Surface and internal modification of composite ion exchange membranes for removal of molybdate, phosphate, and nitrate from polluted groundwater

Abstract

Al 2 O 3 /chitosan-multiwall carbon nanotubes (MWCNTs) were created to increase the exchange capacity of polyvinylidene fluoride (PVDF) ion-exchange membranes. The composite membranes were made by mixing Al 2 O 3 nanoparticles into the PVDF cast solution, then applying a thin coating of chitosan functionalized carbon nano tubes (Cs-MWCNTs) to the PVDF membrane surface. The structure and characteristics of the hybrid membranes were described using XRD, SEM, IR, and TG-DTA. The Al 2 O 3 -PVDF/Cs-MWCNTs membrane beat the other Al 2 O 3 -PVDF/Cs, Al 2 O 3 -PVDF, and PVDF membranes in terms of molybdate, phosphate, and nitrate adsorption. The removal efficiency, pH solution, adsorption capacity, and desorption process of molybdate, phosphate, and nitrate anions by Al 2 O 3 -PVDF and PVDF membranes were investigated. The removal effectiveness of molybdate, phosphate, and nitrate, according to the testing findings, was 94.3, 65.6, and 85.78 %, respectively. The adsorption of MoO 4 2− , PO 4 3− , and NO 3 − increased as the pH increased initially until the best adsorption was achieved, and then decreased significantly as the pH increased further. The total adsorption capabilities of MoO 4 2− , PO 4 3− , and NO 3 − for the Al 2 O 3 -PVDF/Cs-MWCNTs membrane were 65.50, 61.22, and 59.77 mg/g, respectively. Using regeneration and reuse experiments for the simultaneous adsorption of molybdate, phosphate, and nitrate during three consecutive cycles, the adsorption/desorption of Al 2 O 3 -PVDF/Cs-MWCNTs was assessed. Al 2 O 3 -PVDF/Cs-MWCNTs offer a lot of promise when it comes to eliminating MoO 4 2− , PO 4 3− , and NO 3 − from actual wastewater samples.