Effect of Thermal Treatment on the Phase Composition and Surface Properties of WO 3 ‐TiO 2 Nanocomposites Synthesized via Hydro‐Thermal Method

Optimization and reusability of photocatalytic g-C3N4/W-TiO2/PVDF membranes for degradation of sulfamethazine

Pharmaceuticals and personal care products (PPCPs) are prevalent emerging pollutants in the aquatic environment. The photocatalysis process has proven high efficiency in degrading PPCPs; however, the fate and repercussions of photocatalyst residuals are a major concern. To avoid that, we developed a composite from graphitic carbon nitride/tungsten doped with titanium dioxide (g-C3N4/W-TiO2) and loaded it on polyvinylidene fluoride (PVDF) membranes by the phase-inversion method. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and other different analyses implied the successful synthesis of g-C3N4/W-TiO2 composite and coating on PVDF membranes. A Box-Behnken design (BBD) was used to optimize the operational parameters, including pH, g-C3N4 ratio in the composite, and initial SMZ concentration by the response surface methodology (RSM). The highest SMZ degradation percentage was 98.60% after 240 min of irradiation. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) along with suspect screening was used to identify the intermediate transformation products and propose the SMZ degradation pathway. The loss in membrane activity after five cycles of photocatalytic degradation was about 18%. According to the current study, the photocatalytic membrane g-C3N4/W-TiO2/PVDF is promising for removing sulfonamide antibiotics from wastewater.

Ultrasonically assisted hydrothermal synthesis of tungsten(VI) oxide-TiO2 nanocomposites for enhanced photocatalytic degradation of non-narcotic drug paracetamol under natural solar light: insights into degradation pathway, mechanism, and toxicity assessment

Photocatalytic degradation of pharmaceutical residues through natural solar radiation represents a green and economical treatment process. In this work, ultrasonically assisted hydrothermal synthesis of WO3-TiO2 nanocomposite was carried out at 140-150 °C for 5 h and calcinated at 600 °C. The structural and optical properties of the synthesized material were investigated using techniques like XRD, FESEM/EDX, HRTEM, BET surface area, UV-DRS optical analysis, and photocurrent response. The band gap of TiO2 was successfully reduced from 3.0 to 2.54 eV and thus making it effective under solar light. Complete degradation of paracetamol (50 ppm and natural pH of 6.5) was achieved in 3.5 h under natural sunlight at catalyst dose of 0.5 g/l. The extent of mineralization was evaluated by measuring the COD reduction. Based on the degradation products identified by GC-MS/LC-TOF-MS, the degradation process under natural solar-light could be interpreted to initiate through OH. radical species. The toxicity removal of the treated paracetamol solution under natural solar-light was evaluated by the seed germination test using Spinacia oleracea seeds and exhibited 66.70% seed germination, confirming the reduction in toxicity. The enhanced photocatalytic efficiency of the nanocomposite is attributed to the higher surface area, low rutile content, lower band gap, and incorporation of WO3, which led to an extended absorption range and a slower rate of electron-hole recombination. The technical insights presented in this research offer a feasible approach for utilizing natural solar light driven photocatalysis for wastewater treatment in an efficient and sustainable way. The proposed degradation pathway, and seed germination test (toxicity removal) of the treated paracetamol solution under natural sunlight, has not been previously evaluated.