Abstract
Ni50Co50-layered double hydroxide/UiO-66-NH2 metal–organic framework nanocomposite (Ni50Co50-LDH/UiO-66-NH2 NC) was synthesized through a facile ultrasonic-assisted hydrothermal method. UiO-66-NH2 MOF nanocrystals were in situ grown on the surface of ultrathin 2-dimensional functionalized Ni50Co50-LDH nanosheets. Using this method, a uniform nanocomposite architecture was obtained by uniformly distributing MOF nanocrystals on Ni50Co50-LDH. The synthesized LDH/MOF NC possesses essential properties of potential nanoadsorbent such as high surface area (907 m2 g−1), large pore volume (0.91 cm3 g−1), bimodal micro-mesoporous structure, and chemical functionality. Accordingly, Ni50Co50-LDH/UiO-66-NH2 NC was used as an adsorbent for the uptake of toxic thallium (I) from water. Isotherm, thermodynamic, and kinetic studies were conducted to gain a better insight into the adsorption mechanism (s) involved in the removal process. Langmuir and pseudo-first-order models present a better fit to the isotherm and kinetic data, respectively, and the maximum Langmuir adsorption capacity was found to be 601.3 mg g−1 after non-linear fitting analysis (pH=7.0, solution volume=30 mL, initial thallium (I) concentration=50 mg L–1, contact time=15 min, solution temperature=293 K). Thermodynamic parameters were estimated (ΔH0=+64.979 kJ mol−1, ΔS0=+0.335 kJ mol−1 K−1, ΔG0=–33.176 to –39.876 kJ mol−1) and it was found that the adsorption is endothermic and spontaneous with a physicochemical adsorption nature.
Highlights
Toxic heavy metals such as thallium (Tl), chromium (Cr), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), and manganese (Mn) cause significant health effects in both humans and animals
Methoxy groups of CPTMS molecules can react with surface hydroxyl groups of layered double hydroxides (LDHs), and a number of carboxylic groups of metal–organic frameworks (MOFs) linkers (H2N-H2BDC) can form chemical bonds with carbon attached to chlorine atoms in CPTMS to form ester bonds (Fig. 1)
Ni50Co50-LDH/UiO-66-NH2 NC was synthesized through a facile ultrasonic-assisted hydrothermal method
Summary
Toxic heavy metals such as thallium (Tl), chromium (Cr), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), and manganese (Mn) cause significant health effects in both humans and animals. The adsorption method is another approach to removing heavy metals and other pollutants from water and wastewater and has attracted increasing attention in recent years (Pelalak et al, 2021; Marjani et al, 2020; Pelalak et al, 2021) The advantages of this method compared to the techniques mentioned above include designability, selectivity, lower costs, lack of sludge, lower energy consumption, and simplicity of the process (Burakov et al, 2018; Soltani et al, 2020; Soltani et al, 2020; Soltani et al, 2020; Yanyan et al, 226 (2018); Albadarin et al, 2017). In 2018, Hu et al (Hu et al, 2018) reported the preparation of ZIF-8/Zn-Al layered double oxides composite (LDO) using an in situ growth approach for photocatalytic degradation of an organic dye In these works, Zn-Al LDH was fabricated by the coprecipitation of zinc and aluminum nitrate salts in the presence of urea. Due to the presence of abundant adsorption groups in the Ni50Co50-LDH/UiO-66-NH2 NC structure, this material was used as an adsorbent to remove Tl(I) cations from the aqueous solution and its adsorption performance was systematically investigated
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