Effective removal of hexavalent chromium using microbial cellulose/polyaniline cathode and nanosized FeS2 in the form of an integrated electrochemical system

In this study, microbial cellulose (MC) was conductive by polyaniline (PANI) stabilization and used as a biopolymer cathode for the first time in the presence of nano-pyrite (FeS2) for electrochemical removal of hexavalent chromium (Cr (VI)). Characterization of MC/PANI and nano-pyrite was conducted by FE-SEM, FTIR, EDX, and XRD analyzes. According to the results, nano-pyrite, MC, and MC/PANI removed 41.17%, 8.54%, and 35.4% of 10 mg center dot L-1 Cr (VI) within 60 min without the electric current, respectively. At the same time, the highest Cr (VI) removal rate (98.6%) was observed in the electrochemical process (80 mA) with the simultaneous presence of MC/PANI cathode and nano-pyrite. The study of mechanisms showed that creating different electron transfer pathways between MC, PANI, nano-pyrite, and Cr (VI) improves the removal efficiency in this system. The output data from the ICP-OES analysis showed that the amount of total Cr remaining in the solution was 0.11 mg center dot L-1 at the end of the process. Furthermore, the total Cr values based on the weight percentage in the MC/PANI cathode (1.1 g) and nano-pyrite (0.08 g) were 3.9% and 5.4%, respectively. These results suggested that an electrochemical reduction/adsorption process occurred in the Cr removal path. However, redox potential measurements (-383 to -632 mV) showed that the dominant process in Cr (VI) removal was electrochemical reduction. The recording of 71.1% Cr (VI) removal after five runs confirmed the remarkable reusability of the synthesized cathode and catalyst. This study introduced an efficient, sustainable, and economical integrated electrochemical system for Cr (VI) removal through synergistic effect and cooperation between the MC/PANI cathode and the nano-pyrite catalyst.

Automated summary

By utilizing a conductive microbial cellulose (MC) cathode stabilized by polyaniline (PANI) in the presence of nano-pyrite (FeS2), this study introduced an efficient, sustainable, and economical integrated electrochemical system for the electrochemical removal of hexavalent chromium (Cr (VI)). The synergistic effect and cooperation between the MC/PANI cathode and the nano-pyrite catalyst improved the removal efficiency of Cr (VI) through the creation of different electron transfer pathways. The results showed a high Cr (VI) removal rate of 98.6% in the presence of both the MC/PANI cathode and nano-pyrite in the electrochemical process.