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Copyright © 2023 The Author(s). Climate change and global warming, caused mainly by the anthropogenic CO2 emissions, has been recognised to be the biggest threat to global ecosystems. Replacing fossil fuels with sustainable biomass for heat and power generation is a key tool in our fight against climate change. Such combustion, however, generates large quantities of ash which, unlike the coal counterparts, are yet to find major applications in industry. This leads to challenging waste management and thus, necessitating urgent measures to valorise this increasing waste stream. However, producing activated carbon from biomass combustion ash allows for not only effective waste valorisation into value-added products, but also to prepare a sorbent for post-combustion carbon capture from an abundant and cheap source that is readily available for in-situ application (hence, minimising overall costs). This work has focused on preparation and activation of industrial-grade biomass ash-derived porous carbon via an economical direct method, followed by an extensive characterisation of its textural properties as well as an evaluation of the CO2 uptake of both the virgin and the activated carbonaceous sorbents. The final sample was selected based on an extensive optimisation campaign aiming towards maximisation of yield and CO2 uptake. The optimum activated sample adsorbed 0.69 mmol/g, thus, nearly doubling the adsorption capacity of the virgin biomass combustion bottom ash-derived carbon. This work has been funded by the UK Carbon Capture and Storage Research Centre (EP/W002841/1) through the flexible funded research programme “Investigation of Environmental and Operational Challenges of Adsorbents Synthesised from Industrial Grade Biomass Combustion Residues”. The UKCCSRC is supported by the Engineering and Physical Sciences Research Council (EPSRC), UK, as part of the UKRI Energy Programme; EPSRC Impact Accelerator Award (2022); Experimental Techniques Centre (ETC) at Brunel University London; Drax Group UK.

Data Availability Statement: The data that support the findings of this study are openly available in BURA at https://bura.brunel.ac.uk/. Copyright © 2023 The Authors. The condensation heat exchanger has a critical role in the microwave reduction process to separate and capture valuable by-products after the microwave reactor. This study aims to perform a computational fluid dynamics (CFD) simulation of a condenser to assess the heat transfer performance of the heat exchanger comprehensively. The type of heat exchanger used for this study is based upon an existing industrial-scale condenser taken from a conventional thermal pyrolysis end of tires (ELT) reprocessing plant and repurposed for integration into a 1500 kg/h ELT microwave reduction process. The condenser is a shell-and-multiple-tube heat exchanger in which the syngas passes through the tubes while cold water from a cooling tower is placed inside the shell. After the simulation, the effects of inlet temperatures and mass flow rates of the gas and water are investigated. The results show that the heat transfer rate is 58 kW for the inlet air velocity of 0.25 m/s and increases due to the convective heat transfer by 32% and 55% when the air velocity rises to 0.5 and 1 m/s, respectively, for the inlet gas and water temperatures of 80 and 15°C, respectively. Additionally, because the outlet air temperature and the inlet water temperature are strongly correlated with convective heat transfer, the outlet air temperature is equivalent to 17.2, 22.3, and 29.5°C when the inlet water temperature is 15, 20, and 25°C, respectively.

Supporting Information: The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.0c04353. Release of nitrogen content from uncoated urea and commercial sulfur-coated urea (SCU) determined by the HPLC method and the Kjedhal method (PDF). Copyright © 2021 The Authors. In this study, a mineral-based coated urea was fabricated in a rotary pan coater using a mixture of gypsum/sulfur/zeolite (G25S25Z50) as an effective and low-cost coating material. The effects of different coating compositions on the dissolution rate of urea and the crushing strength and morphology of the coated urea were investigated. A 25:25:50 (wt %) mixture of gypsum/sulfur/zeolite (G25S25Z50) increased the coating effectiveness to 34.1% with the highest crushing strength (31.06 N). The effectiveness of coated urea was further improved to 46.6% with the addition of a microcrystalline wax (3%) as a sealant. Furthermore, the release mechanisms of various urea fertilizers were determined by fitting the release profiles with six mathematical models, namely, the zeroth-order, first-order, second-order, Higuchi, Ritger & Peppas, and Kopcha models. The results showed that the release mechanism of the uncoated urea and all other coated urea followed the Ritger & Peppas model, suggesting the diffusional release from nonswellable delivery systems. In addition, due to the increased mass-transfer resistance, the kinetic constant was decreased from 0.2233 for uncoated urea to 0.1338 for G25S25Z50-coated urea and was further decreased to 0.0985 when 3% Witcovar 146 sealant was applied. Rachadapisaek Sompot Fund, Chulalongkorn University, for the postdoctoral fellowship; Petronas Company; Universiti Putra Malaysia.

UK Engineering and Physical Sciences Research Council (Doctoral Training Programme (DTP) Award (2020)), Brunel Research Initiative and Enterprise Fund (BRIEF).

