Sono-synthesized Fe3O4–GO–NH2 nanocomposite for highly efficient ultrasound-assisted magnetic dispersive solid-phase microextraction of hazardous dye Congo red from water samples

Abstract

This research focuses on the preparation of amino-functionalized magnetic graphene oxide nanocomposite (Fe3O4–GO–NH2), which increases the pre-concentration efficiency of Congo red residue in water samples. Their characterizations by FT-IR, SEM, EDX, and VSM were carried out in line with the magnetic property. The magnetic adsorbent was mainly used for the pre-concentration of anionic dye under optimized conditions of ultrasound-assisted magnetic dispersive solid-phase microextraction (UA-MDSPME). Typically, pre-concentration optimization conditions such as the pH of the solution, sorbent amount, power and sonication time, type of eluting solvent and its concentration were precisely investigated before the determination by UV–visible spectrophotometry. The analytical performance of the UA-MDSPE method was validated and found to have a linear range of 1.0–25.0 mg L−1 with R2 > 0.999. The limits of detection and quantification were 4.3 µg L−1 and 14.4 µg L−1, respectively. The precision of the method calculated from the slope of the calibration curve (%RSD, n = 3 × 3) for intra-day and inter-day analyses was 3.23 and 4.74, respectively. The extraction of Congo red dye from real water samples (drinking water, swamp water, and tap water) ranged from 90.65 to 105.8%. The enrichment factor of the developed procedure was averaged to 32.4 folds, ensuring the determination of trace amounts of residual dye in the water samples. It is, therefore, concluded that the magnetic adsorbent is an efficient method for the pre-concentration of hazardous dye from aqueous solution.