Removal of Cationic Dyes, Heavy Metal Ions, and CO₂ Capture by Adsorption on Mesoporous Silica HMS

Mesoporous silica with wormhole framework structure (HMS-OH) and its amine-functionalized material (HMS-NH₂) were prepared through an electrically neutral assembly pathways, post-grafting process of 3-aminopropyltriethoxysilane (APTES), respectively. Their adsorption behaviors toward cationic dyes as well as heavy metal ions in aqueous system and the capture capacities for CO₂ molecules all have been investigated. As-synthesized HMS-OH showed a high removal efficiency and rapid sorption rate to cationic dyes because of large surface area and versatile pore structure. HMS-NH₂ exhibited better heavy metal ions and more CO₂ gas sorption capacities due to the intrinsic property of amine groups grafted on the surface. The adsorption isotherms of methylene blue (MB) onto HMS-OH, Cu(II) onto HMS-NH₂ were fitted with Langmuir model and kinetic processes followed well the pseudo-second order pattern. There results revealed that both HMS-OH and HMS-NH₂ had a potential application in the treatment of cationic dyes, heavy metal ions, and greenhouse gas CO₂.