Carbonaceous adsorbents are one of the most widely-used materials used for the removal of chemical species in gaseous and aqueous media. However, the route from precursor to activated carbon is riddled with myriad techniques and steps, that entail additional costs. Such expenses could be minimized via waste valorization e.g. biomass combustion bottom ash which has been used in this work. In order to develop surface nanoporosity, the waste-derived carbon was thermally treated, increasing the CO 2 adsorption capacity by nearly twofold and thus, producing a cost-effective sorbent for post-combustion CO 2 capture. The effectiveness of such “unconventional” activation route has been verified using Scanning Electron Microscopy, Fourier-Transform Infrared Spectroscopy as well as Proximate Analysis and the CO 2 adsorption data obtained via Thermogravimetric Analysis (TGA). The proposed material and method could serve as a viable alternative to the current methods for decarbonization of the UK power sector through in-situ waste valorization.

The authors would like to acknowledge funding from the Research Councils UK under grants EP/N024567/1 (CCS from Industrial clusters and their Supply chains), NE/P019900/1 (Comparative assessment and region-specific optimisation of GGR) and EP/T033940/1 (Multiphysics and multiscale modelling for safe and feasible CO2 capture and storage).

Achieving negative CO 2 emissions via the combustion of sustainable biomass - known as bioenergy with carbon capture and storage - is inherently linked to the co-production of a significant amount of potentially hazardous waste combustion fly ash. Valorisation of this solid waste stream presents obvious economic, social, and environmental incentives within the context of waste utilisation and environmental protection. However, the origin of the biomass (the regional plantation) used during the combustion, dictates the physicochemical properties of this solid residue, making it suitable for specific applications while rendering it less favourable for others. In this study, a nanoporous zeolite as a CO 2 adsorbent has been synthesised from industrial-grade biomass combustion fly ash generated in one of the largest biomass combustion power plants in the UK. The method of nanoporous zeolite synthesis follows a fusion-assisted hydrothermal procedure and the produced nanoporous zeolite has been characterised by X-ray diffraction. The CO 2 adsorption investigations were conducted via thermogravimetric analysis to estimate the uptake capacity of the prepared adsorbents. TGA studies suggest that the nanoporous adsorbent, run under 100 mol% CO 2 at atmospheric pressure, has an equilibrium capacity of over 0.8 mmolCO2/g at 50°C. The characterisation results are in good agreement with our CO 2 adsorption data, demonstrating the nanoporous structure of our synthesised waste-derived zeolites.

Honeycomb monoliths are carbon-based, ceramic or metallic structures, comprising a significant number of packed, small-in-diameter channels. One of the features associated with the honeycomb monoliths is the demonstrated low pressure drops in processes involving high flow rates. Honeycomb monoliths, with a range of structures, have found increasingly promising applications in various industries. Owing to their physical structures, they keep finding new applications in industrial treatment systems. They are mainly fabricated via two different techniques: extrusion and coating. Monoliths fabricated via each of these techniques demonstrate specific characteristics suitable for a certain number of applications. With the presence of cordierite substrate in the coated monoliths, higher mechanical strength of coated honeycomb monoliths is expected when compared to the integral monoliths. The coated monoliths are suitable when mechanical strength is of importance where the adhesion of the thin layer coating on monoliths is a determining factor in the performance of the entire process. The integral monoliths are most-commonly employed in gas-phase processes rather than liquid phase applications due to their high accessible surface area per total weight (or volume) of the monoliths. Embedding mesoporous carbon coating and nanoparticles into honeycomb monoliths has improved the efficiency of monoliths in comparison to the more conventional preparation methods.

Bioenergy with Carbon Capture and Storage has been regarded as one of the most prominent technologies in the battle against climate change as stated in the latest Intergovernmental Panel on Climate Change reports. However, solid residues generated during the combustion of biomass pose a separate set of environmental and economic challenges that must be addressed. In order to utilise the full potential of this waste stream, an effective nanoporous carbonaceous adsorbent for CO 2 capture has been directly prepared via a simple and low-cost extraction technique from industrial-grade biomass combustion bottom ash generated at a UK power plant. The adsorbent characterisation data (via Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy as well as Fourier- Transform Infrared Spectroscopy) agrees well with the CO 2 adsorption curves obtained through thermogravimetric analysis (TGA). The TGA results have revealed a CO 2 adsorption capacity of 0.73 mmol/g at 25°C and 1 atm under a pure CO 2 gas stream, thus, proposing a promising and viable route towards in-situ decarbonisation of the biomass combustion sector in the UK via effective waste valorisation.

