One pot synthesis of hybrid silica aerogels with improved mechanical properties and heavy metal adsorption: Synergistic effect of in situ epoxy-thiol polymerization and sol-gel process

Hybrid material features strongly depend on the synergy between the individual components used during syn-thesis. To address the current challenges preventing silica aerogels from serving as potential candidates in sustainable chemistry and engineering, we used a novel in situ sulfur-doping synthesis method for silica aerogels to improve the mechanical strength and heavy metal ion adsorption. In this study, three-dimensional monolithic silica aerogels were synthesized using an adaptable one-pot epoxy-thiol reaction to polymerize (3-glycidylox-ypropyl)trimethoxysilane and (3-mercaptopropyl)trimethoxysilane, followed by the sol-gel process and super-critical drying. The synergy between the epoxy and thiol groups in the silane precursors with an optimized precursor-to-solvent ratio is crucial for enhancing compressive strength. The cross-linked aerogels had a strong silica hybrid network with high porosity (-85%-91%), comparable bulk density, and high compressive modulus (-6.3-20.81 MPa, which is over three orders of magnitude higher than that of traditional tetraethoxysilane-based silica aerogels). The prepared aerogels were then used to remove heavy metals, with Pd2+ being adsorbed approximately 100% of the time. The maximum adsorption capacity fitted using the Langmuir adsorption model was 689.65 mg/g. The proposed method offers a new strategy for synthesizing in situ sulfur-doped silica aerogels with enhanced mechanical properties for heavy metal removal.

Automated summary

To enhance the mechanical strength and heavy metal ion adsorption of silica aerogels, a novel in situ sulfur-doping synthesis method was used. Three-dimensional monolithic silica aerogels were synthesized with an adaptable one-pot epoxy-thiol reaction. The cross-linked aerogels exhibited a strong silica hybrid network with high porosity and excellent compressive strength. These aerogels showed high adsorption capacity for heavy metals, particularly Pd2+. This method offers a new strategy for synthesizing sulfur-doped silica aerogels with enhanced properties for heavy metal removal.