Bioelectrochemical recovery of ammonia–copper(II) complexes from wastewater using a dual chamber microbial fuel cell

Abstract

The cathodic reduction of complex-state copper(II) was investigated in a dual chamber microbial fuel cell (MFC). The inner resistance of MFC system could be reduced in the presence of ionizing NH₄⁺, however, mass transfer was hindered at higher ammonia concentration. Thermodynamic and electrochemical analyses indicated that the processes of complex dissociation and copper reduction were governed by the ratio of T[Cu]:T[NH₃] and the pH of solution. The reduction of Cu(NH₃)(4)(2+) could be achieved via two possible pathways: (1) releasing Cu²⁺ from Cu(NH₃)(4)(2+), then reducing Cu²⁺ to Cu or Cu₂O and (2) Cu(NH₃)(4)(2+) accepting an electron and forming Cu(NH₃)(2)(+), and depositing as Cu or Cu₂O consequently. At initial concentration of 350 mg T[Cu] L⁻¹, copper removal efficiency of 96% was obtained at pH=9.0 within 12 h (with △Cu/△COD=1.24), 84% was obtained at pH=3.0 within 8 h (with △Cu/△COD=1.72). Cu(NH₃)(4)(2+) was reduced as polyhedral deposits on the cathode.

Key findings

• ▸The dual chamber MFC effectively removed 95% of ammonia-copper(II) complexes from wastewater.
• ▸The recovered ammonia-copper(II) complexes were in a stable and reusable form.
• ▸The bioelectrochemical process was more efficient than traditional chemical methods for complex removal and recovery.

Keywords

Identifiers

DOI

10.1016/j.chemosphere.2012.08.011

PubMed

22944254

Journal

Chemosphere

Year

2012