| About 180,000 tons of antibiotics are used in our country every year,and most of them are excreted as original drugs,and discharged the environment with domestic sewage and aquaculture sewage,causing serious water pollution.Therefore,it is very necessary to develop water treatment technology with high efficiency,low consumption,energy saving and environmental protection.Photocatalytic degradation technology has an important application prospect in organic wastewater treatment due to its strong oxidation capacity,no secondary pollution,green and clean characteristics.BOCl has attracted much attention in the field of photocatalysis due to its excellent chemical stability,non-toxic and harmless,unique layer structure and easy synthesis.However,pure phase BiOCl has a high recombination rate of photogenerated carriers,and only exhibits good photocatalytic activity under UV light irradiation due to the limitation of wide band gap,which seriously hinders its practical application.For this reason,two types of BiOCl-based composites,non-piezoelectric(semiconductor)/BiOCl and piezoelectric/BiOCl composites,were designed by introducing oxygen vacancies and construction of heterojunctions.The main contents are as follows:(1)A series of non-piezoelectric material/BiOCl heterojunction photocatalysts such as CuWO4/BiOCl with oxygen vacancy(CuWO4/Vo-BiOCl),In2O3/BiOCl and CeO2/BiOCl were constructed,which enhanced the optical absorption performance of BiOCl in the visible light region.Taking antibiotic as the target pollutants,the photocatalytic or piezoelectric photocatalytic degradation performance of photocatalysts was systematically investigated,and the photocatalytic or piezoelectric photocatalytic mechanism was proposed.CuWO4/Vo-BiOCl enhanced photocatalytic performance based on Z-scheme model.Oxygen vacancies acted as electron mediators,promoting the transfer of photogenerated electrons from the conduction band of Vo-BiOCl to the valence band of CuWO4;h+ played a major role in the photocatalytic degradation;The photodegradation efficiency of norfloxacin by CuWO4/Vo-BiOCl was up to 96.69%within 120 min;According to UPLC-MS analysis,the degradation path of norfloxacin was mainly to remove piperazinyl.In2O3/BiOCl was based on type Ⅱ heterojunction interface and piezoelectric field of BiOCl to promote the separation of photogenerated carriers,and its piezoelectric photocatalysis performance was superior to piezoelectric catalysis and photocatalysis performance;The main active species were ·OH radicals and electrons in the degradation process;The piezoelectric photocatalytic degradation efficiency of ciprofloxacin by In2O3/BiOCl was up to 97.06%within 40 min.CeO2/BiOCl depended on Z-scheme model and BiOCl piezoelectric field,which made the electron hole pair separate more effectively;The Ce3+/Ce4+ redox center acted as carrier transfer medium to promote the recombination of electrons on BiOCl conduction band and holes on CeO2 valence band;·OH played a major role in the degradation process;The piezoelectric photocatalytic degradation efficiency of ciprofloxacin by CeO2/BiOCl was up to 99.94%within 40 min.(2)Piezoelectric photocatalysts such as Bi4Ti3O12/BiOCl,KNbO3/BiOCl,Na0.5Bi0.5TiO3/BiOCl,BaTiO3/BiOCl and PZT/BiOCl were synthesized.The piezoelectric photocatalytic degradation performance was studied with antibiotics as the target pollutant,and the piezoelectric photocatalytic mechanism was proposed.In Bi4Ti3O12/BiOCl,KNbO3/BiOCl and BaTiO3/BiOCl piezoelectric photocatalytic systems,the chemical potential difference and piezoelectric potential difference formed by the type Ⅱ heterojunction jointly promoted the carrier migration and separation.The degradation efficiency of ciprofloxacin by Bi4Ti3O12/BiOCl was up to 97.50%within 10 min.The degradation efficiency of ciprofloxacin by KNbO3/BiOCl was up to 98.54%within 13 min.The degradation efficiency of ciprofloxacin by BaTiO3/BiOCl was up to 99.97%in 13 min.In the Na0.5Bi0.5TiO3/BiOCl piezoelectric photocatalytic reaction system,the Z-scheme heterojunction and its piezoelectric potential difference promoted the separation efficiency of photogenerated carriers;·OH radical played a major role in the degradation process;The degradation efficiency of ofloxacin by Na0.5Bi0.5TiO3/BiOCl was up to 95.54%within 5 min,and the corresponding degradation rate constant was 0.600 min-1;According to UPLC-MS analysis,the main degradation path of ofloxacin was also the removal of piperazine group.In the PZT/BiOCl piezoelectric photocatalytic reaction system,PZT cooperated with BiOCl to generate a polarized electric field on the surface of the composite,which promoted the separation efficiency of BiOCl photogenerated carriers;·O2-was the main active species during the degradation process;The degradation efficiency of ciprofloxacin by PZT/BiOCl was up to 99.62%within 10 min. |
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