Adams-Bohart, Yoon-Nelson, and Thomas modeling of the fix-bed continuous column adsorption of amoxicillin onto silver nanoparticle-maize leaf composite

Abstract

This study focused on the use of a fix-bed column in the removal of amoxicillin from an aqueous solution by the application of silver nano-based adsorbents. The silver nanoparticle and nanocomposite were produced by a green synthetic approach. Column adsorption was performed at a flow rate of 5.88 mL/min, bed height of (5.0–7.0 cm), and amoxicillin concentration of 20–40 mg/L. Adsorption data were fitted to Thomas, Adams-Bohart, and Yoon-Nelson models. The color change from light yellow to dark brown showed that silver ions have been reduced to silver atoms. Energy dispersive spectroscopy (EDS) analysis showed the characteristic silver peak of the nano-adsorbents at 3.0 keV containing 57.29% silver in the synthesized silver nanoparticle. Analysis of silver nanoparticles-maize leaf composite revealed its pore distribution to be uneven with an average pore size of 7.44 nm. The data were best fitted to the Thomas model more than Adams-Bohart and Yoon-Nelson’s models. Thomas’s model showed that an increase in concentration and flow rate led to an increase in qo (maximum adsorption capacity) and kTH (Thomas rate constant), However, the increase in bed height led to a decrease in both qo and kTH. The correlation coefficients were in the range 0.6528–0.9797. The results revealed that the silver nanoparticles-maize leaf combo is suitable for the continuous adsorption of amoxicillin in aqueous media with the best performance at a lower concentration, higher bed height, and flow rate.