Enhanced biobased carbon materials made from softwood bark via a steam explosion preprocessing step for reactive orange 16 dye adsorption.

The growing textile industry produces large volumes of hazardous wastewater containing dyes, which stresses the need for cheap, efficient adsorbing technologies. This study investigates a novel preprocessing method for producing activated carbons from abundantly available softwood bark. The preprocessing involved a continuous steam explosion preconditioning step, chemical activation with ZnCl2, pyrolysis at 600 and 800 °C, and washing. The activated carbons were subsequently characterized by SEM, XPS, Raman and FTIR prior to evaluation for their effectiveness in adsorbing reactive orange 16 and two synthetic dyehouse effluents. Results showed that the steam-exploded carbon, pyrolyzed at 600 °C, obtained the highest BET specific surface area (1308 m2/g), the best Langmuir maximum adsorption of reactive orange 16 (218 mg g-1) and synthetic dyehouse effluents (>70 % removal) of the tested carbons. Finally, steam explosion preconditioning could open up new and potentially more sustainable process routes for producing functionalized active carbons.

Synthesis of sustainable mesoporous sulfur-doped biobased carbon with superior performance sodium diclofenac removal: Kinetic, equilibrium, thermodynamic and mechanism.

Over the last years, the strategy of employing inevitable organic waste and residue streams to produce valuable and greener materials for a wide range of applications has been proven an efficient and suitable approach. In this research, sulfur-doped porous biochar was produced through a single-step pyrolysis of birch waste tree in the presence of zinc chloride as chemical activator. The sulfur doping process led to a remarkable impact on the biochar structure. Moreover, it was shown that sulfur doping also had an important impact on sodium diclofenac (S-DCF) removal from aqueous solutions due to the introduction of S-functionalities on biochar surface. The adsorption experiments suggested that General and Liu models offered the best fit for the kinetic and equilibrium studies, respectively. The results showed that the kinetic was faster for the S-doped biochar while the maximum adsorption capacity values at 318 K were 564 mg g-1 (non-doped) and 693 mg g-1 (S-doped); highlighting the better affinity of S-doped biochar for the S-DCF molecule compared to non-doped biochar. The thermodynamic parameters (ΔH0, ΔS0, ΔG0) suggested that the S-DCF removal on both adsorbents was spontaneous, favourable, and endothermic.

Two-stage leaching of calcium and vanadium from high-calcium steelmaking slag.

Vanadium (V) is a critically important element in many industries. A widely used recovery process is a combination of roasting and leaching. However, roasting is an energy-intensive stage. Generally, basic oxygen furnace (BOF) slag is high in calcium (Ca) but low in V. Ca content and its chemical nature can prevent V leaching. This study presents a potential two-stage leaching process for Ca and V from BOF slag. The method is environmentally friendly using low temperatures and enabling leachate recycling. Furthermore, the utilisation rate of the slag can be higher due to Ca recovery. Ca is first leached using ammonium nitrate and nitric acid solution. The V-containing residue is directed to the second stage, where V is leached using ammonium carbonate ((NH4)2CO3). Ca leaching efficiency was 71% achieved with a low temperature (40°C) and in 20 min. > 99% of the dissolved element was Ca. Increasing the total nitrate concentration increased the leaching efficiency. Reducing the L/S ratio improved selectivity. The solid material was analysed after the leaching stages and a clear change was observed after the Ca-stage. The V leaching efficiency was 50%. > 88% of dissolved element was V (L/S 8, [(NH4)2CO3] 200 g/L, 60°C, and 60 min). Increasing [(NH4)2CO3] and L/S ratio slightly improved the leaching efficiency but decreased selectivity. The studied process implements circular economy principles and has been developed for side streams with low V concentrations. However, further optimisation and developments are required regarding the effectiveness of the process.

Adsorption of rare earth elements on a magnetic geopolymer derived from rice husk: studies in batch, column, and application in real phosphogypsum leachate sample.

