Adsorption of three organic dyes on modified diatomite
改性硅藻土对三种有机染料的吸附作用研究

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.