Preparation Of Hydrotalcite-like Photocatalyst And Study On Its Treatment Performance Of Printing And Dyeing Wastewater

With the increased demand for various chemical products,the expansion of production scale and the increase of wastewater discharge,printing and dyeing wastewater had become one of the biggest sources of pollution.Printing and dyeing wastewater contains colored groups and organic components which were difficult to degraded and harmful to people's physical health and ecological environment.The photocatalytic oxidation technology was a simple and effective treatment method for printing and dyeing wastewater,which can degrade the colored groups,organic and inorganic substances existing in the printing and dyeing wastewater under the irradiation of the light source.The photocatalytic reacted process was simple,convenient,green and efficient.The key to this technology was the need for efficient photocatalysts.Hydrotalcite was used in wastewater treatment because of its unique structural characteristics and properties.Most of the traditional hydrotalcites were only used for adsorption,and the morphology and particle size were also difficult to control.Based on the special structure of magnesium-aluminum hydrotalcite,the active components Ni and Ce with photocatalytic effect were introduced to form NiMgAlCe hydrotalcite with photocatalytic properties.In this paper,NiMgAlCe hydrotalcite was prepared by co-precipitation method,and the hydrotalcite under optimal ratio was modified by dielectric barrier discharge low-temperature plasma technology.Hydrotalcite was prepared under different volume fractions of ethylene glycol-water and polyethylene glycol-water cosolvent systems,and the hydrotalcite under the best volume cosolvent system was prepared by hydrothermal method.Photocatalytic experiments were carried out on the prepared hydrotalcite to determine the photocatalytic degradation performance of hydrotalcite in different conditions for simulating printing and dyeing wastewater methyl orange solution.The prepared hydrotalcite photocatalysts were characterized by XRD,EDS,UV-VIS,XPS and FT-IR in order to analyze the effect of plasma modification conditions and the different preparation conditions for the photocatalytic properties of hydrotalcite.Stability tests were carried out on the hydrotalcite and the mechanism of photocatalytic treatment was explored.NiMgAlCe hydrotalcite was prepared by co-precipitation method to study the effect of hydrotalcite composition on photocatalytic performance.Compared with NiMgAlCe hydrotalcite,NiAlCe hydrotalcite prepared by Al³⁺/Ce³⁺of 0.035/0.015 and Mg²⁺/Ni²⁺of 0/0.15 showed good photocatalytic activity.The degradation of methyl orange solution can reach 99%-100%in 48 minutes.The characteristic peak of NiAlCe hydrotalcite was sharper and the crystallinity was higher.At this time,the Ce³⁺/Ce⁴⁺in the hydrotalcite sample was 24%,and the forbidden band width was 1.072.The hydrotalcite samples were modified by dielectric barrier discharge low temperature plasma technology to investigate the effects of different plasma modification conditions on photocatalytic performance.The photocatalytic degradation of methyl orange by modified hydrotalcite samples was better than that of unmodified samples.Among them,the hydrotalcite sample modified under the conditions of 75V,2A,20min can completed 100%degradation of the methyl orange solution in 42minutes.Compared with the hydrotalcite sample before modification,the peak of modified hydrotalcite sample was sharper and the crystallinity was increased.The forbidden band width was reduced to 0.159 and the result of Ce³⁺/Ce⁴⁺increase of 44%,while a smaller band gap and a larger Ce³⁺/Ce⁴⁺were beneficial to the photocatalytic reaction.The results showed that the photocatalytic performance of hydrotalcite was improved after plasma treatment.NiMgAlCe hydrotalcite was prepared by co-precipitation method under different volume fractions of ethylene glycol-water and polyethylene glycol-water cosolvent system,in order to determine the effect of different volume fractions of cosolvent system on the photocatalytic performance of hydrotalcite samples.The experimental results showed that the hydrocatalytic properties of the hydrotalcite prepared under the cosolvent system were better than those of the hydrotalcite not prepared in the cosolvent system.Among them,the hydrotalcite prepared under the volume fraction of10%ethylene glycol-water cosolvent and 15%polyethylene glycol-water cosolvent system can complete the degradation of methyl orange in 42 minutes.At the same time,the photocatalytic effect of hydrotalcite prepared by hydrothermal method under the same conditions was better than that of hydrotalcite prepared by coprecipitation method.Hydrotalcite prepared by hydrothermal method can complete the degradation of methyl orange solution in 36 minutes.The best proportion of hydrotalcite samples were obtained by photocatalytic experiments.The photocatalytic properties of hydrotalcite samples were significantly enhanced after plasma treatment.The photocatalytic properties of hydrotalcite prepared in a 10%by volume ethylene glycol-water and 15%polyethylene glycol-water cosolvent system were superior to those of hydrotalcite samples not prepared in a cosolvent system.And the photocatalytic performance of the hydrotalcite sample prepared by hydrothermal method under the cosolvent system was better than that of the hydrotalcite sample prepared by the coprecipitation method.