Photocatalytic Degradation Of Pollutants In Water Using Catalysts Of Pure Natural Mineral Tourmaline And Tourmaline Coated TiO₂

Tourmaline is an important mineral in China and is rich in storage and distributed in most of the Chinese provinces. Since the discovery of its spontaneous electric field effect in1989, this mineral has been widely utilized in medicine and health, materials of sound and electricity, clothes and paint production, as well as some certain aspects of environmental protection and harm prevention. However, few achievements are based on the photocatalytic process. In this work, we selected the iron tourmaline from a Hebei mine to investigate its application in photocatalytic purification of dye wastewater, both as a single photocatalyst and as the support of anatase TiO2. In another aspect, sulfadiazine was chosen as one kind of sulfa drug, which has been widely accepted as environmentally harmful and is difficult to be removed from water, to investigate its photolytic degradation by ultraviolet and the affecting factors. The synthesized tourmaline-TiO2compound photocatalyst was used to degrade this pollutant by photocatalysis. The main content includes:1. Photocatalytic activity of tourmaline. The crude3000-mesh iron tourmaline was used as the photocatalyst for degradation of a dye pollutant of methyl blue. Various influencing factors were studied and the possible mechanism was discussed. This is the first application of tourmaline as a single photocatalyst without addition of any chemical products. This might promise the broadened usage of this mineral to approach the goal to save energy and eliminate the direct or indirect pollution to the environment.2. Preparation of tourmaline-coated nanometer-size的TiO2photocatalyst. The sol-gel process was carried out to prepare pure anatase TiO2and tourmaline-coated TiO2. The photocatalytic activity was tested using methyl blue as the target compound to investigate parameters during preparation like amounts of Ti(OC2H5)4, calcination temperature and time, appropriate content of tourmaline, etc. The best combination of these parameters was obtained. In the next step, this best compound catalyst was used to process stimulated wastewater of methyl blue, and effects of some factors were investigated to set a basis for its future employment.3. Photolytic degradation and photocatalytic degradation by tourmaline-TiO2compound of sulfadiazine. Photodegradation of sulfadiazine was studied with variation of common factors like addition of ethanol, nitrogen (instead of air), hydrogen peroxide, nitrate, nitrite, sulfate, α-FeOOH as well as the pH values. Sulfadiazine was firstly degraded using tourmaline-coated TiO2, which showed even higher efficiency, demonstrating the wide applicability of this compound catalyst. Our results indicate a potential utilization of tourmaline in photocatalytic removal of a larger variety of organic pollutants.