There is a growing need to develop new strategies for rare earth element (REE) recovery from secondary resources. Herein, a novel approach to utilize biogenic silica (from rice husk) and metakaolin was employed to fabricate magnetic geopolymer (MGP) by incorporating metallic iron. The fabricated MGP adsorbent material was used to uptake Ce3+, La3+, and Nd3+ from synthetic solutions and real phosphogypsum leachate in batch and column modes. The MGP offers a negatively charged surface at pH above 2.7, and the uptake of REEs rises from pH 3 to 6. The kinetic study validated that the kinetics was much faster for Nd3+, followed by La3+ and Ce3+. A thermodynamic investigation validated the exothermic nature of the adsorption process for all selected REEs. The desorption experiment using 2 mol L-1 H2SO4 as the eluent demonstrated approximately 100% desorption of REEs from the adsorbent. After six adsorption-desorption cycles, the MGP maintained a high adsorption performance up to cycle five before suffering a significant decrease in performance in cycle six. The effectiveness of MGP was also assessed for its applicability in recovering numerous REEs (La3+, Ce3+, Pr3+, Sm3+, and Nd3+) from real leachate from phosphogypsum wastes, and the highest recovery was achieved for Nd3+ (95.03%) followed by Ce3+ (86.33%). The operation was also feasible in the column presenting suitable values of the length of the mass transfer zone. The findings of this investigation indicate that MGP adsorbent prepared via a simple route has the potential for the recovery of REEs from synthetic and real samples in both batch and continuous operations modes.

Effect of Secondary Heat Treatment after a Washing on the Electrochemical Performance of Co-Free LiNi0.975 Al0.025 O2 Cathodes for Li-Ion Batteries.

The steadily growing electric vehicle market is a driving force in low-cost, high-energy-density lithium-ion battery development. To meet this demand, LiNi0.975 Al0.025 O2 (LNA), a high-energy-density and cobalt-free cathode material, has been developed using a low-cost and efficient co-precipitation and lithiation process. This article explores how further processing (i.e., washing residual lithium from the secondary particle surface and applying a secondary heat treatment at 650 °C) changes the chemical environment of the surface and the electrochemical performance of the LNA cathode material. After washing, a nonconductive nickel oxide (NiO) phase is formed on the surface, decreasing the initial capacity in electrochemical tests, and suppressing high-voltage (H2) to (H3) phase transition results in enhanced cycle properties. Furthermore, the secondary heat treatment re-lithiates surface NiO back to LNAand increases the initial capacity with enhanced cycle properties. Electrochemical tests are performed with the cells without tap charge to suppress the H2 to H3 phase transition. Results reveal that avoiding charging cells at a high voltage for a long time dramatically improves LNA's cycle life. In addition, the gas analysis tests performed during charge and discharge to reveal how the amount of residual lithium compounds on the surface affects gas formation are studied.

Current Status and Challenges for Metal-Organic-Framework-Assisted Conversion of Biomass into Value-Added Chemicals.

Owing to the abundance of availability, low cost, and environmental-friendliness, biomass waste could serve as a prospective renewable source for value-added chemicals. Nevertheless, biomass conversion into chemicals is quite challenging due to the heterogeneous nature of biomass waste. Biomass-derived chemicals are appealing sustainable solutions that can reduce the dependency on existing petroleum-based production. Metal-organic frameworks (MOFs)-based catalysts and their composite materials have attracted considerable amounts of interest in biomass conversion applications recently because of their interesting physical and chemical characteristics. Due to their tunability, the catalytic activity and selectivity of MOF-based catalyst/composite materials can be tailored by functionalizing them with a variety of functional groups to enhance biomass conversion efficiency. This review focuses on the catalytic transformation of lignocellulosic biomass into value-added chemicals by employing MOF-based catalyst/composite materials. The main focus is given to the production of the platform chemicals HMF and Furfural from the corresponding (hemi)cellulosic biomass, due to their versatility as intermediates for the production of various biobased chemicals and fuels. The effects of different experimental parameters on the conversion of biomass by MOF-based catalysts are also included. Finally, current challenges and perspectives of biomass conversion into chemicals by MOF-based catalysts are highlighted.

