Effect of pH and Calcium on the Adsorptive Removal of Cadmium and Copper by Iron Oxide–Coated Sand and Granular Ferric Hydroxide
KAUST DepartmentWater Desalination and Reuse Research Center (WDRC)
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AbstractIron oxide-coated sand (IOCS) and granular ferric hydroxide (GFH) were used to study the effect of Ca2+ and pH on the adsorptive removal of Cu2+ and Cd2+ from groundwater using batch adsorption experiments and kinetic modeling. It was observed that Cu2+ and Cd2+ were not stable in synthetic waters. The extent of precipitation increased with increasing pH. Removal of Cu2+ and Cd2+ was achieved through both precipitation and adsorption, with IOCS showing higher adsorption efficiency. Increase of pH (from 6 to 8) resulted in a higher overall removal efficiency of both Cu2+ and Cd2+, with precipitation as predominant removal mechanisms at higher pH values, especially for Cu2+. An increase in Ca2+ concentration increased the precipitation of Cu2+ [as Cu2(OH)2CO3 and Cu3(OH)2(CO3)2] and Cd2+ [as Cd(OH)2 and CdCO3]. In addition, Ca2+ competes with Cu2+ and Cd2+ for surface adsorption sites on IOCS and GFH, and reduces their adsorption capacity. The kinetic modeling revealed that the adsorption of Cd2+ onto IOCS is a complex process, with limited contribution of chemisorption that increases in the presence of Ca2+. © 2015 American Society of Civil Engineers.
CitationUwamariya V, Petrusevski B, Lens PNL, Amy GL (2016) Effect of pH and Calcium on the Adsorptive Removal of Cadmium and Copper by Iron Oxide–Coated Sand and Granular Ferric Hydroxide. Journal of Environmental Engineering 142: C4015015. Available: http://dx.doi.org/10.1061/(asce)ee.1943-7870.0001009.
SponsorsThe authors thank the Netherlands Government for providing financial assistance through the Netherlands Fellowship Program for the financial support under Grant No. 32000022.