The Camphor Kind Of Organic UV Filters' Degradation By Advanced Oxidation Processes And The Mechanism Of Degradation

In "cosmetics health standard"?2015 edition,China?,25 kinds of UV absorber are allowed to be used.According to the structure,matrix can be divided into eight categories.And camphor derivative is one of the categories.In "cosmetics health standard"?2007 edition?,6 kinds of camphor derivative ultraviolet absorbent are allowed to be used.3-?4-methylbenzal?camphor?4-MBC?is one of them,which is widely used in sunscreens.Researches have shown that 4-MBC has the effect of endocrine disruptors,and has potential threaten to human health and aquatic ecosystem.At the same time,4-MBC as the UV sunscreen is widely used,its chemical stability is good,and not easy to be degraded by microorganism,with accumulation in the environment,thus the environmental concentration of 4-MBC increases year by year.This paper mainly studies the advanced oxidation degradation of organic UV absorber,which is represented by 4-MBC,and its mechanism is also studied.Concrete study content and the results are as follows:The experimental results show that,in Fenton process,the dose of H₂O₂ has the maximum influence on the degradation of 4-MBC,then followed by the ratio of H₂O₂ and Fe2+,the pH value,and the reaction time.When the ratio of H₂O₂ and Fe2+ is 5:1,the dose of H₂O₂ is 1 ml,pH is 3 and the reaction time is 30 min,the degradation of 4-MBC rate could gain the highest.In photo-Fenton system,the dose of H₂O₂ has the maximum influence on the degradation of 4-MBC,then followed by the reaction time,the pH value,and the ratio of H₂O₂ and Fe2+.When the ratio of H₂O₂ and Fe2+ is 5:1,the dose of H₂O₂ is 0.1 ml,pH is 3 and the reaction time is 60 min,the degradation of 4-MBC rate could gain the highest.In ultrasonic system,when the power of ultrasonic is 192 W,the reaction time is 60 min,the degradation rate is only 16%.In ozone system: the results showed that,when the ozone is produced by dry air,ozone oxidation under neutral conditions has the most efficient degradation.Results show that the ozonation process of 4-MBC followes the first-order-kinetic.In the ozone oxidation process,the ozone molecule and hydroxyl radicals are both important.By using high performance liquid chromatography mass spectrometry technology,two main intermediates are detected.