Barrierless reactions of C2 Criegee intermediates with H2SO4 and their implication to oligomers and new particle formation.

The formation of oligomeric hydrogen peroxide triggered by Criegee intermediate maybe contributes significantly to the formation and growth of secondary organic aerosol (SOA). However, to date, the reactivity of C2 Criegee intermediates (CH3CHOO) in areas contaminated with acidic gas remains poorly understood. Herein, high-level quantum chemical calculations and Born-Oppenheimer molecular dynamics (BOMD) simulations are used to explore the reaction of CH3CHOO and H2SO4 both in the gas phase and at the air-water interface. In the gas phase, the addition reaction of CH3CHOO with H2SO4 to generate CH3HC(OOH)OSO3H (HPES) is near-barrierless, regardless of the presence of water molecules. BOMD simulations show that the reaction at the air-water interface is even faster than that in the gas phase. Further calculations reveal that the HPES has a tendency to aggregate with sulfuric acids, ammonias, and water molecules to form stable clusters, meanwhile the oligomerization reaction of CH3CHOO with HPES in the gas phase is both thermochemically and kinetically favored. Also, it is noted that the interfacial HPES- ion can attract H2SO4, NH3, (COOH)2 and HNO3 for particle formation from the gas phase to the water surface. Thus, the results of this work not only elucidate the high atmospheric reactivity of C2 Criegee intermediates in polluted regions, but also deepen our understanding of the formation process of atmospheric SOA induced by Criegee intermediates.

Effect of industrial alkene ozonolysis on atmospheric H2SO4 formation.

This study has employed the master chemical mechanism (MCM) to investigate the influence of the ozone oxidation pathways in the atmospheric formation of H2SO4 from short-chain olefins in industrialized areas. In-situ H2SO4 formation data were obtained using a high-resolution chemical ionization time-of-flight mass spectrometer, and the simulated H2SO4 concentrations calculated using updated parameters for the MCM model exhibited good agreement with observations. In the simulation analysis of different reaction pathways involved in H2SO4 formation, hydroxyl radicals were found to dominate H2SO4 production during the daytime, while olefin ozone oxidation contributed up to 65% of total H2SO4 production during the night-time. A sensitivity analysis of the H2SO4 production parameters has revealed a high sensitivity to changes in sulfur dioxide, and a relatively high sensitivity to olefins with fast ozonolysis reaction rates and bimolecular reaction rates of resulting stabilized Criegee Intermediates. A high relative humidity promotes daytime H2SO4 formation, but has an inhibiting effect during the night-time due to the different dominant reaction pathways.

Synthesis of cellulose nanofibers from jute fiber by using chemomechanical method.

Background: Jute fiber is one of the most versatile natural fibers that is widely used as a raw material for packaging, textiles, and construction; and as a reinforcement in composite materials for heavy-duty applications. In the past, acid hydrolysis and mechanical treatment via the ball milling method were common in the extraction of cellulose nanofiber (CNFs) from natural plant fibers. However, there are some drawbacks of using those methods where there will be a huge quantity of acidic wastewater generated when the acid hydrolysis method is performed. Method: This study investigated the potential use of a combination of chemical and mechanical methods in the extraction of jute CNFs. Through this method, the jute fibers were first chemically treated using sodium hydroxide (NaOH), sodium chlorite (NaClO 2) and sulphuric acid (H 2SO 4) to remove the non-cellulosic elements followed by mechanical milling by using a planetary ball mill. Results: The shape and size of the obtained CNFs were observed under a field emission scanning electron microscope (FESEM). This study revealed that jute CNFs were successfully extracted through the combination of chemical and mechanical treatment methods where the obtained CNFs reveal themselves in smooth fibrous morphology with a diameter of 23 nm and 150-200nm in length. Conclusions: Jute cellulose nanofibers were successfully drawn out from raw jute fibers by means of a combination of chemical and mechanical treatment. The results obtained confirmed that the chemomechanical method is an effective technique for isolating the CNFs and its potential use as reinforcement material was explained.

The effect of products containing high concentration corrosive substances on the recovery of fingermarks from non-porous surfaces.

