| Due to the continuous development of industry,excessive phosphorus is discharged into the environment,causing eutrophication of water body.The treatment of phosphorus pollution has become an important project related to the ecological environment and human health.The adsorption method is a common strategy of phosphate removal because of its simple operation,high adsorption efficiency,and low equipment cost.Modified mesoporous silica films were a new type of film adsorbent which was commonly used in adsorption.The mesoporous silica film has the advantages of regular pore structure,large specific surface area and special film-like structure,which can avoid the problem of difficult recycling.However,its poor adsorption and mechanical properties restrict its wide application.Therefore,it is of great significance to modify the mesoporous silica film materials to improve its adsorption and mechanical properties.In this paper,using green and environmentally friendly cellulose nanocrystals?CNCs?as templates,La?NO3?3·6H2O as lanthanum source,and tetramethoxysilane?TMOS?as silica source,three types of highly efficient modified mesoporous silica film materials with good adsorption and selective performance were constructed by evaporation-induced self-assembly?EISA?combined with the post-grafting method and ethanol evaporation method.A variety of characterization methods were used to investigate the surface morphology,internal structure,and chemical element composition of the mesoporous silica films.The adsorption and selective performances of the film adsorbents were evaluated by the phosphate adsorption experiment.Finally,the possible mechanism of adsorption was proposed by FT-IR,XPS,Zeta potential.The main work of this paper is as follows:?1?The high-efficiency La-EDA functionalized mesoporous silica films were prepared by post-grafting method.In this system,the amino functional groups were first introduced into the mesoporous silica film using silane coupling agent,and then the lanthanum ions were introduced.This modification was beneficial to improve the stability and uniformity of the lanthanum active sites,and finally achieved the effective adsorption of phosphate.The prepared La-EDA functionalized mesoporous silica films?La-EDA-MSF?could effectively capture phosphate in the pH range of solution 37,showing excellent adsorption performance(40.363 mg g-1).And the adsorbents also showed excellent adsorption efficiency?98.35%?in environmental water samples within 1 h.?2?The cellulose nanocrystals/silica composite films were synthesized by using cellulose nanocrystals as templates and tetramethoxysilane as silica source with the evaporation-induced self-assembly method.Then,the free-standing large-mesoporous silica films were obtained by removing the template using the treatment of sulfuric acid pickling.Finally,lanthanum active sites were introduced by the ethanol evaporation method.In the system,the sulfuric acid pickling to the removal of the template will not cause the collapse of the mesopores.The obtained silica film presented good mesoporous structure and had a large pore size of 21.07 nm.Besides,the effect of La/Si on the adsorption performance was explored in the experiments,and the results showed that when the La/Si molar ratio was 1/5,the modified large-mesoporous silica films?La-MSF-5?exhibited high phosphate adsorption capacity(49.98 mg g-1)and good regeneration performance.?3?La modified rGO/silica large-mesoporous films were prepared by evaporation self-assembly method combined with ethanol evaporation method.In this system,the introduction of rGO into mesoporous silica thin films efficiently improved the hydrophilicity and mechanical properties of the film material,which were favor for the phosphates removal in water.Phosphate adsorption experiments showed that the rGO modified large-mesoporous silica films had a high adsorption capacity(55.045 mg g-1).In the presence of coexisting ions in the phosphate solution,the modified mesoporous film materials also maintained high adsorption capacity,indicating that the materials had good anti-interference performance.The analysis results of the sample La-MSF-5-P obtained after phosphate adsorption indicated that the formation of"rod-like"crystal LaPO4 was the dominant route for phosphate adsorption.This silica film material may open up new ways for phosphate removal. |
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