Research on the mechanism of nanofiltration membrane fouling in zero discharge process of high salty wastewater from coal chemical industry

Abstract

Abstract The influence of representative typical pollutants in the zero-discharge process of coal chemical high-salty wastewater on the fouling behavior of nanofiltration membranes was studied. In this study, a commercially available NF90 nanofiltration membrane was selected, with three inorganic salts, cyclohexanol (C6H12O) and APAM as the main target foulants. Various membrane samples were characterized by Contact angle, AFM and SEM-EDS, and the membrane fouling behavior was quantitatively evaluated by analyzing the influence of the interaction between different components in the feed solution on the membrane flux and interface thermodynamics. The results show that the deposition of fouling is closely related to the interface free energy (ΔG). The AB interfacial energy significantly affects membrane fouling. Membrane fouling is mainly dominated by residual APAM, followed by inorganic salts and cyclohexanol. The interaction between organic and inorganic fouling is the core factor that exacerbates membrane fouling. The interaction between APAM and inorganic salt ions mainly accelerates membrane fouling through charge shielding and complexation. Cyclohexanol accelerates membrane fouling mainly by reducing the solubility of inorganic salts and absorbing on the surface of the fouling layer. The competition and synergy between hydrophilic APAM and hydrophobic cyclohexanol are also the factors that aggravate membrane fouling.