Catalytic performance of polyvinylidene fluoride (PVDF) supported TiO2 additive at microwave conditions

Transfiguration of discarded PVDF ultrafiltration membranes: Optimization of pyrolysis parameters for high-value char production

Disposing vast amounts of non-biodegradable wastes presents engineering and economic challenges to environmental management globally. Concomitantly, recycling and upcycling of non-biodegradable materials can play a crucial role in sustainable waste management, reducing the need for raw material extraction and energy-intensive manufacturing. Accordingly, this study aimed to explore the utilization of discarded polyvinylidene fluoride (PVDF) ultrafiltration membranes for char production via optimized pyrolysis. The Generalized Reduced Gradient (GRG) optimization method was applied to predict the optimal final temperature (T) and residence time (t) to achieve the maximum membrane char (MC) iodine number under reasonable conditions. Factorial analysis revealed curvature in the model with a p-value of 0.001 at a 95 % confidence interval, indicating the potential applicability of the response surface method (RSM). The optimized pyrolysis (584 °C; 111 min) achieved an average yield of 31.3 ± 2.6 % of MC with an iodine number of 242.35 mg/g. The structural, surface, and textural properties of PVDF fibers and MC were extensively characterized. Thermal analysis of discarded PVDF confirmed the oxidative breakdown of the fluorinated polymer and the revocation of the C-F bond. Moreover, the Raman and FTIR spectral analysis revealed the coexistence of β- and γ- crystalline phases in the PVDF fiber. Consequently, the produced MC demonstrated superior carbon properties and high potential application for various industrial and environmental purposes, aligning with the circular economy approach for reutilizing discarded PVDF membranes.

Pollution Removal Performance of Chemically Functionalized Textile Waste Biochar Anchored Poly(vinylidene fluoride) Adsorbent

Preparation of adsorbent materials in powder and polymeric composite form was achieved by controlled carbonization of ZnCl2 pretreated textile waste at low temperatures. Structural and surface properties of carbonized textile waste samples (CTW) and polymeric composites were prepared by the addition of CTW to PVDF-DMF solution at 0, 5, 10, 15, 20, and 30 mass% ratios analyzed by FT-IR, XRD, SEM, and BET analysis. Adsorption performances of powder and composite adsorbents were investigated for MO dye removal from an aqueous solution. Zn-CTW obtained with carbonization of ZnCl2 treated textile waste at 350 °C presented 117.5 mg/g MO removal. Those were higher than CTW-350 and CTW-400. The presence of 1545 cm-1 band at the IR spectrum of Zn-CTW proved the formation of functional groups that increase dye adsorption performance with honeycomb-like pores on the surface. Zn-CTW reflected its properties onto the PVDF matrix. Improved porosity percentage, BET surface, and dye adsorption of Pz20 were recorded as 105.3, 15.22 m2/g, and 41 mg/g, respectively, compared with bare PVDF. Disposal of textile waste and preparation of functional activated carbon were achieved in a low-cost and easy way. Zn-CTW loaded PVDF composites are promising materials to use as a dye removal adsorbent from water or filtration membranes.