Dye wastewater treatment and hydrogen production in microbial electrolysis cells using MoS2-graphene oxide cathode: Effects of dye concentration, co-substrate and buffer solution

Abstract

A single-chamber microbial electrolysis cell (MEC) constructed with MoS2-GO nickel foam (NF) cathode was established for alizarin yellow R (AYR) decolorization and hydrogen production, and influences of AYR initial concentration, co-substrate and buffer on MECs performances were determined. The cathode was obtained by in-situ growing MoS2-GO on NF. Physico-chemical and electrochemical characterizations showed that MoS2-GO NF cathode exhibited superior performance towards catalytic hydrogen evolution. The decolorization efficiency of ∼ 90 % within 10 h was achieved with AYR initial concentrations ranging from 30 to 150 mg/L (PBS + NaAc medium), indicating that MECs performances were not severely inhibited as the mutual impact between electrochemically active bacteria (EAB) and azo dye decolorization. Improved hydrogen production (0.183 m3/d/m3) and COD removal (92.44 %) were obtained with NaAc + glucose co-substrate and PBS buffer, owing to lower cathodic potential, desired solution conductivity for charge transfer, and better growth of microbial communities under neutral condition. Besides, better MECs performances were obtained when using NaHCO3 as buffer, compared to Na2CO3, as milder environment could be provided for microbial growth by NaHCO3. Findings in this study could promote application potential of MECs for synchronous dye removal and clean energy production with proper operations.