Modified empty bed residence time model for copper removal

The removal of copper ions from wastewater has been studied using ion exchange with an iminodiacetate resin. The effects of agitation time, pH value of the solution, and initial concentration of the copper solution have been evaluated. It has been found that the equilibrium is obtained after 72 h. Also, the capacity of the resin for the copper ions has been determined to be 2.2 mmol/g by measuring the equilibrium isotherm at a pH value of 5.0. When the pH value of the solution is lower than 3.2, the adsorption capacity of the resin is reduced drastically. It has been verified that the Langmuir-based isotherm models are the best-fit models for the equilibrium isotherm system. A series of fixed bed column runs have been performed to remove copper from solution and study the effects of solution flow rate, initial copper concentration, and resin particle size. The empty bed residence time model, EBRT, has been used to correlate the fixed bed pilot plant experimental results. The original form of the EBRT model was modified using a time dependent bed depth adsorption capacity to determine the bed exhaustion rate in order to improve the original model which utilized the equilibrium adsorption capacity. The modified model demonstrates that the EBRT can be used to more accurately model copper removal using the chelating ion exchange resin.