Fabrication And Properties Of Photocatalytic Nanomaterials Based On Natural Cotton Cellulose Nanofibers

Semiconductor photocatalyst cause extensive research due to its great potentialapplications in energy and environment. The traditional powder photocatalyst havesome disadvantages of easy to aggregate in the preparation process of photocatalyst ordissolved in the dye waste, and not easily removed in the recycling process, easy todamage and other shortcomings limit its applications. Ultrafine nanofiber hasadvantages of a small size effect, large length to diameter ratio, a large specificsurface area, light, soft and many other features. Furthermore, it has many hydroxylgroups on its surfaces, easy to modification, so it becomes competing carrier ofinorganic nanomaterials. It not only enhancing stability of the nanomaterial,preventing their reunion, but also controling the size distribution of the nanomaterial.All these advantages make the inorganic material get better use in terms of optical,electrical and catalytic performance, evenly, there may produce a new exotic features.These kinds of composites "Mutually complementarity" fully make up for theshortcomings of a single material, produce new performances, and create a newsituation in materials design.In this thesis, we revolves around work “Fabrication and Properties ofPhotocatalytic Nanomaterials based on Natural Cotton Cellulose Nanofibers”. Thedetailed works were summarized as following three aspects:1、Fabrication and Property of Nature Cotton Cellulose/TiO2Composite NanomaterialAccording to our previous work, Nature cotton was dissolved to LiCl/DMAcsolution under magnetic stirring to obtain electrospinning solution, then, cottoncellulose nanofibers were obtained by electrospinning process. The nature cottoncellulose/TiO2composite nanomaterials were prepared by a sol-gel method based onnatural cotton nanofibers. Adjusting the amount of TiO2precursor (tetrabutyl titanate)to control the content of TiO2in the composite materials. In order to improve thecrystallinity of TiO2, the resulting composites were hydrothermally treated for6h at 180℃. The photocatalytic activity of photocatalysts was evaluated by the degradationof methylene blue(MB)．Test results show: amorphous TiO2structure exists in cottonfibers/TiO2composites which were obtained by a sol-gel method, the crystallizationof TiO2were significantly improved after hydrothermal treatment, which becomeanatase structure. Photocatalytic degradation of Methylene Blue experiments showthat the composite material has good catalytic effect for photodegradation MethyleneBlue under UV light irradiation, and within a certain range, the photocatalytic activityof the composite reinforced with TiO2content increasing.2、Fabrication and Property of Nature Cotton Cellulose/CdS Composite NanomaterialThe natural cotton fiber/CdS nanocomposites were prepared by the method ofcontinuous ion adsorption based on superfine cotton fiber. By changing adsorptiontimes, the content, size and distribution of CdS nanoparticles on the cotton fibersurface were controled. The photocatalytic activity of photocatalysts was evaluated bythe degradation of Rhodamine B (RhB)．Test results show: CdS nanoparticles, withcubic zinc-blende structure, can be dispersed uniformly on the surfaces of cottoncellulose nanofibers. The obtained nanocomposites exhibit good photocatalyticactivity for photo-degradation of Rhodamine B (RhB) under visible light irradiation.Preliminary results revealed that the CC/CdS-20nanofibers exhibited the highestvisible light photocatalytic activity than others. Therefore, there is an optimalCdS-loaded amount in CC nanofibers for the visible light photocatalysis. TheCC/CdS-20has degraded ca.99%of the initial RhB dye in the40min. Cotton fiberscan inhibit CdS reunion and ease CdS light corrosion.3、 Fabrication and Property of Nature Cotton Cellulose/CdS/TiO2CompositeNanomaterial with flower-like structureThe flower-like CdS nanocrystals were synthesized on superfine cotton fiber bya hydrothermal method, which is called nature cotton cellulose/CdS compositenanomaterials with flower-like structure. We get the best reaction conditions bystuding how hydrothermal reaction time, temperature, Cd: S ratio affectedmorphology of the composite material. The results show: when Cd: S=1:3at the 200℃for12h, the perfect flower-like CdS structure were obtained, and possiblemechanism of its formation was proposed.We take cotton cellulose/CdS nanocomposites for the carrier, by controllingamount of tetrabutyl titanate to get different TiO2films loaded on the surfaces ofcotton cellulose/CdS Nanocomposites via a sol-gel method, which were a series ofcotton cellulose fiber/CdS/TiO2composite nanomaterials. As a comparison, pureflower-like CdS and CdS/TiO2nanomaterials were prepared. Compared to othermaterials, the nanocomposite material with10ml tetrabutyl titanate has the bestphotocatalytic degradation efficiency to Rhodamine B and the best stability. Inaddition，trapping experiments revealed that hydroxyl radical as the mainly activespecies for the degradation of Rhodamine B. Thus, we put forward the proposedmechanism of photocatalytic degradation of Rhodamine B.