There were no significant differences in the range of the MWD between the influent and effluent samples. The magnitude of the MWD in the effluent was about one half that in the influent, the greatest reduction being in the 6kDa fraction. The 3kDa fractions of both the influent and effluent showed a considerable increase in BOD7, probably due to the removal of compounds harmful to bacteria in 3kDa ultrafiltration. Influent turbidity decreased considerably in microfiltration (8–0.22μm). As the turbidity was removed by 0.22μm filtration, the anionic charge quantity started to decrease. Particles in the influent and effluent contained 19–29% and 14–20% of the total phosphorus, respectively. The major phosphorus fraction was in the form of soluble phosphate. [Copyright &y& Elsevier]

Abstract: The objective of the work was to provide a method to predict CO2 and NH3 yields during composting of the biodegradable fraction of municipal solid wastes (MSW). The compostable portion of MSW was simulated using three principal biodegradable components, namely mixed paper wastes, yard wastes and food wastes. Twelve laboratory runs were carried out at thermophilic temperatures based on the principles of mixture experimental and full factorial designs. Seeded mixed paper (MXP), seeded yard waste (YW) and seeded food waste (FW), each composted individually, produced 150, 220 and 370g CO2–C, and 2.0, 4.4 and 34g NH3–N per dry kg of initial substrate, respectively. Several experimental runs were also carried out with different mixtures of these three substrates. The effect of seeding was insignificant during composting of food wastes and yard wastes, while seeding was necessary for composting of mixed paper. Polynomial equations were developed to predict CO2 and NH3 (in amounts of mass per dry kg of MSW) from mixtures of MSW. No interactions among components were found to be significant when predicting CO2 yields, while the interaction of food wastes and mixed paper was found to be significant when predicting NH3 yields. [Copyright &y& Elsevier]

Abstract: Desired savings in energy, raw materials and processing in the manufacture of coated papers may lead to the development of processes with reduced usage of water. One proposed process, the dry surface treatment (DST) for pigment-coating of paper has been studied in a laboratory scale. The treatment involves the application of dry, powdery coating materials on the paper surface and fixation of the deposited layer in a thermomechanical compression and smoothening phase in a heated roll nip. Electrostatic deposition of charged particles enables a non-contact coating application. In the previous studies, the DST-papers produced with two or multi-component powdery materials, that were formed by drying coating suspensions, exhibited coating coverage, surface strength and smoothness similar to commercial coated mechanical reference papers at equal coat weights, but a generally larger pore size of the dry-formed coatings gave higher levels of oil absorption, air permeability and somewhat irregular ink setting properties. This study aims to explore the possibilities to prepare the DST coating particles in a dry state. The eventual target is to obtain coating particles in the size range used in conventional pigment coating and adjust the binder properties, content and distribution in a favourable way with regard to the structure of the coating layer. Synthesis of particulate polymers under water-free conditions in supercritical carbon dioxide is described and performed. Hybrid coating particles, consisting of the pigment and binder together, were prepared and evaluated for their structure and the coating applicability. [Copyright &y& Elsevier]

The bleaching wastewater effluent from a pulp and paper mill (located in Tianjin, China) was treated with solar photo-Fenton process in a lab-scale reactor (22cm×15cm thermostatic dish). The mill used wastepaper as raw material and the effluent contained 332mgL−1 of total organic carbon (TOC) and 1286mgL−1 of COD. The treatment involved a constant intensity of irradiation (0.2kW/m2) with a solar simulator of 250W xenon lamp and various conditions of pH, temperature, and initial concentrations of H2O2 and Fe(II). The better treatment conditions were searched for in the ranges of initial Fe(II) concentration from 31 to 310mgL−1 (initial pH 3.0, 30°C), initial H2O2 concentration from 0.5 to 3Dth (1Dth=1883mgL−1 for TOC mineralization) (initial pH 3.0, 30°C), initial pH from 2.0 to 6.0 (1 and 2Dth, 10:1 of H2O2/Fe(II), 30°C), and temperature from 30 to 50°C (1Dth, 10:1 of H2O2/Fe(II), initial pH 2.8). TOC removal generally showed the initial fast increase stage within the first sampling time of 15min, followed by the gradual increase stage in the remaining sampling time of 180min experimental time course. The highest percentage of TOC removal in the first stage was about 60% when the initial pH was either 2.8 (H2O2 =1Dth, ratio=10:1, temperature=30–50°C) or 3.5 (H2O2 =2Dth, ratio=10:1, temperature=30°C). Also under the latter condition, the value reached 82% at 120min and was projected to reach 94% at 180min. According to the positive effect of temperature increase on TOC removal observed in this experiment, further increase above these maximum values is possible if the temperature of the above condition were increased from 30 to 40°C or 50°C. Furthermore, under most of the treatment conditions, the TOC removal reached or was projected to reach over 60% toward the end of the experiments. The result indicated that the solar photo-Fenton process has a potential to effectively remove TOC from the wastepaper pulp effluent on a large scale. [Copyright &y& Elsevier]

The interfacial surface area concentration in a short vertical column subject to the through flow of a solid–liquid–gas slurry made by mixing aqueous fibrous paper pulp with a nitrogen–carbon dioxide gas mixture was measured in the study. The gas absorption technique was applied, using CO2 as the transferred species and sodium hydroxide as the alkaline agent in water. The flow regimes in the experiments were visually identified, and the test section void fraction was measured using a Gamma-ray densitometer.The test section was a 1.83 m-long column with 5.08 cm inner diameter. The ranges of experimental parameters were as follows: liquid-pulp superficial velocity 15–94 cm/s; average gas-superficial velocity 17–54.5 cm/s; pulp consistency in the water/pulp mixture 0.0–2.18%; and average mole fraction of carbon dioxide in the gas mixture 0.19–0.95. A total of 33 data points were obtained, each representing the average of three to nine tests that confirmed reasonable repeatability. Statistical analysis of the experimental data indicates strong dependence of interfacial area on average gas superficial velocity and void fraction; and a relatively weak dependence on pulp consistency and liquid superficial velocity. The effect of pulp consistency on the interfacial area concentration in the test section was particularly interesting. The test section average interfacial surface area concentration decreased with increasing consistency up to a consistency of 1.6%, but increased significantly when consistency was further increased to 2.18%. The experimental data were empirically correlated. [Copyright &y& Elsevier]