Removal of nickel ions from synthetic wastewater by bulk liquid membrane
Heavy metals extraction and separation from industrial wastewater has becomes a major
concern for both environmental and economic reasons. This paper describes a comparetive kinetic study of
the removal and recovery of nickel ions from aqueous solutions by bulk liquid membrane (BLM) using
coupled 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 suitable
replacement for the conventional organic solvents in this work. A comprahensive kinetic study was carried
out and effact of various parameters such as, pH of feed and stripping phase, initial concentration of metal
ions, concentration of extractant in the membrane phase and stirring speed were studied. The chelating
characteristics of EDTA was used as stripping agent as well as precipitating agent to enhance the transport
efficiency 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), carrier
concentration (12%) (v/v) TBP and stirring speed (125±10 rpm), respectively.