Periodic Mesoporous Organosilica Materials:Design,Synthesis And Application In Adsorption Of Pollutants

Periodic mesoporous organosilanes（PMO）have been widely studied by researchers for applications in catalysis,adsorption,biomedicine and other fields.In adsorption applications,there are few reports related to the use for adsorption of VOCs,and it is mainly phenyl bridged PMO;when used for adsorption of heavy metal ions,functionalization is often required;based on phenyl bridged PMO,functionalization of PMO often takes a long time to synthesize,or the synthesis requires high reaction temperature or cumbersome synthesis steps,these factors affect the practicality,this thesis intends to develop a simple synthesis method and functional group modification method to study its application in the adsorption of VOCs and adsorption of metal ions.The synthesis of ethane-conjugated periodic mesoporous organic-silicon materials（Et-PMO）with relatively uniform dimensions was carried out by modified Stober method,hydroalcoholic system,ammonia catalysis,cetyltrimethyl ammonium bromide（CTAB）as the soft template and1,2-Bis（triethoxysilyl）ethane（BTEE）as the starting organosilicon material for 3 h.The morphology and structure of Et-PMO were tested by scanning electron microscopy（SEM）,transmission electron microscopy,powder X-ray diffraction（XRD）,and the specific surface area and pore size distribution of Et-PMO were checked by nitrogen adsorption and desorption,and Et-PMO with different specific surface areas and different pore sizes were obtained by adjusting the synthesis temperature;recovering the solvent used for synthesis and the template agent,the secondary synthesized organosilane materials maintained a high specific surface area.A series of synthesized Et-PMO materials were then tested for VOCs adsorption,and various VOCs models were selected as adsorbents,which showed excellent adsorption characteristics for aromatic hydrocarbons,ketones and halogenated hydrocarbons,among which the maximum adsorption capacity of 704 mg·g^-1,554mg·g^-1 and 935 mg·g^-1 was achieved for xylenes,2-butanones and chloroform,and the adsorption capacity was better than the adsorption capacity of activated carbon and Beta zeolite.Et-PMO has good hydrothermal and thermal stability,and the adsorption characteristics can be preserved well by processing.We prepared aminomodified PMO material（Et-PMO-NH₂）in one step by condensing BTEE with 3-Aminopropyltriethoxysilane（APTES）using ammonia-catalyzed acetone aqueous system and CTAB as template,followed by adsorption tests of Cr⁶⁺,Cu²⁺and Ni²⁺ions.In the single component test,Et-PMO-NH₂ showed excellent adsorption performance for Cr⁶⁺ions,and 20 mg of Et-PMO-NH₂ could remove 97%of 70 mg·L^-1Cr⁶⁺ions solution for 50 min.In the coexistence system of Cr⁶⁺,Cu²⁺and Ni²⁺ions,the adsorption capacity of Et-PMO-NH₂ to Cr⁶⁺ions is still very high,accounting for 80%of the total adsorption capacity.It has a certain selectivity to the adsorption of Cr⁶⁺ions.After 5 cycles of tests,it can still maintain nearly 90%of the adsorption capacity...