Efficient water decontamination using layered double hydroxide beads nanocomposites

Abstract

Ni-Al-CO₃-layered double hydroxide (LDH) with Ni:Al ratio (3:1) and their nanocomposites with alginate and chitosan beads were prepared and examined for their efficiency in removal of Cd²⁺ and Cu²⁺ ions from wastewater. Different parameters such as contact time, pH value, adsorbent weight, and heavy metal ion concentration on the removal efficiency were examined and reported. The prepared beads were examined using X-ray diffraction (XRD), TEM, SEM, and FTIR. Our results revealed a successful preparation of the LDH in rhombohedral hexognal crystal form and the alginate-LDH-chitosan beads. The optimized batch experiment conditions in ambient room temperature were found to be 2 g/L adsorbent dose, 50 mg/L initial concentration of meal, contact time of 2 h, and pH ~ 5 and 6 for removal of Cu²⁺ and Cd²⁺, respectively. The adsorption process was well fitted with Langmuir and Freundlich isotherm models (higher R²), with trivial advantage for Freundlich approach. Kinetic studies showed that the adsorption of both Cd²⁺ and Cu²⁺ followed the pseudo-second-order. The current study demonstrated that the Ni-Al-CO₃ LDH and their novel alginate-chitosan-based nanocomposite could be further tailored and used as efficient adsorbents for the uptake of heavy metals from wastewater.

Keywords: Adsorption; Beads; Cu2+ and Cd2+ removal; LDH; Nanocomposite.