Amoxicillin and cefixime simultaneous adsorption by facile synthesized chitosan@polyacrylamide@ZIF-8: isotherm and kinetic study

In recent years, taking medicine has been increasing around the world due to population growth and the spread of disease. Antibiotics as a kind of these medicines include about 10 to 15% of drug consumption. Studies show that antibiotics, which are not completely removed, have a permanent and destructive effect on the environment. In this study, the chitosan@polyacrylamide@ZIF-8 as an adsorbent was simultaneously used to remove cefixime and amoxicillin from the aqueous solution by adsorption methods. XRD and FTIR patterns were analyzed to investigate the surface crystallinity and the chemical properties of the adsorbent. In the following, SEM and TEM images were used for surface morphology study. Finally, a numerical investigation was done for predicting the adsorption effective parameters. The results show that pH 4, contact time 30 min, initial concentration 50 mg/L, temperature 25 °C and 15 mg of adsorbent in 10 mL of polluted water are optimal conditions at which a removal percentage of up to 90% was achieved. The Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms were examined by experimental data and Langmuir model presented the best consistency with the experimental results and the maximum calculated adsorption capacity for amoxicillin and cefixime are 910 mg/g and 588 mg/g, respectively. Pseudo-first order, pseudo-second order and intraparticle diffusion were investigated for kinetic studies. The results of the calculations illustrated the pseudo-second order model has been dominant. Overall, this study expresses, chitosan@polyacrylamide coated by ZIF-8 can be used an appropriate, effective, and economical adsorbent for the adsorption of amoxicillin and cefixime.

Graphical Abstract