Nickel removal from waters using surfactant-enhanced hybrid PAC/MF process. I. The influence of system-component variables

This study takes aim at exploring the effectiveness of a surfactant-added powdered activated carbon/microfiltration (PAC/MF) hybrid process in the removal of nickel ions from water and wastewater as a promising technology. For this aim, the influence of system-component variables related to membrane material and pore size, and adsorbent and surfactant types was investigated, Nickel rejection (R_M), surfactant rejection (R_S), and steady-state flux (J*) were taken into account for more elaborately assessing the technical performance of the process. It was determined that the use of a surfactant in this process is justified only above the critical micellar concentration (CMC). Despite the increasing of nickel rejection with the addition of surfactant into the hybrid membrane process, a considerable decrease in steady-state flux is a major drawback of process. The flux decline observed was strongly dependent on surfactant type. This was interpreted as being due to a secondary membrane layer formed by surfactant micelles on the surface and within the membrane pores. The flux decline could also be related to PAC layer formation. Membrane, adsorbent, and surfactant types seem to have the highest relative influence on R_M, R_S, and J*, respectively. As a conclusion, surfactant type and membrane pore size were established as having the biggest and the smallest total influence on process performance, respectively.