Production of natural zeolite-filled recycled PVDF filters and their application for gray water treatment†

In this study, clinoptilolite (Clp)-doped poly(vinylidene fluoride) (PVDF) membranes (1–4 wt%) were prepared using an electrospinning method. Further, filtration tests on the simulated gray water components were investigated. Methylene blue (MB), linear alkyl benzene sulfonate (LAS), oil (soybean oil), and microplastic (MP) filtration were performed. MB filtration with the PVDF membrane resulted in over 99% of MB rejection. Oil rejection with the PVDF membrane without Clp was observed to be 95%, while the addition of Clp increased the oil rejection to over 99%. It was observed that LAS rejection increased as the Clp content increased. MP rejection using PVDF-based membranes was 100%. Considering all the test results, the membrane containing 3 wt% Clp showed the best performance, and the process parameters and rejection efficiencies were determined through experimental optimization. Synthetic gray water analyses included the chemical oxygen demand (COD), pH, conductivity, and total dissolved solids (TDS). COD rejection was 63.1%, while turbidity rejection was 97.2%.