【作者】 凤迎春；

【导师】 何少华；

【作者基本信息】 南华大学 ， 市政工程， 2007， 硕士

【摘要】 本文研究的天然微孔材料——海泡石是一种纤维状的硅酸盐粘土矿物,因具有巨大的比表面积和独特的孔结构而表现出良好的吸附性。通过实验研究了天然海泡石和热改性海泡石对水中Pb²⁺和Cd²⁺的吸附性能,探讨了吸附剂用量、初始pH、Pb²⁺和Cd²⁺的初始浓度、吸附时间等因素对吸附效果的影响,分析了两种吸附剂的吸附动力学、吸附等温式和吸附热力学。海泡石对Pb²⁺和Cd²⁺有较强的吸附能力,用马弗炉焙烧活化能改善海泡石的吸附性能,提高其吸附能力。影响海泡石对Pb²⁺和Cd²⁺吸附的因素有吸附剂用量、初始pH、Pb²⁺和Cd²⁺溶液的初始浓度,温度和吸附时间。海泡石吸附Pb²⁺和Cd2的去除率随吸附剂用量、初始pH、初始温度和吸附时间的增大而增大,随溶液初始浓度的增大而减小。两种吸附剂对Pb²⁺和Cd²⁺的吸附效果依次为热改性海泡石对Pb²⁺和Cd²⁺吸附的吸附能力>天然海泡石对Pb²⁺和Cd²⁺的吸附能力。两种吸附剂对Pb²⁺和Cd²⁺的吸附都比较快,前5min时的去除率和吸附量上升最快,90min时吸附基本达到平衡,吸附动力学都符合Lagergren准二级反应模型。两种吸附剂对Pb²⁺的吸附等温式都符合Langmuir方程,对Cd²⁺的吸附等温式符合Langmuir方程和Freundlich方程。对海泡石吸附Pb²⁺和Cd²⁺的热力学分析表明:△H0>0,为吸热反应,高温有利于吸附的进行;△G0<0,表明吸附过程均为自发过程;△S0>0,则说明吸附反应为熵值增大的过程。海泡石对Pb²⁺的吸附既有物理吸附又有化学吸附;海泡石对Cd²⁺吸附为物理吸附。更多还原

【Abstract】 Natural pore material-sepiolite,a kind of clay mineral for fibrous silicate, was studied in the paper. The material shows better adsorption because of its giant relative surface and the unique holestructure. The adsorption capability of Pb²⁺ and Cd²⁺ by natural sepiolite and heated sepiolite was studied. The influence of the dosage of sorbent, initial pH, initial concentration of Pb²⁺ and Cd²⁺, and adsorption time on the adsorption effects were discussed, sorption kinetics. Sorption isotherms and chermodynamic on sorbent were analysed.Sepiolite has strong adsorbing capacity to Pb²⁺ and Cd²⁺. Adsorption capability was improved by heated sepiolite with muffle. There are several factors influencing the adsorption of Pb²⁺ and Cd²⁺ by sepiolite including dosage of sorbent, initial pH, initial concentration of the Pb²⁺ and Cd²⁺, temperature and adsorption time. With the rising of dosage of sorbent, initial pH, temperature and adsorption time, the removal rate of Pb²⁺ and Cd²⁺ by sepiolite was increased and with the rising of initial concentration of the Pb²⁺ and Cd²⁺,the removal rate of Pb²⁺ and Cd²⁺ by sepiolite was reduced. The adsorbing effects of the two kinds of sorbent for Pb²⁺ and Cd²⁺ were adsorption capality of Pb²⁺ and Cd²⁺ by heated sepiolite> adsorption capality of Pb²⁺ and Cd²⁺ by natural sepiolite.The adsorption speed of Pb²⁺ and Cd²⁺ with the two kinds of sorbent was rapid.The removal rate and adsorption capacity of Pb²⁺ and Cd²⁺ rised rapidly in 5 minutes. The adsorption equilibrium time is nearly with in 90 minutes. The adsorption dynamics of Pb²⁺ and Cd²⁺ with the two kinds of sorbent all followed the second-order eqution of Lagergren. The adsorption isotherm of Pb²⁺ with the two kinds of sorbent fit to the Langmuir equation, and the adsorption isotherm of Cd²⁺ by sepiolite fit to both Langmuir equation and Freundlich equation. The thermodynamic of Pb²⁺ and Cd²⁺ on sepiolite was analysed. It was found that△H 0 >0 indicated the endothermic reaction and high temperature be advantage to adsorption, that△G 0<0 indicated the adsorption process be the spontaneous, that△S0>0 indicated the adsorption reaction be the process of the increasing entropy. The adsorption mechanism of Pb²⁺ by sepiolite includes both chemical adsorption and physical adsorption, but adsorption mechanism of Cd²⁺ by sepiolite only includes physical adsorption.更多还原