Synergistic Effect Of Strain C412 And Photocatalytic Material On Degradation Of Organic Dye

Under the background of Chinese rapid industrial development,the water pollution problem cannot be underestimated,and the rapid and efficient treatment of printing and dyeing wastewater is one of the urgent problems to be solved.Photocatalytic degradation and biodegradation method have attracted extensive attention due to their unique advantages.In this paper,methylene blue and rhodamine B were explored as main target pollutants,and rapid and efficient methods for degrading them were explored.The main research contents are as follows:Firstly,Bi2WO6 was prepared by hydrothermal method,and then Bi/Bi2WO6 and TiO2/Bi2WO6 photocatalysts were prepared based on Bi2WO6,and characterized by FT-IR,XRD and SEM.Then the photocatalytic degradation ability of the two materials to methylene blue and rhodamine B was investigated.The results showed that the two materials have good photocatalytic degradation ability for both dyes.Then,the experimental conditions for the treatment of two dyes by two photocatalysts were further optimized.After analysis,the decolorization effect of the two dyes by photocatalytic degradation of the two materials was affected by the amount of photocatalysts and the initial concentration of the dyes.The results showed that for 20 mL organic dye degradation system,the initial concentration of methylene blue of 20 mg/L,Bi/Bi2WO6 dosage of 0.05 g,and TiO2/Bi2WO6 dosage of 0.03 g was the most suitable;for 20 mL of Rhodamine B solution degradation system,the initial concentration of rhodamine B of 10 mg/L and the dosage of Bi/Bi2WO6 or TiO2/Bi2WO6 of 0.03 g was most suitable.Then,the biodegradation and biodegradation synergistic photocatalytic degradation methods were investigated for the treatment of methylene blue and rhodamine B.C412 strain could biodegrade methylene blue,and after stimulation with methylene blue,not only the normal growth of C412 strain was not affected,but also its efficiency and activity to degrade methylene blue was improved.When 20 mg/L methylene blue was treated by strain C412,a 94.11%removal rate was achieved within 4 h in the second cycle.High concentrations of methylene blue can be treated by the C412 strain in combination with a sustained release material.The higher concentration of rhodamine B solution(8.35 mg/L)did not affect the growrth of C412 strain,but strain C412 could not degrade rhodamine B.The photocatalytic material could achieve a good treatment effect for the lower concentration of methylene blue simulated dye wastewater,but the timeliness was not ideal.The photocatalyst Bi/Bi2WO6 was successfully loaded onto the electrospinning matrix by electrospinning and obtained an electrospinning Bi/Bi2WO6.Similar to Bi/Bi2WO6,the electrospinning Bi/Bi2WO6 material also has good photocatalytic degradation effect on methylene blue,and the photocatalytic efficiency was lightly improved compared with Bi/Bi2WO6.Electrospinning Bi/Bi2WO6 did not affect the normal metabolism of C412,nor did it affect the ability to biodegrade methylene blue of C412.For the degradation of methylene blue,the C412 strain and the electrospinning Bi/Bi2WO6 can play a synergistic effect,achieving 94.51%removal rate in 1 hour,compared with C412 biodegradation removal rate increased by 37.63%,compared with electrospinning Bi/Bi2WO6 photocatalytic degradation removal rate increased by 60.36%,which not only ensured a good extraction effect,and timeliness was greatly improved.This also provides a certain reference for the actual industrial treatment of printing and dyeing wastewater.Finally,the removal mechanism of organic dyes was explored.Recombinant strain 1587 containing the theory of dioxygenase and recombinant strain 2124 containing the theory of catalase were constructed,but the target gene was not successfully expressed in the recombinant strain.The biodegradation mechanism of methylene blue still needs further experimental research.the mechanism of photocatalytic degradation of methylene blue and rhodamine B was investigated by fluorescence spectroscopy,free radical trapping experiment and mass spectrometry.Fluorescence spectroscopy results showed that during the photocatalytic reaction,the fluorophores of methylene blue and rhodamine B themselves were destroyed and new fluorophores were produced.The results of free radical trapping experiments show that:-OH and h+ should be the main active substances in the methylene blue catalytic degradation reaction system,and the contribution of h+ was greater;"02’and h+ should be the main components of rhodamine B photocatalytic degradation reaction system,in which the contribution of ·O2-was greater.The possible degradation pathways of methylene blue and rhodamine B were obtained by GC-MS mass spectrometry.The results of mass spectrometry further confirmed the hypothesis that methylene blue and rhodamine B molecules were gradually photocatalyzed into small molecular ions and finally converted into CO2.