Structure-property relationships of PVDF membranes incorporating GPTMS-modified lignosulfonate for reactive dye separation

This study explores the fabrication of polyvinylidene fluoride (PVDF) membranes incorporating (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) modified lignosulfonate as a filler for reactive dye filtration. The addition of the modified lignosulfonate altered the membrane morphology, with increases observed in the β-phase fraction, porosity, and pore size. The modified membranes exhibited enhanced hydrophilicity, while the surface roughness decreased at low filler loadings (PLSG0.5 and PLSG1) and increased at higher filler concentrations due to filler aggregation. The PLSG1 membrane exhibited the optimal balance of surface properties and filtration performance. The PLSG1 membrane demonstrated rejection rates of 99.08%, 97.75%, and 91.71% for Reactive Blue 4 (RB4), Reactive Violet 5 (RV5), and Reactive Yellow 145 (RY145), respectively. Statistical analysis confirmed that membranes containing moderate lignosulfonate loading exhibited significantly improved filtration performance compared with pristine PVDF and membranes containing excessive filler. Flux recovery ratio (FRR) analysis demonstrated the superior antifouling performance of the PLSG1 membrane, which maintained the highest fifth-cycle FRR and the lowest irreversible fouling ratio among the membrane formulations. This work highlights the potential of GPTMS-modified lignosulfonate as a sustainable additive for fabricating high-performance PVDF membranes for treating reactive dye-laden wastewater.