Synthesis of PVDF-chitosan-copper oxide composite membranes for the removal of tetracycline from wastewater

Abstract

In this study, poly(vinylidene fluoride) (PVDF) composite membranes were prepared by intercalating chitosan (CS) and copper oxide nanoparticles (CuO NPs) for the treatment of tetracycline (TC) from water. The synergistic effect of CS and CuO NPs significantly improved the dispersion and physicochemical characteristics of PVDF membranes. The PVDF composite membranes with 15 wt.% PVDF, 1 wt.% CS, and 2 wt.% CuO demonstrated an interconnected porous structure and improved surface functionalities, crystallinity, and hydrophilicity, which facilitated excellent TC rejection and water permeability. The PVDF-CS-CuO composite membrane exhibited a TC rejection of 57% at pH 6, a concentration of 50 mg L−1, and a pressure of 4 bar, which is 1.85 times higher than that of the pristine PVDF membrane. The water permeability increased 3.8 times (from 52 LMH to 249 LMH) compared to the PVDF membrane (52 LMH), due to a decrease in the water contact angle from 100° to 60°. The adsorption performance of PVDF and PVDF-CS-CuO composite membranes indicated the highest removal of TC at pH 9, and a maximum adsorption capacity of 8.3–7.1 mg g−1. The adsorption data were well fitted to the Langmuir isotherm and Avrami kinetic models, demonstrating that chemical interactions are the dominant adsorption mechanism. The PVDF composite membrane showed excellent reusability with only 6% decrease in TC rejection performance after five consecutive cycles. The results indicated that incorporating an appropriate amount of inorganic (CuO-NPs) nano-fillers with biopolymer (CS) in the PVDF membrane matrix resulted in a high-performance composite membrane for the efficient remediation of pharmaceutical contaminants from wastewater streams.