The Photocatalytic Purification Of Typical Volatile Organic Compounds Emitted From Industrial Plants

As the pace of China’s industrial powers continues to accelerate,the gross national product（GDP）continues to increase,and the environmental problems brought about by industrial development are increasingly becoming the focus of attention.In particular,various organic waste gases emitted during the industrial production process have a direct or indirect impact on people’s health after entering the environment.Therefore,the study selected volatile organic compounds（VOCs）as the research object.Taking the photocatalytic oxidation technology as the purification method and the laboratory R&D scale test-field test as the research ideas,the degradation efficiency and mechanism of styrene on the reduced graphene oxide（rGO）-TiO₂ composite photocatalyst was first investigated.Then evaluated the efficiency,stability,regeneration activity and by-products of the degradation of styrene in the photocatalytic flow-type small-scale test reactor of foam ceramic-TiO₂ composite photocatalysts.Finally,on the basis of research in the laboratory,further investigation of the photocatalytic integration technology for the recycling of organic waste gas generated in actual paint packaging workshops-purification pilot study,related research can provide for the application and promotion of photocatalytic technology to purify industrial VOCs theoretical and technical support.The main content of this paper includes the following five chapters:In chapter 1,mainly summarizes the domestic and foreign research progress and current situation related to this thesis,and on this basis,puts forward the necessity of this thesis research.In chapter 2,using P25 or tetrabutyl titanate（TBOT）as a titanium source,a one-step hydrothermal method was used to complex r GO with TiO₂ in order to control the photocatalytic stability of TiO₂ by adding rGO（1%-7%）.And degradation products.The results showed that（1%-7%）rGO-P25 showed a 1%rGO-P25 performance in addition to a relatively long-term stable degradation efficiency（10 h,17.5%）;TBOT as a titanium source,rGO1%content The catalyst 1%rGO-TiO₂ has an extended activity time,and the photocatalysis continued for 10 h,the degradation rate remained above 43%,and its mineralization ability was the strongest（CO₂ concentration 120 ppm）.Obviously,rGO regulation increased the stability of the catalyst..There are 11 and 13 intermediates adsorbed on the surface of rGO-P25 and rGO-TiO₂ catalysts（16 in P25 and 19 in TiO₂）,mainly 1,2-dihydroxy-1-phenylacetylene-1-one.2-Hydroxy-1-phenylethanol-1-one,2-（2-chlorophenyl）ethanol-1-ol and 1-phenyl-1,2-diol,which also contain a large amount of benzoic acid The possible degradation pathway of styrene is inferred from the middle and also provides methods and technical support for further study of catalyst deactivation.In Chapter 3,using P25 and water to make a slurry of 1wt%to 5wt%P25.The array ceramics are loaded by the dipping and pulling method,and then the self-made rotary fixed-bed flow with independent gas distribution is used.Phase-catalytic reactors were used to study the catalysts.The results showed that the best loading effect of 3wt%P25 slurry,and the optimal immersion time was 15 min.The styrene concentration of 30±5 ppmv was used as the treatment target,and the overall flow rate was 0.9 m³ h^-1,UV _{185 nm} conditions of the equipment and catalyst performance study,the results show that in the self-designed and processed rotary fixed-bed photocatalytic reactor 3wt%P25 loaded catalyst for the first time the effect of photocatalytic degradation of more than 82%,After 5 cycles of lost activity,the catalyst was reactivated by 4 h,and the degradation efficiency was still more than 80%for a long time.The main intermediates adsorbed on the surface of the catalyst are benzyl alcohol,benzaldehyde,benzoic acid,2-hydroxy-1-phenyl ethane and methyl benzoate,of which the content of benzoic acid is the largest,and this conclusion is consistent with the results in Chapter 2.Consistent.In chapter 4,based on the research of the catalyst and device in the laboratory,a set of adsorption-condensation-photocatalytic integrated device was designed and manufactured.A pilot study on the purification of volatile organic compounds（VOCs）(1.1×10⁶μg m^-3)emitted from paint packaging workshops was conducted at a chemical plant in Foshan.The results show that the main components of VOCs in the workshop are ethylbenzene(average concentration 4.1×10⁴μg m^-3;23.1%of TVOCs concentration);n-heptane(4.0×10⁴μg m^-3;22.3%of TVOCs concentration)Xylene(3.1×10⁴μg m^-3;17.7%of TVOCs concentration);bromodichloromethane(3.0×10⁴μg m^-3;17.0%of TVOCs concentration)and styrene(2.3×10⁴μg m^-3;11.9%of TVOCs concentration).After 60 days of continuous research,it is found that the recovery rate of adsorption-condensation units for VOCs was as high as 96.1%,and the highest removal efficiency of photocatalytic oxidation units for VOCs was 79.4%,and the photocatalytic devices has high activity to polar VOCs.In addition,non-carcinogenic and carcinogenic risks of VOCs produced in the workshop before and after equipment treatment were evaluated.The results show that the equipment can effectively reduce the risk index of health risks,and the occupational exposure risk（Ei）value after degradation is reduced to less than 0.1.In chapter 5,summarizes the research results of this article,clarifies the innovation and shortcomings of this research,and looks forward to the future research.