© 2020 The Authors. The mitigation of climate change, abatement of greenhouse gas emissions and thus, fundamentally, the separation of CO2 from various gas streams are some of the most pressing and multifaceted issues that we face as a society. De-carbonising our entire civilisation will come at a great cost and requires vast amounts of knowledge, initiative and innovation; yet, no matter how much time or money is spent, some sectors simply cannot be de-carbonised without the deployment of carbon capture and storage technologies. The technical challenges associated with the removal of CO2 are not universal – there exists no single solution. Capturing the CO2 on solid sorbents has been gaining traction in recent years given its cost-effectiveness as a result of its ease of application, relatively small energy requirements and applicability in a wide range of processes. Even with the myriad materials such as zeolites, carbons, metal organic frameworks, mesoporous silicas and polymers, the challenge to identify a sorbent with optimal capacity, kinetics, selectivity, stability and ultimately, viability, still persists. By tailoring these solid materials through comprehensive campaigns of surface modification, the pitfalls of each can be mollified and the strengths enhanced. This highly specific tailoring must be well informed so as to understand the mechanisms by which the CO2 is adsorbed, the surface chemistry that has influence on this process, and what methods exist to facilitate the improvement of this. This review endeavours to identify the surface functional groups that interact with the CO2 molecules during adsorption and the methods by which these functional groups can be introduced. It also provides a comprehensive review of the recent attempts and advancements made within the scientific community in the experimental applications of such methods to enhance CO2 capture via adsorption processes. The primary search engine employed in this critical review was Scopus. Of the 421 references cited that embody the literature focussed on surface modification for enhancing the selective adsorption of CO2, 370 are original research papers, 43 are review articles and 7 are conference proceedings. UK Carbon Capture and Storage Research Centre (EP/P026214/1); Engineering and Physical Sciences Research Council; Brunel Research Initiative and Enterprise Fund.

In the past few years, there has been a growing level of interest in the research and development of energy storage systems such as batteries. This is a direct consequence of the soaring rise in global energy demand across various commercial and industrial sectors. Lithium ion batteries have set out a feasible horizon for widespread deployment as small-scale energy storage devices due to their high efficiency and cyclability. However, the availability and cost of lithium have limited the commercial deployment of large-scale systems. On the other hand, zinc-air batteries have demonstrated comparable efficiencies and have been reported to be suitable replacements for lithium batteries in large-scale applications. Nevertheless, more research has been undertaken to address the issues associated with the cycling processes of these batteries. Secondary zinc-air batteries are yet to be commercially proven feasible due to the low charge/discharge cycle life of electrodes. The main problems of secondary alkaline zinc–air batteries are dendritic growth resulting in an alternation of morphology and structure, self-dissolution and the consequent occurrence of hydrogen evolution reactions. However, by and large, inefficient electrolytes are the main culprits responsible for the reduced performance of zinc-air batteries. Therefore, a comprehensive review of current advancements in the development of suitable electrolytes to promote zinc-air batteries towards commercial application will provide a perspective for future rechargeable zinc-air batteries. In this in-depth review, the effects of the types of electrolytes and their properties on the electrochemical performance of Zn anode have been discussed. A demonstration of the current research status and challenges set upon the large-scale deployment of zinc-air batteries will facilitate the educated steering of future research directions in this critically important realm.

In this study, the efficiency of electrochemical reduction of bicarbonate into formic acid was improved by using a composite electrode made up of tin (Sn), nanodiamond (ND) and carbon nanotube (CNT). In the absence of ND, a compositional ratio of 10/90 (Sn/CNT) demonstrated the highest current density. However, by adding ND in a compositional ratio of 10/90/100 (Sn/CNT/ND) the highest efficiency towards formate/formic acid was achieved. It was observed that the presence of ND enhanced the selectivity of product for formic acid. The effects of bicarbonate concentration and scan rate have also been studied to understand the reduction mechanism. The peak potential shifted towards larger negative values of applied potential with an increase in the scan rate from 0.01 to 0.1 V/s, confirming the irreversible nature of the reduction process. The linear relationship between the current and the square root of the scan rate (with a slope value of 0.519) suggested that the reaction process is fully diffusion-controlled. Formic acid was produced using both electrodes; however, the electrode containing nano-diamond successfully improved the process yield for formic acid. Electrochemical impedance study revealed a significant difference between Warburg coefficient for oxidation and reduction processes with values of 29.63 × 1012 and 67.4 Ω. S−0.5 for the applied potentials of 0.5 V and −0.4 V, respectively. This difference confirmed a low resistance at the electrode/electrolyte interface for the reduction potentials.

