Catalytic Dechlorination Of Chloromethanes In Water By Nanoscale Pd/Fe Bimetic Particles

Iron plays an important role in reducing chlorinated organics for its efficiency and convenience. The experiments using bimetallic metals to dehalogenate chlorinated compounds have gain better effect. However, nanoscale palladized iron becomes the focus for its high specific surface area and reaction activation.In the present paper is reported an efficient method of synthesizing nanoscale iron particles, and chose an effective method to deposit palladium on the surfice of nano scale iron through the cystal configuration and the dechloranation efficiency.Using transmission electronic microscopy(TEM), scanning electron microscope (SEM) , X-ray diffraction (XRD), X-ray fluorescence (XRF), energy distribution spectra (EDS) to observe the surface condition, the ratio of palladium/iron(w/w), granule size of the bimetallic metals. BET specific surface area of the nanoscale particleswas determined using nitrogen adsorption method. The nano scale palladized iron is used to dehalogenate chlorinated methanes.Factors of the mass fraction of Pd in the bimetal(ω(Pd/Fe)), the mass concertration of nano Pd/Fe particles in the reaction mixture(ρ(Pd/Fe)), preliminary concentration of chlorinated methanes(C0), initial pH value and chlorination level. Finded that the dechlorination efficiency rose with the rose ofω(Pd/Fe), the rose ofρ(Pd/Fe) and the rose of chlorination level of chlorinated methanes, but it declined with the rose of preliminary concentration of chlorinated methanes (ranging from 20mg/L to 150mg/L). And the optimum pH is 7. The variation of pH, Fe²⁺ and Pd²⁺ concentration is also observed in this experiment, finded that pH rose slowly. Fe²⁺ concentration rised former and decreased latter, and Pd²⁺ concentration was still under the detection limit (0.005mg/L).Intermediate and final products of reaction of dichloromethane, trichloromethane and tetrachloromethane with naniscale Pd/Fe were determined by GC. It can be concluded that the dechlorination reaction of thease chlorinated methanes over nanoscale Pd/Fe particles progresses through catalytic reductive...