Optimum parameters for humic acid removal and power production by Al–air fuel cell electrocoagulation in synthetic wastewater

Abstract

Although humic acid (HA) is a complex natural organic matter, it can potentially harm the environment and human health. In this study, aluminum–air fuel cell electrocoagulation (AAFCEC) was used to remove HAs from water while generating electricity. Initial pH, electrolyte concentration, HA concentration electrode distance and external resistance were investigated to determine the power generation and removal efficiency. The results showed that the better performance of power generation has been acquired in the alkaline solution and larger electrolyte concentration and short electrode distance. Further, Al–Ferron complexation timed spectrophotometry was used to determine the Al speciation distribution in the solution under different parameters. The power density of the cell reached 313.47 mW/cm2 for the following conditions: 1 g/L NaCl concentration, 3 cm electrode distance, 20 Ω external resistor, and pH 9. After about an hour of electrolysis, the optimum removal rate of HA was above 99%. The results demonstrated that the AAFCEC is an efficient and eco-friendly water treatment process, and it could be further developed and disseminated in the rural areas and households. HIGHLIGHTS This Al-air fuel cell electrocoagulation can be used to treatment wastewater without external power source.; The output power density can reach up to 427.59 mW/cm2.; The form of Al in the solution have been studied by Al-Ferron complexation timed spectrophotometry.; The removal rate of HA was above 99% after about an hour electrolysis.;

Keywords

• aluminum–air fuel cell electrocoagulation
• humic acid
• power generation
• wastewater treatment