Studies On Mode Of Distribution, Release And Photolysis Of M-cresol In Ice

Ice is one of the special forms of water, simultaneously, is the potential source of environment and one of media of atmospheric photochemistry. It is important for us to understand the seasonal variation of environment pollution in order to take a just and effective measure. The photochemistry reaction of organic constituents in ice is differ from which in water, some new pollutants are found after photochemistry in ice cause secondary pollution.M-cresol is one of the priority pollutants which is proposed by environmental protection of world. M-cresol is a toxic,volatile and protracted organic; it's difficult to bio-degrade but be absorb easily by skin; the adverse effects of environmental caused by m-cresol is irreversible. Therefore, it would be significant for environmental protection in study of distribution regularity,release profile and photochemistry of m-cresol in ice.This study research on the effect of temperature on distribution regularity and pH on release profile and distributive coefficient at -19℃. The experimental instrument of photochemistry is self-made, the light source is high-pressure mercury lamp which is 125W. The dynamics of photo-degradation and mechanism are investigation also.The m-cresol mainly distribute in inner of ice in different concentration(10mg/L,50 mg/L,200 mg/L ),the content of outside is lower. Organic matter as impurity during ice up process be discharged by water , and be encapsulated at the end.The result of release of m-cresol in ice is opposite to distribution. During the release the content of m-cresol is on descending trend. At beginning, the content has a large decreasing amount, then fluctuates in a cushioning range. The main reason of this result is the stomata during freezing. pH has much effect on release of m-cresol in ice. In acidic medium the content of m-cresol is on increasing trend which is opposite to solution. In alkaline and neutral condition, the release trend is similar with solution, but exist significant difference, which is showed the trending is gentle. This is indicated that the release is relatively slow. This is maybe because the variation of electrical property of m-cresol or the variation of structure of ice with the variation of acid-base property of solution.The ice/water coefficient directly reflects the regularity of m-cresol during freezing process. It is between 0.1 and 0.2 in the rang of experimental concentration .It is showed that the m-cresol mainly exist in water during freezing, which is agree with the theory that the solvent freezing earlier and m-cresol be discharged together in inner.The photochemistry of m-cresol showed that the photochemistry of m-cresol in keeping with first-order reaction. Lighted exposure for 240min, the degraded ration is 32.6%,the degraded ration of TOC is only 9.1% which indicated that m-cresol had not been translated completely into dioxide carbon and water but take reaction between m-cresol molecuars. pH had weak variation during degradation that take increasing trend. The color of products are red brown .We choose GS-MS to analysis and determinate the precipitate after centrifuged and enriched. There are six products of which the structure is similar with biphenyl. The products indicate that the reaction among the m-cresol molecules is prosthesis reaction, the m-cresol molecular don't react with water molecular which is similar with the theory.To sum up, the freezing condition is directly effect on the distribution and release of m-cresol in ice. The products are biphenyl after light exposure. With people paying more attention to the pollutes in ice and the effect on the polar, we study on distribution,release and photochemistry of m-cresol in ice is helpful for us to know the condition of distribution,the mode of release and photochemical property in order to deduce the hazard of m-cresol to environment to take effective measures ,it is important for environmental protection.