RSC sustainability最新文献

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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The solubilities of benzoic acid, (S)-hesperetin, and L-tryptophan in aqueous solutions of ionic liquids (choline glycolate and choline malonate) and the analogous eutectic solvents (choline chloride:glycolic acid and choline chloride:malonic acid) were studied. It is shown that while ionic liquids (IL) and eutectic solvents (ES) were able to increase the solubility of all compounds studied in aqueous solution, ionic liquids were much more efficient for neutral and acidic compounds, while eutectic solvents showed a better performance for the alkaline substances. The results reported here show that the solubility enhancement is related, in the first instance, to the pH of the aqueous solution, which is the dominant effect on the increase in solubility and the main parameter that must be taken into account when selecting a co-solvent to successfully achieve the solubilization of ionizable hydrophobic biomolecules in aqueous solution. In addition, a hydrotropy mechanism was identified when the pH effect was removed, supporting the idea that ionic liquids and eutectic solvents behave as hydrotropes in aqueous solutions. The results here reported show that rather than a focus on the type of solvents (IL vs. ES), the molecular mechanisms such as speciation and co-solvation/hydrotropy, which in some cases may have complementary and synergetic effects, are the parameters that must be addressed in the design or selection of the best solubility enhancer.

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Graphene, a two-dimensional material, has garnered significant interest among researchers globally due to its exceptional characteristics, including a substantial surface area, remarkable chemical stability, elevated electron mobility, and electrical conductivity. The present study explored the synthesis of reduced graphene oxide (rGO), a derivative of graphene materials, by the utilization of gallic acid as a green reducing agent. The successful reduction of graphene oxide (GO) was assessed by X-ray diffraction, UV-vis spectroscopy, Raman, Transmission Electron Microscopy (TEM), and X-ray photoelectron spectroscopy. Cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) investigations were employed to analyze the electrochemical and capacitive performance of reduced graphene oxide (rGO). The specific capacitance of rGO was determined to be 301.7 F g⁻¹ at a current density of 1 A g⁻¹. The electrode exhibits an energy density of 121.1 W h kg⁻¹ at a power density of 853.2 W kg⁻¹, and has an exceptional cycle stability of 91% after undergoing 2000 cycles. This green reduction technique is environmentally friendly and shows promising reduction of graphene oxide (GO) into reduced graphene oxide (rGO). Additionally, the prepared rGO exhibited improved electrochemical and capacitive properties showcasing its potential use in supercapacitor applications.

A graphical abstract is available for this content

A graphical abstract is available for this content

A graphical abstract is available for this content

A graphical abstract is available for this content