ADSORPTION OF ANIONIC DYES ON CORN STALKS MODIFIED BY POLYANILINE: KINETICS AND THERMODYNAMIC STUDIES
in English

L.M. Soldatkina, M.A. Zavrichko
2017 Himia Fizika ta Tehnologia Poverhni  
Extensive use of synthetic dyes in different industries has created a major pollution problem. Among various treatments, adsorption has been considered as an effective method due to its simplicity, availability and effectiveness in removing o f dyes from wastewaters. In the current work, the composite "corn stalks-polyaniline" (CS-PAN) is proposed to be used as alternative adsorbent to expensive activated carbons. We have synthesized the new composite by the chemical polymerization o f aniline
more » ... zation o f aniline on the surface o f corn stalks using (NH4) 2S2O8 as an oxidation agent and H 3PO4 as a dopant. The composite was characterized by using Fourier infrared spectroscopy, specific surface area analysis, p H o f point zero charge, bulk density, and total pore volume. (303, 313, and 328 K) as 7.010-5, 8.310-5, 10.7-10-5 and 9 .8 1 0 -5, 12.2-10-5, 1 6 .010-5 mol/g toward A cid Red and A cid Orange, respectively. The values o f the standard free energy change have been calculated as -29.6, -30.7, -32.6 fo r A cid 313, and 323 K, respectively, which indicating that a spontaneous process occurred. Calculations indicated that the enthalpy changes o f adsorption were 6.7 and 1.3 kJ/mol for A cid Red and A cid Orange, respectively. Besides, the calculated standard entropy changes o f adsorption were 107 and 85 J/mol K for A cid Red and A cid Orange, respectively. Consequently, the composite CS-PAN, an inexpensive, easily synthesized, and efficient adsorbent, could be an alternative fo r more costly adsorbents used fo r removal o f anionic dyes in wastewater treatment. In comparison with corn stalks, the composite CS-PAN had a high adsorption capacity and efficiency toward anionic dyes (Acid R ed and A cid Orange) in the aqueous medium. The adsorption process attains equilibrium within 120-150 min. The adsorption o f the acid dyes increased on CS-PAN composite with increase in temperature. It indicates that the adsorption is an endothermic process. Kinetic studies revealed the adsorption process was best described by the reaction model ofpseudo-second order than pseudo-first order. The activation energy o f adsorption was calculated as 13.1 and 7.8 kJ/mol fo r A cid Red and A cid Orange, respectively. Equilibrium adsorption studies o f the anionic dyes on CS-PAN indicated the Langmuir equation f i t better than the Freundlich equation. Maximum adsorption capacity CS-PAN was calculated at different temperatures
doi:10.15407/hftp08.01.044 fatcat:ng3nsb7itvf2fppuh5mapr4qay