Synergetic facilitated transport of nickel via supported liquid membrane process by a mixture of Di (2-ethylhexyl) phosphoric acid and n-octanol: Kinetic permeation study and approach for a green process

Abstract

This work addresses the synergistic removal of nickel from the electroplating wastewater using a supported liquid membrane (SLM) process. The supported liquid membrane formulation consisting of Di-2-ethylhexyl phosphoric acid (D2EHPA), n-octanol, kerosene, and sulfuric acid as a carrier, synergist, diluent, and stripping agent, respectively. The effects of several significant parameters namely D2EHPA, n-octanol, and sulfuric acid concentrations as well as feed and stripping phases flow rates were investigated. Results revealed that n-octanol as a synergist significantly affected the removal efficiency of nickel since it can modify the D2EHPA molecules in the membrane phase. Besides, a kinetic model for the nickel ion transport across SLM revealed that the transport resistances due to the diffusion across the membrane (Δorg), transport resistances due to the diffusion through the aqueous boundary layer (Δaq), thickness of the aqueous diffusion layer (daq), and diffusion coefficient of the nickel-carrier complex across the membrane (Dorg) were found to be 2.90 × 105 sm−1, 1.94 × 104 sm−1, 1.24 × 10−5 m and 7.20 × 10−10 m2s−1, respectively. Interestingly, an approach to a green process by incorporating palm oil as a diluent showed that it is feasible to be applied and offers a green SLM process in the future.