The Mechanism Of Styrene Removal By Absorption Combined With Electrochemical Oxidation

Volatile organic compounds (VOCs) are the main culprit of air pollutions, which have serious impact on people’s health and daily life.In this study, the mechanism of styrene removal by absorption combined with electrochemical oxidation was investigated.A cylindrical glass reactor was used as the electrolysis reactor for the experiments. The effective volume of the reactor was 250 mL(Φ30 mm× 300 mm). The reactor consisted of a coaxial RuO2/Ti rod as the anode and a cylindrical meshed stainless steel sheet attached to the inner wall of reactor as the cathode. Simulated gas consisted of nitrogen gas and styrene vapor was premixed before the reactor and introduced into the reactor from the bottom of the reactor. Styrene-containing exhaust gas was treated by aqueous solution absorption combined electrochemical oxidation in a tubular glass reactor. The influences of electrolyte and pH on styrene removal were investigated. The reaction products of styrene oxidation were analyzed. Furthermore, Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV) were conducted to investigate the electrochemical behavior of the anode to study the mechanism of the styrene removal.It was found that the styrene removal decreased with the increase of pH of solution at current density 0.02 A/cm2, both in 0.5 mol/L Na2SO4 solution and 0.5 mol/L NaCl solution. And, the removal of styrene was higher in NaCl solution than that in Na2SO4 solution. Main products of styrene oxide likely benzal dehyde, benzal alcohol, styrene oxide and phenyl-1,2-ethanediol were detected by GC and GC-MS. Under the operation condition:scan rate 50mV, scan voltage 1-2V,5cm distance both the cathode and the anode, in 0.5mol/L Na2SO4 electrolyte, oxygen evolution potentials at the surface of the anode in the acid solution were higher than those in the alkaline solution; In 0.5 mol/L NaCl electrolyte, chlorine evolution potentials at the surface of the anode in the acid solution were lower than those in the alkaline solution. By comparing cyclic voltammograms at the surface of the anode in both solutions with and without the styrene addition, it was found that indirect oxidation in the electrochemical reaction process might mainly contribute to the styrene removal, which was further proved by batch experiments.