Semicontinuous enhanced electroreduction of Cr(VI) in wastewater by cathode constructed of copper rods coated with palladium nanoparticles followed by adsorption

Conventional techniques used for reduction of Cr(VI) in wastewater product great amounts of metal sludge due to the use of reducing chemicals. Since in electrochemical process, the reducing agent is the electron, so the main advantage of this method is its adaptability to the environment. The aim of the current study is to reduce Cr(VI) from electroplating wastewater by the electrochemical method and to adsorb Cr(III) by cellulose sulfate adsorbent. Furthermore, to enhance the reduction efficiency of Cr(VI), the cathode was modified with Pd nanoparticles. In the present study, recovery in the electrochemical column was conducted continuously and semi-continuously. In addition, the effect of pH, amperage, flow rate, and initial concentration of Cr(VI) was investigated. To remove Cr(III) from the wastewater, the cellulose sulfate adsorbent was provided from modification of cotton health wastes. The highest recovery rate (99.63%) was witnessed at pH = 1.5, 1 A amperage, flow rate of 4.24 mL min(-1), and initial concentration of 50 mg L-1. The sewage was removed from the system after several consecutive cycles and during 20-55 min reached recovery efficiency of 99.99%. Based on the results, pH had the highest effect on the process. The optimum removal percentage was 85.74% occurred at a pH of 5.6, chromium concentration of 150 mg L-1, and adsorbent concentration of 400 mg L-1. The removal rate of the pollutant was 97.32%, done by cellulose sulfate adsorbent. (C) 2020 Elsevier Ltd. All rights reserved.