Preparation and characterisation of alkali-activated blast furnace slag and Na-jarosite catalysts for catalytic wet peroxide oxidation of bisphenol A.

In this study, cost-effective alkali-activated materials made from industrial side streams (blast furnace slag and Na-jarosite) were developed for catalytic applications. The catalytic activity of the prepared materials was examined in catalytic wet peroxide oxidation reactions of a bisphenol A in an aqueous solution. All materials prepared revealed porous structure and characterisation expressed the incorporation of iron to the material via ion exchange in the preparation step. Furthermore, the materials prepared exhibited high specific surface areas (over 200 m2/g) and were mainly mesoporous. Moderate bisphenol A removal percentages (35%-37%) were achieved with the prepared materials during 3 h of oxidation at pH 7-8 and 50°C. Moreover, the activity of catalysts remained after four consecutive cycles (between the cycles the catalysts were regenerated) and the specific surface areas decreased only slightly and no changes in the phase structures were observed. Thus, the prepared blast furnace slag and Na-jarosite-based catalysts exhibited high mechanical stability and showed good potential in the removal of bisphenol A from wastewater through catalytic wet peroxide oxidation.

Wood waste-based functionalized natural hydrochar for the effective removal of Ce(III) ions from aqueous solution.

In this study, a sustainable and easily prepared hydrochar from wood waste was studied to adsorb and recover the rare earth element cerium (Ce(III)) from an aqueous solution. The results revealed that the hydrochar contains several surface functional groups (e.g., C-O, C = O, OH, COOH), which largely influenced its adsorption capacity. The effect of pH strongly influenced the Ce(III) removal, achieving its maximum removal efficiency at pH 6.0 and very low adsorption capacity under an acidic solution. The hydrochar proved to be highly efficient in Ce(III) adsorption reaching a maximum adsorption capacity of 327.9 mg g-1 at 298 K. The kinetic and equilibrium process were better fitted by the general order and Liu isotherm model, respectively. Possible mechanisms of Ce(III) adsorption on the hydrochar structure could be explained by electrostatic interactions and chelation between surface functional groups and the Ce(III). Furthermore, the hydrochar exhibited an excellent regeneration capacity upon using 1 mol L-1 of sulfuric acid (H2SO4) as eluent, and it was reused for three cycles without losing its adsorption performance. This research proposes a sustainable approach for developing an efficient adsorbent with excellent physicochemical and adsorption properties for Ce(III) removal.

Optimized Morphology and Tuning the Mn3+ Content of LiNi0.5Mn1.5O4 Cathode Material for Li-Ion Batteries.

The advantages of cobalt-free, high specific capacity, high operating voltage, low cost, and environmental friendliness of spinel LiNi0.5Mn1.5O4 (LNMO) material make it one of the most promising cathode materials for next-generation lithium-ion batteries. The disproportionation reaction of Mn3+ leads to Jahn-Teller distortion, which is the key issue in reducing the crystal structure stability and limiting the electrochemical stability of the material. In this work, single-crystal LNMO was synthesized successfully by the sol-gel method. The morphology and the Mn3+ content of the as-prepared LNMO were tuned by altering the synthesis temperature. The results demonstrated that the LNMO_110 material exhibited the most uniform particle distribution as well as the presence of the lowest concentration of Mn3+, which was beneficial to ion diffusion and electronic conductivity. As a result, this LNMO cathode material had an optimized electrochemical rate performance of 105.6 mAh g-1 at 1 C and cycling stability of 116.8 mAh g-1 at 0.1 C after 100 cycles.

Sustainable Biomass-Derived Carbon Electrodes for Potassium and Aluminum Batteries: Conceptualizing the Key Parameters for Improved Performance.

