ACS Sustainable Resource Management最新文献

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.

Nanostructured SiO₂ shells from diatom microalgae are a promising feedstock for the production of high-performance SiO₂ anodes for next-generation lithium-ion batteries (LIBs), and diatom biomass has been proposed as a carbon source for producing SiO₂/C nanocomposites of improved cyclability. A standard approach before implementing diatoms as an anode material involves an acid washing step for removing minor impurities from diatom shells. In this work, we perform the first comprehensive analysis on the effect of minor chemical species present on diatom shells on the electrochemical properties of diatom-SiO₂/C anodes. Unwashed and acid-washed single species cultured diatoms containing their original biomass content were subjected to thermal treatments at 600, 700, 800, and 900 °C, and the resulting SiO₂/C composites were fully characterized by XRD, BET, TGA, Raman, SEM/EDX, and TEM techniques. The electrochemical performance of the resulting anodes reveals the key role of impurities in improving the cycling properties. While acid-washed SiO₂/C composites displayed higher surface area, their electrochemical performance was comparable to non-coated SiO₂. On the other hand, unwashed SiO₂/C anodes exhibited a specific capacity up to twice that of SiO₂. The best-performing SiO₂/C anode was the unwashed diatom-SiO₂ heat-treated at 800 °C, showing a specific capacity of 661 mAh·g^–1 after 100 cycles at a current density of 200 mA·g^–1. Results on the beneficial effects of impurities on SiO₂/C anodes are crucial for an effective implementation of diatoms in LIB technology.

Nanostructured carbon-coated SiO₂ from biomass-derived diatom microalgae are promising candidates for high-performance next-generation lithium-ion battery anodes.

This study investigates the potentiality of Gladiolus hybrida leaf fibers (GHLFs) as an eco-friendly reinforcing substance for polymer-based composites. Novel natural fibers were harvested from Gladiolus hybrida leaves (GHL) and treated with NaOH alkali (T-GHLF) to assess their influence on physical, strength, molecular, and heat-related properties. Initially, the obtained fibers had a diameter of 0.3084 mm, which reduced to 0.2524 mm following alkali treatment. Chemical investigation indicated that the cellulose content increased to 57.16 wt %, an enhancement of 11.38% over the untreated fibers, which had a cellulose content of 51.32 wt %. The degree of crystallinity percentage of the raw and processed fibers was 57.85% and 60.82%, respectively, without significant change in the cellulose phase. The thermogravimetric analysis indicated that T-GHLF exhibited improved thermal stability up to 257.77 °C, with the kinetic activation energy (Ea) measured at 81.56 kJ/mol. Fourier transform infrared spectroscopy (FTIR) has been employed to observe the distribution of different chemical groups on the fiber surface. Scanning electron microscopy (SEM) revealed that the fibers had a roughened surface. According to tensile testing of a single fiber, the Young’s modulus values for GHLFs and T-GHLFs were 2.08 and 2.21 GPa, respectively. These evidences suggested that GHLFs exhibited characteristics comparable to those of presently used natural fibers, positioning them as a strong contender to replace organic fibers in resin matrix composites. As a result, these novel natural resources may assist in achieving the Sustainable Development Goals of the United Nations through the sustainable utilization of agricultural waste in polymer matrix composites.

Exploiting efficient methods for converting biomass-based resources into high-value-added chemicals has attracted extensive interest in sustainable development in the chemical industry. Here, we have developed a chemoenzymatic sequence for synthesizing 2-furonitrile (2-FN) from xylose, a biobased five-carbon monosaccharide derived from agricultural waste. Firstly, a 1,2-dichloroethane (DCE)/H₂O biphasic system (1:1, v/v) was adopted to produce 2-furaldehyde oxime (2-FOx) from xylose by integrating two steps of dehydration and oximation in a one-pot sequence using a temporal compartmentalization strategy, resulting in a yield of 2-FOx from xylose over 78%. Secondly, the catalytic efficiency of aldoxime dehydratase from Pseudomonas putida F1 (OxdF1) was significantly improved by engineering the substrate access tunnel and a distal residue. The activity of an optimal mutant L318I–N266S has reached 3.94 U·mg^–1 towards 2-FOx, approximately 6 times higher than that of the wild-type OxdF1 (0.65 U·mg^–1). Consequently, 2-FN was prepared in a 400 mL reaction mixture at room temperature using a continuous feeding strategy. After 1.5 h, 100 mM 2-FOx was completely converted to 2-FN with a space-time yield of 6.2 g·L^–1·h^–1. The chemoenzymatic process proposed an alternative strategy for synthesizing 2-FN from biomass-based materials under mild conditions without using highly toxic cyanide.

