Alkaline treatment of antifoulant PVB/SA-grafted ε-MnO2 adsorptive nanocomposite membrane for synchronous separation of pollutants from pharmaceutical effluents

Abstract

Conventional membrane filtration processes suffer from severe fouling and permeance decrement due to the accumulation of co-existing pharmaceutical pollutants in pores and valleys of the surface of membranes. Adsorptive nanocomposite (ANC) membranes possess a double function of adsorption and filtration for synchronous separation of pollutants, nevertheless, nano-leaching is a considerable challenge for their applications. Herein, a new high-performance alkali-treated PVB/SA-grafted ε-MnO2 ANC membrane was fabricated through a facile phase inversion technique, and used for synchronous separation of Cd(II) ions and tetracycline (TC) from aqueous solutions. The chemical structure, elemental characteristic, surface and cross-section morphology, surface hydrophilicity, and surface topography of the fabricated alkali-treated ANC membrane (OH-PVB/SA-ε-MnO2) were respectively investigated through FTIR, XPS, FE-SEM, water contact angle and AFM techniques. The alkaline treatment enhanced the pure water flux from 311.54 to 394.62 L/m2.h.bar, which was much higher than that for the pristine PVB membrane. The rejection rates of Cd(II) and TC by the OH-PVB/SA-ε-MnO2 membrane were respectively 98.55 and 98.73 % at pH = 6. The flux recovery ratio of 99.04, 98.66 and 97.61 % was obtained after the first, second and third successive cycles respectively. This verified the excellent antifouling performance of OH-PVB/SA-ε-MnO2 membrane that was originated from the enhancement of hydroxyl group content.