Application of α, β and γ cyclodextrin polyurethanes in the removal of size specific copper derivatives

Abstract

Copper can be found in many wastewater sources including, printed circuit board manufacturing, electronics plating, plating, wire drawing, copper polishing, paint manufacturing, wood preservatives and printing operations. Typical concentrations vary from several thousand ppm from plating bath waste to less than 1 ppm from copper cleaning operations. Copper can be removed from wastewater by precipitation as an insoluble hydroxide salt or by ion exchange. In this study, single batch adsorption experiment of copper derivatives, e.g. CuCl 2. 2H 2 O, Cu(CH 3 COO) 2 and CuSO 4 .5H 2 O from aqueous solutions with epichlorohydrin linked α, β and γ cyclodextrin polyurethanes (CDPs) have been investigated for a wide range of experimental conditions: pH, metal concentration and CDP amounts. The aim of this study was to specify highly effective derivatives of copper to fit on the CDP backbone as the size of the copper molecules is different to each other. Recent studies have shown that α, β and γ CDPs are capable of removing copper ions of all derivatives from water to desirable levels with enhanced sorption capabilities. The adsorption efficiencies of CDPs were surprisingly similar and found to be independent for each type of copper derivatives. The phosphate buffer with pH 6.5-7.5 was found the best alkaline environment to remove the ions. Current technologies have been removed 95% copper ions from solution and unit gram of β-CDP was capable to remove 118 mg of copper ions. These polymers already established as the good carries of organic substances and by combining the inorganic compounds removal, it may be possible to develop a simultaneous system to confiscate both organic and inorganic compounds from waste water.