改性哈密钾长石对Pb^(2+)的吸附特性

Adsorption characteristics of Pb^(2+) by modified potassium feldspar from Hami

为了拓宽钾长石的利用途径,以合成氧化锌对哈密钾长石进行改性,用扫描电子显微镜、X射线衍射和X射线能谱分析方法对钾长石改性前后的变化进行表征。采用静态吸附试验考察了改性钾长石添加量、Pb^(2+)初始浓度、溶液初始pH值、吸附时间等因素对改性钾长石吸附溶液中Pb^(2+)的影响。研究结果表明,随着改性钾长石的增加,其对Pb^(2+)的吸附量呈下降趋势,但去除率呈增加趋势;Pb^(2+)质量浓度对吸附量有很大影响,吸附量随Pb^(2+)质量浓度升高而增大;溶液pH值为1~5时,改变pH值对改性钾长石吸附Pb^(2+)的影响显著;在240 min时吸附量趋于稳定。通过Langmuir、Freundlich和Redlich-Peterson等温方程进行拟合,发现Freundlich和Redlich-Peterson方程能较好的描述吸附过程。动力学和热力学拟合结果显示,双常数动力学模型拟合效果最好,表明Pb^(2+)的扩散速度是决定其吸附速率快慢的关键;△H>0,表明Pb^(2+)在改性钾长石上的吸附为吸热过程,提高温度有利于吸附过程的进行;△G<0,表明吸附为自发进行的过程。

In order to broaden its utilization, the potassium feldspar in Hami was modified by synthetic Zinc oxide and SEM, XRD and EDX were used to characterize the changes of potassium feldspar before and after modification. The effects of the adsorbent amount, initial ion concentration, initial solution p H value and the time of Pb（2＋） adsorption in the modified potassium feldspar were investigated by the static adsorption test. The results showed that with the increase of modified potassium feldspar, the adsorption capacity of Pb（2＋） decreased, while the removal rate increased. The mass concentration of Pb（2＋） had a great influence on the amount of adsorption, and the adsorption amount increased with the increasing Pb（2＋） mass concentration. When the p H of the solution was 1-5, the change of p H value had significant influence on the adsorption of Pb（2＋） by modified potassium feldspar. The adsorption capacity tended to be stable at 240 min. Through Langmuir, Freundlich and Redlich-Peterson isotherm equations, it was found that Freundlich and Redlich-Peterson equation well described the adsorption process. The kinetic and thermodynamic fitting results showed that the double constant kinetic model fitting effect is the best, indicating that the diffusion rate of Pb（2＋） is the key to determine the adsorption rate. △H〉0 showed that the adsorption of Pb（2＋） on modified potassium feldspar was an endothermic process and increasing the temperature favored the adsorption process and △G〈0 indicated that the adsorption was a spontaneous process.