Mechanism adsorption–reduction into the incorporation of microbial fuel cell–metal organic framework and overview of hydrodynamics effects for enhanced reduction of Cr(VI). (October 2022) - Hidayat, Alvin Romadhoni Putra
Abstract: Due to the limitation of a sole method for removal of hexavalent chromium (Cr(VI)) which unable to process higher concentrations and limited efficiency of removal. Thus, the integrated reduction and adsorption system was designed by combining microbial fuel cell (MFC) and adsorbent (MOF type HKUST-1, UiO-66, and ZIF-8) to remove Cr(VI). HKUST-1 showed the highest adsorption capacity and Cr(VI) removal percentages compared to other MOF types, reaching 78.616 mg/g and 96.551 % in 90 min (batch adsorption), respectively. In addition, the pseudo-2nd-order kinetic and Langmuir isotherm type matched well with the suggested adsorption mechanism based on the adsorption kinetics and isotherms analysis. On the other hand, the highest power density resulted from the simultaneous integration of MFC adsorption, namely 198 mW/m 2, and the removal rate of 99.34 % at 75 mg/L Cr(VI) concentration owing to MOF simultaneously adsorbs by forming a coordinating covalent bond and reducing it with electron donor groups in the organic linker of the MOF. Several important factors influencing the reduction rate of Cr(VI) in the MFC adsorption integration were pH, the Cr(VI) concentration, and substrate at the anode. Moreover, the hydrodynamic effect (agitation) can also increase the performance of the MFC, due to an increase in current leading to a high Cr(VI) removal. Furthermore, the MFC-adsorption integration showed better stability up to five cycles for 35 days. Overall, combining adsorption and MFC for Cr(VI) removal provides promising potency to be explored and developed for the wastewater treatment process. Graphical abstract: Unlabelled Image Highlights: Integrating reduction and adsorption by combining MOF (HKUST-1, UiO-66, and ZIF-8) sequentially and simultaneously with MFC to remove Cr(VI) was studied HKUST-1 demonstrated the highest adsorption capacity and percent removal of Cr(VI) among other MOF types (78, 616 mg/g and 96.551% in 90 minutes, respectively) The pseudo-2nd-order kinetic approach and Langmuir isotherm well demonstrate the adsorption process The simultaneous integration of MFC-adsorption led to the highest power density, which was 198 mW/m 2, and a removal rate of 99.34% at 75 mg/L Cr(VI). The effect hydrodynamic leads to a large enhancement in current and Cr(VI) reduction in principle