酯类液晶酸浸分解转化特性及环境风险

Acid leaching transformation characteristics and environmental risk of ester liquid crystals.

选取酯类液晶为研究对象,通过气相色谱仪-质谱仪联用(GC-MS)、傅里叶变换红外光谱仪(FTIR)研究了不同酸浸参数对其分解转化及产物类型的影响,利用ECOSAR毒性评估软件评价了酸浸产物的毒性及环境风险.结果表明:液晶酸浸分解转化率随硫酸浓度、反应时间、反应温度的提高而增加,分别最高可达46.3%、25.33%、35.41%,且对比发现转化产物类型不受酸浸参数变化影响;酯类液晶在硫酸强氧化作用下分解成含有酰基、羧基、羟基等自由基的化合物,这些自由基再进一步结合,最终生成液晶中间体及小分子有机物,酯类液晶酸浸产物包括氰基联苯酚、环戊酸,2-乙酰基-5-甲基-、3-壬烯酸、4-戊基苯酚这4种物质,分解产物类型与液晶结构有关;酸浸产物除环戊酸,2-乙酰基-5-甲基-外,均为有毒有害物质,对环境具有潜在威胁,需加以关注.

Ester liquid crystal was selected as the research object.Gas Chromatography-Mass Spectrometry(GC-MS)and Fourier Transform Infrared Spectroscopy(FTIR)were used to reveal the effects of different leaching conditions on its decomposition,transformation and by-products.The toxicity and environmental risk of the by-products were evaluated by the toxicity assessment software,ECOSAR.The results showed that the decomposition rate of the ester liquid crystal increased with the sulfuric acid concentration(46.3%),reaction time(25.33%)and reaction temperature(35.41%).However,the by-product types were not affected by the change in leaching conditions.The ester liquid crystal was decomposed into compounds containing acyl,carboxyl,hydroxyl groups and other groups under the strong oxidation of sulfuric acid.These compounds were further bonded to form intermediates and small molecular organics.The by-products included cyanobiphenol,cyclopentanoic acid,2-acetyl-5-methyl-phenol,3-nonenoic acid and 4-pentylphenol.The formation of the by-products was related to the chemical constitution of the parent liquid crystal.These by-products were toxic,except for the cyclopentanoic acid and 2-acetyl-5-methyl-phenol.Therefore,the potential threat to the environment require attention.