The value of dispatchable, low carbon thermal power plants as a complement to intermittent renewable energy sources is becoming increasingly recognised. In this study, we evaluate the performance of post-combustion CO 2 capture using monoethanolamine (MEA) retrofitted to a 600 MW CCGT, with and without exhaust gas recycle (EGR). Our results suggest that the EGR ratio plays a primary role in the regeneration energy penalty of the process. We contrast a gas-CCS process with its coal counterpart and show that whilst CCGTs have a greater energy penalty per tonne of CO 2 captured than coal ( i.e. , G J t C O 2 G a s > G J t C O 2 C o a l ), owing to the high thermal efficiencies of CCGTs relative to coal-fired power plants, the energy penalty per MWh of low carbon energy generated is lower for gas than it is for coal ( i.e. , G J M W h G a s G J M W h C o a l ), making CCGT-CCS an attractive choice for low carbon electricity generation.

Bio-degradable calcined egg-shell/sodium alginate (CES/SA) beads were prepared and functionalized using aqueous ammonia (33%). The tailor-made beads were then used as adsorbent for CO 2 capture in a fixed-bed reactor. The performance of the prepared beads was evaluated under various experimental conditions ( i.e. 1 2 concentration between 20 to 45 vol%). Modification with ammonia could successfully introduce additional functional groups containing nitrogen onto the surface of the CES/SA (up to 10.56 wt%). The results showed an increase in CO 2 adsorption with ammonia-impregnated CES/SA, compared to the non-impregnated CES/SA. A maximum CO 2 adsorption capacity of 0.2380 mmol/g was obtained for the gel beads with 45% CO 2 concentration at 1 bar and 30 °C. The adsorption capacity decreased with an increase in temperature and increased with an elevation in the inlet CO 2 concentration, pressure and flow rate. Among the investigated isotherm models ( i.e. Sips, Freundlich and Toth), the Toth isotherm model best described the adsorption data. The thermodynamic properties using the adsorption isotherm data revealed the entropy change (ΔS > 0) reflected the affinity of the adsorbent with the CO 2 molecules. The CO 2 adsorption/desorption process indicated a drop in the CO 2 adsorption capacity of the gel beads in the second cycle; however, this almost remained constant in the subsequent cycles. This observation pointed out to a chemisorption process for the fresh adsorbent and a physical adsorption mechanism for the subsequent adsorption cycles.

The increasing trends in gas emissions have had direct adverse impacts on human health and ecological habitats in the world. A variety of technologies have been deployed to mitigate the release of such gases, including CO2, CO, SO2, H2S, NOx and H2. This special issue on gas-capture processes collects 25 review and research papers on the applications of novel techniques, processes, and theories in gas capture and removal.

In this work, we employed a computational fluid dynamics (CFD)-based model with a Eulerian multiphase approach to simulate the fluidization hydrodynamics in biomass gasification processes. Air was used as the gasifying/fluidizing agent and entered the gasifier at the bottom which subsequently fluidized the solid particles inside the reactor column. The momentum exchange related to the gas-phase was simulated by considering various viscous models (i.e., laminar and turbulence models of the re-normalisation group (RNG), k-&epsilon, and k-&omega, ). The pressure drop gradient obtained by employing each viscous model was plotted for different superficial velocities and compared with the experimental data for validation. The turbulent model of RNG k-Ɛ was found to best represent the actual process. We also studied the effect of air distributor plates with different pore diameters (2, 3 and 5 mm) on the momentum of the fluidizing fluid. The plate with 3-mm pores showed larger turbulent viscosities above the surface. The effects of drag models (Syamlal&ndash, O&rsquo, Brien, Gidaspow and energy minimum multi-scale method (EMMS) on the bed&rsquo, s pressure drop as well as on the volume fractions of the solid particles were investigated. The Syamlal&ndash, Brien model was found to forecast bed pressure drops most consistently, with the pressure drops recorded throughout the experimental process. The formation of bubbles and their motion along the gasifier height in the presence of the turbulent flow was seen to follow a different pattern from with the laminar flow.

In this work, a novel hydrogen production process (Integrated Chemical Looping Water Splitting “ICLWS”) has been developed. The modelled process has been optimised via heat integration between the main process units. The effects of the key process variables (i.e. the oxygen carrier-to-fuel ratio, steam flow rate and discharged gas temperature) on the behaviour of the reducer and oxidiser reactors were investigated. The thermal and exergy efficiencies of the process were studied and compared against a conventional steam-methane reforming (SMR) process. Finally, the economic feasibility of the process was evaluated based on the corresponding CAPEX, OPEX and first-year plant cost per kg of the hydrogen produced. The thermal efficiency of the ICLWS process was improved by 31.1% compared to the baseline (Chemical Looping Water Splitting without heat integration) process. The hydrogen efficiency and the effective efficiencies were also higher by 11.7% and 11.9%, respectively compared to the SMR process. The sensitivity analysis showed that the oxygen carrier–to-methane and -steam ratios enhanced the discharged gas and solid conversions from both the reducer and oxidiser. Unlike for the oxidiser, the temperature of the discharged gas and solids from the reducer had an impact on the gas and solid conversion. The economic evaluation of the process indicated hydrogen production costs of $1.41 and $1.62 per kilogram of hydrogen produced for Fe-based oxygen carriers supported by ZrO2 and MgAl2O4, respectively - 14% and 1.2% lower for the SMR process H2 production costs respectively.

