Study On The Adsorption Performance Of Cellulose-based Porous Polymers For Aromatic Substances In PO/SM Wastewater

The propylene oxide-styrene monomer（PO/SM）co-production technology is an important process for the chemical industry to produce propylene oxide and styrene monomer.There are still a lot of aromatic substances（ethylbenzene,styrene,acetophenone,1-phenylethanol,etc.）in the wastewater after pretreatment.Thus,it is important to recover useful resources from PO/SM wastewater.In this paper,cellulose-based porous polymers were used to recover the useful substrates in PO/SM wastewater.The specific content is as follows:（1）Using TEMPO oxidized cellulose（TOC）as the precursor,a TEMPO-oxidized cellulose-grafted-polystyrene hypercrosslinked polymer（TOC-PS-HCP）was synthesized facilely by grafting polystyrene and post crosslinking route,dichloro-p-xylene（DCX）as crosslinker.The evolution process of material structure was verified by FTIR,¹³C NMR,TG and other characterizations.The physical structure of the material was analyzed by N₂ adsorption-desorption,SEM,TEM and water contact angle tests.Subsequently,ethylbenzene and styrene were used as adsorption substrates to systematically explore the ability of the adsorbent to recover resources.The adsorption of ethylbenzene and styrene on TOC-PS-HCP could reach equilibrium within 10 and 15 min,respectively.The theoretical maximum adsorption capacities of TOC-PS-HCP for ethylbenzene and styrene were calculated as 94.52 mg·g^-1 and 103.38 mg·g^-1 by isothermal experiments.The recovery rate of adsorbent could maintain good and stable in the complex aqueous system.TOC-PS-HCP showed a stronger affinity for ethylbenzene and styrene than others in the simulated wastewater multi-component adsorption.It can be verified that the main driving forces for adsorption include van der Waals force,π-πinteraction and pore size effect by theoretical simulation calculations.（2）In order to further study the recovery performance of useful resources in the wastewater from PO/SM by other cellulosic porous polymers,this chapter continues to use TOC as the precursor,and prepare modified cellulose as the adsorbent by co-polymerization and crosslinking.Cellulose-based composite microsphere（CMS）was synthesized by suspension polymerization.Benzylated cyclodextrin（Bn CD）was decorated on CMS by formaldehyde dimethyl acetal（FDA）,then obtained a new type of cellulose-based microsphere porous polymer（Bn CD@CMS）.The existences of cellulose skeleton,the introduction of Bn CD and the evolution of morphology of samples were verified by structural characterization.Subsequently,selecting acetophenone（AP）and 1-phenylethanol（PE）as adsorption substrates to investigate the adsorption performance of Bn CD@CMS.The adsorption of AP and PE by Bn CD@CMS could reach equilibrium in 20 min and 60 min,respectively.These processes are a multi-molecular layer self-heating physical adsorption process,and the theoretical maximum adsorption was calculated as 389.39和189.70 mg·L^-1 by Langmiur model.The synergistic and competitive effects existed in the process of binary adsorption of AP and PE on Bn CD@CMS,and the adsorbent was well regeneration.The adsorption results of different steps samples illustrated that both strategies of crosslinking and Bn CD modification contributed to this adsorption process.Compared with the samples which were reported by other literatures,Bn CD@CMS has a greater potential in the adsorption-recovery of AP/PE.The adsorption process was further explained through theoretical calculations,which were mainly driven by the following:pore structure,π-πstacking,cavity inclusion,and hydrogen bonding.（3）In view of that Bn CD enhanced adsorption of AP and PE on Bn CD@CMS at last chapter,introduced favorable functional monomers in the process of preparing functional cellulose-based microspheres by suspension copolymerization:Sodium-p-styrenesulfonate（SSS）and N-Vinyl-2-Pyrrolidinone（NVP）at this chapter.After the copolymerization conditions were discussed,the functionalized CMS was further crosslinked with FDA as the crosslinking agent.The successful introduction of functional monomers in the copolymerization process was verified by a series of characterizations.The specific surface area of the functionalized HCMS was reduced to varying degrees,resulting in no significant improvement in the adsorption performance in the AP-PE binary system.In summary,this paper synthesized a series of cellulose-based porous polymers and applied them to the adsorption and recovery of pollutant components in PO/SM wastewater.The research results provided a certain theoretical basis for the adsorption of organic pollutants,and gave new ideas for the application of cellulose-based adsorbent materials.