Removal of nickel ions from synthetic wastewater by bulk liquid membrane

Heavy metals extraction and separation from industrial wastewater has becomes a majorconcern for both environmental and economic reasons. This paper describes a comparetive kinetic study ofthe removal and recovery of nickel ions from aqueous solutions by bulk liquid membrane (BLM) usingcoupled faciletated transport mechenisms and two carriers of diffarent chemical nature: tributyl phosphate(TBP) and di-2-ethylhexyl phosphoric acid (D2EHPA). Xylene oil was used as the liquid membrane phase.In addition, environmentall friendly materials such as vegetable oils (soybean oil) used as a suitablereplacement for the conventional organic solvents in this work. A comprahensive kinetic study was carriedout and effact of various parameters such as, pH of feed and stripping phase, initial concentration of metalions, concentration of extractant in the membrane phase and stirring speed were studied. The chelatingcharacteristics of EDTA was used as stripping agent as well as precipitating agent to enhance the transportefficiency of the nickel ions. The extraction and recovery efficiency were found as 80.89% and 87.80%respectively for nickel ions, At the optimum process conditions for transport of Ni(II) were found as follows:pH in the feed phase (4), pH in the stripping phase (8), initial concentration of nickel ions (120 ppm), carrierconcentration (12%) (v/v) TBP and stirring speed (125±10 rpm), respectively.