Fingermark recovery plays a crucial role in investigating corrosive substance attacks, which are becoming increasingly common. Building upon previous research, this study aimed to identify effective visualization processes for recovering fingermarks from diverse substrates exposed to wide range of commercially available corrosive materials. The study investigated glass, PVC and HDPE substrates with fingermarks deposited 1 day and 2 weeks before exposure to the corrosive substance, and used commercially available substances at concentrations higher than any previous study. It was found that fingermarks could still be recovered from all substrates studied after exposure to most of the corrosive substances, although in general exposure to corrosive substances was detrimental to the quality of marks recovered. The most detrimental corrosive substances were found to be those based on concentrated sulfuric acid. Black and white powder suspensions were the most effective of all processes used in this study, with the highest recovery rates observed from the glass substrate. Age of mark was not found to have a significant effect on recovery rates. Overall the results show that fingermarks may survive exposure to even the most concentrated acids used in this study and provide the initial basis for guidance on processes that could be used on materials used in corrosive substance attacks.

Sulfuric acid-induced skin neoplasms in immunocompetent mice.

This study investigates the carcinogenic potential of chronic dermal exposure (16 weeks) to sulfuric acid (SA) in immunocompetent mice. Clinical assessments, histopathological analyses, immunohistochemical analyses and biochemical assays were conducted to evaluate skin irritation, oxidative stress biomarkers and the potential carcinogenic effect of SA. Results indicated that prolonged exposure to SA leads to various alterations in skin structure, notably inflammation, preneoplastic and neoplastic proliferation in hair follicles, as well as hyperkeratosis and acanthosis, resulting in an increased epidermal thickness of 98.50 ± 21.6 µm. Immunohistochemistry analysis further corroborates these observations, showcasing elevated nuclear expression of p53 and Ki-67, with a significant mitotic index of (57.5% ± 2.5%). Moreover, biochemical analyses demonstrate that SA induces lipid peroxidation in the skin, evidenced by a high level of Malondialdehyde and a consequential reduction in catalase activity. These findings suggest that prolonged exposure to SA can induce skin neoplasms, highlighting the need for stringent safety measures in environments where SA is frequently used. This study underscores the potential occupational health risks associated with SA exposure.

Comparison of acid and hydrothermal pretreatments of date waste for value creation.

The production of date syrup yields a substantial amount of date press cake (DPC), fibrous and moisturising material with great potential for generating value through bioprocessing. However, the recalcitrant structure of DPC affects the yield of products in bioprocesses. To boost the accessibility of the structure as well as increase the soluble fraction of carbohydrates and facilitate further enzymatic hydrolysis, hydrothermal and dilute acid (0.5% (v/v) sulfuric acid) pretreatments as cost-effective and feasible methods were applied on DPC at relatively low temperatures (80, 100, 120 and 140 °C) and reaction times (60 and 90 min). The success in pretreatment was then evaluated by a post-enzymatic treatment using an enzyme cocktail of cellulases and hemicelluloses. Based on total accessible sugar with minimum produced inhibitors, an optimal operating condition was considered acid pretreatment at 120 °C for 90 min with a 55.02% increase in total sugar yield. To explore the potential use of pretreated DPC, an anaerobic digestion was conducted on untreated and acid-pretreated DPC at 120 °C for 90 min. The results showed that pretreatment increased the total bioproduct yield, including hydrogen, ethanol, and volatile fatty acid yields, by 59.75%. This demonstrates the significant impact of pretreatment on product yields in a bioprocess.

Selective removal of iron from sulfuric acid leaching solution of aerospace magnetic material scraps by jarosite process.

