L-Histidine doped-TiO2-CdS nanocomposite blended UF membranes with photocatalytic and self-cleaning properties for remediation of effluent from a local waste stabilization pond (WSP) under visible light

Abstract

In this study, a dual photocatalyst of TiO2-CdS doped by C, N nonmetals with the aid of l-Histidine (C, N-doped TiO2-CdS) was synthesized and then incorporated into polyethersulfone (PES) ultrafiltration (UF) membrane matrix in order to endow photocatalytic and self-antifouling properties. The resulting photocatalytic nanocomposite was first characterized by analyses of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL), and UV–Vis diffuse reflectance spectroscopy (DRS). The fabricated membranes were identified through tests of SEM, contact angle and Atomic force analysis (AFM). The membranes performance was evaluated in terms of pure water flux (PWF) and antifouling experiments in a dead end set up. To find out optimum conditions and investigate photocatalytic properties under continuous visible light irradiation, the impacts of two operating variables, i.e. working pressure (P, 1−5bar) and cross flow rate (Q, 50−150L/h) at three levels on four responses were investigated in a continuous regime using filtration of effluent from waste stabilization pound (WSP). From the results, the highest PWF, FRR and Rr were found to be 80.37kg/m2h, 80. 2 %, and 56. 1 % for the membrane modified by 0.5wt. % C, N doped TiO2-CdS contrast to 60.69kg/m2h, 33 % and 15.6 % obtained for the control membrane. At optimum conditions, i.e. 3bar and 150L/h, the values of PWF, FRR and COD removal were 150.6kg/m2h, 89.5 % and 65.26 %, respectively. An improvement of 1.4, 1.5 and 1.3 times in PWF, FRR, and COD removal, respectively, were achieved for the 0.5wt.% membrane under visible light irradiation compared to the control one. These results were attributed to super hydrophilicity, photocatalytic properties and self-antifouling.