Application of Ion Exchange Resins in Selective Separation of Cr(III) from Electroplating Effluents

Abstract

In this study, a chelating resin containing iminodiacetic acid group (Diaion CR11) was investigated to separate trivalent chromium, copper and iron from synthetic and industrial effluents. To determine single-component equilibrium isotherms for those species, batch experiments were performed at 25°C and 50°C. On the basis of these results, it was found that the resin exhibited better selectivity for Cu(II) and Fe(III) over Cr (III). It was demonstrated that the sorption of Cr(III) increases with increasing temperature. The maximum ion-exchange capacities were 0.62 mequiv./g_dry resin at 25°C and 0.95 mequiv./g_dry resin at 50°C. The Langmuir model enabled a good description of the ion exchange equilibrium data. A mathematical model considering dispersed plug flow for the liquid phase, intraparticle mass transfer by pore diffusion and external mass-transfer resistance at the pore/wall interface enabled a reasonable description of the experimental breakthrough curves for monocomponent, Cr(III)/Diaion, and multicomponent, Cr(III)/Cu(II)/Diaion, systems. The saturation of the Diaion with industrial effluent demonstrated that the breakthrough capacity of the resin is little affected by the presence of other species in solution. High regeneration efficiency of the resin was found by eluting Cr(III) with HCl followed of the mixture of NaOH/H₂O₂.