Zinc-Iron Silicate Catalytic Ozonation Of Acrylic Acid In Aqueous Solution

Acrylic acid wastewater has the characteristics of high COD concentration,strong acidity,strong corrosiveness,odor and slow microbial degradation.If it is discharged directly in water,it will seriously pollute the water body and affect the ecological environment and human health.However,there are some problems for common water treatment processes treated acrylic acid wastewater,such as unstable operation,difficult operation and high cost.Therefore,it is urgent to find a new treatment process to treat acrylic acid wastewater.Based on the project of National Natural Science Foundation of China entitled"Effect and Mechanism of Metal Silicate Catalytic Ozone Oxidation of Organic Pollutants in Water",acrylic acid in water was taken as the target pollutant,and four kinds of composite metal silicates prepared in laboratory were used as catalysts.Under the condition of semi-continuous flow in laboratory,the removal efficiency of acrylic acid in aqueous solution by catalytic ozonation processes were investigated.The catalysts with the best catalytic activity were studied detailed,and it's physical and surface properties were also characterized.The effects of different factors on the removal efficiency of acrylic acid in aqueous solution were investigated.The ozonation catalytic mechanism of acrylic acid was also studied.Specific work is divided into the following aspects:?1?Four kinds of composite metal silicates,zinc-iron,iron-copper,zinc-manganese and iron-manganese,were prepared in the laboratory.In the semi-continuous flow experiment,four kinds of composite metal silicates have good catalytic activity for ozonation degradation of acrylic acid,and the composite zinc-iron silicate has the highest catalytic activity.?2?Composite zinc-iron metal silicates are amorphous,which contain a large number of zinc-iron oxides,Fe-O-Si and Zn-O-Si complexes and are encapsulated by amorphous silicates.Through adsorption and desorption experiments,it is found that the composite zinc-iron metal silicates have a certain adsorption capacity and a wide pore size distribution.X-ray photoelectron spectroscopy?XPS?results show that the composite zinc-iron metal silicates have a certain adsorption capacity and a wide pore size distribution.Surface oxygen of zinc iron silicate has many states,but mainly exists in hydroxyl oxygen and adsorbed oxygen.?3?In the semi-continuous flow experiment,the effects of various influencing factors on the performance of acrylic acid in the catalytic oxidation of complex zinc-iron metal silicates were investigated.The results show that the composite zinc-iron silicate has the best catalytic effect when the reaction temperature is 20°C,the ozone flow rate is0.3 L/min,the initial acrylic acid concentration is 1000 mg/L,and the catalyst dosage is500 mg/L.The removal rate of acrylic acid can reach more than 96%.The Na⁺,K⁺,Ca²⁺and Mg²⁺ions commonly found in water have little effect on the removal of acrylic acid,but Cl-has the greatest influence on the degradation rate of acrylic acid.The composite zinc-iron silicate can maintain high catalytic activity after repeated use.?4?The results of free radical inhibition test and electron spin resonance analysis?ESR?show that the hydroxyl group on the surface of the catalyst can accelerate the decomposition of ozone to produce strong oxidizing hydroxyl radicals during the catalytic oxidation of acrylic acid by complex zinc-iron silicate.Thereby improving the removal efficiency of acrylic acid.