Management of caffeine in wastewater using nanolayered material: An integrated study of process kinetics, modeling,...

This work suggests a unique way to manage caffeine (CAF) removal from water by adsorbing it onto an processed industrial waste, cement kiln dust (CKD). To optimze the adsorption process, the main adsorption parameters; pH, time, initial CAF concentration, and dose were evaluated. The results showed that CAF adsorption onto the CKD is a pH-independent (from pH 2 to pH 9) and also it is characterstic with fast equlibrium time (5 min). The maximum adsorption capacity is 1769.03 mg CAF/g of CKD. Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) analyses were used to delve into the materials and learn more about their unique properties. The adsorption kinetics showed that Pseudo 2nd order and Pseudo 1st order models fit the data well. All models of the adsorption process, including Freundlich, Dubinin-Radushkevich, Langmuir, Sips, Redlich-Peterson, Langmuir-Freundlich, Baudu and Fritz-Schlunder models were found to have high correlation coefficient values, indicating good agreement. The Transformed Human Liver Epithelial-2 (THLE-2) MTT test was used to determine the 50 % inhibitory concentration (IC50) for cytotoxicity in vitro. Future research into cytotoxicity for reusing CKD should focus on this topic because the IC₅₀ for CKD was 306.9 g mL^-1 but increased to 771.1 g mL^-1 following CAF adsorption.