Effect of Opuntia ficus indica mucilage on copper removal from water by electrocoagulation-electroflotation technique

Abstract

Electrocoagulation-electroflotation (EC-EF) process assisted with the mucilage of Opuntia ficus indica (OFI) plant was investigated in order to enhance copper removal efficiency. ECEF tests with aluminum electrodes were conducted for the treatment of a synthetic copper solution of 100 mg/L, to estimate the influence of the mucilage on removal of copper metal ions, aluminum and hydrogen Faradaic yields, settling process and specific electrical energy consumption. It was mainly found that: (i) copper removal efficiency reached 100% in less than 5 min with 30 mg/L OFI mucilage at pH 7.8; (ii) OFI mucilage affected aluminum and hydrogen Faradaic yields at high removal efficiencies; (iii) copper sludge settling rate rises with increasing mucilage concentrations, and was enhanced by 15%; (iv) OFI mucilage reduced specific energy consumption at a fixed current density along with removal efficiency increase. Furthermore, the formed flocs, in the presence or not of mucilage, were identified by scanning electron microscope analysis (SEM). This work promotes the use of OFI mucilage as an active natural coagulant aid for the removal of copper species from water, by suggesting the substitution of chemical coagulants that are often added to the EC-EF technique.