The Electrospinning Synthesis Of Bismuth Phosphate And The Photodegradation Of Methylene Blue

Photocatalytic oxidation technology in the treatment of refractory organic wastewater in the field of high efficiency and low energy consumption,no two pollution has attracted widespread attention,and the structure and properties of removal rate depends largely on the photocatalytic material of organic pollutants,so the choice of appropriate photocatalytic material is extremely important,but because of the special structure of bismuth phosphate and its semiconductor properties so it has excellent UV photocatalytic activity,the photocatalytic activity is about 3.2 times of the traditional ultraviolet light catalyst TiO2 powder catalyst.In this paper,the preparation method by electrospinning technique,bismuth phosphate nano fiber catalyst was synthesized by sol-gel method,with the two kinds of catalysts based on methylene blue degradation,were investigated on the degradation rate and mineralization rate of methylene blue under UV light.The bismuth phosphate particles prepared by hydrothermal method have high degradation efficiency of methylene blue solution.Bismuth phosphate nanofibers prepared by electrospinning,compared with bismuth phosphate particles prepared by hydrothermal method.The photoelectrochemical properties have obvious difference in light or dark conditions,the AC impedance radius of bismuth phosphate nano fiber obviously than the impedance of nanoparticles of small radius,phosphorus bismuth nano fiber will be easier photochemical reaction,which resulted in changes of Photocatalytic rate,is the main factor affecting its activity.Moreover,both bismuth phosphate and bismuth phosphate fiber have high activity relative to TiO2,because the inductive effect of phosphate is beneficial to the separation and conduction of electron hole.The advantages of this phosphate in photocatalytic reaction and the restriction factors on its activity may be universal for other non metallic acid salt photocatalysts.Based on the first principle calculation of DFT,band structure,density of States and electron density were calculated and analyzed with bismuth phosphate,6p hybridization band is mainly O 2p and Bi formation of bismuth phosphate,combined with UV visible absorbance measurement,using the classical Schoonen formula,the calculation of the valence band position of bismuth phosphate about 3.67 V vs.standard hydrogen electrode SHE,which indicates that the bismuth phosphate photohole has strong oxidation,which is conducive to the generation of direct oxidation of organic pollutants in the hole and hydroxyl radical,which is favorable for photocatalytic reaction.The calculation of electron density in phosphate bismuth phosphate structure with electron withdrawing effect is very strong,so that the electron cloud density on phosphate near the formation of a built-in electric field,which can attract a large number of photogenerated electrons,thus disguised promoted the separation of photogenerated electrons,which may is one of the reasons has a strong photocatalytic activity of bismuth phosphate.In addition,the bismuth phosphate MB photocatalytic degradation experiments such as variable inquiry,effects of pH value and initial MB concentration were studied and discussed.Results showed that at treatment time 100 min,the decolourization rate reached 87% and 63%,respectively.Both reactions kinetics are first order dynamical and the kinetic constant are 0.0206 and 0.0073 min-1.In addition,the reaction system optimization for bismuth phosphate nanometer fiber on MB treatment was also investigated.Treatment at pH value 3 and initial MB concentration 50mg/L was selected as the optimum condition.Finally,a brief analysis was studied on the mechanism of bismuth phosphate nanometer fiber during MB degradation process.As t-butanol and EDTA were chosen as trapping agent,results showed that radical reaction is responsible for MB degradation.