The development of sustainable, safe, low-cost, high energy and density power-density energy storage devices is most needed to electrify our modern needs to reach a carbon-neutral society by ~2050. Batteries are the backbones of future sustainable energy sources for both stationary off-grid and mobile plug-in electric vehicle applications. Biomass-derived carbon materials are extensively researched as efficient and sustainable electrode/anode candidates for lithium/sodium-ion chemistries due to their well-developed tailored textures (closed pores and defects) and large microcrystalline interlayer spacing and therefore opens-up their potential applications in sustainable potassium and aluminum batteries. The main purpose of this perspective is to brief the use of biomass residues for the preparation of carbon electrodes for potassium and aluminum batteries annexed to the biomass-derived carbon physicochemical structures and their aligned electrochemical properties. In addition, we presented an outlook as well as some challenges faced in this promising area of research. We believe that this review enlightens the readers with useful insights and a reasonable understanding of issues and challenges faced in the preparation, physicochemical properties and application of biomass-derived carbon materials as anodes and cathode candidates for potassium and aluminum batteries, respectively. In addition, this review can further help material scientists to seek out novel electrode materials from different types of biomasses, which opens up new avenues in the fabrication/development of next-generation sustainable and high-energy density batteries.

Zn(II) removal from wastewater by an alkali-activated material prepared from steel industry slags: optimization and modelling of a fixed-bed process.

Removal of dissolved zinc (Zn) from water by a novel alkali-activated material (AAM) prepared from steel industry slags in a fixed-bed column was investigated. Design of experiments was used to find the optimum operation parameters [flow rate (Q), adsorbent mass, (mads), and initial Zn concentration (C0)] for the removal of Zn2+ from a ZnCl2 solution. Regression models for the breakthrough (qb), and saturation (qsat) capacities of the bed and three other response parameters as functions of Q, mads and C0 were fitted with coefficients of determination (R2) ranging from 0.48 to 0.99. Experimental values of qb and qsat varied within 1.42-7.03 mg Zn/g and 10.57-17.25 mg Zn/g, respectively. The optimum operation parameters were determined to be Q= 1.64 ml/min and mads= 4.5 g, whereas C0 had negligible effect on the response parameters in the range 73-107 mg Zn/l. Finally, three empirical breakthrough curve (BTC) models were employed to describe the individual BTCs of which the modified dose - response model was found to give the best fit (0.960 ≤ R2 ≤ 0.998). The results of the present work demonstrate that the novel AAM has considerable potential to be utilized in water purification applications.

Removal of antimony from model solutions, mine effluent, and textile industry wastewater with Mg-rich mineral adsorbents.

Naturally occurring layered double hydroxide mineral, brucite (BRU), was compared with hydromagnesite (HYD) and a commercial Mg-rich mineral adsorbent (trade name AQM PalPower M10) to remove antimony (Sb) from synthetic and real wastewaters. The BRU and HYD samples were calcined prior to the experiments. The adsorbents were characterized using X-ray diffraction, X-ray fluorescence, and Fourier transform infrared spectroscopy. Batch adsorption experiments were performed to evaluate the effect of initial pH, Sb concentration, adsorbent dosage, and contact time on Sb removal from synthetic wastewater, mine effluent, and textile industry wastewater. Several isotherm models were applied to describe the experimental results. The Sips model provided the best correlation for the BRU and M10. As for the HYD, three models (Langmuir, Sips, and Redlich-Peterson) fit well to the experimental results. The results showed that the adsorption process in all cases followed the pseudo-second-order kinetics. Overall, the most efficient adsorbent was the BRU, which demonstrated slightly higher experimental maximum adsorption capacity (27.6 mg g-1) than the HYD (27.0 mg g-1) or M10 (21.3 mg g-1) in the batch experiments. Furthermore, the BRU demonstrated also an efficient performance in the continuous removal of Sb from mine effluent in the column mode. Regeneration of adsorbents was found to be more effective under acidic conditions than under alkaline conditions.

