Optimization of an Activated Carbon Adsorber for Cadmium Removal in Wastewater

Abstract

In this paper, we are presenting preliminary results of tests aimed at exploiting cadmium adsorption kinetics in different kind of ideal reactors (stirred tank, fixed bed column and fluidised bed) at lab scale. Based on a dedicated experimental analysis, the present work sought to compare the performance of the different adsorber configurations investigated, and to clarify the rate controlling mechanisms of cadmium adsorption. Experiments revealed that cadmium adsorption is controlled by external mass transfer only if the activated carbon is loaded below a critical value qcr, which for the investigated conditions corresponds to 0.21 mg/g. For higher loading, the adsorption rate is controlled by an internal mechanisms well described by the Elovich model. The final objective of the study is to suggest appropriate guidelines to select optimal adsorber design.