The potential of carbon capture and storage to provide a low carbon fossil-fueled power generation sector that complements the continuously growing renewable sector is becoming ever more apparent. An optimization of a post combustion capture unit employing the solvent monoethanolamine (MEA) was carried out using a Taguchi design of experiment to mitigate the parasitic energy demands of the system. An equilibrium-based approach was employed in Aspen Plus to simulate 90% capture of the CO2 emitted from a 600 MW natural gas combined-cycle gas turbine power plant. The effects of varying the inlet flue gas temperature, absorber column operating pressure, amount of exhaust gas recycle, and amine concentration were evaluated using signal to noise ratios and analysis of variance. The optimum levels that minimized the specific energy requirements were a: flue gas temperature = 50 &deg, C, absorber pressure = 1 bar, exhaust gas recirculation = 20% and, amine concentration = 35 wt%, with a relative importance of: amine concentration &gt, absorber column pressure &gt, exhaust gas recirculation &gt, flue gas temperature. This configuration gave a total capture unit energy requirement of 5.05 GJ/tonneCO2, with an energy requirement in the reboiler of 3.94 GJ/tonneCO2. All the studied factors except the flue gas temperature, demonstrated a statistically significant association to the response.

The influence of various sulphur-oxygen (SO) group additives has been investigated in retarding the self-corrosion of Al anode in a 4M KOH solution, in order to effectively enhance the overall performance. The studied additives in this work were all found to be capable of decreasing H2 evolution, and could mitigate aluminium self-corrosion, with the corrosion inhibition towards the cathodic protection process. The less pitting corrosion and holes were observed for inorganic additives in comparison to the organic counterparts. The Al-air batteries demonstrated an improvement in the discharge capacities: 2604, 2393, 2348 and 2048 mAh g−1 for Na2SO4, Na2SO3, C2H6SO, and C6H5SO2OH, respectively, in comparison to that associated with the 4M KOH (2021 mAh g−1). K2S2O8, an inorganic additive, exhibited a hydrogen evolution efficiency of 21%, but the lowest discharge performance (1973 mAh g−1). This may be due to the instability of the anions in redox reactions. The low inhibition efficiency of the hybrid additives in Al self-corrosion, when compared to single additives, may be ascribed to the involvement of Al3+ in complex formation of the inorganic-organic hybrid additives. A stable discharge-charge cycling test over 6 h with a voltage gap of around 0.7 V is observed for Na2SO4, demonstrating the efficient performance compared to the additive-free KOH electrolyte. It could be concluded that efficient additives containing SO group, successfully mitigated the self-corrosion and hydrogen evolution associated with the Al anode that was confirmed with DFT results.

The authors would like to acknowledge High Impact Research (grant number HIR/MOE/ENG59), University of Malaya, Kuala Lumpur, Malaysia, and Northeastern University, Boston, MA, USA, for their earnest cooperation of this research.

In this study, the reduction of bicarbonate in the presence four amines on a silver oxide/carbon nanotube (Ag2O/CNT) composite electrode has been investigated. The studied amines include ethanolamine (MEA), diethylenetriamine (DETA), diisopropylamine (DIPA) and aminoethylpiperazine (AEP). Regardless of amine type, in the absence of a bicarbonate solution, no reduction/oxidation peaks were observed. However, in the presence of bicarbonate, a single reduction peak along with simultaneous H2 evolution was clearly observed. The cyclic voltammetry measurements showed that only diisopropylamine (DIPA) had a significant catalytic effect toward bicarbonate reduction on the composite electrode. No peak was observed in the anodic direction of the reverse scans, suggesting the irreversible nature of the electrochemical process. The effect of scan rate revealed that the irreversible reduction mechanism is governed by both diffusion and adsorption pathways. In addition of carbonate ions, format ions also have been detected in liquid phase. In order to study the mechanism of bicarbonate reduction in the DIPA solution on Ag2O/CNT electrode, electrochemical impedance spectroscopy (EIS) was employed. The EIS results showed that the charge transfer resistance decreased when the potential decreased from -0.1 to -0.9 V then faded with a further rise in potential to up to -1.9 V. In addition, an inductive loop under certain conditions was observed in the complex plane due to the formation of adsorbed intermediates onto the electrode surface. Chulalongkorn University (Rachadapisek Sompote Fund for postdoctoral Fellowship).