An Overview of Treatment Approaches for Octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine (HMX) Explosive in Soil, Groundwater, and Wastewater.

Octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine (HMX) is extensively exploited in the manufacturing of explosives; therefore, a significant level of HMX contamination can be encountered near explosive production plants. For instance, up to 12 ppm HMX concentrations have been observed in the wastewater effluent of a munitions manufacturing facility, while up to 45,000 mg/kg of HMX has been found in a soil sample taken from a location close to a high-explosive production site. Owing to their immense demand for a variety of applications, the large-scale production of explosives has culminated in severe environmental issues. Soil and water contaminated with HMX can pose a detrimental impact on flora and fauna and hence, remediation of HMX is paramount. There is a rising demand to establish a sustainable technology for HMX abatement. Physiochemical and bioremediation approaches have been employed to treat HMX in the soil, groundwater, and wastewater. It has been revealed that treatment methods such as photo-peroxidation and photo-Fenton oxidation can eliminate approximately 98% of HMX from wastewater. Fenton's reagents were found to be very effective at mineralizing HMX. In the photocatalytic degradation of HMX, approximately 59% TOC removal was achieved by using a TiO2 photocatalyst, and a dextrose co-substrate was used in a bioremediation approach to accomplish 98.5% HMX degradation under anaerobic conditions. However, each technology has some pros and cons which need to be taken into consideration when choosing an HMX remediation approach. In this review, various physiochemical and bioremediation approaches are considered and the mechanism of HMX degradation is discussed. Further, the advantages and disadvantages of the technologies are also discussed along with the challenges of HMX treatment technologies, thus giving an overview of the HMX remediation strategies.

Facile Synthesis of Sustainable Activated Biochars with Different Pore Structures as Efficient Additive-Carbon-Free Anodes for Lithium- and Sodium-Ion Batteries.

The present work elucidates facile one-pot synthesis from biomass forestry waste (Norway spruce bark) and its chemical activation yielding high specific surface area (S BET) biochars as efficient lithium- and sodium-ion storage anodes. The chemically activated biochar using ZnCl2 (Biochar-1) produced a highly mesoporous carbon containing 96.1% mesopores in its structure as compared to only 56.1% mesoporosity from KOH-activated biochars (Biochar-2). The latter exhibited a lower degree of graphitization with disordered and defective carbon structures, while the former presented more formation of ordered graphite sheets in its structure as analyzed from Raman spectra. In addition, both biochars presented a high degree of functionalities on their surfaces but Biochar-1 presented a pyridinic-nitrogen group, which helps improve its electrochemical response. When tested electrochemically, Biochar-1 showed an excellent rate capability and the longest capacity retentions of 370 mA h g-1 at 100 mA g-1 (100 cycles), 332.4 mA h g-1 at 500 mA g-1 (1000 cycles), and 319 mA h g-1 at 1000 mA g-1 after 5000 cycles, rendering as an alternative biomass anode for lithium-ion batteries (LIBs). Moreover, as a negative electrode in sodium-ion batteries, Biochar-1 delivered discharge capacities of 147.7 mA h g-1 at 50 mA g-1 (140 cycles) and 126 mA h g-1 at 100 mA g-1 after 440 cycles.

Preparation and Characterization of Pulp and Paper Mill Sludge-Activated Biochars Using Alkaline Activation: A Box-Behnken Design Approach.

