Streaming potential for identification of foulants adsorption on PVDF membrane surface

The streaming potential was used for foulant adsorption analysis on a PVDF membrane surface. Bovine serum albumin (BSA), sodium humate (SH) and sodium alginate (SA) solutions of different concentrations, pH and combinations were tested for adsorption. The pH and particle size of the different solutions were measured to identify their relationship to adsorption. During adsorption, the streaming potential increased constantly until adsorption equilibrium. Compared to 1 mg/L and 5 mg/L solutions, the higher concentrations of 25 mg/L and 125 mg/L solution could greatly enhance adsorbance under all conditions. For single-component solutions, the SH and SA showed much higher adsorbability than BSA, and the adsorption of SA played the dominate role in the mixed solution. However, no obvious relationship was observed between zeta potential/particle size and adsorbance. The streaming potential change indicated adsorption on the PVDF membrane surface was in the order of SA > SH > BSA. For 250 mL of foulant solution filtration under 0.1 MPa, it lasted 4.5 min, 5.3 min, 16.5 min and 12.3 min for BSA, SH, SA and the mixed solution, respectively, with 25 mg/l of concentration, which indicated that the results of streaming potential change accorded well with the membrane fouling condition.