硝酸改性活性炭吸附Cd^(2+)的性能分析

Analysis on Cd^(2+)adsorption capability of activated carbon modified by HNO_3

为提高活性炭对Cd2+的吸附效果,采用硝酸对活性炭进行改性,通过BET、Boehm滴定等手段对改性前后活性炭进行表征分析,并在不同反应条件下,考察了活性炭改性前后对Cd2+的吸附效果。结果表明,经硝酸改性后的活性炭比表面积有所增加,含氧官能团总量上增加明显。在pH中性条件下,GAC、10%N-GAC、70%N-GAC对Cd2+的去除率分别为10%、41%、57%左右,改性后的活性炭对Cd2+去除率有较大的提高;各种活性炭对Cd2+去除率随着活性炭投加量的增加都有较大的提高;pH值是影响活性炭吸附去除Cd2+的主要因素,各种活性炭对Cd2+的去除效果均随着pH的增大而增大。吸附动力学研究表明,10%N-GAC吸附Cd2+反应在前20min符合Lagergren准一级反应模型,20min后的反应更符合Lagergren准二级反应模型。

In order to improve the absorption ability of Cd2＋ , the activated carbon is modified by HN（）a. Additionally, the structure changes of activated carbon with and without treatment are studied in virtue of BET, Boehm and other instruments. The research demonstrates that the specific surface area and the number of activated carbon surface functional groups dramatically change after treatment, and the specific surface area and the figure of acid functional groups after HNOa oxidizing increase. It is worth mentioning that under the condition of pH with 7. 00, the removal rate of Cdz＋ by raw activated carbon is approximately 10~./0, in contrast, the removal efficiency reached 41~/00 by 10% N-GAC and 570/00 by 700/00 N GAC, the removal effects of Cd2＋ could be improved after modification. With the dosing quantity of modified activated carbon increased, the removal effects of Cd2＋ are also increased. PH is the biggest influence factor of removing Cd2＋. As the pH of solution increases, the removal rates of three kinds of adsorbent for Cd2＋ increases. Adsorption kinetic research shows that the adsorption reaction of Cd2＋ on 10% N-GAC is suitable to Lagergren pseudo-first-order （PFO） reaction in the former 20 rain and more suitable to Lagergren pseudo-second-order （PSO） reaction after 20 min.