The growing global emphasis on sustainability and waste reduction has led to a thorough investigation of agricultural by-products, especially those containing valuable bioactive chemicals. The study was conducted to optimize solvent and extraction methods to compare tamarind and litchi shell extracts’ total phenolic contents and antioxidant capacities. The extracts were evaluated for the total phenolic content (TPC) and antioxidant activity using various assays from maceration, microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE). The litchi shell extract TPC was highest for MAE with 29.93 ± 0.21 mg of GAE/g of DW for acetone:water (50:50; v/v) followed by UAE with 27.41 ± 0.09 mg of GAE/g of DW, whereas 16.90 ± 0.15 mg of GAE/g of DW TPC was reported, which is 43.54 and 38.34% higher than the values from maceration. The tamarind shell has contradictorily the highest TPC of 29.40 ± 0.15 mg of GAE/g of DW in maceration compared to MAE and UAE. With a mixture of methanol, water, and acetic acid, the MAE technique demonstrated the highest diphenyl-2-picrylhydrazyl (DPPH) antioxidant activity (94.86%), followed by 94.78% with a methanol/water combination. The greatest ferric-reducing ability of plasma (FRAP) value of 6.60 mg of TE/g for acetone:water in maceration was observed for 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) values varying between 0.824 and 0.974 mg of TE/g for all extraction techniques. A moderately positive correlation was observed in the TPC and different antioxidant assays. A strong positive correlation was noticed between the extraction method and the antioxidant activity of litchi and tamarind shell extracts. The study concludes that the optimized extraction method can obtain high-quality extracts from tamarind and litchi shells that can potentially be used as natural antioxidants in various applications.

The white light-emitting diode (W-LED) is a new generation of lighting devices, and its key technology is light-emitting materials. Biomass-derived carbon dots (CDs) are expected to be favorable candidates for a new generation of environmentally friendly fluorescent materials. However, the insufficient absolute photoluminescence quantum yield (PLQY) and lack of effective emission bands of most biomass-derived CDs limit their further applications. Herein, Defatted Sichuan pepper seed, an inexpensive biowaste, was used for the raw materials of fluorescent CDs. The preparation of highly efficient panchromatic (415–650 nm) CDs by a simple one-step solvothermal method were reported. Defatted Sichuan pepper seed biowaste was used as a carbon source, and 1,4-dihydroxynaphthalene was used as a modifier to modulate the formation of conjugated domains in CDs, and the surface structures of CDs were modified in different solvents. Meanwhile, optical trichromatic CDs with high absolute PLQY (blue CDs: 82%, green CDs: 62%, and red CDs: 48%) were selected for characterization and analysis and further mixed to prepare white CDs (W-CDs). Then, the W-CDs were embedded in starch and a PVP matrix to construct solid phosphors with excellent photoluminescence (PL) thermal stability and resistance to photobleaching. The phosphors can be used as color conversion layers for light-emitting diodes (LEDs). The final packages realized blue LED (B-LED), green LED (G-LED), red LED (R-LED), and warm W-LEDs. What’s more, the R-LED shows a high color purity of 93.7%, and the W-LED exhibits a high color rendering index (CRI) of 96.2, with a color coordinate (CIE) of (0.40, 0.39). This work provides a new way for exploring biomass-derived high-efficiency CDs to build low-cost, high-performance, and environmentally friendly LED devices.

The purpose of this research is to assess the corrosion and scaling the potential of a water distribution network (WDN) using Geostatistics (GS⁺) software, and to estimate the operation and maintenance costs of some home appliances (heating and cooling units). The inquiry scheme was to monitor the water quality of WDN of Saveh City (Iran), and 40 points from four districts on the WDN were sampled. The pH, temperature, electrical conductivity (EC), total dissolved solids (TDS), total alkalinity (TA), total hardness (TH), and calcium hardness (CH) were all measured and used to calculate various corrosion and scaling indices such as the Langlier saturation index (LSI), Ryznar stability index (RSI), Puckorius scaling index (PSI), and aggressive index (AI). The pH value for all districts follows EPA standards and WHO guidelines, with an average value of 7.92 ± 0.34. Overall, values of TDS (1728.83 ± 167.83 mg/L) and EC (3.53 ± 0.31 mS/cm) are relatively high, indicating brackish water quality. Furthermore, the TH and CH values are 519.55 ± 65.33 and 297.70 ± 69.44 mg/L, respectively, indicating a tendency to precipitate calcium carbonate (CaCO₃) and scale formation. According to spatial modeling, the highest R² = 0.640 achieved was related to the exponential model for the RIS index and showed a high confidence level for RIS data set and forecasted trends. The results of the spatial analysis demonstrated that the variation of the scaling tendency of water in the four districts of Saveh WDN followed the different sources of water supply. According to the cost estimates, people in the study area spend about 212,652 USD per year on the maintenance of household appliances. To provide better customer service, the water company needs to chemically improve water quality by modifying CH and TA concentrations for stable water and rethink network management strategies.