This study utilized pulp and paper mill sludge as a carbon source to produce activated biochar adsorbents. The response surface methodology (RSM) application for predicting and optimizing the activated biochar preparation conditions was investigated. Biochars were prepared based on a Box-Behnken design (BBD) approach with three independent factors (i.e., pyrolysis temperature, holding time, and KOH:biomass ratio), and the responses evaluated were specific surface area (SSA), micropore area (S micro), and mesopore area (S meso). According to the RSM and BBD analysis, a pyrolysis temperature of 800 °C for 3 h of holding and an impregnation ratio of 1:1 (biomass:KOH) are the optimum conditions for obtaining the highest SSA (885 m2 g-1). Maximized S micro was reached at 800 °C, 1 h and the ratio of 1:1, and for maximizing S meso (569.16 m2 g-1), 800 °C, 2 h and ratio 1:1.5 (445-473 m2 g-1) were employed. The biochars presented different micro- and mesoporosity characteristics depending on pyrolysis conditions. Elemental analysis showed that biochars exhibited high carbon and oxygen content. Raman analysis indicated that all biochars had disordered carbon structures with structural defects, which can boost their properties, e.g., by improving their adsorption performances. The hydrophobicity-hydrophilicity experiments showed very hydrophobic biochar surfaces. The biochars were used as adsorbents for diclofenac and amoxicillin. They presented very high adsorption performances, which could be explained by the pore filling, hydrophobic surface, and π-π electron-donor-acceptor interactions between aromatic rings of both adsorbent and adsorbate. The biochar with the highest surface area (and highest uptake performance) was subjected to regeneration tests, showing that it can be reused multiple times.

Aerosol processing technique for the synthesis of mixed-phase copper on carbon catalyst: insights into CO2adsorption and photocatalytic activity.

In this study, spray pyrolysis; an aerosol processing technique was utilized to produce a mixed-phase copper on carbon (Cu/CuxO@C) catalyst. The catalyst production was performed via chemical reduction of copper nitrate by a reducing sugar, i.e. glucose, using aqueous solution. The physical and chemical properties of the produced particles was assessed using various characterization techniques. The synthesis temperature had pronounced effect on the final particles. Since CO2adsorption onto the catalyst is an important step in catalytic CO2reduction processes, it was studied using thermogravimetric and temperature programmed desorption techniques. Additionally, photocatalytic activity of the particles was evaluated by gas-phase oxidation of acetylene gas which revealed excellent activity under both UV and visible light irradiation indicating the possible use of wider range of the solar spectrum.

Suitable Cathode NMP Replacement for Efficient Sustainable Printed Li-Ion Batteries.

N-methyl-2-pyrrolidone (NMP) is the most common solvent for manufacturing cathode electrodes in the battery industry; however, it is becoming restricted in several countries due to its negative environmental impact. Taking into account that ∼99% of the solvent used during electrode fabrication is recovered, dimethylformamide (DMF) is a considerable candidate to replace NMP. The lower boiling point and higher ignition temperature of DMF lead to a significant reduction in the energy consumption needed for drying the electrodes and improve the safety of the production process. Additionally, the lower surface tension and viscosity of DMF enable improved current collector wetting and higher concentrations of the solid material in the cathode slurry. To verify the suitability of DMF as a replacement for NMP, we utilized screen printing, a fabrication method that provides roll-to-roll compatibility while allowing controlled deposition and creation of sophisticated patterns. The battery systems utilized NMC (LiNi x Mn y Co z O2) chemistry in two configurations: NMC523 and NMC88. The first, well-established NCM523, was used as a reference, while NMC88 was used to demonstrate the potential of the proposed method with high-capacity materials. The cathodes were used to create coin and pouch cell batteries that were cycled 1000 times. The achieved results indicate that DMF can successfully replace NMP in the NMC cathode fabrication process without compromising battery performance. Specifically, both the NMP blade-coated and DMF screen-printed batteries retained 87 and 90% of their capacity after 1000 (1C/1C) cycles for NMC523 and NMC88, respectively. The modeling results of the drying process indicate that utilizing a low-boiling-point solvent (DMF) instead of NMP can reduce the drying energy consumption fourfold, resulting in a more environmentally friendly battery production process.

Precipitation of struvite using MgSO4 solution prepared from sidestream dolomite or fly ash.

