TY - JOUR AU - Rey-Mafull, Carlos A. AU - César-LLópiz, Julio AU - Hotza, Dachamir AU - García-Gallardo, Raquel PY - 2016/05/26 Y2 - 2024/03/28 TI - Thermodynamic process of theophylline adsorption in vitro on to activated carbon in simulated gastric fluid JF - Revista Cubana de Química JA - Rev Cub Quim VL - 28 IS - 2 SE - DO - UR - https://cubanaquimica.uo.edu.cu/index.php/cq/article/view/1148 SP - 625-644 AB - <p>The in vitro adsorption of theophylline onto seven selected materials (NB, NE, BDH, Ch3J, Merck, Panreac, ML) was studied in simulated gastric fluid at pH 1.2 and 4 h by using shaker water bath within a temperature range 300 to 317 K in batch experiments. The experimental adsorption was fitted by eight isotherms models: Langmuir Type I and II, DR, Halsey, Freundlich, Harkins-Jura, Temkin and BET. Materials were characterized by pHzpc, and N2 77 K. The best linear (R2=098) and non linear (R2=0.95, RAMSE=43) fittings of isotherms models were obtained with Langnuir TI which assumes monolayer adsorption and specific interactions. The theophylline adsorption was controlled by chemisorptions and exothermically process (∆H = -36.81-88.70 kJ/mol) with maximal capacity, qm (316-587 mg/g). The ΔG&lt;0 indicate the spontaneous character and more favourable at lower temperature. ΔS&lt;0 suggests a decrease in the order of the adsorbed system with losses of freedom willingly.</p><p><strong>Keywords:</strong> activated carbon, theophylline, thermodynamic parameters, adsorption isotherms.</p> ER -