Kinetics and thermodynamic studies of Cr(VI) adsorption using environmental friendly multifunctional zeolites synthesized from coal fly ash under mild conditions. Issue 6 (2nd June 2020)

• Record Type: Journal Article
• Authors: Ghasemi, Zahra; Sourinejad, Iman; Kazemian, Hossein; Hadavifar, Mojtaba; Rohani, Sohrab; Younesi, Habibollah
• Is Part Of: Chemical engineering communications. Volume 207:Issue 6(2020)
• Page Start: 808
• Page End: 825
• Publication Date: 2020-06-02
• Subjects: Cationic surfactants -- Coal fly ash -- Cr(VI) -- Eco-friendly modified zeolite -- Equilibrium adsorption isotherms -- Gibbs free energy; Chemical engineering -- Periodicals; 660.205
• DOI: 10.1080/00986445.2019.1630389
• Languages: English
• ISSNs: 0098-6445

Abstract

Abstract: The Na-P1 zeolite was produced from coal fly ash and modified with different environmental friendly surfactants. The potential of these green modified zeolites was investigated as adsorbents for Cr(VI) ions in a batch system. XRD, SEM, XRF, and ICP-AES analyses were used for the characterization of raw materials and zeolite samples. The environmental friendly modified zeolites successfully immobilized different toxic elements in their framework inhibiting the transfer of these toxic elements to the surrounding liquid phase. The effects of various operational parameters on Cr(VI) removal were studied. The Hexamethylenediamine (HDTMA) and Ammonyx KP (KP) modified zeolites had larger chromium removal potential than the other samples at all temperatures. The effectiveness of Cr(VI) ions elimination became greater as the pH decreased and the adsorbent dose increased. The Freundlich, Langmuir, and Dubinin–Radushkevich isotherms were fitted to the equilibrium data. The Dubinin–Radushkevich and Langmuir models gave a better fitness to equilibrium data of HDTMA-Na-P1 and KP-Na-P1, respectively. The positive and high Δ H ° values showed the endothermic nature of the total Cr(VI) sorption procedure and indicated that Cr(VI) adsorption onto HDTMA-Na-P1 and KP-Na-P1 is a chemisorption. The negative Δ S ° values also showed that chromium ions were stable on the surface of adsorbents. The adsorption potential of the developed eco-friendly KP-Na-P1 was higher than those of other adsorbents reported in the literature.