LAUSR

Abstract In the present study humic acid modified magnetite (HA-Fe 3 O 4) nanoparticles as a novel magnetic adsorbent was synthesized by in situ co-precipitation method for malachite green (MG) remediation. The physio-chemical properties of the prepared nanoparticles were fully examined by using FTIR, SEM–EDX, XRD and UV–Vis, analysis. The pH pzc , specific surface area and suspension stability in aqueous system of the synthesized Nps were also evaluated. The various characterization revealed that HA–Fe 3 O 4 was effectively synthesized and HA effectively control aggregation and oxidation of Fe 3 O 4 in aqueous system. The XRD result reveals that the synthesized materials have a crystal size of 9.17 and 11.21 nm for HA-Fe 3 O 4 and Fe 3 O 4 Nps respectively. The operational parameters on the removal of MG by the synthesized Nps were also evaluated. The temperature dependence data also revealed that MG sorption process was feasible, spontaneous and endothermic. The MG adsorption rates were described by the pseudo 1st order model and Freundlich isotherm model. The maximum adsorption monolayer capacity of HA-Fe 3 O 4 and Fe 3 O 4 was 79.3 mg/g and 62.2 mg/g respectively. The reusability is an important factor to evaluate the HA-Fe 3 O 4 and Fe 3 O 4 in real applications and the optimum desorption was attained at 0.1 M of HCl for both Nano-sorbents. Based upon the results, the prepared Nano sorbent could be efficient for the removal of different cationic dyes from waste water. Graphic Abstract