HDTMA-凹凸棒土的制备表征及其对HCH的吸附研究

Preparation and characterization of HDTMA-attapulgite and adsorption behavior to hexachlorocyolohexane

采用超声改性法制备了十六烷基三甲基溴化铵(HDTMA-Br)修饰的HDTMA–凹凸棒土,并通过扫描电镜(SEM)、红外光谱(FT-IR)、热重分析(TG-DSC)对其结构进行了表征.结果表明,经超声分散后,凹凸棒土的棒晶分散均匀;HDTMA+成功进入到凹凸棒土的表面和层间.吸附实验表明,HCH在HDTMA-凹凸棒土上的吸附动力学符合准一级动力学Lagergren方程,3种HCH异构体的速率常数K大小顺序为:Kα–HCH<Kγ–HCH<Kδ–HCH.HDTMA–凹凸棒土层间存在HDTMA有机相,使其对HCH的吸附量比未改性凹凸棒土增加了近40倍,由于吸附过程中存在HDTMA有机相和所吸附的HCH的协同作用,其吸附机理较复杂,吸附等温线不能用Langmuir、Freundlich、Linear3种吸附等温方程模型进行描述.

Attapulgite was modified with the surfactant of hexadecyltrimethylammoniurn bromide （HDTMA-Br） by ultrasonic to obtain the organic-modified HDTMA-attapulgite. The HDTMA-attapulgite was characterized by scanning electron microscope （SEM）, FT-IR spectroscopy （FT-IR） and thermogravimetry-differential scanning calorimetry （TG-DSC）. The SEM images showed that attapulgite were well dispersed after ultrasonication. The FT-IR and TG-DSC analyses indicated that HDTMA were intercalated on the interlayered of attapulgaite. The kinetic reaction of hexachlorocyolohexane （HCH） adsorption on HDTMA-attapulgite fitted well with the pseudo-first-order kinetic model. The adsorption capacities of HCH on HDTMA-attapulgite were much higher than that on natural attapulgite because of existing synergistic adsorptive effect of the HDTMA organic phase with adsorption of HCH. The Langmuir, Freundlich and Linear isotherm equation models could not be used to describe the adsorption of riCH on HDTMA-attapulgite due to the existence of complex adsorption mechanisms.