ACS Sustainable Resource Management最新文献

New food packaging technologies are being developed as alternatives to synthetic polymers. Biodegradable active packaging from natural and sustainable sources has gained prominence by considering a circular economy and extending the food shelf life. This study aimed to develop and characterize an active biodegradable packaging based on cassava starch and poly(vinyl alcohol) with the brewer’s spent grain extract (BSGE) as a natural antioxidant. The BSGE was evaluated for its antioxidant activity using the ABTS^●+ and DPPH^● methods, and the total phenolic content (TPC) was determined, showing a high antioxidant potential, with values of IC50 of 185.95 μg/mL (ABTS^●+) and >250.00 μg/mL (DPPH^●) and the TPC of 263.23 ± 10.97 mg EAG/g of extract. The increase in the concentration of the BSGE in the active film formulations resulted in an increase in their thickness and density due to higher soluble solids in the extract samples. The films did not experience negative impact on their tensile strength and elongation at break when higher concentrations of the BSGE were added; also, their microstructural characteristics were preserved, which makes them potential candidates for being applied as active food packaging. The release of the TPC from the films in water media occurs with a higher intensity in the initial stages. These results indicate that biodegradable active films with higher concentrations of the BSGE (10BSGE) have potential as sustainable and efficient packaging for food preservation, contributing to the reduction of the environmental impact and adding value to the industrial byproducts.

The use of industrial byproducts as sources of active ingredients contributes to the development of a circular economy. Biodegradable and sustainable materials are crucial in providing alternatives to plastics.

We developed a novel metal-organic framework (MOF) that incorporates a polymeric chain comprising a transition metal and a conducting polymer. It differs from traditional MOFs that rely on rigid organic linkers. Zinc ion was trapped between two pyrrole rings to form a stable complex, which was polymerized, resulting in a polymeric chain-based MOF (ZP-MOF); the conducting polymer served as a ligand. Because of its innovative structure, ZP-MOF functioned as a freestanding, binder-free electrode and exhibited a remarkable specific capacitance of 232.44 F g^–1 at a current density of 1 A g^–1, energy density of 26 Wh kg^–1, and power density of 1807 W kg^–1. The ZP-MOF delivered outstanding electrochemical performance and demonstrated exceptional cyclic stability, retaining 84% of its initial capacitance after over 5000 charge-discharge cycles at 10 A g^–1. The ZP-MOF also showed excellent potential in environmental applications such as degrading dyes, as 50 mg of it removed 98.52% of methylene blue dye from an aqueous solution (50 mL) within 40 min, even at high dye concentrations of 50 mg/L. These findings highlight the dual functionality of the as-developed ZP-MOF as an efficient energy storage material and a promising agent for dye wastewater treatment, underscoring its potential for diverse practical applications and setting new standards for MOF design.

The current study aimed to produce hydrochar from sunflower stalks using the catalytic hydrothermal carbonization (HTC) technique and to evaluate its effectiveness in the pyrolysis process. The hydrochar was pyrolysed in a thermogravimetric analyser at three different heating rates (10, 20, and 40°C/min) for the evaluation of kinetic, thermodynamics and reaction mechanisms. Characterization methods such as Fourier transform infrared spectroscopy and X-ray diffraction were applied to examine the functional groups and phases, respectively. The isoconversional methods were applied for the estimation of kinetic parameters, which included Kissinger Akahira Sunose (KAS), Vyazovkin (VZK), and Ozawa Flynn Wall (OFW). The average activation energy obtained for the catalytic hydrochar based on the VZK method was 125.81 kJ/mol, significantly lower than those for the raw biomass and sole hydrochar pyrolysis. The z(α) master plot approach was applied to deduce the reaction mechanism. The use of catalytic hydrochar may reduce the total environmental effect and greenhouse gas footprint of solid fuel combustion, easing the transition to low-carbon power generation.

Brewer’s spent grain (BSG) contains a large fraction of proteins, lignin, and carbohydrates. However, its heterogeneous composition limits its use in the food industry. The current work evaluated a cascade process for fractionation of these compounds. Two different thermally diluted acid pretreatments prior to enzymatic hydrolysis steps were evaluated. Condition 1 (C1) corresponded to 0.49% (v/v) HCl at 87.7 °C for 92.7 min, and C2 used 0.80% HCl at 121.0 °C for 142 min. Three different solid fractions were obtained for each condition, a fine solid (FS) (particle size <25μm), a coarse solid (CS) rich in protein and fiber, and an alkaline solid (AS) rich in fiber. The fractions had water retention capacities between 4.0 and 8.8 g_H2O/g_TS. The highest protein content was obtained for C1-FS (31.5% w/w), and the highest total fiber content for C2-AS (>80%). Some of those fractions have characteristics similar to those of current market ingredients used in the food industry.