Aerospace magnetic material scraps are abundant in cobalt and nickel. Sulfuric acid leaching process is an efficient method for extracting them. But it is a non-selective process, a significant amount of iron dissolves in the solution. This study focuses on the selective removal of iron from this solution using the jarosite process. Eh-pH diagram of K-S-Fe-H2O system was established. Based on thermodynamic analysis, H2O2 is used to oxidize Fe2+ into Fe3+, achieving efficient and selective removal of iron from the solution containing cobalt and nickel. The optimal conditions are as follows: temperature 95°C, K2SO4 dosage coefficient 1.5, seed dosage 10 g/L, time 90 min, pH 1.76, and endpoint pH controlled at approximately 3. Under these conditions, the iron removal efficiency is above 99%, while the loss ratios of cobalt and nickel are below 2%. The product is characterized by XRD and SEM-EDS. Results indicate that the product is jarosite ((K,H3O)Fe3(SO4)2(OH)6), exhibiting an ellipsoid structure with the mean particle size in the range of 0.2-5.0 µm. Temperature, pH value and seed dosage significantly affect reaction rate, particle size and crystallinity, and K2SO4 dosage mainly affects reaction rate and the morphology of jarosite. The jarosite crystallization kinetics can be described by the Avrami equation, with an Avrami index (n) of approximately 2.5 and the apparent activation energy of 42.68 kJ/mol.

Enhanced reducing capacity of citric acid for lithium-ion battery recycling under microwave-assisted leaching.

The management and sustainable recycling of spent lithium-ion batteries (LIBs) holds critical importance from both economic and environmental standpoints. H2O2 and ascorbic acid are widely used inorganic and organic reductants in the hydrometallurgical process for battery recycling. In this study, citric acid, as a reductant, was found to have superior metal leaching efficiencies under microwave-assisted leaching than H2O2 and ascorbic acid. The enhanced performance was attributed not only to the inherent reducing property of citric acid but also to the chelation of citric acid with Cu and Fe, resulting in the formation of reductive radicals under microwave. The effect of acid type, H2SO4 concentration, citric acid concentration, solid-liquid (S/L) ratio, reaction time, and temperature were investigated. 99.5 % of Li, 99.7 % of Mn, 99.5 % of Co, and 99.3 % of Ni were leached from spent lithium nickel manganese cobalt oxides (NCM) battery black mass using 0.2 mol/L H2SO4 and 0.05 mol/L citric acid at 120 °C for 20 min with a fixed S/L ratio of 10 g/L in the microwave-assisted leaching process. Leaching kinetic results were best fitted with the Avrami model, suggesting that the microwave-assisted leaching process was controlled by diffusion. The leaching activation energies of Li, Mn, Co, and Ni were 30.11 kJ/mol, 27.48 kJ/mol, 21.32 kJ/mol, and 33.29 kJ/mol, respectively, providing additional evidence that supports the proposed diffusion-controlled microwave-assisted leaching mechanism. This method provided a green and efficient solution for spent LIBs recycling.

Efficient biodiesel production by sulfonated carbon catalyst derived from waste glycerine pitch via single-step carbonisation and sulfonation.

Glycerine pitch is a highly alkaline residue from the oleochemical industry that contains glycerol and contaminants, such as water, soap, salt and ash. In this study, acidic heterogeneous glycerol-based carbon catalysts were synthesised for biodiesel production via single-step partial carbonisation and sulfonation using pure glycerol and glycerine pitch, producing products labelled as SGC and SGPC, respectively. Carbon materials were obtained by heating glycerol and concentrated sulfuric acid (1:3) at 200℃ for 1 h. The produced SGC and SGPC displayed high densities of sulfonic group (-SO3H), i.e. 1.49 and 1.00 mmol·g-1, respectively, alongside carboxylic (-COOH) and phenolic (-OH) acid. In the catalytic evaluation, excellent oleic acid conversions of 96.0 ± 0.4 % and 92.4 ± 0.5 % were achieved using SGC and SGPC, respectively, under optimised reaction conditions: 1:10 M ratio of oleic acid to methanol, 5 % (w/w) catalyst, 64℃ and 5 h. SGPC was found to be recyclable with 68.5 % conversion after the 6th cycle, which was attributed to the loss of -SO3H and catalyst deactivation by the deposition of oleic acid on its surface. Remarkably, despite the impurities present in the glycerine pitch, the obtained results demonstrated that the reactivity of SGPC is comparable to SGC and superior to that of commercial solid acid catalysts, which demonstrated that the presence of impurities appears to have minimal impact on the production of carbon materials and their properties.