Slag, a by-product of steelmaking industries, has invaluable potentials for various environmental applications. Slag is generally produced in different types of furnaces working under various operating conditions and contains alumina, calcium oxide, silica and so on. Physical and chemical properties of a typical slag dictate the distinct methods of slag solidification including air cooling, steam introduction and injection of additives. Owing to this uniquely-widespread range of properties, slags are being increasingly considered attractive materials in a broad range of applications. They are widely used in transportation industry, construction, and cement manufacturing as well as wastewater and water treatment. This makes slag an important substitute for natural resources, leading to significant minimization in natural resource utilization. This paper walks through a comprehensive essay of steelmaking slag retained in a wide range of furnaces, their modifications and their applications alike.

In this research a new heterogeneous catalyst has been prepared for biodiesel production. The catalyst was prepared by sulfonating industrial sugar waste. Unlike homogeneous catalysts, which require further purification and separation from the biodiesel production reaction media, this inexpensive synthetic catalyst does not need to go through an additional separation process. This advantage consequently minimizes the total application costs. The catalyst was prepared by partially carbonizing sugar beet pulp at 400 °C. The carbonization product was then sulfonated with concentrated H2SO4 vapor in order to produce a solid catalyst. The prepared catalyst was used in the esterification reaction between palm fatty acid distillate (PFAD) and methanol. The effects of the temperature, methanol/PFAD ratio, reaction time and catalyst dosage on the efficiency of the production were individually investigated. The optimum biodiesel production occurred at 85 °C, a reaction time of 300 min, catalyst dosage of 3 g and methanol/PFAD ratio of 5:1 (mol/mol), lowering the acid value from 198 to 13.1 (mg KOH/g oil) or the equivalent, with a fatty acid methyl ester yield of around 92 %. The results suggest that the synthesized inexpensive catalyst is useful for biodiesel production from PFAD.

In this research, porous carbon rod-shaped has been successfully fabricated by using almond shell as a lignocellulosic starting material. The porous carbon rods were prepared using powdered almond shell plus chitosan as a binder that both of ingredients are agriculture and marine wastes. This homogeneous and readily moldable mixture was next forced through a stainless-steel cylindrical die using a uniaxial press at 30 °C while applying a pressure of 100 kPa during the 4 min of the run. The dried rods were later carbonized at different temperatures ranging from 500 to 800 °C and were then physically activated in an oxidizing gas flow (O 2 /Ar). This study well demonstrated that surface area increases with an increase in the carbonization temperature. While almond shell has low specific surface area and pore volume, the almond shell rods take advantage of an increased surface area from 43 to 67 m 2 /g and a pore volume of less than 0.1 cm 3 /g when the carbonization temperature increased from 500 to 800 °C. The surface area and pore volume of the physically activated rods have increased by 14% and 23%, respectively compared to non-activated ones. The stability of rods resulting from properties such as inheriting crack-free, crumbling and peeling off was tested using aqueous solution of methylene blue. By applying solid wastes, the porous carbon rod shaped in both liquid and gaseous phases, can be considered as a promising adsorbent and contributing to reach a clean environmental. The adsorption capacities of methylene blue and phenol demonstrated that porous carbon rod-shaped has a moderate adsorption capacity.

During the past few years the scientific and medical community has been confronted with a continual interest in vitamin E with the interest prompted by new discoveries. Tocopherols and tocotrienols, commonly known as vitamin E, are extremely invaluable compounds and have various nutritional functionalities and benefits to human health. Great deals of research projects have been launched in order to develop effective methods for the extraction of vitamin E. By and large, three distinct extractive methods are usually employed: supercritical fluid extraction (SFE), molecular distillation, and adsorption methods. These methods are sensitive to different experimental conditions, such as pressure, temperature, and flow rate with noticeable effects on the efficiency of the extraction and enrichment of vitamin E. This review has covered the most commonly adapted extraction methods and has probed into the extraction yields under variable operational parameters.

Bicarbonate reduction on a silver-oxide (Ag2O)-based electrode was studied via cyclic voltammetry and electrochemical impedance spectroscopy techniques. The effects of electrode composition, electrolyte concentration and the scan rate (10–250 mV/s) were investigated at a temperature of 27 °C. An optimum mass ratio of 70/30 (Ag2O/CNT) led to a maximum current density of 83 mA cm−2 at −0.43 V (VS Ag/AgCl). At scan rates between 10 and 250 mV/s, a negative shift with a displacement of around 1.032 V was observed – indicating the presence of irreversible reduction reactions. The observed irreversibility suggested that the reaction mechanism can be described by both diffusion and adsorption phenomena. The standard heterogeneous rate constant (ko) and the formal redox potential (Eo) were found to be 1.51 × 10−4 cm/s and 1.218 V, respectively. The EIS results confirmed the formation of the inductive loops at reduction potentials – a consequence of the adsorption of the generated species. A reduction in charge transfer resistance and a continual drop in the potential from −0.1 down to −1.4 V was also observed. This was accompanied by H2 evolution and bicarbonate production. The calculated pKa value of 10.20 upon the completion of the bicarbonate reduction reactions, confirmed the conversion of bicarbonate to carbonate ions.