The amount of waste generated by the automotive industry from carbon-fiber-reinforced thermoplastic (CFRTP) has been increasing every year due to the rising demand for these materials, as they lead to weight reduction and improved vehicle performance. Carbon-fiber-reinforced polyamide 6 (CF/PA6) is a thermoplastic matrix composite utilized in this sector, typically fabricated through lamination followed by part cutting. This manufacturing process generates waste with high mechanical properties and comes at a high cost. In this work, we suggest a simple and efficient method to recycle this waste. The waste from CF/PA6 composites was cut into small squares of various sizes and dried in an oven. Laminates measuring 300 × 300 mm were then prepared by randomly arranging the waste in an aluminum mold and subjected to hot compression. Laminates with varying proportions of neat PA6 were also prepared. Standardized specimens were cut using a CNC router cutting machine following processing and subsequently inspected via ultrasound. The recycled laminates were characterized by various mechanical properties, including Charpy impact strength, three-point flexural strength, interlaminar shear strength (ILSS), and Shore D hardness. Thermal properties were evaluated through differential scanning calorimetry, thermogravimetric analysis, Vicat softening temperature (VST), and heat deflection temperature (HDT). Morphological characteristics were analyzed via fractography of specimens post-impact test using scanning electron microscopy. Visual inspection and ultrasound analysis confirmed the quality of the processed laminates. The recycled composites exhibited promising mechanical properties, with average Charpy impact values of 878 J/m, a Shore D hardness of 81, flexural strength of 310 MPa, ILSS of 33 MPa, and HDT and VST exceeding 200 °C. Fractographic analysis indicated excellent fiber–matrix interface bonding. Consequently, the feasibility of mechanical recycling of CF/PA6 composite waste, with 40 wt % neat PA6, was demonstrated as a viable solution for manufacturing new laminates suitable for secondary applications.

The mechanical recycling process of thermoplastic composites reinforced with carbon fibers is essential for minimizing environmental impact and recovering high-value-added waste.

Glycoside hydrolases (GHs) play an essential role in plant biomass degradation and modification for the sustainable production of biochemicals. The filamentous Ascomycete fungus Penicillium subrubescens contains a higher number of GH12 candidates compared to related species. Therefore, we aimed to compare P. subrubescens GH12s for their ability and substrate specificity for plant cell wall polysaccharide degradation and species’ potential as a source of novel enzymes for plant biomass valorization. Our re-evaluated phylogenetic analysis of fungal GH12 members showed that the P. subrubescens GH12s were located in different (new) clades. Biochemical characterization marked PsEglA as an endoglucanase and four other P. subrubescens GH12s (i.e., PsXegA–D) as xyloglucanases. Interestingly, structural features of PsXegD and PsXegE were more comparable to those of Basidiomycete GH12 xyloglucanases with a unique open substrate-binding cleft. PsUegA displayed dual xyloglucanase and endoglucanase activity and also showed distinct structural features. Comparative transcriptome analysis supported the functional diversity of P. subrubescens GH12s in plant biomass degradation. The gene encoding PsUegA was expressed under diverse conditions, suggesting a scouting role for this enzyme.

Penicillium subrubescens GH12 enzymes obtain new and diverse structural features, product profiles, and functions, which supports the species’ potential as a source of novel enzymes for plant biomass valorization.

Rare earth elements (lanthanides) are critical materials for many applications, particularly those involved in new energy. Extracting these elements economically from low-concentration sources may be challenging. This study investigates the interaction of Ce and Gd with microalgae that have been triggered to form phosphate-rich granules. Lanthanides usually occur in nature as phosphates, and therefore, we hypothesized that phosphate accumulation in microalgae may facilitate lanthanide sequestration. Synchrotron-based scanning transmission X-ray microspectroscopy (STXM) was used to map the distribution of Gd, Ce, and P in and around cells of Chlamydomonas reinhardtii. STXM provided X-ray absorption (XAS) spectra at the Gd M_4,5-edge, the Ce M_4,5-edge, and the P K-edge, supported by bulk X-ray absorption spectroscopy at another beamline, and elemental maps from scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS). Gd was associated with P in polyphosphate granules within C. reinhardtii and with P outside the cells. Ce was associated with P outside the microalgal cells but not with the P granules inside the cells. Gd and Ce were found to react with phosphate to form a distinct compound apparent in X-ray absorption near edge spectroscopy (XANES) of bulk samples. However, this compound is not found in the P granules that are coincident with Gd inside the alga. These differences in uptake by the microalga between Ce and Gd may suggest a selective extraction technique and could be generalized to other rare earth elements that are otherwise hard to separate.

The Sri Lankan government’s 2021 policy to ban mineral fertilizer imports and shift to green agriculture provides an opportunity to examine the potential for nutrient recycling in a more circular economy. Here, we examined national-level nutrient flows in Sri Lanka to determine the capacity to offset mineral fertilizer with alternative nutrient sources, considering nitrogen (N) and phosphorus (P). Beyond animal manure already applied to croplands, other nutrient sources, including municipal solid waste (MSW) compost and human excreta, have limited potential to offset mineral fertilizer imports. For example, MSW compost and early adoption of nutrient recovery from human excreta could provide N and P equal to only ≤10% of mineral fertilizer use. Furthermore, we used a grid-based resource recovery and distribution model to identify priority areas for the nutrient management transition in Sri Lanka. Reuse of recovered nutrients from MSW compost and human excreta in model scenarios was in urban and peri-urban areas, including home gardens, distant from much of the nation’s agriculture. Our findings reinforce calls for long-term strategic planning for transitions in nutrient management. Future policies should consider fundamental constraints on alternative nutrient sources and emphasize increasing capacity for both effective nutrient recycling and efficient mineral fertilizer use.

This paper identifies constraints on nutrient availability influencing the outcome of Sri Lanka’s controversial 2021 mineral fertilizer ban and makes broadly applicable recommendations for future agricultural nutrient management transitions.