A greener method to recover critical metals from spent lithium-ion batteries (LIBs): Synergistic leaching without reducing agents.

Efficient recycling of critical metals from spent lithium-ion batteries is vital for clean energy and sustainable industry growth. Conventional methods often fail to manage large waste volumes, leading to hazardous gas emissions and dangerous materials. This study investigates innovative methods for recovering critical metals from spent LIBs using synergistic leaching. The first step optimized thermal treatment conditions (570 °C for 2 h in air) to remove binder materials while maintaining cathode material crystallinity, confirmed by X-ray diffraction (XRD) analysis. Next, response surface methodology (RSM), I-optimal, was used to examine the synergistic effects of sulfuric acid (SA) and organic acids (Org, citric and acetic acids) and their concentrations (SA: 0.5-2 M and Org: 0.1-2 M) on metal leaching for an eco-friendlier process. Results showed that adding citric acid to SA was more effective, especially at lower concentrations, than using acetic acid. The medium was tested to evaluate the impact of reductant addition. Remarkably, it was discovered that the optimized leaching mixture (1.25 M SA and 0.55 M citric acid) efficiently extracted metals without the need for any reductant like H2O2, highlighting its potential for a simpler and more eco-friendly recycling process. Further optimization identified the ideal solid-to-liquid ratio (62.5 g/L) to minimize acid use. Finally, RSM (D-optimal) was used to investigate the effects of time and temperature on leaching, achieving remarkable recovery rates of 99% ± 0.7 for Li, 98% ± 0.0 for Co, 90% ± 6.6 for Ni, and 92% ± 0.4 for Mn under optimized conditions at 189 min and 95 °C. Chemical cost analysis revealed this method is about 25% more cost-effective than conventional methods.

Efficient cellulose dissolution and derivatization enabled by oxalic/sulfuric acid for high-performance cellulose films as food packaging.

The performance of cellulose-based materials is highly dependent on the choice of solvent systems. Exceptionally, cellulose dissolution and derivatization by efficient solvent have been considered as a key factor for large-scale industrial applications of cellulose. However, cellulose dissolution and derivatization often requires harsh reaction conditions, high energy consumption, and complex solubilizing, resulting in environmental impacts and low practical value. Here we address these limitations by using a low-temperature oxalic acid/sulfuric acid solvent to enable cellulose dissolution and derivatization for high-performance cellulose films. The dissolution and derivatization mechanism of the mixed acid is studied, demonstrating that cellulose is firstly socked by oxalic acid, then more hydrogen bonds ionized by sulfuric acid break cellulose chain, and finally the esterification reaction between oxalic acid and cellulose is catalyzed by sulfuric acid. Solutions containing 8 %-10 % cellulose are obtained and can be stored for a long time at -18 °C without significant degradation. Moreover, the cellulose film exhibits a higher tensile strength of up to 66.1 MPa, thermal stability, and degree of polymerization compared to that fabricated by sulfuric acid. These unique advantages provide new paths to utilize renewable resources for alternative food packaging materials at an industrial scale.

General instability of dipeptides in concentrated sulfuric acid as relevant for the Venus cloud habitability.

Recent renewed interest in the possibility of life in the acidic clouds of Venus has led to new studies on organic chemistry in concentrated sulfuric acid. We have previously found that the majority of amino acids are stable in the range of Venus' cloud sulfuric acid concentrations (81% and 98% w/w, the rest being water). The natural next question is whether dipeptides, as precursors to larger peptides and proteins, could be stable in this environment. We investigated the reactivity of the peptide bond using 20 homodipeptides and find that the majority of them undergo solvolysis within a few weeks, at both sulfuric acid concentrations. Notably, a few exceptions exist. HH and GG dipeptides are stable in 98% w/w sulfuric acid for at least 4 months, while II, LL, VV, PP, RR and KK resist hydrolysis in 81% w/w sulfuric acid for at least 5 weeks. Moreover, the breakdown process of the dipeptides studied in 98% w/w concentrated sulfuric acid is different from the standard acid-catalyzed hydrolysis that releases monomeric amino acids. Despite a few exceptions at a single concentration, no homodipeptides have demonstrated stability across both acid concentrations studied. This indicates that any hypothetical life on Venus would likely require a functional substitute for the peptide bond that can maintain stability throughout the range of sulfuric acid concentrations present.

