改性活性炭的制备表征及吸附Zn^(2+)的影响因素

Preparation and characterization of modified activated carbon and their impact factors on adsorption for Zn^(2+)

采用不同方法对活性炭(GAC)进行表面改性处理,通过BET,Boehm滴定、扫描电子显微镜(SEM)和傅里叶变换红外光谱法(FT-IR)测定等方法对改性前后活性炭进行了表征分析,并在不同反应条件下,考察了活性炭改性前后对Zn2+吸附效果.结果表明:活性炭经不同方法改性后,比表面积和表面各种含氧官能团的种类和数量发生变化,经过硝酸氧化改性的活性炭比表面积有所增加,其官能团总量上增加明显;在pH中性条件下,GAC对Zn2+的去除率为12%左右,10%N-GAC对Zn2+的去除率为37%左右,70%N-GAC对Zn2+的去除率为44%左右,改性后的活性炭对Zn2+去除率有较大的提高;随着活性炭投加量的增加,各种改性活性炭对Zn2+去除率都有较大的提高;pH值是影响Zn2+的吸附去除率的最大因素,随着pH的增大,3种吸附剂对Zn2+的去除率均增大.动力学研究表明:10%N-GAC吸附Zn2+反应在前30min属于Lagergren准一级(PFO)反应,吸附30min后的反应属于Lagergren准二级(PSO)反应.

Additionally,the structure changes of the activated carbon with treatments were studied in virtue of BET,Boehm,SEM,FT-IR and other instruments.The research results demonstrate that the specific surface area and the number of activated carbon surface functional groups dramatically changed after the treatment.For example,the specific surface area and the figure of acid functional groups after HNO3 oxidization increased,and thus the adsorption ability of Zn2＋ on the activated carbon was improved.Under the condition of pH at 7.00,the removal efficiency of Zn2＋ by raw activated carbon was approximately 12%,in contrast,the removal efficiency reached 37% by 10%N-GAC and 44% by 70%N-GAC,so the removal effects of Zn2＋ could be improved by modification.With the increase in dosing quantity of the modified activated carbon,the removal effects of Zn2＋ increased also.The pH was the most important impact factor of removing Zn2＋,the removal rates of the three kinds of adsorbent for Zn2＋ increased with the increase of the pH of solution.Adsorption kinetic research showed that the adsorption reaction of Zn2＋on 10%N-GAC was suitable for Lagergren pseudo-first-order（PFO） reaction in the former 30 min and more suitable for Lagergren pseudo-second-order（PSO） reaction after 30 min.