Electrochemical oxidation of reverse osmosis concentrates using enhanced TiO2-NTA/SnO2-Sb anodes with/without PbO2 layer

The traditional dimensional stable anodes (Ti/SnO2-Sb, Ti/PbO2) have poor electrochemical properties for further practical application. In this study, we fabricated two types of anodes for the treatment of reverse osmosis concentrates (ROCs). These two anodes were fabricated based on the enhanced nanotube array (ENTA) as internal structure. One anode is only coated by SnO2-Sb layer on the ENTA (Ti-ENTA/SnO2-Sb), while the other one is coated by SnO2-Sb layer and plus PbO2 layer (Ti-ENTA/SnO2-Sb/PbO2). It was found that the ENTA improved the electrochemical properties (e.g., oxygen evolution potential, HO center dot production) of the anodes. The conversion service lifetime of novel anodes were enhanced greatly than the traditional one. Then, we found that Ti-ENTA/SnO2-Sb anode has superior electro-catalytic than Ti-ENTA/SnO2-Sb/PbO2. In the range of current density of 5-20 mA cm(-2), the COD removal rate of ROCs for Ti-ENTA/SnO2-Sb anode and Ti-ENTA/SnO2-Sb/PbO2 anode were 0.12-0.23 mg min(-1) and 0.11-0.19 mg min(-1), respectively. Finally, we comprehensively compared the current efficiency and cost of ROCs degradation among various anodes. It was mentioned that novel anodes require lower energy cost (similar to 6.1 $/kg COD) during electrochemical process. Overall, electrochemical process is a cost-effective process and a very promising technology for practical application.