Dilute acid-assisted microbubbles-mediated ozonolysis of Eucheuma denticulatum phycocolloid for biobased L-lactic acid production.

Biobased L-lactic acid (L-LA) appeals to industries; however, existing technologies are plagued by limited productivity and high energy consumption. This study established an integrated process for producing macroalgae-based L-LA from Eucheuma denticulatum phycocolloid (EDP). Dilute acid-assisted microbubbles-mediated ozonolysis (DAMMO) was selected for the ozonolysis of EDP to optimize D-galactose recovery. Through single-factor optimization of DAMMO treatment, a maximum D-galactose recovery efficiency (59.10 %) was achieved using 0.15 M H2SO4 at 80 °C for 75 min. Fermentation with 3 % (w/v) mixed microbial cells (Bacillus coagulans ATCC 7050 and Lactobacillus acidophilus-14) and fermented residues achieved a 97.67 % L-LA yield. Additionally, this culture approach was further evaluated in repeated-batch fermentation and showed an average L-LA yield of 93.30 %, providing a feasible concept for macroalgae-based L-LA production.

Boosting Catalytic and Anti-fluorination Performance of the Ru/Vanadia-Titania Catalyst for the Oxidative Destruction of Freon by Sulfuric Acid Modification.

Chlorofluorocarbons (CFCs) exert a strong greenhouse effect and constitute the largest contributor to ozone depletion. Catalytic removal is considered an effective pathway for eliminating low-concentration CFCs under mild conditions. The key issue is the easy deactivation of the catalysts due to their surface fluorination. We herein report a comparative investigation on catalytic dichlorodifluoromethane (CFC-12) removal in the absence or presence of water over the sulfuric-acid-modified three-dimensionally ordered macroporous vanadia-titania-supported Ru (S-Ru/3DOM VTO) catalysts. The S-Ru/3DOM VTO catalyst exhibited high activity (T90% = 278 °C at space velocity = 40 000 mL g-1 h-1) and good stability within 60 h of on-stream reaction in the presence of 1800 ppm of water due to the improvements in acid site amount and redox ability that promoted the adsorption of CFC-12 and the activation of C-F bonds. Compared with the case under dry conditions, catalytic performance for CFC-12 removal was better over the S-Ru/3DOM VTO catalyst in the presence of water. Water introduction mitigated surface fluorination by the replenishment of hydroxyl groups, inhibited the formation of halogenated byproducts via the surface fluorine species cleaning effect, and promoted the reaction pathway of COX2 (X = Cl/F) → carboxylic acid → CO2.

Reactive transport modelling as a toolbox to compare remediation strategies for aquifers impacted by uranium in situ recovery.

More than 60% of worldwide uranium production is based on the In Situ Recovery mining technique. This exploitation method directly falls within the scope of the applications of reactive transport modelling to optimize uranium production and limit its associated environmental impact. We propose a modelling approach which is able to represent the natural evolution of an aquifer impacted by an ISR test performed using sulfuric acid. The model is calibrated on a 12 year-long data series obtained from 12 monitoring wells surrounding an ISR pilot cell. Through this process-based approach, we simulate the impact of several remediation strategies that can be considered in these contexts. In particular, we model the impact of Pump & Treat combined with reverse osmosis, as well as the circulation of non-impacted fluids through the reservoir with different operating strategies. Our approach allows to compare the effectiveness of these strategies. For this small-scale ISR pilot, monitored natural attenuation constitutes an interesting approach due to its faster pH recovery time with respect to Pump & Treat (5-10 years to pH ∼ 6), whose efficiency can be improved by the addition of exchangeable cations. Circulation of unimpacted fluids can reduce pH recovery times if performed for periods longer than the ISR exploitation and/or deployed with a delay. Combined with an economic evaluation of their deployment, this modelling approach can help the mining operator select and design optimal remediation strategies from an environmental and economical standpoint.

