Experimental and Theoretical Study of Diphenoxylate Solubility in Supercritical CO 2
Asokan Vasudevan, Kamel A. Saleh, Zeina T. Khaleel, Suleiman Ibrahim Mohammad, Djaloliddin Mansurov, Sarmad S. Abdullah, Irwanjot Kaur, Neeraj Bainsal, Laxmidhar Maharana, Karthikeyan JayabalanABSTRACT
This study investigated the solubility of diphenoxylate in supercritical CO 2 with and without methanol as a cosolvent (2 and 4 mol%) at pressures of 170–410 bar and temperatures of 308–348 K. In pure supercritical CO 2 , solubility ranged from 0.21 × 10 −4 to 2.25 × 10 −4 , whereas methanol increased solubility to 1.08 × 10 −4 –5.47 × 10 −4 (2 mol%) and 1.42 × 10 −4 –8.06 × 10 −4 (4 mol%). The maximum solubility was obtained at 410 bar and 348 K with 4 mol% methanol, representing a 3.58‐fold enhancement over pure CO 2 . Semiempirical models and the Peng–Robinson equation of state successfully correlated solubility data, with the Garlapati (ii) and Jouyban models providing the best performance for binary and ternary systems, respectively.