Optimization of Process Parameters using Response Surface Methodology for the Removal of Zinc(II) by Solvent Extraction
 D. Beyersmann , H. Haase, “Function of zinc in signaling, proliferation and differentiation of mammalian cells,” Biometals, vol .14 , pp. 231-341, 2001.
 N. Wellinghausen, H. Kirchner, and L. Rink, “The Immunobiology of Zinc,” Immunol. Today, vol. 18, pp. 519-552, 1997.
 Olugbenga J. Owojori, Adriaan J. Reinecke, and Andrei B. Rozanov, “Effet of salinity on partitioning, uptake and toxicity of zinc in the earthworm Eisenia fetida,” Soil Biology et Biochemistry, vol. 40, pp. 2385-2393, 2008.
 Wei-Chun ma, Luc T.C. Bonten, “Bioavailability pathways underlying zinc-induced avoidance behavior and reproduction toxicity in Lumbricus rubellus earthworms,” Ecotoxicology and Environmental Safety, vol. 74, pp. 1721-1726, 2011.
 S. Azabou, T. Mechichi, and S. Sayadi,” Zinc precipitation by heavy-metal tolerant sulfate-reducing bacteria enriched on phosphogypsum as a sulfate source,” Miner. Eng., vol. 20, pp. 173-178, 2007.
 M. Stasiak, M. Regel-Rosocka, and A. Brorowiak-Resterna, Zinc extraction from chloride solutions with mixtures of solvating and chelating reagents,” Hydrometallurgy, vol 162, pp. 57-62, 2016.
 F. Tang, X. Li, C. Wei, G. Fan, R. Zhu, and C. Li,” Synergistic extraction of zinc from ammoniacal/ammonia sulfate solution by a mixture of β-diketone and 2-hydroxy-5-nonylacetophenone oxime,” Hydometallurgy, vol. 162, pp; 42-48, 2016.
 B. Guezzen, M. A. Didi, “Removal of Zn(II) from Aqueous Acetate Solution Using Di (2-Ethylhexyl) Phosphoric Acid & Tributylphosphate,” International Journal of Chemistry, vol.4, pp. 32-41, 2012.
 J. Plaza Cazon, M. Viera, E. Donati, and E. Guibal, “Zinc and cadmium removal by biosorption on Undaria pinnatifida in batch and continuous processes,” Journal of Environmental Management, vol. 129, pp. 423-434, 2013.
 S. Afroze, T. Kanti Sen, and H. Ming Ang, “Adsorption removal of zinc (II) from aqueous phase by raw and base modified Eucalyptus sheathiana bark: Kinetics, mechanism and equilibrium study,” Process Safety and Environmental Protection, vol. 102, pp. 336-352, 2016.
 M.F. San Roman, I. Ortiz Gandara, R. IBnez, I. Ortiz, “Hybrid membrane process for the recovery of major components (zinc, iron and HCl) from spent pickling effluents,” Journal of Membran Science, vol. 415, pp. 616-623, 2012.
 M.A. Martín-Lara, I.L. Rodríguez, G. Blázquez, M. Calero, “Factorial experimental design for optimizating the removal conditions of lead ionsfrom aqueous solutions by three wastes of the olive-oil production,” Desalination, vol. 278, pp. 132-140, 2011.
 S. J. Nejad, H. Abolghasemi, Mohammad A. Moosaviana, Mohammad G. Maragheh, “Fractional factorial design for the optimization of supercritical carbon dioxide extraction of La3+, Ce3+ and Sm3+ ions from a solid matrix using bis(2,4,4-trimethylpentyl)dithiophosphinic acid + tributylphosphate,” chemical engineering research and design, vol. 89, pp. 827-835, 2011.
 N. Ozturk, D. Kavak, “Boron removal from aqueous solutions by adsorption on waste sepiolite and activated waste sepiolite using Full Factorial design,” Adsorption, vol.10, pp. 245-257, 2004.
 B. Guezzen, M. A. Didi, “Removal and Analysis of Mercury (II) From Aqueous Solution by Ionic Liquids,” J Anal Bioanal Tech, vol.7, 1-8, 2016.
 W. Thanasarakhan, S. Liawruangrath, S. Wangkarn, and B. Liawruangrath, “Sequential injection spectrophotometric determination of zinc (II) in pharmaceuticals based on zinc (II)–PAN in non-ionic surfactant medium,” Talanta, vol. 71, pp. 1849-1855, 2007.
 K. Vimalashanmugam, T. Viruthagiri, “Response surface methodology optimization of process parameters for xylanase production by Aspergillus fumigatus in SSF using central composite design,” International Journal of Engineering Research and Applications, vol.2, pp.277-287, 2012.
 M. Rajasimman, R. Sangeetha, and P. Karthik, “Statistical optimization of process parameters for the extraction of chromium (VI) from pharmaceutical wastewater by emulsion liquid membrane,” Chemical Engineering Journal, vol. 150, pp. 275-279, 2009.
 G.P.E. Box, W.G. Hunter, and J.S. Hunter, “Statistics for Experimenters,” 2nd ed., Wiley, Hoboken, NJ, pp. 363-385, 1978.