改性硅藻土对三种有机染料的吸附作用研究

以天然硅藻土分别负载十六烷基三甲基溴化铵(CTMAB)、四甲基溴化铵(TMAB)和壳聚糖,制得一系列改性硅藻土,研究了改性硅藻土吸附水中的阴离子染料(活性红120)、阳离子染料(亚甲基蓝)、酸性染料(玫瑰红B)的适宜条件及吸附机理.结果表明,天然硅藻土对亚甲基蓝、四甲基溴化铵改性硅藻土对玫瑰红B和壳聚糖改性硅藻土对活性红120的饱和吸附量分别为51.15、49.56、56.64mg.L-1,效果良好,可被直接利用.延长吸附时间、增大吸附剂用量、控制溶液的pH值(<6)都能提高改性硅藻土吸附剂的吸附效果;3种染料在各自吸附剂上的平衡吸附量Qe与平衡浓度Ce之间的关系均符合Freundlich等温吸附方程,表明改性硅藻土吸附染料以分配作用、弱的溶质吸收为主.改性剂的引入可以改变硅藻土的表面电性,从而对不同类型染料的吸附能力产生不同影响.

Adsorption of three organic dyes on modified diatomite

Natural diatomaceous-loaded CTMAB, TMAB and chitosan were produced into a series of modified diatomite. The optimum adsorption conditions and adsorption mechanism for anionic dyes (reactive red 120), cationic dye (methylene blue) and acidic dye (rose red B) on modified diatomite were investigated. The results showed that the maximum adsorption capacity of natural diatomite, TMAB-modified diatomite and chitosan-modified diatomite for methylene blue, rose red B and reactive red 120 were 51.15 mg·L^-1, 49.56 mg·L^-1and 56.64 mg·L^-1,respectively. The adsorptions were significant enough to be used directly. Extending the adsorption time, increasing the amount of adsorbent, and lowering the solution pH value could improve the adsorption capacity. The adsorption isotherms of the three dyes on diatomite were well fitted by Freundlich model. This indicated that the adsorption mechanism was mainly about distribution with a weak solute adsorption. The modification could change the surface structure of diatomite, therefore the modified diatomite had different adsorption and ion exchange capacities for different dyes.