Evaluation of arsenate adsorption efficiency of mill-scale derived magnetite particles with column and plug flow reactors

Magnetite particles were synthesized by co-precipitation method from the mill-scale and characterized with FTIR, SEM, EDS and XRD. The proficiency of magnetite particles for arsenate removal is determined with batch adsorption experiments and various types of continuous reactors including column reactor fed from bottom to top, column reactor fed from top to bottom and plug flow reactor. The columns with upward feed direction, downward feed direction and plug flow reactor were operated for 96, 49 and 96 days, respectively. The maximum arsenate adsorption capacity for magnetite was evaluated 9.34 mg/g, while the pH value for point of zero charge was found around 6.35. The crystalline size of the magnetite particle was found 7.4 nm. The obtained equilibrium data was finely explained by Langmuir isotherm model as compared with Freundlich isotherm model. The column reactor with upward influent direction indicated almost 100% arsenate removal efficiency. However, the arsenate removal efficiency for the plug flow reactor and the column reactor fed from top to bottom was appeared around 94 and 95%, respectively. The used particles from batch experiments were regenerated with 0.2 N alkali solution for 4 h. Based on experimental outcomes, mill-scale derived magnetite particles are offered for the adsorptive removal of arsenic (V) from the contaminated water.