Green, organic, and facile synthesis of mesoporous silica aerogels for highly efficient Pb(II) removal from synthetic wastewater : isotherm and kinetic studies

Akhter, Faheem and Soomro, Suhail Ahmed and Inglezakis, V. J. (2023) Green, organic, and facile synthesis of mesoporous silica aerogels for highly efficient Pb(II) removal from synthetic wastewater : isotherm and kinetic studies. Biomass Conversion and Biorefinery. ISSN 2190-6815 (https://doi.org/10.1007/s13399-023-04060-9)

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Abstract

Two highly mesoporous silica aerogels (SA-Iso and SA-Sim) were synthesized via rapid modified sol–gel aging and ambient pressure drying. Biomass waste of rice husk ash was used as a precursor and sol–gel as facile, green, and sustainable method. TEOS, ethanol, and heptane were used as organic solvents to modify the aerogels. One aerogel (SA-Iso) was aged separately while the other (SA-Sim) was aged simultaneously inside the solvents. This was a novel approach that resulted in reduced synthesis time and enhanced properties. The aerogels were characterized by SEM, FTIR, XRD, and BET. As per results, surface area, pore size, pore volume, and porosity % for SA-Iso were 312 m2/g, 9.6 nm, 0.85 cm3/g, and 85%, and for SA-Sim as 298 m2/g, 9.2 nm, 0.75 cm3/g, and 79.5% respectively. The aerogels were analyzed for Pb(II) removal from aqueous solutions. Both the adsorbents showed excellent removal efficiencies; however, with isolated aging, the variant SA-Iso comparatively showed enhanced removal than SA-Sim. The highest Pb removals by SA-Iso and SA-Sim at 0.1 g of adsorbent dose were 98.45% and 86.9%. However, when the adsorbent dose increased to 0.2 g, both the aerogels achieved nearly 100% removal. Finally, isotherm and kinetic studies were carried out. It was shown that the adsorption data followed well the pseudo-second-order (kinetic study) and Langmuir isotherm models (adsorption isotherm).

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