Investigation of process performance and fouling mechanisms in micellar-enhanced ultrafiltration of nickel-contaminated waters

Nickel removal from aqueous solution by micellar-enhanced ultrafiltration (MEUF) with relatively low transmembrane pressures was investigated at varying conditions of sodium lauryl ether sulfate (SLES) and nickel concentrations, transmembrane pressure and sodium chloride content. Process employed in continuous filtration mode, could be operated within a short time of 30 min presenting high rejection of nickel and SLES at high transient fluxes. Under the effect of increasing transmembrane pressure, the rejection of nickel and SLES increased, but the transient flux decreased. The existence of salt caused to decrease both rejections and flux. Nickel rejection, SLES rejection and flux were establihed as 98.6%, 75.7% and 0.304 m3/m2 h, respectively, for the conditions of surfactant to metal (S/M) ratio of 10 (SLES = 2 mM), transmembrane pressure of 250 kPa without NaCl content at the end of 90-min operation time. The analyses related to the membrane fouling were carried out using adsorptive fouling models. It has been determined that, the fouling occurs as a dynamic function of various process conditions studied, and depends strongly on mechanisms controlled by the formation of gel layer and its bridging over the pore entrances simultaneously together with partial constriction of membrane pores by surfactant adsorption.