Acid Red 57 (AR57) has been successfully removed from aqueous solution by adsorption on our synthesized mesoporous carbon-coated monolith (MCCM). For the first time, a powerful artificial neural network (ANN) model has been developed to predict the removal efficiency of AR57 on MCCM. Three critical parameters in adsorption systems, that is, solution’s initial pH, initial dye concentration, and contact time were incorporated in the ANN model in order to optimize the observed adsorption process. Langmuir and Freundlich adsorption models were then fitted to the adsorption data to estimate the adsorption capacity. It was concluded that Langmuir isotherm was best-fitted to the data showing a maximum monolayer adsorption capacity of 1,162.7 mg/g. The pseudo-first-order and pseudo-second-order kinetic models were subsequently tested to evaluate the kinetics of the adsorption process. It was revealed that the adsorption kinetics could be better represented by the pseudo-second-order model. A comparison wa...

Mesoporous char prepared through the pyrolysis of used cigarette filters was chemically modified with nitric acid to enhance its surface acidity. The effects of acid concentration and contact time on BET surface area of the synthesized char were investigated for the first time by applying a full factorial design of experiment with each parameter at three levels. The analysis of variance (ANOVA) showed that both acid concentration and contact time had significant effects on the BET surface area. Response surface method (RSM) analyses showed an excellent R2 value of 88.98% for the developed model. Nitrogen adsorption•desorption experiments revealed a certain but special degree of mesoporosity in the modified char with an average pore size of 3.24 nm. The proximate analysis confirmed a considerable reduction in total ash content of the surface-modified char compared to the non-modified char. A 57.8% increase in the surface acidity compared to the non-modified char was further confirmed by Boehm titration nominating the modified carbon for the adsorption of specific components such as heavy metals.

A three-layered photoanode has been synthesized by the introduction of an additional layer of mixed WO3 and Fe2O3. A total of nine differently-packaged films were prepared by sol-gel method. The fabricated photoanodes were then successfully characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). A comparative study was also done to differentiate the films fabricated with WO3, Fe2O3 and their mixture. Compact, columnar tree and shallow patterns were observed on the cross cleavage of the synthesized layers. These distinct patterns were associated with the growth of layers which consequently led to unique surface morphologies. An increase in photocurrent density was observed on the bicomponent film which has been linked to a high degree of surface roughness as well as improved internal porosity. Three-layered photoanodes, modified with an additional bicomponent layer of WO3:Fe2O3 established much higher photocurrent outputs compared to that of nanostructured WO3 or Fe2O3, regardless of the bicomponent layer arrangement. However, with the bicomponent layer on top and middle, the measured photocurrent soared more than three times as much compared to a slight increase observed when the bicomponent was placed on the bottom.

Sol–gel method was applied to synthesize WO3/Fe2O3 three-layer films in order to improve the generated photocurrent under UV–vis light irradiation. The films were deposited on FTO glass substrates through doctor bladding method. The samples were then calcined at 500 °C. The photocurrents of the synthesized photoanodes were evaluated by measuring the electric current and voltage under UV–vis light at room temperature. Scanning electron microscopy (SEM) revealed unique surface morphologies owing to the presence of the intermediate layers. At an applied potential of 1300 mV, the WO3\Fe2O3\WO3 and Fe2O3\WO3\Fe2O3 photoanodes exhibited photocurrent densities up to 0.1 mA/cm2 and 0.6 mA/cm2, respectively. It was found that porous films with easy accessibility to the inner surface reveal high photocurrents. The intermediate layer of WO3 demonstrated higher values of photocurrent due to roughness enhancement on the upper surface with columnar tree-growth particles. However, a compact state was observed on the cross section of Fe2O3 growth. A comparison was also drawn between the two and three-layer photoanodes using Fe2O3 andWO3. The films were characterized by XRD, SEM/EDX, and UV–vis irradiation to determine the photocurrent densities.

