Effects Of Pore Structure Of Hypercrosslinked Polymeric Adsorbents On Adsorption And Desorption Of Halohydrocarbon

Pore structure is one of the major factors affecting the adsorption/desorption properties of hypercrosslinked polymeric adsorbents.A series of micro-mesoporous hypercrosslinked polymeric adsorbents MM-1,MM-2,MM-3 and commercialization NDA-150 were selected as adsorbents.The adsorption equilibrium,adsorption kinetics and desorption performance of dichloromethane,dichloroethane and trichloroethylene on four adsorbents were investigated.The effects of pore structure on adsorption and desorption process were well elucidated.The main contents and results are as follows:(1)Thermogravimetric analyzer were used in adsorption equilibrium research of dichloromethane,dichloroethane and trichloroethylene adsorption on the resins.Compared to Langmuir and Freundlich equation,DA equation can better fit hypercrosslinked resins adsorption of halogenated hydrocarbons;associating pore structure and adsorption capacity were analysis under low relative pressure and high relative pressure.The results showed that when p/p0=0.1,the adsorption capacity of the resins and the micropore volume exhibited positive correlation;when p/p0=0.4-0.7,the adsorption capacity and the total volume had a good linear relation,correlation coefficient R2>91%.(2)Adsorption kinetic experiments were also conducted with thermogravimetric analyzer.LDF model can fit the adsorption kinetic curve well.The adsorption kinetics analysis of dichloromethane showed:when p/p0<0.3,adsorption occured mainlyin micropore and the adsorption process was mainly controlled by surface diffusion.The adsorption rate constant increased with the amount of adsorption.After the completion of micropore filling,the increase of adsorptive capacity was mainly due to multilayer adsorption and capillary condensation.Knudsen diffusion contributed chiefly to diffusion process.The adsorption rate constant increased slightly or remained invariant with the amount of adsorption.The higher the temperature,the faster the adsorption rate.Moreover,it was found that rising temperature was more favorableto adsorption kinetics of resins containing more mesopores.The calculation of dichloromethane activation energy were consistent with the mesopore surface area order.(3)TG-dTG curve was get from temperature-programmed desorption experiments.The desorption rate of the order of four kinds resins were:MM-3>MM-2>MM-1>NDA-150.The desorption rate was faster when more mesopores in adsorbent.Desorption peak of three halohydrocarbon appeared in the vicinity of their boiling points,indicating that desorption reached a maximum rate at the temperature near their boiling point.The low boiling point adsorbate desorbed more readily.When the desorption temperature reached 200?,three kinds of halohydrocarboncan be completely desorption from the resins.The desorption efficiencyattained above 99%.