【作者】 王诗生；

【导师】 彭书传；

【作者基本信息】 合肥工业大学 ， 环境工程， 2005， 硕士

【摘要】 凹凸棒石是一种链层状镁铝硅酸盐矿物,早在19世纪就已被发现,但是至今该矿物对有机物的吸附机理的研究较少。 本文从凹凸棒石分离提纯入手,以阳离子桃红FG、亚甲基蓝和直接耐酸大红4BS三种水溶性染料为例,从吸附热力学和吸附动力学两方面来研究凹凸棒石对三种染料的吸附性能及机理。 凹凸棒石对三种水溶性染料的吸附平衡数据能够较好地符合Langmuir吸附等温方程。对阳离子桃红染料FG和亚甲基蓝的吸附焓变分别为0.49和0.26kJ/mol,是一吸热过程。而对直接耐酸大红4BS的吸附焓变为-19.68 kJ/mol,是一放热过程。凹凸棒石对三种水溶性染料吸附自由能均为负值,是常温常压下可以自发的过程,是物理和化学吸附并存的过程。凹凸棒石吸附三种水溶性染料均是熵增过程。 凹凸棒石对亚甲基蓝和直接耐酸大红4BS的吸附能够较好地符合准二级动力学方程;表观吸附活化能分别为13.92和11.91kJ/mol,表明此吸附并不是单一的以化学吸附为速率控制步骤,同时也存在一个以液膜扩散为速率控制步骤,是由液膜扩散和化学吸附共同控制的过程。更多还原

【Abstract】 Palygorskite is a chain-layer magnesium-aluminum silicate clay minerals. Since it was discovered in the 19th century, few attention has been paid on the adsorption mechanism of organic substances onto palygorskite.Adsorption thermodynamics and kinetics were carried out on adsorption properties and mechanisms of cationic pink FG, methylene blue and direct acid proof scarlet 4BS onto purified palygorskite which was prepared from Guanshan palygorskite clay.The results show that adsorption data of three water soluble dyestuffs onto purified palygorskite fitted well to the Langmuir isotherms; adsorption of cationic pink FG and methylenen blue were endothermic processes, but direct acid proof scarlet 4BS is exothermic in nature. The adsorption enthalpy changes of cationic pink FG, methylene blue and direct acid proof scarlet 4BS are 0.49,0.26 and -19.68kJ/mol respectively, adsorption Gibbs free enegy changes are in the range of -27.48—-31.21 kJ/mol. The negative of adsorption Gibbs free enegy changes in all the cases are indicative of the spontaneous nature,which show chemical sorption coexist with physical sorption. and the values of adsorption entropy changes are positive.Good correlation coefficients of methylene blue and 4BS were obtained for the pseudo-second order kinetics model. The apparent adsorption activation energy of adsorption is 13.92 and 11.91kJ/mol respectively. A relatively low apparent adsorption activation energy suggest that the adsorption dyestuffs may involve not only chemisorption but also physical adsorption process, which is likely due to its combined control of chemisorption and film diffusion.更多还原