Degradation Of Chlorinated Organic Matter By Zero-Valent Iron/Composite Oxides

Chlorinated hydrocarbons, which can be transferred and transported into the aquatic environment in many ways, are widely used in the field of agriculture, industries and daily life. Due to their toxicity and stable structure, they can do great harm to the human beings and are listed as Priority Pollutants in many countries.In this thesis, to improve the traditional techniques of dechlorination with the zero-valent iron, the intercalation of Cl~- into LDHs by reaction of calcined LDO with the system of dechlorination can be used to improve the efficiency of dechloridation. When the calcined LDO comes back to be LDHs, it contains with Cl~-, which makes the reaction moving forwards.Degradation of high and low concentration tetrachloromethane in aqueous solution were achieved by zero-valent iron/ composite oxides and zero-valent iron, respectively. The results show that tetrachloromethane can be reductive degradation with zero-valent iron, so the toxicity of tetrachloromethane is reduced quickly. When zero-valent iron and composite oxides coexisted, compared to zero-valent iron alone, the degradation efficiency of the high concentration tetrachloromethane aqueous solution was dramatically enhanced. The reason is that composite oxides can rehydrate and combine with the chloride anions in solution to reconstruct the original hydrotalcite like structure so that the degradation efficiency is increased. In addition, it indicates that zero-valent iron was still very effective for the degradation of low concentration tetrachloromethane aqueous solution.