SDBS改性桑杆吸附剂对Cd2+的吸附机制试验研究

Adsorption Mechanism for Cd2+ of Mulberry Twigs Adsorbent Modified by SDBS

研究了采用十二烷基苯磺酸钠(SDBS)对桑杆吸附剂进行改性,考察了改性桑杆吸附剂对Cd^2+的吸附动力学及吸附等温线,表征了改性前后、吸附前后桑杆吸附剂表面官能团的结构。结果表明:1)用SDBS改性后的桑杆吸附剂中多个官能团的特征吸收峰明显变强,表明SDBS已结合在桑杆吸附剂上,改性有效;改性吸附剂吸附Cd^2+后,羟基和C—O官能团的吸收峰变强变宽,表明桑杆表面的这些官能团是Cd^2+吸附反应的结合点位。2)改性桑杆吸附剂对水溶液中Cd^2+的吸附容量较大,在吸附时间3h、吸附温度50℃、溶液中Cd^2+初始质量浓度25mg/L、溶液pH=7、吸附剂用量7.5g/L条件下,Cd^2+吸附率可达96.8%以上。3)改性桑杆吸附剂对Cd^2+的吸附过程可用准二级动力学吸附模型加以描述,吸附过程符合Freunndlich等温吸附模型,吸附易于进行。

The modification of mulberry twigs adsorbent by dodecyl benzene sulfonate(SDBS) was studied.Adsorption kinetics and adsorption isotherm of the modified adsorbent for Cd^2+ were investigated.The structure changes before and after modification of the adsorbent were characterized by FTIR .The result shows that:1)after modification by SDBS,the surface functional groups of the are changed to a certain extent,and the absorption peak intensity is significantly enhanced,which indicate that the modified agent SDBS is combined on mulberry twigs and the modification is effective.The absorption peaks of hydroxyl and C-O functional groups of the modified adsorbent become stronger and wider after adsorbting Cd^2+,which confirming that these functional groups on the surface of the adsorbent are the binding sites of Cd^2+.2)The adsorption capacity of the modified adsorbent for Cd^2+ in water is higher.Under the conditions of adsorption time of 3 h,temperature of 50 ℃,Cd^2+ initial concentration of 25 mg/L,pH of 7 and adsorbent dosage of 7.5 g/L,the adsorption rate for Cd^2+ can be up to 96.8%.3)The adsorption process can be described by quasi-second-order kinetic adsorption model.The adsorption behavior is more in line with Freunndlich isothermal equation,the adsorption reaction is easy.