Controlled Synthesis Of Bismuth-based Materials And Their Applications In Water Purification

With the rapid development of industrialization and growth of population,the heavy metals,organic dyes and antibiotics in water have severely affected the ecosystems.In addition,these pollutants can be accumulated in water and further harm aquatic organisms and humans.The adsorption is a kind of simple and effective methods for heavy metal treatment.Photocatalytic technique possesses low-cost and environmentally friendly characteristics for dye degradation.And photoelectrocatalysis represents a kind of highly efficient technique for the degradation of antibiotics.However,how to develop efficient adsorbents,photocatalysts and photoelectrocatalysts remains a challenging work.Bismuth-based semiconductors display excellent stability and low toxicity.It can also absorb sunlight.All of these advantages make it an environmentally-friendly purifier.In this dissertation,the adsorption capability and photocatalytic activity of Bi₂O₂CO₃ was enhanced through the introduction of oxygen vacancies?OV?.The photoelectrocatalytic activities of BiVO₄for the degradation of tetracycline hydrochloride and production of H₂O₂ were improved through the co-doping of Mo⁶⁺and Gd³⁺ions.This study focuses on the adsorption of Cd²⁺ions,photocatalytic degradation of Rh B,and photoeletrocatalytic degradation of tetracycline hydrochloride over Bismuth-based semiconductors.The main contents are listed below:?1?Rose-like Bi₂O₂CO₃ hierarchical microspheres with rich?Bi₂O₂CO₃-ROV?and poor OV?Bi₂O₂CO₃-POV?were synthesized through a facile hydrothermal route and H₂O₂ oxidation treatment at room temperature,respectively.The as-synthesized products were characterized by FE-SEM,TEM,XRD,XPS,ESR and many more in detail.The adsorption capability of Bi₂O₂CO₃-ROV and Bi₂O₂CO₃-POV toward Cd²⁺ions was studied.As a result,Bi₂O₂CO₃-ROV hierarchical microspheres showed2.4-times larger adsorption capacity than Bi₂O₂CO₃-POV counterparts.Taking Rh B as dye model,the former also showed obviously enhanced photocatalytic activity for Rh B degradation in aqueous solution under air,N₂ and Ar atmospheres compared to the latter,especially under anaerobic conditions.Our work demonstrated that OV engineering could provide a new strategy for enhancing adsorption capability and photocatalytic activity under both aerobic and anaerobic conditions of the materials.?2?Mo⁶⁺and Gd³⁺ions co-doped BiVO₄?Mo-Gd-BiVO₄?photoanode was prepared by using electrodeposition and post-heating treatment.The Fe loaded carbon cloth?Fe/C?was prepared by ultrasonic method and further used as cathode.The photoelectrocatalytic system was fabricated by the as-prepared photoanode and cathode.Taking tetracycline hydrochloride as antibiotic model,the influences of electrolyte,electrode,potential,and some other factors on photoelectrocatalytic activity for degradation of tetracycline hydrochloride were systematically studied.The experimental results showed that the degradation rate of tetracycline hydrochloride could reached 78%within 2 h at an applied potential of 1.8 V vs.RHE.In addition,Fe/C cathode not only showed enhanced stability but also improved degradation efficiency of tetracycline hydrochloride.Furthermore,in order to understand the degradation mechanism,the main active species in the photoelectrocatalytic system were detected by adding proper capturing agents.It was found that hole and H₂O₂were main active species and H₂O₂ can efficiently degrade tetracycline hydrochloride as well.The present study develops a highly efficient photoelectrocatalytic system for the degradation of tetracycline hydrochloride,without use of additional O₂ and H₂O₂,which provides a new idea for purifying waste water.