Research On Reductive Dechlorination Of Chlorinate Methane From Fluorine Industrial Wastewater By Iron Metal

The research firstly focused on the effects of catalytic reductive dechlorination of the composite wastewater with chloroform and tetrachloromethane by zero-valent iron, optimizations of influencing factors on the dechlorinating process, and kinetics of chloroform dechlorination. Subsequently, the feasibility of the processes of the catalytic reduced dechlorination were affirmed in a pilot scale by the treatment of the industrial wastewater containing chloroform and tetrachloromethane from the fluorine industrial factory of Zhejiang Juhua Corporation.The research dealt with the availability of dechlorination by zero-valent iron, optimization of the main factors on the dechlorination, options of the catalyst, kinetics of the dechlorination of chloroform, the effects of neutralization and flocculation on the removal of chloroform and tetrachloromethane, and so on. It was determinated from the experiment that the optimized conditions for the dechlorination were as follows, m_铁=lg/L, pH=l, particle size=85, catalyst B, reaction time 1.5h (under catalyst B). while the temperature ranged from 25 ℃ to 45 ℃, the removal efficiencies of the chloroform in the composite wastewater was only between 60% and 85%, while the tetrachloromethane removal efficiencies was 90%. After zero-valent iron dechlorination, the calcium carbide residue was applied for neutralization. The experiment showed that calcium carbide residue appeared not only neutralization but also flocculation, meanwhile, the Fe ²⁺ and Fe³⁺ from zero-valent iron reduction formed hydroxid to flocculate and furtherly remove 80% chloroform and 10%tetrachloromethane respectively. It was indicated that the chloroform dechlorination was a two-order reaction, and the apparent activation energy as Ea was 86.578kJ/mol.From these experiments, it was confirmed that catalytic reductive dechlorination by zero-valent iron was a valid method to reduce the chloroform and tetrachloromethane in the wastewater from the chlorinated compound industry. The experiments results as above would been validated with the industrialisation Equipment.