Separation Science and Technology, Vol.37, No.1, 203-216, 2002
Enhancement of phosphonomethylated PEI-Cu2+ complex flocculation by Ca2+ ions: A new approach for heavy metal removal from aqueous solutions
Removal of Cu2+ ions from aqueous solutions by induced flocculation of PPEI with Ca2+ ions was studied. Considerable floc formation accompanying Cu2+ sequestration was demonstrated even at low initial metal concentration of 5 mg L-1. Flocculation capacity as high as 4.7 mmol Cu2+/g PPEI at pH 6 was obtained. Ca2+ showed minimal competition with Cu2+ ions for adsorption sites in the polymer. The PPEI-Ca2+ flocculant system was effective over a wide range of pH so that at an equilibrium pH of 1.5, more than 50% Cu2+ removal was possible. The [CaCl2]/[PPEI] ratio is a significant parameter with regards to achieving complete Cu2+ removal. At optimized condition, the process is capable of scavenging, Cu2+ ions to background levels.
Keywords:phosphonomethylated-polyethyethyneimine;flocculation;copper removal;calcium;chelation;wastewater treatment