The Performance Research Of Chlorinated Hydrocarbons By Porous Adsorbent Materials

The water pollution of chlorinated hydrocarbons endangered the environment and human health seriously.The adsorption technology has been extensively studied due to the characteristics of rapid reaction and simple operation.At present,the development of high-efficiency adsorbents is the focus of research.In this study,activated carbon fiber and metal organic framework were modified to prepare ACF/SiO2 and UiO-66/GrO composites.Carbon tetrachloride（CT）,trichloroethylene（TCE）and tetrachloroethylene（PCE）were used to evaluate the adsorption performance of adsorbents.The adsorption kinetics,thermodynamics,isotherm model,and mechanisms of adsorption are studied.ACF/ZnO,ACF/La₂O₃ and ACF/SiO₂ were prepared.The results show that the ACF/SiO₂ composites have the best adsorption effect.Characterization showed that the SiO₂ particles were successfully loaded onto the ACF surface;the specific surface area and pore volume of the composite decreased,but the pore size was increased.The results showed that the removal efficiency of three kind of CHCs was R_PCE>R_TCE>R_CT at the same concentration.With the increase of initial concentration of pollutants,the removal effciency gradually decreased.The low temperature is benefit to remove CHCs;the pH and salinity of the solution have little effect on the removal of CHCs;The adsorption process of CHCs by ACF/SiO₂ was described by the pseudo-second-order kinetic model;The Langmuir and Freundlich adsorption models were fitted well to the adsorption.The thermodynamic calculation results showed thatΔG⁰<0、ΔH⁰<0、ΔS⁰>0,indicating that the adsorption was a spontaneous and exothermic process with increased randomness;The adsorption reaction was mainly affected by the dispersion force.UiO-66/GrO were prepared successfully,the results showed that the high content of GrO（10%）hinders the formation of crystallization of UiO-66.The characterization indicated that the diffraction peaks of the composites with the increase of GrO content.The morphology of the particles was irregular with the increase of GrO.The specific surface area of and pore volume of UiO-66/GrO-5 composites were improved compared to the raw UiO-66.The adsorption performance of UiO-66/GrO-5 on the adsorption properties of CT,TCE and PCE were studied.The results showed that the removal rate of contaminants decreased with the increase of contaminant concentration;The alkaline solution or high temperature was not benefit for UiO-66/GrO-5 to remove CHCs;The adsorption process of CHCs by UiO-66/GrO-5 was described by the pseudo-second-order kinetic model;The Langmuir and Freundlich adsorption models were fitted well to the adsorption.The thermodynamic calculation results showed thatΔG⁰<0、ΔH⁰<0、ΔS⁰>0,indicating that the adsorption was a spontaneous and exothermic process with increased randomness;The adsorption effect of promoting the adsorption of CHCs by UiO-66/GrO owing to interaction between non-polar VOC and hydrophobic sites,increasing of specific area,dispersion forces and defects on the crystal surface.