Adsorption of phenols from contaminated water through titania-silica mixed imidazolium based ionic liquid: Equilibrium, kinetic and thermodynamic modeling studies

• Published in: Journal of macromolecular science. Part A, Pure and applied chemistry Pure and applied chemistry, 2016-10, Vol.53 (10), p.619-628
• Main Authors: Ismail, Nor Atiqah, Bakhshaei, Shabnam, Kamboh, Muhammad Afzal, Abdul Manan, Ninie Suhana, Mohamad, Sharifah, Yilmaz, Mustafa
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Fourier transforms; Infrared spectroscopy; ionic liquid; Ionic liquids; kinetic and thermodynamic modeling studies; Sol gel; Surface chemistry; titania-silica; Titanium
• ISSN: 1060-1325; 1520-5738
• DOI: 10.1080/10601325.2016.1212309

The present study describes the synthesis and characterization of titania-silica mixed imidazolium based ionic liquid (Ti-Si-IL) as well as evaluation of its adsorption behavior towards the 2,4-dinitrophenol (2,4-DNP) and 2,4,6-trichlorophenol (2,4,6-TCP). Synthesized Ti-Si-IL adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), BET surface area Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA) and elemental analysis (CHN). The adsorption of 2,4-DNP and 2,4,6-TCP on Ti-Si-IL was investigated systematically by evaluating the effects of adsorbent dosage, initial pH, contact time and temperature. Satisfactory adsorption 95% and 65% for 2,4-DNP and 2,4,6-TCP was observed at pH 4 and 6, respectively. The kinetic results for 2,4-DNP and 2,4,6-TCP on Ti-Si-IL indicated that the kinetic data follows pseudo-second-order model (R 2 = 0.9985 and 0.9750, respectively). Adsorption isotherms were fitted well by the Langmuir model for 2,4-DNP (q m = 44.64 mg g −1 at 318 K) and Freundlich model for 2,4,6-TCP (K F = 0.63 mg g −1 at 318 K). The +ΔH° and -ΔG° values demonstrated that the adsorption of 2,4-DNP was endothermic and spontaneous in nature. While the -ΔH° and +ΔG° values for 2,4,6-TCP adsorption demonstrated exothermic and comparatively nonspontaneous. During the removal process, the role of different functional groups, cyclic structure was monitored and found that the ionic property as well as π-π interactions of host molecules played important role in the extent of adsorption.