Application of Porous N-Methylimidazolium Strongly Basic Anion Exchange Resins on Cr(VI) Adsorption from Electroplating Wastewater

The porous N-methylimidazolium functionalized strongly basic anion exchange resins (PCl) were synthesized, characterized and applied for Cr(VI) adsorption from electroplating wastewater. FT-IR and elemental analysis of PCl were used to characterize the structure and the content of functional groups of PCl. The bath model results show that the adsorption capacities of PCl for Cr(VI) are above 139 mg g(-1) at pH range 2.0-5.0, and the Cr(VI) can be easily desorbed with the mixture solution of 0.2 mol L-1 NaOH + 0.2 mol L-1 NaCl. PCl resins with precipitation technologies were successfully used for the separation and recovery of toxic Cr(VI), and co-existing Cr(III), Fe(III), Cu(II), Zn(II), Ni(II), and Al(III) heavy metals from electroplating wastewater in the bench scale. Cr(VI) was separated and precipitated as value industrial product BaCrO4 with purity higher than 99%. The recovery yields of other heavy metals are more than 99% within the optimum pH values range from 8.0 to 9.0. After the treatment of the wastewater using PCl-based high efficient, economical and clean technique, the concentrations of total Cr, Cr(VI) and other heavy metals in water are less than the national emission standard