The efficiency of lead removal from aqueous solution using non-modified and nitric acid-modified charred carbon has been investigated. The charred carbon was obtained through the direct pyrolysis of used cigarette filters, one of the world’s largest solid wastes. The effects of lead solution’s pH, adsorbent dosage, initial lead concentration, and contact time on lead uptake from water by the two carbons were studied. It was revealed that the maximum lead uptake from water was at optimum pH values of 5 and 4 for non-modified and surface modified carbons, respectively. However, the effect of adsorbent dosage was almost identical for both carbons with an optimum value of 0.1 g. The equilibrium was reached after almost 24 h of contact time for both types of carbons. The adsorption data were fitted by the Freundlich and Langmuir adsorption isotherm models. The adsorption for both carbons was best explained by Freundlich adsorption isotherm. The kinetics of the adsorption were also investigated. Pseudo-...

Taguchi method has been applied to evaluate the effects of operational parameters on the efficiency of vacuum membrane distillation (VMD) in the desalination of water. It was observed that permeate increases with an increase in feed temperature and vacuum pressure. However, feed salt concentration adversely affected the amount of the collected permeate due to the reduction of vapour pressure as a result of the presence of the solute in water. Flow rate, however, could only increase the permeate if it was increased from 37.5 to 50 ml/s. Any further increase in flow rate to 100 ml/s, negatively lowered the permeate due to the limited feed/membrane contact time. We observed that at very high salt concentration (300 g/l) the permeate reduces accordingly, highlighting the fact that VMD should be used with care due to the presence of membrane fouling and/or other simultaneous flux-lowering effects present at concentrated feeds.

This work highlights the effect of post-washing stage on the surface morphology and ash content of the final porous carbon. Three different acids were selected to post-wash charred carbon including nitric, sulfuric and phosphoric acids. Scanning electron microscopy (SEM) showed that the surface of the washed carbon was not much affected by acidic washing. Moreover, the amount of retained ash for the three acids (proximate analyses) showed that nitric acid-washed carbon could best remove surface ash from the charred carbon. Energy dispersive x-ray (EDX) also showed the presence of various heavy metals and heteroatoms on carbon surface. The results suggest that nitric acid would be best among the investigated acids to remove our charred carbons surface ash. This would enable the synthesized carbon to be used in more sensitive applications. However, the available ash still needs to be reduced if the carbon is to target highly sensitive applications such as drinking water treatments.

One-step pyrolysis was applied to synthesize mesoporous charred carbon from used cigarette filters. Proximate analysis suggested that cigarette filters are decent carbon precursors due to their moderate carbon (around 11 %) and low ash (around 0.1 %) contents. To investigate the effects of pyrolysis parameters on porous surface area, a full factorial design of experiment including heating rate, soaking time and pyrolysis temperature was used with each factor at three levels. The analysis of variance revealed that the temperature and heating rate had the most significant effects on total surface area of the synthesized carbon. Response surface model (RSM) was applied to best fit a surface through the experimental data. It was seen that the quadratic RSM model with a reasonable R2 value of 63 % was the best developed model. The maximum BET surface area (597 m2/g) was reached at a pyrolysis temperature of 900 °C when the precursor was heated at 5 °C/min and hold at this temperature for 3 h. The produced N2 adsorption–desorption isotherm showed a certain degree of mesoporosity in the charred carbon with an average pore size of 3.32 nm calculated by Barrett–Joyner–Halenda method. Scanning electron microscopy also showed the presence of macroporosity on the charred carbon surface. Fourier transform infrared spectroscopy revealed the presence of acidic surface functional groups such as carboxyl and phenol which were accordingly confirmed by Boehm titration. In addition, Boehm titration showed that the produced carbon’s surface was more acidic than basic in nature.

This work investigates the applicability of electrocoagulation using aluminum (Al) electrodes to treat a typical Malaysian leachate sample. The treated leachate sample well met Malaysian discharge standards in terms of chemical oxygen demand (COD) and color. Color was lowered by 72 %. To the knowledge of the authors, no earlier study on the use of Al electrodes in the treatment of a real leachate sample has been reported elsewhere. This work suggests that Electrocoagulation using Al electrodes could an efficient approach in real leachate treatment processes.

Cellulosic materials and cellulose derivatives have been long used in the synthesis of numerous materials. These include various products such as papers, cigarette filters and sanitary pads. Cigarette filters, containing 95% cellulose acetate fibers, are responsible for one of the largest solid wastes generation today. In this work, a simple one-step carbonization of cigarette filters under various operational parameters is used in order to produce porous carbon. The effects of various pyrolysis parameters including carbonization temperature, heating rate and hold time on the final porous carbon product have been investigated. Adsorption-desorption isotherms, scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) as well as thermal gravimetric analysis (TGA) have been employed to characterize the pyrolyzed product. The optimum conditions for the production of porous carbon from cigarette filters in relation to its maximum specific surface area (637 m2/g BET surface area) is understood to be at a heating rate of 5 °C/min at 900 °C for 1 hour.