Synthesis And Adsorption Performances Of The Polystyrene Phenol-Formaldehyde Hypercrosslinked Resin

Hypercrosslinked polystyrene resins are a series of weakly polar polymeric adsorbent with high specific surface area.Porous phenol-formaldehyde resins are a series of polar adsorbent resins rich in hydrogen bond donors.In this dissertation,in order to combine the advantages of hypercrosslinked polystyrene resins and porous phenol-formaldehyde resins,a series of hypercrosslinked polystyrene/phenol-formaldehyde hybrid resins were prepared,and their structure and adsorption performances were studied.The main contents of this dissertation are as following:1.Three polystyrene-phenols?shorted as PS-P?resins were prepared by bonding phenols to the macroporous crosslinked polystyrene resin via the Friedel-Crafts reaction of chloromethyl groups of chloromethylated polystyrene resin with the benzene rings of phenol,catechol,and pyrogallol,which were shorted as PS-P1,PS-P2,and PS-P3 resin respectively.Furthermore,three hypercrosslinked polystyrene/phenol-formaldehyde?shorted as HCPS-PF?resins were prepared by post-crosslinking the three PS-P resins in swollen state with dimethoxymethane via the Friedel-Crafts reaction,which were shorted as HCPS-PF1,HCPS-PF2,and HCPS-PF3 resin respectively.Moisture holding capacity,weakly acidic cation exchange capacity,and residual chlorine content,infrared spectra,and pore structure of the PS-P resins and HCPS-PF resins were tested to determine their structures.The results showed that the phenols were successfully bonded to macroporous crosslinked polystyrene resin,and the specific surface area of the HCPS-PF resins was significantly higher than that of the PS-P resins,which implied that the PS-P resins were successfully post-crosslinked to give the hypercrosslinked resins of HCPS-PF.2.Static adsorption and dynamic adsorption performances of the PS-P resins and the HCPS-PF resins for organic compounds containing hydrogen bond donors or acceptors such as phenol,theophylline,and caffeine in aqueous solution were studied.The results of static adsorption study showed that:?1?The adsorption of phenol,theophylline and caffeine onto the resins from aqueous solution was spontaneous,exothermic,and entropy reductive process;?2?Adsorption capacities of the HCPS-PF resins were obviously higher than those of the PS-P resins;?3?In order to investigate the adsorption mechanism,a hypercrosslinked resin was synthesized by using toluene instead of phenols,which was shorted as HCPS-TF resin,and the adsorption capacities of the HCPS-PF resins were larger than those of the HCPS-TF resin,which indicated that the adsorption of phenol,theophylline,and caffeine onto the HCPS-PF resins in aqueous solution was based on both?-?interaction and hydrogen bonding;?4?For the adsorbates with a initial concentration of500 mg·L^-11 at 288K,the HCPS-PF1 resin had the highest adsorption capacity for phenol among the three HCPS-PF resins,which amounted to86.0 mg·g^-1,and the HCPS-PF2 resin had the highest adsorption capacities for theophylline and caffeine,which were 104.8 mg·g^-11 and127.1 mg·g^-11 respectively.The results of dynamic adsorption study at 288K showed that:?1?When the initial concentration of the adsorbates was2000 mg·L^-1,saturated adsorption capacity of HCPS-PF1 resin for phenol,theophylline and caffeine amounted to 230.5 mg·g^-1,244.0 mg·g^-1,and263.2 mg·g^-11 respectively;?2?The desorption percentage for phenol,theophylline and caffeine amounted to 95.1%,94.9%,and 94.2%respectively by using anhydrous ethanol as eluent,and the adsorption capacities of the regenerated resin could reach more than 93%of those of the original resin.The static adsorption performance of the PS-P and HCPS-PF resins for boric acid in aqueous solution was investigated.The results showed that:?1?The PS-P2 resin had the highest adsorption capacity for boric acid in aqueous solution among the PS-P and HCPS-PF resins,and the adsorption capacity amounted to 16.1 mg·g^-1?calculated by boron element?;?2?The adsorption of boric acid onto the resins from aqueous solution was spontaneous,exothermic,and entropy reductive process;?3?The two resins bonded with catechol,PS-P and HCPS-PF,had higher adsorption capacity as compared with the other four resins,which was resulted from the complexation between B?OH?₄^-and the two ortho hydroxy groups of catechol;?4?The HCPS-PF2 resin had a slightly lower adsorption capacity as compared with the PS-P2 resin,which might be resulted from the higher steric hindrance of the phenolic hydroxyl groups after post-crosslinking.