Preparation Of Titanium Dioxide/Inorganic Fiber Composites By Microwave Hydrothermal And Their Photocatalytic Activity

Photocatalytic technology is an efficient and eco-friendly technology.It uses photocatalyst as the core to generate redox reactions on pollutants which need to be degraded,resulting in almost complete degradation of pollutants.Due to high processing efficiency and eco-friendly features,it has become the most promising emerging technologies in current environmental problems.So far,the photocatalytic technology has been widely used in many fields,such as indoor formaldehyde purification,drinking water sterilization,photoelectric conversion,wastewater treatment and self-cleaning surfaces.Especially in the field of dealing with pollutants in the environment,it has received much attention.The focus of photocatalytic technology is photocatalyst.In 1972,researchers found that TiO2(titanium dioxide)could be decomposed to produce hydrogen,which opened the door for TiO2 to be used as photocatalyst.TiO2 has many advantages,for example,the absorption threshold of 387.5nm enables photocatalytic reaction under the condition of sunlight.Moreover,TiO2 also has the advantages of low price,simple preparation equipment and stable chemical properties.However,nano-sized TiO2 powder particles are easily to aggregate and lose photocatalytic effect in the process of degradation of organic pollutants.And the recovery problem in the liquid phase system also needs further improvement.Therefore,the preparation of a supported photocatalyst is of great significance.In this paper,the supported TiO2 photocatalysts with different inorganic fibers as carriers were studied for the degradation of colored dyes.And then the photocatalytic properties of composite materials prepared with three different carriers were investigated.Main contents of the paper as follows:(1)The TiO2/BF(basalt fiber)composites were prepared by microwave hydrothermal method.The effects of pretreatment conditions on the surface roughness of BF and the photocatalytic properties of TiO2/BF composites were studied.The suitable roughness of the fiber surface can increase the bonding force of TiO2,so as to increase the loading rate and improve the photocatalytic efficiency.The experimental results show when the microwave heating time was 30min and the microwave temperature was 200?,the combination of TiO2 and fiber could be successfully confirmed by field emission scanning electron microscopy(FE-SEM).And X-ray diffractometry(XRD)characterization shows that the TiO2 nanocrystals are the most suitable anatase type with uniform grain size at this condition.When the condition of BF is treated with 0.1mol/L HF at 55? for 15min,the surface of BF has appropriate roughness.The loading rate of TiO2/BF composite is 13.75%.Moreover,the degradation efficiency of 60mL RhB(rhodamine B)solution was 97%within 300min.Furthermore,the photocatalytic efficiency was still 84%after 10 cycles.(2)The pretreatment conditions of CF(carbon fiber)were found out,and TiO2/CF composite materials were prepared under optimized microwave hydrothermal conditions.The SEM results show that CF with rough surface but unaffected physical properties can be obtained after oxidation with acetone and concentrated HNO3 for 4h.And UV-vis characterization show that TiO2/CF composite could effectively degrade 96%of RhB solution within 60min,and it still had 88%photocatalytic efficiency after 10 cycles.(3)GF(glass fiber)was treated with isopropanol to remove the oil agent on surface.Then it etched by HF to facilitate the loading of TiO2.Finally,the TiO2/GF composite material was prepared.SEM and UV-vis results show when the condition of GF is treated with HF at 65?for 5min,the etching effect is best.TiO2 was uniformly loaded on GF with a loading rate of 9.31%.The degradation efficiency of 60mL RhB solution was 96%within 150min.Furthermore,the photocatalytic efficiency was still 86%after 10 cycles.