Electrochemical synthesis of PANI-ERGO composite electrode and its application in the reduction of hexavalent chromium

Abstract

Electroreduction is a promising approach for toxic Cr (VI) remediation due to its efficiency and excellent environmental compatibility. This study researches the facile electrode preparation and high mass transfer efficiency in Cr (VI) reduction application. Firstly, polyaniline (PANI)/electrochemically reduced graphene oxide (ERGO)/Ti electrode was synthesized in situ on a titanium mesh substrate via a three-step electrochemical method. The pretreated electrodes were characterized by SEM, FTIR, XPS. The EIS and CV were also adopted to prove further at the performance of electron transfer and electrocatalytic activity of Cr (VI) on the interface of the composite film. Subsequently, the reduction efficiency of Cr (VI) was invested in the electroreduction process by the PANI/ERGO/Ti electrode, factors such as potential condition, pH, and initial concentration of Cr (VI) were also considered. It showed higher degradation percentage and current efficiencies of the PANI/ERGO/Ti compared to the PANI/Ti and the ERGO/Ti. And revealed that lower pH is more favorable, and higher initial concentration is more accessible to reduce. The proposed test result reached 99.29% Cr (VI) reduction efficiency with the potential of − 0.8 V, pH of 2, and concentration of Cr (VI) is 10 mg/L within 2 h. Based on the above analysis, reasons for these results may attribute to a combination mechanism of adsorption and electro-reduction. Furthermore, PANI/ERGO/Ti presented good durability and achieved the expected application in actual wastewater in the system. This research could offer an effective strategy for graphene-supported polymer film electrodes which can be utilized for effective electrochemical reduction of Cr (VI)-containing wastewater.