Assessing the Efficacy of Three Hatchery Disinfectants for the Inactivation of a Lake Sturgeon Herpesvirus (Family: Alloherpesviridae).

Infectious diseases are a leading cause of losses in the aquaculture industry and conservation programs globally. Simultaneously, infectious diseases pose a substantial risk to fish being hatchery-reared and released into natural habitats for conservation purposes, including the Great Lakes lake sturgeon (Acipenser fulvescens, i.e., GL-LST). Recently, an alloherpesvirus (lake sturgeon herpesvirus 2, i.e., LSHV-2) capable of inducing disease and/or mortality in adult and juvenile GL-LSTs was detected in two adult GL-LST populations. To begin developing disease prevention and/or control methods, in vitro experiments were designed to determine the susceptibility of LSHV-2 to disinfectants commonly used in hatchery and aquaculture facilities (Virkon®-Aquatic: potassium peroxymonosulfate; Ovadine®: polyvinylpyrrolidone iodine complex; and Perox-Aid®: hydrogen peroxide). Cultured LSHV-2 was exposed to each disinfectant at two concentrations (Virkon®-Aquatic: 0.5% and 1%; Ovadine®: 50 and 100 ppm; and Perox-Aid®: 500 and 1000 ppm) in duplicate for durations of 1, 10, and 30 min. Following exposure, the disinfectant was neutralized, and after a 14-day incubation period on a white sturgeon × lake sturgeon hybrid cell line (WSxLS), percent reduction was calculated by comparing the 50% tissue culture infectious doses (TCID50/mL) of the virus with and without disinfectant exposure. When exposed to Perox-Aid®, LSHV-2 percent reduction ranged from 58.7% to 99.5%. When exposed to Ovadine®, the percent reduction ranged from 99.4% to 100%. Lastly, the percent reduction when exposed to Virkon®-Aquatic was 100% for both concentrations and all timepoints. The results herein provide evidence that both Virkon®-Aquatic and Ovadine® are virucidal to LSHV-2 and may represent a means to reduce virus transmission risk under field settings.

Unveiling the overlooked threat: antibiotic resistance in groundwater near an abandoned sulfuric acid plant in Xingyang, China.

Groundwater near a sulfuric acid plant in Xingyang, Henan, China was sampled from seven distinct sites to explore the prevalence of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs). Results showed that genes aadA, blaCTX-M, tetA, qnrA, and sul1 were detected with 100% frequency followed by aac(6')-Ib (85.71%), ermB (85.71%), and tetX (71.42%). Most abundant ARGs were sul1 in LSA2 (1.15 × 1011 copies/mL), tetA in LSA6 (4.95 × 1010 copies/mL), aadA in LSA2 (4.56 × 109 copies/mL), blaCTX-M in LSA4 (1.19 × 109 copies/mL), and ermB in LSA5 (1.07 × 109 copies/mL). Moreover, in LSA2, intl1 as a marker of class 1 integron emerged as the most abundant gene as part of MGE (2.25 × 1011 copies/mL), trailed by ISCR1 (1.57 × 109 copies/mL). Environmental factors explained 81.34% of ARG variations, with a strong positive correlation between the intl2 and blaCTX-M genes, as well as the ISCR1 gene and qnrA, tetA, intl2, and blaCTX-M. Furthermore, the intI1 gene had a strong positive connection with the aadA, tetA, and sul1 genes. Moreover, the aac(6')-Ib gene was associated with As, Pb, Mg, Ca, and HCO3-. The intl2 gene was also shown to be strongly associated with Cd. Notably, network analysis highlighted blaCTX-M as the most frequently appearing gene across networks of at least five genera. Particularly, Lactobacillus, Plesiomonas, and Ligilactobacillus demonstrated correlations with aadA, qnrA, blaCTX-M, intI2, and ISCR1. Based on 16S rRNA sequencing, the dominant phyla were Proteobacteria, Firmicutes, Bacteroidota, Acidobacteriota, and Actinobacteriota, with dominant genera including Pseudomonas, Ligilactobacillus, Azoarcus, Vogesella, Streptococcus, Plesiomonas, and Ferritrophicum. These findings enhance our understanding of ARG distribution in groundwater, signaling substantial contamination by ARGs and potential risks to public health.

