Synthesis And Properties Of Photocatalytic Composites Based On Waste Rice Noodle

Photocatalytic degradation technology has a wide range of applications in water pollution treatment,but the current commercial semiconductor photocatalytic degradation materials generally have problems such as expensive and low utilization of visible light energy.On the other hand,cooking waste may bring pollution to the natural environment such as water bodies,and the current resource utilization of cooking waste has some problems such as low added value of the products.In this thesis,we combined the resource utilization of cooking waste with the preparation of photocatalytic materials.Using waste rice noodle as raw material,the carbon quantum dots（CQDs）was synthesized by hydrothermal method,and then compounded with different inorganic raw materials to prepare three kinds of low-cost and high-performance photocatalytic composites respectively.Their composition,structure and performance were investigated in-depth,and the main factors affecting the product performance study were explored.In addition to excellent performance and high product added value,the obtained materials also have the advantages of mild reaction conditions,convenient synthesis and no secondary pollution,which can provide a new way for the efficient resource utilization of cooking waste and the development of low-cost photocatalytic composites.The main results of the paper are as follows:（1）A carbon quantum dots/titanium dioxide（CQDs/TiO₂）photocatalytic composites based on waste rice noodle were synthesized for the first time by hydrothermal conversion of waste rice noodle into carbon quantum dots（CQDs）and then compounded with titanium dioxide（TiO₂）.Their structure,photocatalytic performance and photocatalytic mechanism were investigated.The results showed that the CQDs/TiO₂composite had better photocatalytic degradation performance than the commercial TiO₂,and its degradation rate to methylene blue could reach81.84%in 10 min and 99.87%in 80 min.In addition,the CQDs/TiO₂composite also displayed a nice photocatalytic degradation effect on other water-soluble dyes such as rhodamine B,malachite green,methyl violet and basic magenta effectively.（2）The first carbon quantum dots/zinc oxide（CQDs/ZnO）photocatalytic composites based on waste rice noodle were synthesized by converting the raw material into carbon quantum dots（CQDs）by hydrothermal method and then compounded with zinc oxide（ZnO）.The structures,photocatalytic properties and photocatalytic mechanism of the resulted CQDs/ZnO composite were investigated.The results showed that the photocatalytic degradation performance of CQDs/ZnO composite was better than that of commercial ZnO and the aforementioned CQDs/TiO₂composite,whose degradation rate to methylene blue could reach 96.92%in 5 min and 98.88%in 10 min.In addition,the CQDs/ZnO composite was also able to photocatalytic degrade water-soluble pollutants such as rhodamine B,malachite green,methyl violet,basic magenta,tetracycline,and aniline effectively.（3）Using waste rice noodle and waste iron oxide scale as raw materials,the waste rice noodle was firstly converted into carbon quantum dots（CQDs）by hydrothermal method,while the iron oxide scale was calcined to obtain iron oxide（FeO_x）.The carbon quantum dots and iron oxides based on waste rice noodles were combined to transform the two wastes（waste rice noodles and discarded iron oxides）into low cost,magnetic carbon quantum dots/iron oxides（CQDs/FeO_x）photocatalytic composites for the first time.The structures,photocatalytic properties and photocatalytic mechanism of the resulted CQDs/FeO_xcomposite were investigated.The results show that the CQDs/FeO_xcomposite can effectively degrade water-soluble pollutants such as methylene blue and tetracycline hydrochloride,with98%degradation rate to methylene blue within 6 h.Meanwhile,the material exhibits good magnetic properties and can be conveniently recycled and repeatedly using magnetic field after the photocatalytic degradation process.