Titanium dioxide incorporated in polyvinylidene fluoride hollow fiber membrane for carbaryl removal and degradation

Pesticide accumulation and environmental dispersion pose significant concerns in agricultural practices. This study investigates the kinetics of carbaryl removal from synthetic wastewater using photocatalytic membranes fabricated from polyvinylidene fluoride (PVDF) loaded with titanium dioxide (TiO₂) nanoparticles of two sizes: 25 nm (P25) and 100 nm (P100). The PVDF hollow fiber membranes, incorporating 2% w/w TiO₂, were produced via the dry-jet wet spinning method. Characterization of the membranes included analysis of morphology, mechanical properties, and chemical functional groups. The carbaryl removal performance was evaluated using a PVDF/TiO₂ microfiltration membrane with an approximate pore size of 0.5 µm in a 2.0 L batch photocatalytic membrane reactor (PMR), under conditions both with and without UV illumination. Results indicate that TiO₂ particle size significantly impacts membrane morphology and separation performance. Membranes with smaller TiO₂ particles demonstrated higher mechanical strength and a more uniform particle distribution. Water flux measurements revealed slightly higher values for membranes with smaller TiO₂ particles, at 18.28 ± 0.90 L/m² h for PVDF/TiO₂-P25 and 17.93 ± 0.91 L/m² h for PVDF/TiO₂-P100. Carbaryl degradation was significantly more efficient with smaller TiO₂ particles, achieving 99% removal within 20 min, compared to 48% removal by membranes with larger particles. The photocatalytic degradation kinetics of carbaryl adhered to a first-order reaction model, with rate constants (k) ranging from 0.040 to 0.375 mg-Carbaryl/L min. The enhanced specific surface area of smaller TiO₂ particles contributes to their superior photocatalytic activity and increased carbaryl removal efficiency.