Preparation Of Composite Material BiOI And Its Application In Dyeing Wastewater

In recent decades, exploring the high efficiency photocatalysts with narrow band gap which function in the visible light region has attracted a remarkable attention. However, the BiOI shows limited photocatalytic efficiency, due to rapid electron-hole recombination. We resolve these issues to improve the study of photocatalytic material BiOI,details as follows:（1） The BiOI were prepared by a solvothermal process with bismuth nitrate pentahydrate （Bi（NO₃）₃·5H₂O） and potassium iodide （KI） were used as the Bi and I sources and ethylene glycol as the reaction media. The experiment using single element of variables, study different pH values, reaction temperatures and time to filter out the optimum conditions. The as-prepared BiOI was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, and nitrogen sorption. The photocatalytic activity of the as-prepared sample was evaluated by degradation of methylene blue （25mg/L MB）, Rhodamine B（10mg/L RhB） under visible light irradiation. The reaction was carried out at high temperature （160℃） for a long time （16h）. The degradation experimental results confirmed that the BiOI expresses a high photocatalytic activity and can achieve a 98% degradation to MB and RhB after 30 min.（2） The HZSM-5 has well-ordered pores can provide the high surface area and the absorbent capacity, cooperate to increase the efficiency of the catalytic process. The flower-like BiOI/HZSM-5 composites were synthesized via a facile and environmentally-benign hydrothermal method. The crystalline structures and morphologies of the powder have been characterized by X-ray diffraction （XRD） and Scanning electron microscopy （SEM）. The photocatalytic activity of samples was tested for degradation of methylene blue （MB） and Rhodamin B （RhB） dye under simulated solar light irradiation. The degradation rate of MB and RhB by BiOI/HZSM-5 composite photocatalysts respective reach 99.6% and 98.6% under visible light irradiation, BiOI/HZSM-5 exhibited the highest photocatalytic performance when compared with BiOI. In addition, flower-like BiOI/HZSM-5 composites are stable during the reaction and can be used repeatedly.（3） Photocatalysts is still limited mainly due to difficult separation from treated water and the low reused rate. In order to solve the problem, BiOI can be coated on the Fe2O3 magnetic carriers. The experiment expect to obtain composite photocatalyst with higher catalytic activity and magnetic recycling property. The phases and microstructure of Fe2O3/BiOI were analysized by XRD and SEM, et al. The photocatalytic performance and recyclable performance of ceramics material was studied by degradation of MB and RhB. The results indicated that about 95% and 99% of MB and RhB was degradation with Fe2O3/BiOI after 60min degradation under visible light, After three cycles, degradation efficiency of MB aqueous solution by Fe2O3/BiOI were only reduced little under visible light. The Fe2O3/BiOI porous ceramics showed a good photocatalytic and recyclable degradation performance, and can be separated and recovered quickly under the effect of external magnetic field.（4） Due to difficult separation from treated water and the low reused rate. The BiOI can be coated on the plexiglass（PMMA） carriers to prepared PMMA/BiOI composites. Methyl methacrylate as monomers by suspension polymerization preparation spherical PMMA in the experiment. Furthermore, the photocatalytic properties of the obtained samples with different morphologies were investigated by the photodegradation of MB and RhB under visible light irradiation. When the polymerization reaction time is 1.5-2h added BiOI powder to form composite PMMA/BiOI pellets. The results revealed that PMMA/BiOI composite material can enhance the separation, about 33.3% and 45.3% of MB and RhB was degradation with PMMA/BiOI after 60min degradation under visible light.（5） The molecular imprinting technique （MIP） has drawn extensive attention recently for its advantages of selectivity, easy preparation and inexpensiveness. In this paper, we try to synthesis of molecularly imprinted catalyst type SMIP-BiOI by combination of functional monomer and BiOI catalyst as the carrier, neutral red as a template. It can be seen that the neutral red degradation over SMIP-BiOI is 95% after 60min of visible-light irradiation. Compared to this, the MB degradation over is only 37%. The results of this study have indicated SMIP-BiOI can selectively priority degradation neutral red.