十六烷基三甲基溴化铵改性生物炭对水中镉离子吸附性能的影响

Effect of adsorption of cadmium from aqueous solution by hexadecyl trimethyl ammonium bromide modified biochar

针对水体重金属污染治理问题,通过十六烷基三甲基溴化铵(CTAB)对竹炭(BC)、椰壳炭(CSC)进行改性,采用傅里叶红外变换光谱(FT-IR)、扫描电镜(SEM)、X射线光电子能谱分析(XPS)和热稳定性分析(TGA)对改性前后的材料进行了表征,探究了投加量、pH对2种改性材料吸附去除水中镉离子性能的影响,并进行了动力学方程拟合及等温吸附模型拟合,探讨了CTAB改性前后活性炭吸附水中镉离子的机理。结果表明:2种CTAB改性材料基本结构虽未改变,但提升了竹炭(BC)和椰壳炭(CSC)的吸附性能,改性后材料的饱和吸附量分别为12.56 mg·g-1(CTAB-BC)、 10.71 mg·g-1 (CTAB-CSC),较改性前分别提高了111%和92%;同时,CTABBC、CTAB-CSC的吸附量受pH影响较大,对二者的最适pH分别为4~7、6~7;CTAB-BC、CTAB-CSC均能较好地拟合准二级动力学方程(R2CTAB-BC=0.999 9, R2CTAB-CSC=0.993 7)及Langmuir模型(R2CTAB-BC=0.970 3, R2CTAB-CSC=0.9768)。通过分析可知,CTAB-CSC、CTAB-BC 2种材料对含镉废水均有较好的去除效果。

In this study,two kinds of biocarbons were prepared by modifying bamboo charcoal(BC)and coconut shell charcoal(CSC)with hexadecyl trimethyl ammonium bromide(CTAB)for heavy metal pollution control.FT-IR,SEM,XPS and TGA were used to characterize the charcoals before and after modification.The effects of dosage and pH on the adsorption performance for cadmium ion from aqueous solution by the modified biochar were investigated,and the adsorption behaviors were simulated by dynamic and isothermal adsorption models.Their corresponding adsorption mechanisms were also identified.The results showed the adsorption capacities of BC and CSC were significantly improved by modifying with CTAB,although their basic structures were not changed.The saturated cadmium ion adsorption capacities of CTAB-BC and CTAB-CSC were 12.56 mg·g-1 and 10.71 mg·g-1,which were 111%and 92%higher than those of BC and CSC,respectively.Besides,their adsorption capacities were greatly affected by pH,and the corresponding optimum pH ranges were 4~7 and6~7,respectively.The cadmium ion adsorption by CTAB-BC and CTAB-CSC could be better fitted by quasisecondary kinetic equations(R2 CTAB-BC=0.999 9,R2 CTAB-CSC=0.993 7)and Langmuir models(R2 CTAB-BC=0.970 3,R2 CTAB-CSC=0.976 8).Thus,both CTAB-CSC and CTAB-BC had good performance on the treatment of wastewater containing cadmium.