Development of a Three-Dimensional Electrochemical System Using a Blue TiO₂/SnO₂–Sb₂O₃ Anode for Treating Low-Ionic-Strength Wastewater

Abstract

Reducing energy use is crucial to commercialize electrochemical oxidation technologies. We developed a three-dimensional (3-D) electrochemical system that can significantly reduce the applied voltage and effectively degrade organic contaminants in low-ionic-strength wastewaters. The 3-D system consisted of a composite wire mesh anode (composed of blue TiO2 nanotubes covered with SnO2–Sb2O3), a proton exchange membrane, and a stainless-steel wire mesh cathode, which were compressed firmly together. For the 3-D system, we placed the anode of a 3-D electrode toward the wastewater that flowed past the anode. Both the two-dimensional (2-D) and 3-D systems had the same anode and cathode. We found that the 3-D system could reduce the applied voltage by 75.7% and reduce the electrical efficiency per log order reduction (EE/O) by 73% for 0.001 M Na2SO4. For Na2SO4 concentrations greater than 0.05 M, the 2-D system had a slightly lower EE/O. We also compared the EE/O of electrochemical advanced oxidation processes (EAOPs) with that of other advanced oxidation processes (UV/H2O2, UV/persulfate, O3/H2O2, UV/ TiO2, and UV/chlorine). We found that EAOPs have a much higher EE/O for low BA concentrations (20 mg/L) and a much lower EE/O for high BA concentrations (2000 mg/L).

Accelerating FeIII-Aqua Complex Reduction in an Efficient Solid–Liquid-Interfacial Fenton Reaction over the Mn–CNH Co-catalyst at Near-Neutral pH

“…Advanced oxidation processes (AOPs), which could produce reactive oxygen species (ROS) through a simple operation process for the oxidative destruction of organic pollutants in water, have been an irreplaceable strategy for wastewater treatment. , Among AOPs, the traditional Fenton reaction (Fe II /H 2 O 2 ) that relies on the Fe III /Fe II redox cycle for H 2 O 2 activation (eqs and ) is the most practical and simple technology, and hydroxyl radicals ( • OH) with a high reactivity ( k = 10 9 M –1 s –1 ) and nonspecificity are considered as the dominant oxidants. − However, the inherent limitation to Fenton processes is the slow reduction rate of Fe III to Fe II (eq ). As an aqueous free-radical chain reaction, the pH-dependent hydrolysis of unstable Fe III should be considered .…”

Application of Pulsed Electrochemistry to Enhanced Water Decontamination

“…Chemical oxygen demand (COD) was determined according to standard methods, and the current efficiency and • OH utilization were calculated on the basis of the COD value as reported previously. 20,23,24 The energy consumption (EC, kWh g −1 COD) for the DC mode was calculated by 1,25 = −…”

“…The apparent kinetic rate ( k , h –1 ) was obtained from the slope of −ln­( C / C 0 ) – t regressive lines by assuming phenol oxidation to follow the pseudo-first-order kinetics, where C 0 and C (mg L –1 ) are the initial and terminal concentrations of phenol and t (min) is the time of electrolysis. Chemical oxygen demand (COD) was determined according to standard methods, and the current efficiency and • OH utilization were calculated on the basis of the COD value as reported previously. ,, The energy consumption (EC, kWh g –1 COD) for the DC mode was calculated by , where U (V) is the cell voltage, j (mA cm –2 ) is the current density, A (cm 2 ) is the geometric area of the anode, t (min) is the anodic time, and V is the total liquid volume. The EC for PC mode was calculated by where the subscripts i and j represent the anodic and resting parameters in each pulsed-current period and n is the total pulsed number for 120 min of electrolysis.…”

Physico‐chemical processes

“…Researchers also did experiments using electrochemical oxidation (EO) method to treat the same wastewater and proposed tan application potential to integrate EC and EO processes. Meng, Chen, Wang, et al (2019) created a electrochemical system with a 3-D electrode to treat low-ionic-strength wastewater. A 3-D system had a higher electricity efficiency than a 2-D system per log order reduction, which could help reduce the energy cost.…”

“…Meng, Chen, Wang, et al (2019) created a electrochemical system with a 3‐D electrode to treat low‐ionic‐strength wastewater. A 3‐D system had a higher electricity efficiency than a 2‐D system per log order reduction, which could help reduce the energy cost.…”