Struvite (NH4MgPO4∗6H2O) is a slow-release fertilizer produced from phosphorus and nitrogen-containing wastewater in the presence of Mg salts. Commercial Mg salts are the single most significant cost of struvite precipitation. In this study, H2SO4 formed as an industrial sidestream was used to prepare MgSO4 solution from waste dolomite (DOL) and fly ash (FA). MgSO4 solution was then used to precipitate struvite from a synthetic (NH4)2HPO4 solution and from actual industrial process waters. The best results were obtained with real process waters where over 99% of phosphate and about 80% ammonium removals were achieved with both MgSO4 solutions after 30 min of reaction time. A higher molar ratio between Mg and P improved the phosphate removal efficiency, especially with DOL-based MgSO4 solutions; however, it had no practical effect on ammonium removal. The struvite content of precipitates was 75.49% with an FA-based chemical and 60.93% with a DOL-based chemical; other valuable nutrients (Ca, K, S, Fe, Mn, and Cl) were captured in the precipitates. The results indicate that both sidestream-based reagents perform well in struvite precipitation and that the formed precipitates could be used as fertilizers.

Furfural and 5-Hydroxymethylfurfural Production from Sugar Mixture Using Deep Eutectic Solvent/MIBK System.

Choline chloride (ChCl) / glycolic acid (GA) deep eutectic solvent (DES) media with high water content but without any additional catalyst are introduced in furfural and 5-hydroxymethylfurfural (HMF) production. The effects of water content, reaction time, and reaction temperature are investigated with two feedstocks: a glucose/xylose mixture and birch sawdust. Based on the results, 10 equivalent quantities of water (32.9 wt.%) were revealed to be beneficial for conversions without rupturing the DES structure. The optimal reaction conditions were 160 °C and 10 minutes for the sugar mixture and 170 °C and 10 minutes for birch sawdust in a microwave reactor. High furfural yields were achieved, namely 62 % from the sugar mixture and 37.5 % from birch sawdust. HMF yields were low, but since the characterization of the solid residue of sawdust, after DES treatment, was revealed to contain only cellulose (49 %) and lignin (52 %), the treatment could be potentially utilized in a biorefinery concept where the main products are obtained from the cellulose fraction. Extraction of products into the organic phase (methyl isobutyl ketone, MIBK) during the reaction enabled the recycling of the DES phase, and yields remained high for three runs of recycling.

Multiple heavy metal removal simultaneously by a biomass-based porous carbon.

Activated carbon from sawdust was produced with an environmentally friendly process involving single-stage carbonization and activation with steam at 800°C. Production process is scalable because lignocellulosic biomass is ubiquitous worldwide as a waste or as a virgin material. Single-stage production without any cooling steps between carbonization and activation is easier in larger scale production. Monometal adsorption and multimetal adsorption of cobalt, nickel, and zinc were investigated by using the produced carbon, with a commercial one as control. Effect of pH, initial metal concentration, adsorbent dosage, and adsorption time was evaluated in batch experiments. Multimetal experiments showed the order of the maximum adsorption capacities: zinc > nickel > cobalt. Experimental adsorption capacities were 17.2, 6.6, and 4.5 mg/g for zinc, nickel, and cobalt, respectively, in multisolute adsorption. In case of monometal adsorption, adsorption capacity was notably lower. Experimental data fitted into the single-solute and multisolute Freundlich models. The best fit kinetic model varied among the metals. The Weber and Morris intraparticle diffusion model was used. Regeneration was performed with 0.1 M HNO3 , 0.1 M HCl, or 0.1 M H2 SO4 . The adsorption capacity remained at the same within three adsorption-desorption cycles. PRACTITIONER POINTS: Activated carbon was produced from sawdust with environmentally friendly process Monometal adsorption and multimetal adsorption with heavy metals were studied Best-fitting models to the experimental data were single-solute and multisolute Freundlich models Regeneration could be performed with diluted acids Worldwide available raw material successfully used as adsorbent for heavy metals.