Cu(II) and Zn(II) metal ions’ sorption utilising halloysite nanotubes derivative

ABSTRACTABSTRACTDesigning and developing clay-based adsorbents with a strong preference for removing copper and zinc metal ions, reduced cost, eco-friendliness, and good recyclability is a good strategy for water remediation. Herein, halloysite nanotubes (HNT) were activated by (3- chloropropyl) trimethoxy silane (CPTM) as a linker for polyethyleneimine to give HN-PEI. The hybrid organic/inorganic sorbent HN-PEI was analysed by Fourier-transform infrared spectroscopy, CHN/O (elemental analysis), scanning electron microscopy, textural properties (via the Brunauer – Emmett – Teller technique), X-ray diffraction, and thermogravimetry coupled with differential scanning calorimetry. The HN-PEI's textural properties show a reduced specific surface of 10.92 m2/g and pore size of 18.2 nm compared to its Pristine HNT (65.33 m2/g) and pore size (⁓10.1 nm), respectively with a dominant mesoporous structure. The selectivity and sorption characteristics of the Cu(II) and Zn(II) metal ions were exploited, while HN-PEI exhibited a remarkable improvement in terms of removing these ions from the aqueous media. At pH 4.5, the sorption capacities for Cu(II) were 2.8 mmol g−1 and for Zn(II) were 1.8 mmol g−1, with equilibrium reached within 120 and 150 min, respectively. There was an acceptable fitting of the pseudo-second-order and Langmuir equations, and the experimental data enabled mono-layer chemisorption reactions. The sorption was exothermic and spontaneous. The sorbent HN-PEI shows high durability over multiple cycles, and after 3 cycles, the sorption/desorption efficacy decreased by less than 6% using HCl (1 M) for Cu(II) and H2SO4 (1.5 M) for Zn(II). According to the bi-system solution sorption test, KSC(Cu(II)/Zn(II)) was ⁓2.0. Finally, HN-PEI had excellent selectivity and efficiency for Cu(II), Pb(II), and Zn(II) ions, especially for Cu(II).KEYWORDS: Halloysite nanotubesgraftingwater remediationadsorption AcknowledgmentsThe research leading to these results received funding from the Government of the Russian Federation under RFBR grants Agreement No 17-03-00641 and 18-29- 12129mk. The researcher A.M. Abu El-Soad is funded by a scholarship under the Joint (Executive program between the Arab Republic of Egypt and the Russian Federation). This work is derived from the work presented in the doctoral thesis of A.M. Abu El-Soad.Disclosure statementNo potential conflict of interest was reported by the authors.Supplementary materialSupplemental data for this article can be accessed online at https://doi.org/10.1080/03067319.2023.2235282.Additional informationFundingThe work was supported by the Government of the Russian Federation under RFBR grants Agreement [No 17-03-00641 and 18-29- 12129mk].