Enhanced adsorption and recyclability of surface modified hydrophobic silica aerogel with triethoxysilane: removal of cefixime by batch and column mode techniques

Amine modified pumice-derived silica aerogel (AMPDSA) was synthesized and grafted up to 6.52 mu molm(-2) with (3-amino-propyl) triethoxysilane for cefixime antibiotic adsorption. Using Response surface methodology, at the pH of 3, the maximum removal of cefixime of 80.42% for an initial concentration of 3.56 mg L-1 was achieved at an equilibrium time of 150 min. The compliance of various kinetic and isotherm models for the batch sorption system was corroborated from the correlation coefficient (R-2) values. The maximum adsorption capacity of 19.76 mg g(-1) and 49.63 mg g(-1) was calculated for Langmuir and Khan isotherm models, respectively. The removal by fixed-bed column as a function of flow rate, initial cefixime concentration, and bed height was also performed. The maximum adsorption capacity of column with the bed height of 15 cm was found to be 31 mg g(-1) at the flow rate of 10 mL min(-1) for the initial concentration of 20 mg L-1. The compliance of Thomas model with the column sorption was observed. The characterization using SEM, BET, and XRD was carried out for the virgin and regenerated AMPDSAs. The regeneration experiments confirmed the ability of AMPDSA for its cefixime removal efficiency of 80% up to eight cycles.

Automated summary

Amine modified pumice-derived silica aerogel (AMPDSA) was synthesized and grafted with (3-amino-propyl) triethoxysilane to enhance its adsorption capacity for cefixime antibiotic. Response surface methodology was used to optimize the adsorption conditions, and various kinetic and isotherm models were evaluated for their fit with the batch sorption system. Fixed-bed column experiments were conducted to investigate the effects of flow rate, initial concentration, and bed height on the adsorption capacity. SEM, BET, and XRD characterization confirmed the regeneration ability of the material.