Degradation Of Malachite Green In Aqueous Solution By High-voltage Discharge Plasma And Carbon Nanotubes

High-voltage discharge is an advance oxidation technology which can produce theUV radiation and various active species. As the carbon material, carbon nanotubes(CNTs) has the high adsorption ability due to their high specific surface area and highchemical stability. The organic compounds can be transformed into carbon dioxide andwater by high-voltage discharge. From the study on removal of malachite green withhigh-voltage discharge synergistic CNTs, the combinative removal mechanism wasstudied.Firstly, the efficient adsorption of MG with the CNTs was explored in this study. Theresults showed that the pseudo-second-order kinetic model was more suitable todescribe the adsorption of MG onto CNTs; The sorption data could be well interpretedby the Langmuir model; The overall rate process appeared to be mainly governed byexternal mass transfer; The adsorption mechanism was mainly dominated by chemicaladsorption; The adsorption amount of MG onto CNTs decreased with increasingtemperature; The adsorption thermodynamic data showed that adsorption of MG ontoCNTs was spontaneous and exothermic process in the high temperatures; With theincrease of ionic strength, the adsorption capacity was promoted on the adsorptionprocess; The adsorption quantity was increased with the increasing pH value in theacidic conditions.Secondly,the efficient removal of MG with high-voltage discharge was explored inthis study. The results showed that incearsing the initial concentration was unfavorablefor the removal of MG; because the active substance could be decomposited by highoutput power, the removal efficiency of MG decreased with increasing output power;the degradation rate of MG firstly increasing and then decreasing with increasing the airflow rate; the generated O3and H2O2played an important role in the removal of MG;the acut biological toxicity of MG sample firstly decreased and then increased withincreasing discharge time; the value of pH and TOC decreased with increasingdischarge time; the degradation byproduct and the removal mechanism of MG wereproposed according to the analysis of LC-MS and GC-MS, and the decomposition ofconjugated structure reaction may be the MG to remove the main way.Finally, the efficient removal of MG with high-voltage discharge synergistic CNTswas explored in this study. The results showed that incearsing the initial concentrationand output power were unfavorable for the removal of MG; the degradation rate of MG firstly decreasing and then increasing with increasing the air flow rate; the acutbiological toxicity of MG sample firstly decreased and then increased with increasingdischarge time; the degradation rate of TOC during combinative discharge course washigher than that during individual discharge course; the degradation byproduct and theremoval mechanism of MG during combinative discharge courses were proposedaccording to the analysis of LC-MS and GC-MS, the degradation degree of MG duringcombinative discharge courses was higher than that during individual dischargecourses.