Effect of surface chemistry on the uptake of lignin-derived aromatic molecules on ordered mesoporous silica

A series of functionalized ordered mesoporous silica (OMS) materials were synthesized, characterized, and tested for their ability to uptake lignin-derived molecules such as guaiacol from dilute aqueous solution. A key observation was that OMS materials functionalized with hydrophobic groups have modest guaiacol uptake (<0.5 mmol/g), similar to what was observed with poly(styrene-co-divinylbenzene). Contact angle measurements show that samples with intermediate hydrophobicity in terms of wetting (between 60 and 100 degrees) display superior uptake properties. Oasis HLB, an example of such a material displays higher guaiacol uptake (0.8 mmol/g) as does as-made MCM-41, wherein the CTAB is left in the pores (AM-MCM-41, 0.7 mmol/g). Pore-expanded FDU-12 with a range of surface chemistries was synthesized and tested in an effort to generate a covalently grafted analogue of AM-MCM-41, however none of the materials showed uptakes above 0.35 mmol/g. Finally, other aromatic molecules such as vanillin, catechol, pyrogallol also showed high uptake (0.4 mmol/g or high) over Oasis HLB and AM-MCM-41. The findings suggest new routes for designing hybrid materials that can selectively remove lignin derivatives from dilute aqueous solutions.

Automated summary

A series of functionalized ordered mesoporous silica materials were synthesized and tested for their ability to uptake lignin-derived molecules from dilute aqueous solutions. The study found that materials functionalized with hydrophobic groups exhibited lower uptake, while samples with intermediate wetting properties displayed superior uptake abilities. Furthermore, materials such as Oasis HLB and as-made MCM-41 showed higher uptake rates, suggesting potential new routes for designing hybrid materials for selective removal of lignin derivatives.