Kuśmierek K, Świątkowski A, Wierzbicka E, Legocka I. Modified Halloysite as an Adsorbent for the Removal of Cu(II) Ions and Reactive Red 120 Dye from Aqueous Solutions.
Molecules 2024;
29:3099. [PMID:
38999051 PMCID:
PMC11243603 DOI:
10.3390/molecules29133099]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 06/25/2024] [Accepted: 06/27/2024] [Indexed: 07/14/2024] Open
Abstract
The adsorption of copper ions and Reactive Red 120 azo dye (RR-120) as models of water pollutants on unmodified halloysite (H-NM), as well as halloysites modified with sulfuric acid (H-SA) and (3-aminopropyl)triethoxysilane (H-APTES), was investigated. The results showed that adsorption of both the adsorbates was pH-dependent and increased with the increase in halloysite dosage. The adsorption kinetics were evaluated and the results demonstrated that the adsorption followed the pseudo-second-order model. The adsorption isotherms of Cu(II) ions and RR-120 dye on the halloysites were described satisfactorily by the Langmuir model. The maximum adsorption capacities for the Cu(II) ions were 0.169, 0.236, and 0.507 mmol/g, respectively, for H-NM, H-SA, and H-APTES indicating that the NH2-functionalization rather than the surface area of the adsorbents was responsible for the enhanced adsorption. The adsorption capacities for RR-120 dye were found to be 9.64 μmol/g for H-NM, 75.76 μmol/g for H-SA, and 29.33 μmol/g for H-APTES. The results demonstrated that APTES-functionalization and sulfuric acid activation are promising modifications, and both modified halloysites have good application potential for heavy metals as well as for azo dye removal.
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