Study On Modified Preparation Of Immobilized Bi₂WO₆ Photocatalyst And Degradation Performance Of Coupled Microorganism

Bi₂WO₆ has been widely studied as a photocatalyst with high potential in semiconductor photocatalytic oxidation technology.Its advantages include narrow band gap width,low excitation energy,lamellar structure and strong photocatalytic oxidation activity.However,it has the disadvantage of high electron recombination rate in photocatalytic oxidation process and small response range to light,and only absorbs light in the range less than 450nm.In order to improve the photocatalytic activity of Bi₂WO₆,respectively,in the process of synthesis with glucose preparation of spherical carbon materials and the preparation of chitosan is more interfaces pass carbon materials as the carrier load Bi₂WO₆ crystal,while adding surfactants inhibition of Bi₂WO₆ crystal crystal shape,make the growth on the surface of the carbon material,Bi₂WO₆ crystal small and uniform particle size,the final could be prepared by the micro spherical carbon material as the carrier of C1/Bi₂WO₆ and more interfaces pass carbon materials as the carrier of C2/Bi₂WO₆,both with strong photocatalytic activity.At the same time,the heterojunction structures of Carbon supported Bi₂WO₆ and Bi₂O₃ were prepared by simply changing the synthesis conditions,which also had strong photocatalytic activity.By changing the amount of carbon materials in the process of synthesis,testing two kinds of composite materials,the photocatalytic degradation rate of dye rhodamine B solution,the results show that when the addition amount of 0.06 g of carbon materials,degrade the performance of two kinds of composites are the best,Bi₂WO₆ and Bi₂O₃ heterojunction structure also in the 0.06 g for the amount of carbon material shows the best performance.The degradation rates of C1/Bi₂WO₆and C2/Bi₂WO₆ to rhodamine B reached 93%and 72%respectively at 40min.All the peaks in the X-ray diffraction spectra of the composites with the best performance were in accordance with the standard card of orthorhombican Bi₂WO₆（JCPDS 39-0256）and Bi₂O₃（JCPDS76-2478）.Scanning electron microscopy（SEM）shows that the composite material conforms to the expected microsphere and multi-mesoporous structure.The u V-visible diffuse reflection spectrum proved that the light absorption intensity of C1/Bi₂WO₆ increased compared with C2/Bi₂WO₆ and pure Bi₂WO₆.The calculated band gap of C-@Bi₂WO₆/Bi₂O₃ was 2.45e V,which was reduced compared with the 2.8EV of pure Bi₂WO₆,indicating the effective formation of heterojunction structure.The specific surface area of the two kinds of composite materials increased greatly compared with that of pure Bi₂WO₆.Photosynthetic bacteria are often used to degrade azo dyes,so Rhodospirillum photosynthetic bacteria are selected for culture.From the growth curve,it can be seen that 0-12h is the adaptation period of photosynthetic bacteria,12-48h is the growth period of photosynthetic bacteria,and 48-132h is photosynthetic The stable period of bacteria,132h later is the decay period of photosynthetic bacteria.In order to explore the conditions affecting the activity of photosynthetic bacteria,the photosynthetic bacteria in the growth phase were selected to degrade the methyl orange solution,and the concentration of the external carbon source was changed.When the added amount of glucose was 800mg/L,the photoynthetic bacteria showed the best activity,which proved sufficient The addition of a carbon source is beneficial to increase the activity of photosynthetic bacteria;the p H value of the degradation system is changed to find that the p H value is 8 that the activity of photosynthetic bacteria is the best With the best performance of C/Bi₂WO₆ and photosynthetic bacteria immobilized with sodium alginate,the photocatalyst immobilization material CB@CA,photosynthetic bacteria immobilization material R@CA,and photocatalyst-photosynthetic bacteria immobilization material CB were prepared respectively./R@CA,through the 8h degradation rate and 96h COD removal rate test of methyl orange simulated wastewater,the 8h degradation rate and 96h COD removal rate of CB/R@CA are 91%and 85.6%,respectively.Change the photocatalyst addition amount of CB/R@CA,it is concluded that when the ratio of photocatalyst to sodium alginate is1,2 the performance of the composite material is the best;change the addition amount of photosynthetic bacteria of CB/R@CA,with the photosynthesis The increase in the ratio of bacteria addition to sodium alginate increases the degradation rate and COD removal rate,but when the ratio is 4,photosynthetic bacteria desorption occurs,which reduces the COD removal rate,so the best performance is when the ratio is 3;Change the initial p H value,it is concluded that the degradation rate is higher when the p H value is 6,7,and 8,the COD removal rate is the highest when the p H is 8,so the performance is the best when the p H=8.CB/R@CA under the optimal conditions with external carbon source,photocatalyst,photosynthetic bacteria,and initial p H value are all under the best conditions for 3 cycles of degradation tests,and the degradation rate of the methyl orange simulated wastewater for the 3 times is obtained.All of them are above 95%;the 3 COD removal rate tests proved that the COD removal rate for methyl orange simulated wastewater was high,but the third time the carrier mechanical reduction caused the photocatalyst and photosynthetic bacteria desorption phenomenon,which led to the COD removal rate There is a certain degree of reduction.In summary,CB/R@CA has strong cyclic degradation stability.