Electro-assisted Adsorption of Zn(II) on Activated Carbon Cloth in Batch-Flow Mode: Experimental and Theoretical Investigations.

High levels of zinc ion (Zn2+) in environmental scenarios have long been considered to be harmful, and this study was experimentally and theoretically performed to explore the feasibility of electro-assisted adsorption of Zn2+ on activated carbon cloth from aqueous solutions in batch-flow mode. The characteristics of carbon cloth were systematically evaluated using cyclic voltammetry and various surface characterization techniques. Effects of operating parameters, including charging voltage, feed Zn2+ concentration, solution volume, and flow rate, on the dynamic removal process of Zn2+ were examined. Meanwhile, a theoretical model was developed to quantitatively describe the electro-assisted adsorption of Zn2+, and an excellent agreement between the modeling results and the experimental data was observed. The Zn2+ removal mechanisms involve both nonelectrostatic interactions (physi- or chemisorption) and electrostatic interactions. Experimental and theoretical results demonstrated a significant enhancement of Zn2+ adsorption capacity on the carbon electrodes under the electro-assistance. Moreover, the carbon electrodes exhibited good regeneration performance achieved via a simple short-circuiting method and provided good reproducibility over consecutive runs for the removal of Zn2+. The validated model could be applied to predict the effects of important parameters that are difficult to be experimentally manipulated, and is expected to play an important role in establishing the electro-assisted adsorption as a viable treatment technology for zinc wastewater.