Adsorption of Thallium(I), Lead(II), Copper(II), Bismuth(III) and Chromium(III) by Electrolytic Manganese Dioxide
Adsorption of Thallium(I), Lead(II), Copper(II), Bismuth(III) and Chromium(III) by Electrolytic Manganese Dioxide
复制标题
DOI：
10.1177/026361749601300402
复制
发表时间：
1996-08
影响因子：
2.9
通讯作者：
M. P. Dahal;G. Lawrance
中科院分区：
文献类型：
--
作者：
M. P. Dahal;G. Lawrance
电解二氧化锰（EMD）对铊（I）、铅（II）、铜（II）、铋（III）和铬（III）的吸附在20 ℃和0.5的离子强度下在pH 2-5之间进行[铋（III）除外，其中采用单一pH 1.5]，使用从5 × 10−5 mol/dm 3到5 × 10−2 mol/dm 3的宽范围的初始金属离子浓度。吸附等温线均很好地符合简单的朗缪尔吸附方程。对铅和铜离子，吸附量随pH值的增加而增加。然而，对于铊和铬，在pH 3和4之间的吸附显着下降，观察到，与低电荷的羟基物种在较高的pH值的主导存在。在pH 4时，吸附顺序为Pb Ⅱ> Cu Ⅱ> TII >> Cr Ⅲ，而在pH ≤ 2时，吸附顺序为Bi Ⅲ ≤ Pb Ⅱ> TII> Cr Ⅲ> Cu Ⅱ。在低pH值范围内，这是很大程度上免费的水解物种，吸附的等电子铋，铅和铊系列似乎是由电荷为主，和电荷出现的过渡金属对也占主导地位的因素。还研究了在110、400和650°C下长时间热处理的EMD样品对铅（pH 4和5）和铋（pH 1.5）的吸附。在110°C下干燥的样品主要仅损失表面水，并且显示出与未处理样品类似的吸附特性。在400°C下加热的样品失去了所有结合的水，但仍显示出显著的吸附，而在600°C下加热的样品转化为Mn 2 O3，并显示出非常小但可测量的金属离子吸附。
The adsorption of thallium(I), lead(II), copper(II), bismuth(III) and chromium(III) by electrolytic manganese dioxide (EMD) has been followed between pH 2–5 [except for bismuth(III)), where a single pH of 1.5 was employed] at 20°C and an ionic strength of 0.5, employing a wide range of initial metal ion concentrations from 5 × 10−5 mol/dm3 to 5 × 10−2 mol/dm3. The adsorption isotherms all fitted a simple Langmuir adsorption equation quite well. The amount of metal ion adsorbed increased with pH for lead and copper ion. However, for both thallium and chromium, a significant drop in adsorption between pH 3 and 4 was observed, associated with the dominant presence of lower-charged hydroxy species at higher pH values. At pH 4, adsorption was in the order PbII > CuII > TII >> CrIII, whereas at pH ≤ 2 the order was BiIII ≤ PbII > TlI > CrIII > CuII. In the low pH range, which is largely free of hydrolysis species, the adsorption of the isoelectronic bismuth, lead and thallium series appears to be dominated by charge, and charge appears a dominant factor with the transition metal pair also. The adsorption of lead (at pH 4 and 5) and bismuth (at pH 1.5) to samples of EMD subjected to prolonged heat treatment at 110, 400 and 650°C were also examined. Samples dried at 110°C mainly lost only surface water, and showed adsorption characteristics similar to untreated samples. Samples heated at 400°C lost all their combined water but still showed significant adsorption, whereas samples heated at 600°C were converted to Mn2O3, and showed very small though measurable metal ion adsorption.