University Of Tehran Press Pollution 2383-451X 3 4 2017 10 01 Removal of caffeine from aqueous solution using multi-wall carbon nanotubes: kinetic, isotherm, and thermodynamics studies 539 552 62771 10.22059/poll.2017.62771 EN Mehdi Bahrami Department of Water Engineering, College of Agriculture, Fasa University, Fasa, Iran Mohammad Javad Amiri Department of Water Engineering, College of Agriculture, Fasa University, Fasa, Iran Sara Koochaki Department of Water Engineering, College of Agriculture, Fasa University, Fasa, Iran Journal Article 2017 04 04 The occurrence of contaminants in wastewaters, and their behavior during wastewater treatment and production of drinking water are key issues to re-use water resources. The present research aims to remove caffeine from aqueous solutions via adsorption technique, using Multi-Wall Carbon Nanotubes (MWCNTs) as an adsorbent under different experimental conditions. The processing variables such as pH (2-12), contact time (1-30 min), initial concentration of caffeine (2-314 mg/L), temperature (25, 50, 80 °C), and adsorbent mass (0.02-0.15 g) have been investigated with equilibrium and kinetic studies on adsorption of caffeine onto MWCNTs being also developed. Maximum caffeine removal has been obtained at pH=7 and adsorption equilibrium has been achieved in 5 min. The use of pseudo second-order kinetic model with determination coefficient of 99.3% (R²=0.993), has made the adsorption kinetics to be well fitted. The caffeine equilibrium adsorption data have been best fitted to Langmuir-Freundlich Model with a relatively high determination coefficient of 96.5% (R²=0.965) and maximum adsorption capacity of 35.61 mg/g of caffeine on MWCNTs. The thermodynamic parameters display that the adsorption of caffeine onto MWCNTs has been non-spontaneous and endothermic in nature. https://jpoll.ut.ac.ir/article_62771_036a52365df46b6446a134832d79a022.pdf