Preparation of magnetic Fe₃O₄ nanocomposites modified with MnO₂, Al₂O₃, Au and their application for preconcentration of arsenic in river water samples

In this study, the nanometer-sized ferrous-ferric oxide magnetic nanocomposite (Fe₃O₄@MnO₂@Al₂O₃@Au) was successfully synthesized using co-precipitation and sol gel methods The structural, morphological and magnetic properties of the nanocomposite material were characterized by FTIR, BET, XRD, SEM/EDS, Zeta-potential measurements, TEM and VSM. The nanocomposite was applied as a sorbent for preconcentration of As via ultrasound assisted magnetic solid phase extraction (UA-MSPE). The preconcentrated arsenic was quantified using ICP-MS. A 2⁵⁻¹ fractional factorial design was used as a tool for optimizing the developed analytical methodologies. Under optimized conditions, the limit of detection and quantification were 8.6 and 28.5 ng L⁻¹ respectively. The intraday (n = 15) and interday (n = 5) precisions of the developed UA-MSPE method expressed in terms of relative standard deviation (%RSD) were 4.1 and 6.2% and the enrichment factor was found to be 95. The extraction efficiency of the current method was greater than 95%. The developed UA-MSPE method was successfully applied in the preconcentration of arsenic in environmental water samples and nanocomposites modified with MnO₂, Al₂O₃, Au and their application for preconcentration of arsenic in river water sample and the concentration ranged from 0.13–0.18 μg L⁻¹. The Fe₃O₄@MnO₂@Al₂O₃@Au nanoadsorbent combined the advantages of magnetic separability and high affinity toward arsenic adsorption.