RSC sustainability最新文献

The biosorption process offers a sustainable and promising solution for treating wastewater contaminated with industrial effluents containing dyes, heavy metals, personal care products, pharmaceuticals, and phenolic compounds. Different types of biomass, such as agricultural waste products, animal waste, biopolymers, etc., have been reported in contemporary times as environmentally friendly, low-cost, and efficient materials for treating different categories of wastewater. Many researchers often utilized surfactants to modify the surface properties of these biomaterials to enhance their removal efficiency. A considerable amount of research conducted on surfactant-modified biomaterials (SMBs) for treating wastewater in modern times has prompted us to prepare a review article on the same. The main aim of the current article is to focus on the recent developments that took place in this field, the behavior of different surfactants towards different categories of pollutants, and explore underlying mechanisms in depth. Notable advancements, such as the practice of new optimization techniques and the deployment of SMBs for real wastewater decontamination, have also been highlighted. The emergence of SMBs in accordance with the United Nations Sustainable Development Goals (UNSDGs) has been justified. Several current hindrances, along with future outlooks, are briefly presented before the conclusion. This review aims to be highly relevant in the present times, encouraging scientists and engineers to explore novel SMBs for industrial effluent clean-up programs.

Improving enzyme activity and stability as well as preserving selectivity is a must for rendering biocatalysis an economically viable technology. These improvements can be achieved by immobilizing the biocatalyst on the surface of metal oxide magnetic nanoparticles. The aim of this work is to rational design Biocatalyst Magnetic Nanoarchitecture (BMN) consisting of spinel iron oxides nanoparticles having optimized morpho structural (i.e., particles size, shape and crystallinity), textural (i.e., high surface area) and magnetic properties. Candida antarctica lipase B (CaLB) was immobilized on the nanoparticles' surface investigating the optimal bioconjugation conditions and performing the biochemical characterizations to quantify protein concentration and to assess enzymatic activity. Once immobilized on the magnetic nanoparticles surface, CaLB was tested for an enzymatic polycondensation reaction to synthesize polyesters starting from renewable monomers such as the dimethyl ester of adipic acid and 1,8-octanediol. Conversion of monomers was >87% over three reaction cycles while the number average molecular weights of the products were between 4200 and 5600 Da with a dispersity <2. Efficient recycling of the enzyme upon magnetic separation was demonstrated for three reaction cycles.

CO₂ capture and utilization technologies can make an important contribution to the decarbonization of industry. However, capture processes entail significant economic and energy costs, mainly associated with the purification, compression and transport of CO₂. These costs would be reduced if captured CO₂ could be transformed in situ into useful products, avoiding purification, compression and transport costs. This work presents a hydrothermal process in which CO₂ absorbed in aqueous solutions as bicarbonate is reduced with biomass waste to give formic acid as a joint product of the biomass and CO₂ transformation, and acetic and lactic acids as byproducts from the decomposition of the biomass. Several biomass materials are applied as reductants: softwood, sugarcane bagasse, sugar beet, cork, pine needles, vermicompost and pure cellulose as reference material. Moreover, different catalysts are tested to improve conversion yield: Pd(5%)/C and Pd(10%)/C, Ru(5%)/C and activated carbon. The best results (18% formic acid yield) are obtained using pure cellulose as biomass and Pd(5%)/C catalyst. The next best results are obtained with the biomasses with the highest cellulose content, such as wood (11%) and sugarcane bagasse (9%). Experiments performed with labelled H¹³CO₃⁻ as carbon source at 300 °C using the Pd(5%)/C catalyst demonstrate that over 70% of the produced formic acid is formed from the inorganic bicarbonate carbon source. These high yields of conversion using renewable biomass as reductant can contribute to improve the technical and economic feasibility of CO₂ capture technology.

The choice and optimization of electrode materials are crucial for maximizing the energy density and optimizing the overall performance of supercapacitors. Layered metal dichalcogenides (LMDs), such as SnS₂, are promising faradaic materials for hybrid supercapacitors due to their layered structures and abundant sites for effective charge transport. However, their performance is often limited by low electrical conductivity and poor stability owing to low ionic transport and high volumetric expansion. This study presents a straightforward method for enhancing the performance of SnS₂-based electrodes by doping with copper through a facile solid-state synthesis. The incorporation of copper doping significantly improved the specific capacitance, demonstrating a near 40% increase compared to pristine SnS₂ without any complicated optimization procedures or the need to form any composites/heterostructures. The maximum specific capacitance achieved at a current density of 1 A g⁻¹ is 98 F g⁻¹ for pristine SnS₂ and 140 F g⁻¹ for 5% Cu-doped SnS₂ in aqueous 1 M AlCl₃ electrolyte that highlights the potential of copper-doped SnS₂ as a high-performance electrode material for aqueous Al-ion supercapacitors, paving the way for further optimization and development of efficient and sustainable energy storage devices.

The use of hydrocarbon solvents for zeolite-catalyzed polyolefin cracking narrows the molecular weight distribution of the products, which enhances the efficiency of polyolefin chemical recycling to naphtha, a key precursor to polyolefins. However, solvent consumption remains a challenge. In this study, zeolite microporosity was used to achieve shape-selective polyolefin cracking while allowing solvent recovery. With an H-MFI type zeolite catalyst combined with cyclooctane as the solvent, polypropylene was selectively converted without cyclooctane reactivity. In a typical case, 84% of polypropylene was converted into C3-27 aliphatic and monocyclic aromatic compounds (equivalent to liquid petroleum gas, naphtha, kerosene, jet and diesel) with 79% selectivity, while 95% of cyclooctane was recovered. This study is the first to demonstrate solvent recyclability in polyolefin cracking on an acidic zeolite, contributing to the chemical recycling of polyolefin into its precursor, naphtha, with high selectivity facilitated by the presence of solvent but without solvent consumption.

