核桃壳水热炭对六价铬的吸附特性

A study on adsorption of Cr(Ⅵ) by hydrothermal carbon from walnut shell

以核桃壳为前体采用水热炭化法制备水热炭,利用低温液氮物理吸附仪和傅里叶变换红外光谱仪测定水热炭的孔结构和表面官能团;实验研究其对液相中Cr(Ⅵ)的吸附特性,考察吸附剂加入量、Cr(Ⅵ)初始浓度、p H值、吸附时间等因素对吸附效果的影响。结果表明,水热炭的孔径分布范围较宽,表面含氧官能团丰富,能够很好地吸附溶液中的六价铬;溶液p H值对Cr(Ⅵ)的脱除影响很大,p H值呈酸性时吸附效果较好,p H值为2时脱除率达98.85%。当反应温度35℃、Cr(Ⅵ)初始浓度50mg/L、水热炭投加量为16g/L、p H值为6、吸附时间为100min时,Cr(Ⅵ)离子的去除率可达98%以上。核桃壳水热炭对Cr(Ⅵ)具有良好的吸附能力,吸附过程符合准二级吸附动力学模型,可用Freundlich吸附等温模型来描述,吸附等温线的线性相关性显著。

Walnut shell based hydrothermal carbon（HTC） was synthesized,characterized and used as an adsorbent to removal Cr（Ⅵ） from aqueous solution. The influence of p H values,adsorbent dosage,initial Cr（Ⅵ） concentration and contact time on its removal was investigated. The results showed that the HTC has a wide pore size distribution and contains a large amount of oxygen-containing functional groups,which are favorable for the adsorption. The adsorption process largely depends on the p H values and reaches a maximum（98.85%）at p H 2. The results showed an efficient removal at p H 6,within 100 min,by using 16mg/L HTC and 50mg/L Cr（Ⅵ） at 35℃. High R2 value of 0.98889 was obtained with the pseudo-second-order model. The adsorption isotherms data of Cr（Ⅵ） on HTC obtained at 35℃,45℃ and 55℃ were analyzed by Langmuir and Freundlich isotherm models,which showed that it is better described by the Freundlich isotherm model.