论文部分内容阅读
为有效去除水中氟离子,减少高氟水对人体的危害,壳聚糖与镧反应制备得到新型除氟吸附剂.用间歇吸附实验测定了不同浓度、温度和接触时间下新型吸附剂对氟离子的吸附.结果表明镧改性能显著提高壳聚糖对氟离子的吸附容量.Langmuir、Fre-undlich及Dubinin-Radushkevich(D-R)方程分别用来对吸附等温线进行拟合,结果表明氟离子在镧改性壳聚糖上的吸附等温线符合Langmuir方程,常温下最大吸附量为4008mg·kg-1.吸附动力学过程用一级、二级及粒内扩散模型进行分析,结果发现氟离子在镧改性壳聚糖上的吸附为准二级动力学;粒内扩散不是控制吸附过程的唯一步骤.吸附热力学函数则进一步揭示氟离子在镧改性壳聚糖上的吸附为自发、吸热、熵增过程;D-R自由能E为13~17kJ·mol-1.据此推测氟离子在镧改性壳聚糖上的吸附为化学吸附.图4,表2,参16.
In order to effectively remove fluoride ions in the water and reduce the harm of high-fluorine water to the human body, a new type of de-fluoride adsorbent was prepared by reacting chitosan with lanthanum.The effect of the new adsorbents with different concentration, temperature and contact time on the fluoride ion .The results showed that lanthanum modification could significantly increase the adsorption capacity of fluoride to chitosan.Langmuir, Fre-undlich and Dubinin-Radushkevich (DR) equations were used to fit the adsorption isotherms, respectively. The results showed that the adsorption of fluoride on lanthanum The adsorption isotherms of the modified chitosan conformed to the Langmuir equation and the maximum adsorption capacity was 4008 mg · kg-1 at room temperature. The adsorption kinetics was analyzed by the first-, second-, and intra-particle diffusion models. The adsorption on modified chitosan is quasi-second-order kinetics, and intragranular diffusion is not the only step to control the adsorption process.The adsorption thermodynamic function further reveals that fluoride adsorption on lanthanum-modified chitosan is spontaneous, endothermic, Entropy increase process; DR free energy E is 13 ~ 17kJ · mol-1 .From this, it is speculated that the adsorption of fluoride ions on lanthanum-modified chitosan is chemisorption.Figure 4, Table 2,