Abstract
The extraction of Zinc (II) in acetate medium with di (2-ethylhexyl) phosphoric acid (D2EHPA) in chloroform diluent was investigated under different experimental conditions, in order to have a better understanding of the extraction mechanism. The extraction yield was found to depend on the concentrations of Zinc (II) and D2EHPA, and the equilibrium pH. The effects of acetic acid and the salting-out agent were also studied. The nature of the extracted species was investigated by the slope analysis method. Graphs of log D vs. log [D2EHPA] and log D vs. pH were plotted for Zn (II), and the species extracted into the organic phase was found to have the composition (ZnCH3COO)R.HR. The best performance was reached (80%) with zinc concentrations lower than 5 mM in a neutral medium. The extraction yield of metals decreased as the acetic acid concentration increased with any given extractant concentration. The addition of sodium acetate to the aqueous phase strongly increased the zinc extraction yield (99.5%). A synergistic effect was observed by the addition of tributhylphosphate (TBP) with the organic phase.
Highlights
Heavy metals, apart from being hazardous for living organisms when exceeding the specific limits, have accumulating characteristics in nature as they cannot be biodegraded (Veli et al, 2007)
The extraction yield increased while increasing the O/A molar ratio, for 0.05 M of di (2-ethylhexyl) phosphoric acid (D2EHPA) concentration (Ymax= 83.53%)
The maximum of the extraction yield is reached for a value of O/A equal to 1 (Ymax = 51.17%) for 0.01 M of D2EHPA concentration
Summary
Apart from being hazardous for living organisms when exceeding the specific limits, have accumulating characteristics in nature as they cannot be biodegraded (Veli et al, 2007). The main symptoms of poisoning are dehydration, electrolyte imbalance, stomachache, nausea, dizziness and incoordination in muscles (Jain et al, 2004) These metals can be treated from wastewater by using various physicochemical methods like Adsorption, chemical settling, reverse osmosis and solvent extraction which are the most frequently used methods. They are used for the purification of the liquid effluents likely to contain heavy metals (Ritcey et al, 1979). Mellah et al (2006) reported the solvent extraction of zinc and cadmium from a phosphoric acid solution using D2EHPA diluted in kerosene, and proposed some compounds, such as ZnA2 www.ccsenet.org/ijc. The organic solvent, di (2-ethylhexyl) phosphoric acid in chloroform diluents, was used for the extraction of zinc from an aqueous acetate medium in one step.
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