Study on PVDF-TiO2 mixed-matrix membrane behaviour towards humic acid adsorption

Despite the expansion and successful application of membrane systems in water industry, membrane fouling which predominantly caused by the irreversible adsorption is still a critical problem. The objective of this work is to study the adsorptive behaviour of membrane for the removal of humic acid (HA). Apart of neat membrane that has very often been used in adsorption study, PVDF-TiO2 mixed-matrix membranes (MMMs) with varied titanium dioxide (TiO2) concentration (0.001 g/L, 0.01 g/L, and 0.1 g/L) were explored in the present work. A dynamic stirring cell with continuous stirring for 24 h at 250 rpm was applied in this study. Different operating parameters such as initial HA solution concentration, calcium chloride (CaCl2) concentration, and HA solution pH were performed in this study. HA adsorption ratio in each single batch of experiment was determined by measuring the HA adsorbance as a function of time. The results, interpreted in terms of adsorption ratio (A/A0) yield severe HA adsorption at low pH and high initial HA solution concentration. In addition, it was found that, increased CaCl2 concentration reduces the electrostatic repulsion between HA aggregates and membrane surface, consequently appears to be more adapted to HA adsorption.