Enhanced adsorption of Direct Orange 26 dye in aqueous solutions by modified halloysite
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Institute of Chemistry, Military University of Technology, 00-908 Warsaw, Poland
Łukasiewicz Research Network - Industrial Chemistry Institute
Ewa Wierzbicka   

Łukasiewicz Research Network - Industrial Chemistry Institute
Publication date: 2020-06-24
Physicochem. Probl. Miner. Process. 2020;56(4):693–701
The usefulness of untreated (H-NM) as well as modified by sodium benzoate (H-SB) and sulfuric acid (H-SA1 and H-SA2) halloysites as low-cost adsorbent for the removal of Direct Orange 26 azo dye from aqueous solutions was investigated. The kinetic data were evaluated in terms of the pseudo-first order and pseudo-second order kinetic models, while the equilibrium adsorption data were analyzed by the Freundlich and Langmuir isotherm equations. The data follows the pseudo-second order kinetic and Langmuir adsorption models. The DO26 adsorption capacities were 64.93, 74.07, 303.0, and 384.4 µmol/g for the H-NM, H-SB, H-SA1, and H-SA2, respectively. Adsorption of the dye was strongly pH dependent; no effect of ionic strength was observed. The study revealed that halloysites, especially acid-activated halloysites, could be used as an effective and low-cost adsorbents.