Enhancing Electrochemical Oxidation Using NEAT
Initial studies have shown that adding NEAT’s TAML catalyst to an electrochemical reactor can greatly improve the treatment performance.
Introduction
Water scarcity and increasing regulatory limits on effluent discharge are increasing the need for more thorough wastewater treatment across all industries. As such, advanced oxidation processes (AOPs) have become an important part of many wastewater treatment trains. Electrochemical oxidation (EOx) is a burgeoning AOP that benefits for its ease of use and broad applicability. However, it remains a niche technology mainly due to the high operation cost based on energy demand. Multiple companies are working to improve the performance of electrochemical reactor for wastewater treatment, however this is focused almost exclusively on improving the material properties of the electrodes. NEAT has shown that the addition of its proprietary homogeneous catalysts to the waste stream greatly enhances the rates of degradation of substrate, decreasing both the time to treatment and energy required for treatment. This finding should be relevant to all treated waste streams and independent of the electrode material. The decrease in energy and treatment time should lead to substantially reduced operating costs making this technology much more competitive in the market.
Results
According to BlueTech Research, two of the leading markets for EOx are textiles and pharmaceuticals, the basis for our selection of initial contaminants; Orange II Dye and two APIs, acetaminophen and sulfamethoxazole. Figure 1 shows the difference in rate of degradation of Orange II by the addition of NEAT catalyst using an electrochemical cell in batch mode. With the addition of 60 ppb of NT7 catalyst, the rate of degradation increased compared to the 10 mA/cm2 control and matched the performance of a 50 mA/cm2 control. This shows NEAT achieving the same treatment performance as a cell with ~20x higher energy consumption. Figure 2 shows that increasing the addition of NEAT increases the degradation rate, providing evidence that NEAT can improve throughput capacity for an existing EOx design. Additional experiments have shown that the addition of catalyst can also enable the same treatment performance at 1/10th the concentration of electrolyte. Figure 3 shows the performance comparison of electrochemical degradation of acetaminophen and sulfamethoxazole. As was observed in with Orange II, the rates of degradation are remarkably increased by the presence of sub-ppm concentrations of NEAT. For acetaminophen the initial rate of degradation with catalyst present was 36 times that of the control.
Conclusion
These initial results have shown that adding Fe-TAML catalyst to an electrochemical reactor can greatly improve the treatment performance. The reductions in energy input, increase in reaction rates, and reduced need for electrolyte will enable electrochemical oxidation of water at greatly reduced operating costs with increased flow rates over a broader spectrum of wastewater. This makes electrochemical oxidation a much more competitive technology relative to other AOPs.
C. Pasichny, S. Hancox, S. Kim , P. Wittbold, University of Massachusetts, Amherst