Selective Adsorbents from Ordered Mesoporous Silica

Ordered mesoporous silica adsorbents were prepared by grafting amino- and carboxylic-containing functional groups onto MCM-41 for the removal of Acid blue 25 and Methylene blue dyes from wastewater. The amino-containing OMS−NH2 adsorbent has a large adsorption capacity and a strong affinity for the Acid blue 25. It can selectively remove Acid blue 25 from a mixture of dyes (i.e., Acid blue 25 and Methylene blue). The OMS−COOH is a good adsorbent for Methylene blue displaying excellent adsorption capacity and selectivity for the dye. The better selectivity of the OMS-based adsorbents means longer operating life and less maintenance. Furthermore, these adsorbents can be regenerated by simple washing with alkaline or acid solution to recover both the adsorbents and the adsorbed dyes.