An effective, low-cost and recyclable bio-adsorbent having amino acid intercalated LDH@Fe3O4/PVA magnetic nanocomposites for removal of methyl orange from aqueous solution

Abstract

At first, layered double hydroxides (LDH) was intercalated with eco-friendly molecule using the coprecipitation method, which this act was confirmed using X-ray diffraction showing the increase of interlayer space to 1.36 nm. In the second step, we hybridized the intercalated LDH material with the pre-synthesized Fe3O4 nanoparticles via ultrasound waves as a simple technique. Then, different percentages of the LDH hybrid were applied for the fabrication of crosslinked poly(vinyl alcohol) (PVA) nanocomposites (NCs), and their physiochemical properties were examined. Hence, thermogravimetry analysis showed the great thermal stability of obtained NCs. Also, NCs had a mesoporous structure with high specific surface area. Finally, the influence of crosslinked PVA on the adsorption ability of LDH hybrid as an efficient magnetic adsorbent was studied to remove methyl orange (MO) from water test solution. The maximum adsorption efficiency of the NC toward MO was obtained at pH = 6 using 100 mg of the adsorbent. Consequently, we used various error functions to find the suitable adsorption isotherm among linear and non-linear forms of isotherm models. The results showed that linear Freundlich model was the better model of the adsorption process. Also, we did the same calculations for the linear and non-linear forms of kinetic models and outcomes were match better with the non-linear form of Pseudo-second-order model. Subsequently, the observed results of the adsorption thermodynamic revealed the spontaneous and exothermic nature of the adsorption process. At the end, the multi-cycling study indicated the stable and remarkable adsorption efficiency of NC 6 wt% after 3 cycles.