Optimization of arsenic removal with Fe3O4@Al2O3@Zn-Fe LDH as a new magnetic nano adsorbent using Box-Behnken design

Abstract

This work is focused on arsenic removal using Fe3O4@Al2O3@Zn-Fe LDH as a new magnetic nanoadsorbent based on ultrasound-assisted dispersive magnetic solid phase extraction. The determination of Arsenic content of samples was performed by Atomic Fluorescence Spectroscopy. The synthesized nanoadsorbent was characterized by means of Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), X-Ray Diffraction (XRD) and Brunauer–Emmett–Teller (BET). An effecient Box-Behnken Design (BBD) approach was used to optimize the variables affecting the arsenic removal. The predicted maximum removal percentage was 97.3, yielded at pH, 4.0; adsorbent amount, 28.9 mg; removal time, 12.8 min and initial concentration, 65.6 μg L−1. The adsorption isotherms were studied by plotting Langmuir and Freundlich models. It was found that the obtained empirical adsorption data were well fitted to the Langmuir equation with a maximum adsorption capacity of 67.57 mg g−1. Moreover, detailed kinetics studies confirmed that the adsorption kinetic follows a pseudo-second-order model. The prepared sorbent proved to be enormously efficient for arsenic removal from tap water sample, with the repeatability in the range of 4.8–7.8%. Finally, the proposed analysis method was found to be a promising monitoring methodology for arsenic removal in various tap and waste water samples.