This study explores the catalytic oxidation of homologous alcohols (2-propanol, 2-butanol, and 2-pentanol) by the diperiodatoargentate(III) (DPA) complex in a cetyltrimethylammonium bromide (CTAB) micellar medium. Notably, the use of a micellar medium avoided the need for organic solvents, aligning with green sustainable chemistry principles. The reaction kinetics were monitored by UV-vis spectroscopy, tracking the reduction of Ag(III) to Ag(I) at 360 nm. For all three alcohols, the maximum rate augmentation is observed at a 5 mM CTAB concentration. Zeta potential measurements supported the significant enhancement in reaction rate of the studied reactions in a micellar medium. NMR, DLS, and UV-vis studies revealed interactions between CTAB and DPA. A bathochromic shift is observed in the UV-vis study in the region of 0.8–2 mM CTAB concentrations in the CTAB–DPA system. The critical micelle concentration (CMC) of CTAB was evaluated in the presence of DPA, demonstrating its impact on micelle formation. This green catalytic system demonstrates promising efficiency and sustainability for alcohol oxidation reactions, with potential applications in organic synthesis and industrial processes.

Microbial electrosynthesis (MES) is a progressive technology that can sequester carbon dioxide (CO₂) to produce high-value multi-carbon organic compounds. However, the limited organic production rate is the primary bottleneck, limiting the real-life application of this technology. To overcome this challenge, the present investigation explores sludge-derived hydrochar as a cathode catalyst to enhance CO₂ bioreduction in MES. The hydrochar composite synthesized using anaerobic sludge (ANS) and alum sludge (ALS) exhibited excellent electrochemical properties with higher limiting current density and lower charge transfer resistance. Additionally, key structural properties, such as elevated specific surface area, abundant surface functional groups, and the presence of nitrogen in the form of pyridinic and graphitic nitrogen, are primarily responsible for enhancing the organic product synthesis in MES. Furthermore, the hydrochar composite catalyzed MES resulted in an acetate production of 41.14 ± 5.03 mM L⁻¹, which was nearly twice that of the uncatalyzed MES. Moreover, the current and carbon recovery efficiencies were found to be 52.44% and 45.44%, which were 1.47 and 2.44 times that of uncatalyzed MES. These results demonstrate the potential of sludge-derived hydrochar as a promising cathode electrocatalyst for enhancing CO₂ bioreduction in MES.

Expanded polystyrene (EPS) is a widely used plastic material that poses significant environmental challenges due to its resistance to degradation. While mealworms have been reported to degrade EPS, several critical questions remain unanswered: (1) Do mealworms actually chemically degrade the polystyrene backbone in EPS? (2) Can mealworms effectively derive nutrition from EPS consumption? and (3) What mechanisms, if any, enable EPS degradation by mealworms? This study addresses these questions by feeding mealworms two types of EPS diets: pure EPS without additives and commercial EPS containing additives. Mealworms were individually housed (to prevent cannibalism) and categorized into age-specific groups, and their growth and survival were monitored on diets of pure EPS, commercial EPS, or under starvation conditions. Our results demonstrated that, compared to starvation, both pure and commercial EPS diets failed to sustain mealworm growth, and survival rates decreased, indicating that EPS consumption is toxic to mealworms. Gel permeation chromatography and attenuated total reflectance-Fourier transform infrared spectroscopy analyses of the frass revealed partial degradation of commercial EPS, characterized by a reduction in higher molecular weight fractions and increased carbonyl group formation. Additives likely caused EPS degradation. In contrast, pure EPS was essentially unaffected by passage through the mealworm digestive tract, providing clear chemical evidence that neither mealworms nor their gut microbiota possess enzymes capable of breaking down EPS for energy. These findings reveal that previous studies overstated the ability of mealworms to digest and derive energy from EPS, while providing new insights into the chemical processes involved in limited EPS degradation. Our results emphasize the need for further research into alternative organisms, pretreatment methods, and integrated waste management strategies that can more effectively address the challenge of EPS degradation.

Supercapacitors have received more attraction in energy storage technology owing to their low cost, high capacity, and good stability. Herein, a bio-mass-derived carbon source is prepared from peanut shells and incorporated with heteroatom boron (B-PAC), nitrogen (N-PAC), and metal oxide (cobalt oxide (Co-PAC)). The structural and surface morphology of the obtained PACs is studied using X-ray diffraction (XRD) and Raman spectroscopy, scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis. The electrochemical behavior of PAC-coated electrodes is evaluated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge study (GCD). Compared to boron, the nitrogen heteroatom enhances electric double capacitance up to 302 F g⁻¹ at 2 A g⁻¹. Moreover, cobalt oxide exhibits a synergetic effect with the carbon matrix to boost electrochemical-specific capacitance behavior, and the capacitance value is 295 F g⁻¹ at 1 A g⁻¹ in the three-electrode system. Asymmetric supercapacitor devices were made using N-PAC as the negative electrode and Co-PAC as the positive electrode. The N-PAC//PVA-KOH//Co-PAC device delivers 45 W h kg⁻¹ energy density and 846 W kg⁻¹ at 1 A g⁻¹ power density with 100% capacitance retention after 3000 cycles. The higher energy and power density and long cycle life of the N-PAC//PVA-KOH//Co-PAC device render it as a potential energy storage device for practical applications.

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