Pretreatment and fractionation technologies have been used to separate and isolate biomass polymers for conversion into fuels, chemicals, and other products. A great deal of work has focused on dialing in reaction conditions (e.g., time, temperature, acid concentration, etc.) that are amenable to isolating an uncondensed lignin product that could be converted into high value aromatic platform molecules. Pretreatment severity emerged as a term that combines time, temperature, and acid concentration into a single value that can be used to compare various pretreatment technologies. However, combining the effects of these conditions into a single term, while convenient, confounds the effects that these conditions have on lignin quality, both individually and when they are combined with each other. Moreover, pretreatment and fractionation reactors do not have a severity “knob,” and several different sets of conditions could mathematically achieve the same severity but have different effects on the resulting lignin product slate. In this study, we set out to model the effects of time (10–30 min), temperature (140–180 °C), and acid concentration (0.025–0.1 M H₂SO₄) on lignin yield (up to quantitative), molecular weight (Mw = 700–2000 g/mol), and hydroxyl group content (3.55–6.06 mmol OH/g) using the co-solvent enhanced lignocellulosic fractionation (CELF) process on switchgrass. Our results show that the lignin yield is most sensitive to acid concentration, with an additional 4.96% yield per 10 mM of acid. In addition, molecular weight is sensitive to acid concentration and temperature, with a decrease of 77.9 g/mol per 10 mM of acid and a decrease of 19.3 g/mol per °C. Moreover, total hydroxyl group content decreases at a rate of 89 μmol total OH per g lignin per min at short time (t = 12 min, T = 160 °C) and is increases at a rate of 125 μmol total OH per g lignin per min at long time (t = 28 min, T = 160 °C). Finally, our results demonstrate that the residence time does not have a statistically significant effect on yield or molecular weight within the studied ranges, which could have implications for continuous and flow-through processes, where short residence times could lead to substantial cost savings. Overall, these results demonstrate that practitioners can design a process that maximizes one or more of the industrially relevant lignin properties by exerting careful control of fractionation conditions, which could ultimately lead to greater utilization of lignin for fuels, chemicals, and other products.

Controlling the distribution of cross-links within a polymeric network is challenging using conventional methods, which often involve random chain scission to achieve a higher gel fraction. Here, we engineer a molecule to facilitate “homo-cross-linking”, enabling precise control over the cross-link distribution and micro phase separation. Establishing a closed-loop circular economy within the plastics or polymer industry is imperative. However, efficiently managing post-consumer recycled (PCR) plastics, including their collection, sorting, and processing, remains a significant challenge. While dynamic cross-linking of virgin polypropylene (PP) has advanced plastic upcycling, its application to PCR PP is limited. This study presents a simple and scalable approach to convert PCR PP into cross-linked PCR PP, enhancing their mechanical strength and rheological properties and enabling circular upcycling. Utilizing a designer dynamic cross-linker, imine installed castor oil (iCO), we establish a dual dynamic covalent adaptable network (CAN) that bridges fragmented maleated-PP chains within the PCR PP matrix besides rendering “homo-cross-linking” in the cross-linked polymer. This local “cross-link distribution” within the “global” matrix (PCR PP) overcomes challenges in upcycling PCR PP, which often undergoes global chain scission during network formation, as observed in other reports. Even at higher cross-linker concentrations (up to 30 wt %), there is minimal impact on percentage crystallinity, promoting amorphous miscibility within the PCR PP and no significant phase separation which has been observed by SAXS and SEM analysis. Cross-linked PCR PP exhibits superior dimensional stability and re-processability, retaining over 90% of their mechanical properties after three rounds of rigorous recycling involving extrusion followed by injection molding techniques. The ability to transform waste PP into a thermoformable material with reprocessing capabilities and favorable thermomechanical properties expands upcycling opportunities, thereby advancing circularity within the industry.