The Research For Adsorption Of Chlorpyrifos-degrading Strain Cupriavidus Nantongensis Lux-X1 On Soil Particles

The extensive use of pesticides In agricultural production cause a series environmental problem.Soil pesticide pollution has become increasingly serious.In recent years,soil microbial remediation has become a hot topic in the field of soil remediation.The research object of this article is Lux-X1,a degrading bacterium that can efficiently degrade chlorpyrifos,which was screened from the waste water of pesticide plants.Three kinds of soil particles with different particle sizes:clay(<2?m),powder(2~50?m)and sand(>50?m)were used to adsorb Lux-X1.The adsorption isotherms of soil-degrading bacteria and the effects of organic matter,ionic strength,pH,and several low-molecular-weight organic ligands on soil-degrading bacteria were investigated.Scanning electron microscopy and Fourier infrared spectroscopy were used to explain the mechanism of adsorption from a microscopic perspective.The results of the study are summarized as follows:1.The scanning electron microscope results of the degrading bacteria,soil and soil-degrading bacteria complexes showed that the degrading bacteria Lux-X1 can adhere well to the surface of soil particles.The results of Fourier infrared spectroscopy analysis showed that water molecules on the surface soil minerals were involved in bacterial adsorption.2.Explicit concentration of degrading bacteria and soil minerals:The suitable concentration for the adsorption of chlorpyrifos-degrading bacteria,Lux-X1 in soils with three particle sizes is:clay particles,3 mg/ml;powder particles,5 mg/ml;and sand particles,30 mg/ml.3.The adsorption of Lux-X1 on the three kinds of particle size soil can be well fitted by Langmuir isotherm equation.The adsorption of Lux-X1 by soil particles increased with the decrease of particle size.At the same time,it was found that the adsorption capacity of Lux-X1 in soil containing organic matter was higher than that of organic soil removal.4.Environmental factors have a significant effect on the soil adsorption and degradation bacteria Lux-X1.When the pH of the sorption system increased from 4.0 to 10.0,the adsorption capacity of the soil particles to the degrading bacteria showed an increase first,and the adsorption amount reached the maximum at pH 6.0,and then the adsorption amount decreased with the increase of the pH value.The Na~+concentration in the adsorption system increased,and the adsorption capacity of the soil to the Lux-X1degrading bacteria gradually increased.The increase of K~+in the adsorption system could promote the adsorption of the degrading bacteria Lux-X1 by soil particles.5.Several low molecular weight sodium oxalate,sodium acetate and sodium citrate were used to study the effects of three different particle size soils on the adsorption and degradation of Lux-X1.The results showed that sodium oxalate,sodium acetate and sodium citrate all had a certain role in promoting soil adsorption and degrading bacteria.6.Scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FT-IR)analysis showed that soil particles could adsorb Lux-X1.The carboxyl groups and amide groups on the surface of bacteria are the active groups for adsorption of bacteria and soil particles.The water molecules on the soil minerals are involved in bacterial adsorption.