ABSTRACT
A novel lamellar Al(OH)3/CuMnAl-layered double hydroxide (LDH) nanocomposite was successfully synthesized via the hydrothermal method and tested as a highly efficient adsorbent for the removal of Congo red (CR) dye from aqueous solution. Structural, morphological, and spectroscopic characterization of the Al(OH)3/CuMnAl-LDH nanocomposite were studied by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, photoluminescence (PL) analysis, and UV-visible spectroscopy analysis techniques. The CR dye adsorption performance of the prepared materials increased with an increase in functionality. The adsorption capacity of the Al(OH)3/CuMnAl-LDH nanocomposite (172 mg/g, pH 7, temp 30 °C) was found to be higher than that of pure Al(OH)3 (32 mg/g, pH 7, temp 30 °C) and CuMnAl-LDH (102 mg/g, pH 7, temp 30 °C). The results revealed that anion exchange and hydrogen bonding are mainly responsible for the adsorption of CR onto the Al(OH)3/CuMnAl-LDH nanocomposite. Moreover, the adsorption of CR in the presence of Cu(II) and NaCl salt showed a synergistic and antagonistic effect while the presence of anionic Cr(VI) ions had no significant effect. The adsorption thermodynamics, isotherm, and kinetics modeling analyses were also conducted to study the interactions between CR molecules and the Al(OH)3/CuMnAl-LDH nanocomposite. The adsorption of CR was found to be endothermic and followed by the pseudo-second-order kinetics and the Langmuir adsorption isotherm model. The developed nanocomposite showed excellent potential for treating industrial wastewater.
