Diversified Applications Of Transparent Mesoporous Silica Gel Monolith

The general idea of material chemistry research is to design and synthesize specific materials based on the needs of a specific field of application,and one of the goals clearly pursued by material chemists is for further multi-functional applications in a wider field after completing the application of its preset functions.This work is based on the transparent mesoporous silica gel monolith and the Al-doped modified transparent mesoporous silica gel monolith synthesized previously by the research group by using three different nonionic block copolymer surfactants(F127,P123,Brij56)as templates.In order to understand the performance of materials from different aspects,the optical transparency of the synthetic gel can be used to dope dyes into transparent gel to study the optical properties,the integrity of the macroscopic morphology of the material and its high specific surface area after removing templates through calcination can be treated as hard template to nano-cast mesoporous carbon materials to study its electrochemical properties and be used as adsorbents to systematically investigate their adsorption properties on dyes such as methylene blue in simulated dye wastewater treatment,respectively.The main findings are as follows:First of all,the laser dyes Rh6G(Rhodamine 6G)and RhB(Rhodamine B)were respectively directly introduced into a transparent mesoporous gel synthesized by different templates,and the effects of dye concentration,templating agent concentration and structure,Al doping and other factors on the optical properties of the material were systematically studied,and compared with pure silica without template addition and silica-alumina monoliths,The results show that the F127 and P123 templates with larger sizes are more favorable for the dispersion of dye molecules than Brij56.In addition,doping of Al in the framework within a certain Si/Al ratio range contributes to the dispersion of the dye molecules,however when Si/Al is as low as 20,the dye molecules may quench and deactivate due to aggregation as the Al content is continuously increased.Compared with the template-free gel,the presence of the templating agent contributes to both the integrity control of the monolith and the dispersion of the dye molecules,which is an optical matrix material with potential application value.Secondly,the gel sample after completion of the optical property study was calcined to remove the dye and the template and used as a hard template for nano-casting the mesoporous carbon monolith that its specific surface area was up to 1243 m~2/g.The morphology of the prepared mesoporous carbon can be controlled according to the morphology of the gel monolith precursor,and it has sufficient strength to be directly used as an electrode.Therefore,the cumbersome process and cost of manufacturing the electrode can be eliminated as compared with the mesoporous powder carbon material.The preliminary electrochemical performance test results show that the specific capacitance of the mesoporous carbon monolith obtained by the F127 template gel replication can reach 197 F/g,which is an excellent electrode material with great potential.Finally,the mesoporous gel after completion of the optical property study was to use for adsorbent by calcination aiming to remove the dye and the template,and its adsorption performance on MB(methylene blue),RhB and CR(Congo red)dyes in simulated wastewater was systematically studied.At the same time,the adsorption kinetics process and adsorption mechanism were simulated.The results show that:the gel synthesized by P123 as the template under the same preparation conditions showed higher adsorption efficiency than the F127 and Brij56 template gels due to the largest specific surface area,and the saturated adsorption capacity of MB and RhB reached 190.8 mg/g and129.5 mg/g respectively.The adsorption process accords with the Langmuir isotherm monolayer adsorption model,and the adsorption kinetics is more in line with the pseudo-second-order kinetic model.The Al-doped gel has a reduced adsorption performance due to a decrease in specific surface area.The study of temperature effect shows that the adsorption process is an exothermic process,and the elevated temperature is not conducive to the increase of adsorption amount,but the temperature effect on RhB adsorption onto the Brij56 template gel is opposite,which the reason is not clear.