Design Of Bismuth Phosphate Based Material Towards Photocatalytic Degradation Of Antibiotics

Recently,the continuously serious environmental pollution problems of antibiotics have caused special attention,so it is urgent to find a suitable way for the degradation of antibiotics.Photocatalytic technology is a new technology which can convert solar energy into chemical energy directly and degrade the contaminant thoroughly.It has some merits such as high efficiency of pollutant degradation,high utilization rate,simple operation process and no secondary pollution,thus photocatalytic technology has been widely used in hydrogen production,reduction of carbon dioxide,air purification and wastewater treatment.This paper considered adopting photocatalytic technology to dispose of the antibiotics pollution.The research and development of high-efficiency photocatalyst was the key point.Photocatalytic materials with appropriate interface and matching energy band can accelerate the separation efficiency of charge carriers,so it was vital to design suitable composites for the enhancement of photocatalytic degradation antibiotics.In this paper,the main photocatalyst BiPO₄ was studied,and it was modified by BN and two types of quantum dots such as N-CQDs and Ag QDs with large surface area to obtain BiPO₄-based photocatalyst with high photocatalytic activity.The main research contents are as follows:?1?BiPO₄ was regarded as the research subject and it was modificated by BN nanosheets.BN/BiPO₄ composites and BiPO₄ materials were successfully synthesized by ionic liquid assisted solvothermal method.A series of characterization such as X-ray diffraction?XRD?,infrared spectrum?FT-IR?,X-ray photoelectron spectroscopy?XPS?,transmission electron microscopy?TEM?and photoluminescence spectroscopy?PL?and ultraviolet-visible diffuse reflection spectrum?DRS?and electrochemical impedance spectroscopy?EIS?were used to characterize structure,morphology,optical and electrical properties of the samples.The photocatalytic activity of BN/BiPO₄ for quinolone antibiotic enrofloxacin?ENR?was investigated and the photocatalytic mechanism was explored.The main conclusions were as follows:the characterization results showed that the prepared materials were BiPO₄ and BN/BiPO₄ materials,and BN sheets were dispersed on the surface of the BiPO₄ nanoparticles and interface formed.ENR was served as the substrate pollutant,the results showed that the 1 wt%BN/BiPO₄ composite performed the highest degradation efficiency of 91.5%for ENR after UV light irradiation for 120 min.The main active species in BN/BiPO₄ photocatalytic system were holes,superoxide radicals and hydroxyl radicals.The existence of BN can decrease the recombinant rate of photogeneration electron-hole pairs and increased the concentration of free radical,thus improved the photocatalytic efficiency for ENR.?2?BiPO₄ was regarded as the research subject and it was modificated by Ag QDs.Ag QDs/BiPO₄ composites and BiPO₄ materials were successfully synthesized by ionic liquid assisted solvothermal method.A series of characterization such as XRD,FT-IR,XPS,TEM,PL,DRS and EIS were used to characterize structure,morphology,optical and electrical properties of the samples.The photocatalytic activity of Ag QDs/BiPO₄ for quinolone antibiotic ciprofloxacin?CIP?and ENR were investigated and the photocatalytic mechanism was explored.The main conclusions were as follows:the characterization results showed that the prepared materials were BiPO₄ and Ag QDs/BiPO₄ materials,Ag QDs particles were uniformly distributed on the BiPO₄ nanoparticles and interface formed.The introduction of Ag QDs can extend the light absorption range of BiPO₄ and enhanced the optical absorption performance of Ag QDs/BiPO₄.CIP was served as the substrate pollutant and the results showed that the Ag QDs/BiPO₄-0.5?0.74 wt%Ag QDs/BiPO₄?composite performed the highest degradation efficiency of 81.2%for CIP after UV light irradiation for 120 min.The degradation rate of Ag QDs/BiPO₄-0.5 for ENR was 76.5%under irradiation for 120 min,which was higher than BiPO₄.The main active species in Ag QDs/BiPO₄ photocatalytic system were holes,superoxide radicals and hydroxyl radicals.In this photocatalytic system,the thermal electrons produced by Ag QDs can better activate the molecular oxygen,the separation efficiency of carriers was increased and more superoxide radicals were generated,thus improved the efficiency of photocatalytic efficiency of CIP and ENR.?3?BiPO₄ was regarded as the research subject and it was modificated by N-CQDs.N-CQDs/BiPO₄ composites and BiPO₄ materials were successfully synthesized by ionic liquid assisted solvothermal method.A series of characterization such as XRD,FT-IR,XPS,TEM,PL,DRS and EIS were used to characterize structure,morphology,optical and electrical properties of the samples.The photocatalytic activity of N-CQDs/BiPO₄ for quinolone antibiotic CIP and ENR were investigated and the photocatalytic mechanism was explored.The main conclusions were as follows:the characterization results showed that the prepared materials are BiPO₄ and N-CQDs/BiPO₄ materials,and N-CQDs were dispersed on the surface of BiPO₄ nanorod and interface formed.CIP and ENR as the target pollutants,the results showed that N-CQDs/BiPO₄-1?0.96 wt%N-CQDs/BiPO₄?composite performed the highest degradation efficiency for CIP and ENR,and after UV light irradiation for 120 min,the degradation rate of CIP and ENR were 87.5%of and 64.7%,respectively.The results manifested that the main radicals were holes,superoxide radicals and hydroxyl radicals.The oxygen defects and?conjugated structure of N-CQDs was the key point to improve the separation rate of carriers and thus the concentration of radicals were increased,eventually improved the degradation rate of CIP and ENR.