Modification Of TiO₂ Photocatalyst Using Mussel Shells And Study Of Its Degradation Of Indoor VOC

Indoor air pollution has attracted widespread public attention,as people usually spend most of their time indoors.Formaldehyde,as a typical indoor volatile organic compound（VOC）,has garnered increasing attention.Among the numerous ways for formaldehyde degradation,the use of titanium dioxide photocatalytic degradation is green and effective,but titanium dioxide also has its limitations.A problem that needs to be investigated immediately is how to overcome the limitations of titanium dioxide.Insufficient utilization of marine waste shells often leads to serious environmental problems.However,by optimizing the use of marine waste shells’inherent benefits for synthesizing high value-added products,they will become a useful solution to numerous critical challenges.Based on the two issues above,this paper will employ the physical and chemical properties of marine shells and their potential to replace the high purity chemical reagents as multifunctional material modification and modified photocatalyst for the degradation of indoor VOCs.The work of this paper can be summarized as follows:（1）The mussel shell was acidified to remove a large amount of calcium carbonate,then the cuticle（JST）was separated from the internal insoluble protein（MST）.In this process,a typical ternary Ti O₂/C/Ca CO₃composite photocatalyst（TCC）was precisely designed by an optimized solvothermal process in the presence of mussel shell extract（MST）.The photocatalysts were characterized by various techniques.The results revealed that the TCC photocatalyst with the optimal MST ratio could be synthesized by doping multi-elements that are naturally present in the MST.The synthesized composite photocatalyst exhibited a small diameter,abundant oxygen defects,and an efficient capacity for interfacial charge transfer.The photocatalytic investigation demonstrated that the typical sick-house gas HCHO could be effectively and thoroughly degraded within 80 minutes over TCC-0.4 under visible light at room temperature,without any by-products produced.Furthermore,the HCHO removal rate over the sample remained up to 95%after five cyclic photocatalytic reactions,revealing the high stability of the composite photocatalyst.The improved photocatalytic property can be attributed to the synergistic effect of in situ synthesized ternary Ti O₂/C/Ca CO₃composite photocatalyst.This work sheds fresh light on the efficient,cost-effective,and sustainable photocatalyst for indoor air purification.（2）Mussel cuticle powder（JST）,as a hard protein containing multiple elements,can be used to modify Ti O₂as a smart template and dopant.The amino acids in the cuticle can self-shrink to form a spherical Ti O₂/C binary catalyst via a reasonable solvent thermal reaction.The organic matter within the catalyst is burned during aerobic calcination,resulting in the formation of a Ti O₂/C hollow ball structure.The special structure boosts the catalyst’s specific surface area and active site,while the existence of C expands the light absorption range,improves the transfer efficiency of photoborne carriers,and greatly increases the activity of the photocatalyst.With formaldehyde as the target contaminant,the composite catalyst TJ-1.5 achieves the complete degradation of 358 ppm formaldehyde within 45 min.（3）Based on the above chapter,the cuticle of hard protein biological carbon is used as a natural reducing agent to reduce potassium permanganate and synthesize Ti O₂/C/Mn O₂ternary composite catalyst.Some of the excitation electrons in the conduction band（CB）of manganese dioxide can be transferred and combined with holes in the valence band（VB）of titanium dioxide,while electrons within the conduction band（CB）of manganese dioxide and the valence band（VB）of titanium dioxide can be transferred to C,hence effectively improving the separation of electron and hole.At the same time,with toluene as the target pollutant,the composite catalyst achieves the complete degradation of 209 ppm toluene within 80min,and its stability was demonstrated by five cycle experiments.