Simplified creation of polyester fabric supported Fe-based MOFs by an industrialized dyeing process: Conditions optimization, photocatalytics activity and polyvinyl alcohol removal

Green separation and decomposition of crystalline silicon photovoltaic module's backsheet by using ethanol

The treatment and recycling of discarded crystalline silicon photovoltaic modules (c-Si PV modules) has become a research focus, but few research have paid attention to the standardized treatment of c-Si PV module's fluorinated backsheet. Improper management of fluorinated backsheet can pose ecological and human health risks. Therefore, this study presents a novel method for processing the backsheet. The proposed approach entailed the utilization of ethanol (CH3CH2OH) to separate the backsheet from the PV module. Subsequently, the separated backsheet underwent decomposition using an alkaline ethanol (NaOH-CH3CH2OH) solution. Finally, the backsheet was recovered in the form of terephthalic acid (TPA) with a purity of 97.47 %. This recovered TPA can then serve as a valuable raw material for producing new backsheets, fostering a closed-loop material circulation. Experimental results demonstrate that immersing the PV module in a 75 % CH3CH2OH-H2O solution at a temperature of 343 K for 30 min achieved 100 % separation of the backsheet. Furthermore, subjecting the separated backsheet to a 60 min reaction in an NaOH-CH3CH2OH solution with a temperature of 343 K and a NaOH concentration of 1.0 mol/L achieved complete decomposition. The reaction mechanism was analyzed through characterization methods such as SEM/EDS, NMR, FTIR and XRD. This method is efficient, non-toxic organic reagent-free and environmentally friendly, so it holds significant potential for further development in the field of c-Si PV module recycling.

The interactions between mixed waste from discarded surgical masks and face shields during the degradation in supercritical water

The widespread use of surgical masks made of polyolefin and face shields made of polyester during pandemics contributes significantly to plastic pollution. An eco-friendly approach to process plastic waste is using supercritical water, but the reaction of mixed polyolefin and polyester in this solvent is not well understood, which hinders practical applications. This study aimed to investigate the reaction of waste surgical masks (SM) and face shields (FS) mixed in supercritical water. Results showed that the optimal treatment conditions were 400 °C and 60 min, achieving a liquid oil yield of 823.03 mg·g-1 with 25 wt% FS. The interaction between polypropylene (PP), polyethylene terephthalate (PET), and iron (Fe) in SM and FS mainly determined the production of liquid oil products such as olefins and benzoic acid. The methyl-branched structure of PP enhanced PET hydrolysis, resulting in higher production of terephthalic acid (TPA). The degradation of PP was facilitated by the acidic environment created by TPA and benzoic acid in the reaction. Moreover, the hydrolysis of PET produced carboxylic acid, which coordinated with Fe3+ to form Fe-H that catalyzed the polymerization of small olefins, contributing to higher selectivity for C9 olefins. Therefore, this study provides valuable insights into the degradation mechanism of mixed PPE waste in supercritical water and guidance for industrial treatment.

Solid-phase extraction and separation of indium with P2O4-UiO-66-MOFs (di-2-ethylhexyl phosphoric acid-UiO-66-metal-organic frameworks)

Compared with the traditional liquid-liquid extraction method, solid-phase extraction agents are of great significance for the recovery of indium metal due to their convenience, free of organic solvents, and fully exposed activity. In this study, P₂O₄ (di-2-ethylhexyl phosphoric acid) was chemically modified by using UiO-66 to form the solid-phase extraction agent P₂O₄-UiO-66-MOFs (di-2-ethylhexyl phosphoric acid-UiO-66-metal-organic frameworks) to adsorb In(III). The results show that the Zr of UiO-66 bonds with the P-OH of P₂O₄ to form a composite P₂O₄-UiO-66-MOF, which was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The adsorption process of indium on P₂O₄-UiO-66-MOFs followed pseudo first-order kinetics, and the adsorption isotherms fit the Langmuir adsorption isotherm model. The adsorption capabilities can reach 192.8 mg/g. After five consecutive cycles of adsorption-desorption-regeneration, the indium adsorption capacity by P₂O₄-UiO-66-MOFs remained above 99%. The adsorption mechanism analysis showed that the P=O and P-OH of P₂O₄ molecules coated on the surface of P₂O₄-UiO-66-MOFs participated in the adsorption reaction of indium. In this paper, the extractant P₂O₄ was modified into solid P₂O₄-UiO-66-MOFs for the first time. This work provides a new idea for the development of solid-phase extractants for the recovery of indium.

Fabrication of Multifunctional Electronic Textiles Using Oxidative Restructuring of Copper into a Cu-Based Metal-Organic Framework

This paper describes a novel synthetic approach for the conversion of zero-valent copper metal into a conductive two-dimensional layered metal-organic framework (MOF) based on 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) to form Cu3(HHTP)2. This process enables patterning of Cu3(HHTP)2 onto a variety of flexible and porous woven (cotton, silk, nylon, nylon/cotton blend, and polyester) and non-woven (weighing paper and filter paper) substrates with microscale spatial resolution. The method produces conductive textiles with sheet resistances of 0.1-10.1 MΩ/cm2, depending on the substrate, and uniform conformal coatings of MOFs on textile swatches with strong interfacial contact capable of withstanding chemical and physical stresses, such as detergent washes and abrasion. These conductive textiles enable simultaneous detection and detoxification of nitric oxide and hydrogen sulfide, achieving part per million limits of detection in dry and humid conditions. The Cu3(HHTP)2 MOF also demonstrated filtration capabilities of H2S, with uptake capacity up to 4.6 mol/kgMOF. X-ray photoelectron spectroscopy and diffuse reflectance infrared spectroscopy show that the detection of NO and H2S with Cu3(HHTP)2 is accompanied by the transformation of these species to less toxic forms, such as nitrite and/or nitrate and copper sulfide and Sx species, respectively. These results pave the way for using conductive MOFs to construct extremely robust electronic textiles with multifunctional performance characteristics.