Novel electrochemical process for recycling of valuable metals from spent lithium-ion batteries.

Effective recovery of Li, Co, Ni and Mn from cathode materials of spent lithium-ion batteries (LIBs) has become a global concern. In this study, electrolysis of copper sulfate to produce sulfuric acid and electrons were utilized to recover Li, Co, Ni and Mn from spent LIBs. The obtained results showed that 93 % of Ni, 91 % of Co, 89 % of Mn and 94 % of Li were leached and 99 % of Cu was deposited during leaching process by adopting the 0.225 mol/L of copper sulfate with a solid/liquid ratio of 15 g/L at a current density of 50 mA/m2 and 80 °C for 4.5 h. Then, a current efficiency of 72 % for the cathode and 30 % for the anode was achieved at a current density of 40 mA/m2, 70 °C and pH 2.5 during electrodeposition process. The Ni-Co deposition followed the principle of anomalous codeposition and the complete deposition time of Co, Ni and Mn were 3 h, 9 h and 10 h, respectively. Eventually, the Ni, Co, Mn, Li and Cu can be recovered as Ni-Co alloy, MnO2 and Li2CO3 and Cu metals with the corresponding recovery rates of 99.40 %, 91.00 %, 90.68 %, 85.59 % and 89.55 %, respectively. This study proposes a promising strategy for recycling cathode materials from spent LIBs without addition of chemical reductants and acids.

Pressurized microwave-assisted hydrothermal treatment with various salts for efficient production of monosaccharides from rice straw.

This study proposed a two-stage pressurized microwave hydrothermal treatment with a catalyst, followed by enzymatic saccharification, as a pretreatment method for efficiently converting cellulose and hemicellulose from rice straw into glucose and xylose. The use of various inorganic salts and dilute sulfuric acid as catalysts enhances sugar production. Using 1 wt% sulfuric acid as a catalyst at 150 °C for 5 min for the first-stage and then 180 °C for 5 min for the second-stage yielded the highest sugar production from rice straw compared with other inorganic salts tested. The filtrate and enzymatic saccharification solution contained a total sugar of 0.434 g/g-untreated rice straw (i.e. 0.302 g-glucose/g-untreated rice straw and 0.132 g-xylose/g-untreated rice straw). When inorganic salts such as NaCl, MgCl2, CaCl2, and FeCl3 were used as catalysts, the highest sugar yield of 0.414 g/g-untreated rice straw (i.e. 0.310 g-glucose/g-untreated rice straw and 0.104 g-xylose/g-untreated rice straw) was obtained when using 1 wt% FeCl3 at 170 °C for 5 min in the first-stage and 190 °C for 5 min in the second-stage, with a value close to that of 1 wt% sulfuric acid. These findings suggest that two-stage treatment with a catalyst is a suitable pretreatment method for the production of glucose and xylose from rice straw owing to the different hydrolysis temperatures of cellulose and hemicellulose.

Preparation of biochar from anaerobic digested sludge for enhancement of sludge dewatering.

Effective dewatering is vital for both sludge treatment and resource recovery. This study focuses on converting post-anaerobic digested sludge into biochar to enhance sludge dewatering. The sludge-derived biochar is further modified with polyacrylamide (PAM-ADBC) and applied with sulfuric acid-modified montmorillonite (HMTS) for better performance. Significant advancements in dewatering were noted, even at reduced HMTS (0.1 g/g DS) and PAM-ADBC (25 g/kg DS) dosages. These improvements resulted in a remarkable 41.96% enhancement in capillary suction time (17.2 s) and a notable 20.26% reduction in moisture content (66.33%), respectively, all while maintaining a stable pH level. HMTS, with leached cations, improved dewatering by decomposing the extracellular polymeric substance structure through electro-neutralization to release the internal bound water within sludge flocs. Simultaneously, PAM-ADBC coagulated decomposed sludge particles into larger flocs to form a skeletal structure with itself to discharge internal water in compression dewatering. This study introduces a resource recovery method for anaerobically digested sludge and highlights its potential for sustainable utilization.