Study On The Reaction Of Salicylic Acid Oxidation By Sodium Hypochlorite

In recent years, because of the traditional wastewater treatment process can not have a effective degradation to the pharmaceutical and personal care products(PPCPs), the PPCPs’ concentration have a sustainable growth in the water natural environment and that has cause the attention of people. Salicylic acid(SA) as a kind of PPCPs class material, have been detected in a variety of water environment at present. Salicylic acid is a kind of disinfection antiseptic and it has been widely used in medicine and cosmetics industries. It has irritating it eye, long or repeated contact with skin may cause dermatitis and even burn the skin. It has irritating to respiratory tract, when inhaled can cause coughing and chest discomfort, can stimulate intestines and stomach and mucous membrane, react with human protein. Taking ample salicylic acid into body may cause salicylic acid poisoning, cause tinnitus, electrolyte disorders, renal damage, etc. Salicylic acid into the environment may have influence to the ecological system. Sodium hypochlorite, as a kind of strong oxidizer, has bactericidal, oxidative, disinfectant, faded effect. It is easy to operate and safe to store. This paper mainly discusses the degradation of sodium hypochlorite and salicylic acid oxidation reaction, and the influence of reaction factors and the toxicity of the product.After establishing the analysis method of salicylic acid in water, we studied the degradation of sodium hypochlorite and salicylic acid oxidation reaction. The results show that sodium hypochlorite can remove the salicylic acid. The results showed that the degradation of SA by sodium hypochlorite followed second order kinetics. Increase the concentration of available chlorine is conducive to speed up the reaction. however, apparent reaction rate constant decreased when increase the concentration of salicylic acid. pH value had great influence on the degradation of SA. The reaction rate constant increased along with pH value decrease. Temperature also played a role on the reaction---the removal rate of SA increased along with temperature increasing, which followed Van’t Hoff Rule. Through the determination of TOC and bright light-emitting bacteria toxicity test showed that H2O、CO2 and some organic matter which are difficult to decomposed have been generated in the reaction. Product in the process of oxidative degradation, the toxicity is to reduce to increase first, then decreased, and increased, and decreased in the end.We also studied the influence of other coexistence substances to the reaction. Research shows that nitrite ion had great influence on the degradation of SA. The reaction rate constant decrease along with nitrite ion increased. Zinc ion and twain-80 has no effect on the degradation. Adding bromide ion and copper ion into the reaction accelerated the degradation of SA. Humic acid inhibits the degradation of salicylic acid reaction, and the inhibition will be stronger while humic acid concentration increases. Anionic surfactant(SDBS) have promoting effect to the degradation in low concentration. When SDBS reach a certain concentration, the promoting effect is not increased, achieve stability.