Optimizated Operational Conditions for Removal of Discharged Toxic Silver Nanoparticles from Wastewater using Electrocoagulation

Document Type : Research article

Authors

1 Alexandria-Egypt El Shatbey

2 Chemistry department-Faculty of Science- Damanhour University

Abstract

Novelty of this study is that it achieved complete removal of toxic silver nanoparticles (AgNPs) by using modified electrocoagulation (EC) technology at low energy consumption via optimiz-ing operational conditions. It is the first time to explore electrochemical behaviour of anodes materials in EC system. A simple electrolytic (power source 3V and 200 mA) cell is used. Alu-minium anode is more superior to steel (iron) anode. Percent removal efficiency for both iron and aluminium anodes is increased at high current density reached 97% for aluminium at 30 mA cm-2 at low energy consumption 3.1 kW h m-3 . Supporting electrolyte 10 v/v 0.1M NaCl used for increasing solution conductivity and ionic strength. Current efficiency reached 95% at optimized operational conditions including current density, electrolysis time, pH and electrodes materials. Designed simple EC reactor at laboratory scale can be scaled up for pilot plant. Redox reactions at electrodes surfaces controlled removal efficiency. Treated effluent was colourless and no AgNPs were detected. Optimized conditions for removal of orange colour aqueous solution 200 ppm AgNPs are: Al anode, pencil cathode, pH 4, low current density 30 mA cm-2 at agitation speed 50 rotation per min. Efficiency of Al anode is discussed on the basis of electrochemical behaviour using cyclic voltammetry. Electricity consumption decreased by increasing electro-lytes conductivity and decreasing electrode spacing.

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