Abstract
Layered double hydroxides (LDHs), distinguished by their lamellar nano-sheet structures, are highly effective materials for hosting and intercalating functional chemicals, making them suitable for water contaminant remediation. Elevated nitrate (NO3−) levels in water and wastewater, attributed to the high solubility of nitrates, pose significant risks to aquatic ecosystems and human health. This study outlines a simple co-precipitation method for synthesizing zinc-aluminum layered double hydroxides (Zn-Al-LDH) and evaluates their performance in efficiently removing nitrate ions under optimal conditions. The characterization of the Zn-Al-LDH nanostructures was conducted through various techniques, including X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA/DTA), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Key parameters influencing nitrate adsorption, such as NO3− concentration, pH, adsorbent dosage, contact time, and the effect of temperature on Zn-Al-LDH performance, were thoroughly examined in a systematic manner. Notably, the calcined form of LDH (Zn-Al-LDH-C) exhibited the highest nitrate adsorption capacity of 94%, with optimal adsorption at pH 6.9 at low temperature. Equilibrium was reached in 80 minutes, and adsorption capacity rose to 16 mg/g. FTIR analysis confirmed the intercalation of nitrate ions into the calcined material's structure. Adsorption isotherm studies revealed that nitrate adsorption onto Zn-Al-LDH followed the Langmuir model (R² = 0.99), indicating a uniform surface and monolayer adsorption mechanism, as opposed to the Freundlich model (R² = 0.90). This study demonstrates the potential of enhancing Zn-Al-LDH-C nanostructures to improve their efficiency in removing contaminants from water and wastewater, presenting a promising approach for advanced water treatment solutions.