The Preparation Of BiOI And Its Composites And Study On Their Performance Of Adsorption Of Phosphate And Photodegradation

Environmental pollution has become an increasingly serious problem due to the rapid development of economy.Photocatalytic is considered as an ideal,green and effective technology to solve water pollution.Among various photocatalysts,BiOI shows the smallest band-gap（¹.8 eV）and is an effective visible-light photocatalyst for photodegradating various pollutants which attracts more and more attention.However,due to its high recombination of photocarriers and difficulty to separate from water as powder photocatalyst,its practical application is limited.Therefore,in order to obtain the photocatalyst with high photocatalytic activity and good stability and reusability,we devoted to researching BiOI-based semiconductor composites to promote its application in environmental treatment.The main research contents has been summarized as follows:1.The 3D microsphere-like BiOI was synthesized by a facile solvothermal method with Bi（NO）₃·5H₂O as Bi resource with high photodegradtion of anionic dyes and high adsorption capacity of phosphate.Evaluation on performance of simultaneously photodegrading dyes and adsorbing phosphate revealed that the as-prepared samples exhibited 1)high adsorption capacity towards phosphate,up to 55.80 mg P/g;2)excellent photodegradation activity towards cationic dyes（RhB was 100%photodegraded within 50 minutes,while the photodegradation rate of MB and FB were 92%and 95%within 100 minutes,respectively.）,but no photodegradation activity towards anionic or nonionic dyes in phosphate-dye binary system.The corresponding mechanism was also revealed.2.The PANI/BiOI/rGH photocatalyst was successfully prepared by step-by-step solvother-mal method.The results showed that 70%PANI/BiOI/rGH shows the highest photocatalytic degradation rate of RhB which was 8 times,33 times and 130 times higher than that of 30%BiOI/rGH,8%PANI/BiOI and BiOI,respectively.The optical properties of the as-prepared materials were characterized by DRS,EIS and photocurrent which showed that the significant improvement of photocatalytic activity was attributed to the enhancement of visible-light adsorption and the improvement of the photocarriers separation due to the addition of rGH and PANI,and the hydrogel structure solved the problem of difficult separation from water compared to powder photocatalysis.The photocatalytic activity was still good after 5 cycles meaning that its stability is very good,and its possible photocatalytic mechanism was proposed.3.The Au/BiOCl/BiOI composite was successfully prepared using a facile solvothermal-thermal reduction method.We demonstrated that the best reaction conditions was that the adding concentration and volume of HAuCl₄ was 5 mM and 20 mL,and the thermal reduction temperature and time were 100 ^oC and 30 min,respectively.And the photocatalytic performance of Au/BiOCl/BiOI is 3.6 times,5.8 times and 8.6 times than that of BiOI,Au/BiOCl and BiOCl,respectively,and which is because of the obviously accelerated separation efficiency of photo-generated carriers due to the addition of Au nanoparticles and the formation of heterojunction with BiOCl.And the corresponding photocatalytic degradation mechanism was studied.