Evaluation of caffeine adsorption by MgAl-LDH/biochar composite.

In the present work, the composite MgAl-LDH/biochar using activated carbon from bovine bone as support for the layered double hydroxide particles was successfully synthesised and used as an alternative adsorbent for caffeine removal from water. Kinetic studies showed that the equilibrium was achieved in only 20 min of contact between the adsorbent and the adsorbate. The pseudo-first-order model represented the experimental data more satisfactorily (R = 0.95), suggesting a physical adsorption process. The isotherms were performed at three temperatures, in which it was observed the decrease in the adsorption in higher temperatures. It was obtained a maximum adsorption capacity of 26.219 mg/g at 40 °C, and the experimental data were better adjusted by Redlich-Peterson, R > 0.9942. In short, the study demonstrated that the composite was satisfactorily synthesised and its use in the caffeine removal was quite attractive, being a potential adsorbent for water treatment applications.