Removing and measurement of trace amounts of Rhodamine B in aqueous samples based on synthesis of Fe3O4 nanoparticles modified with SiO2 and polydopamine nano-sorbent by magnetic solid phase extraction

Abstract

Rhodamine B (RDB) dyes are generally toxic and cause problems such as carcinogenic activities, neurological disorders, and respiratory tract irritations. However, some individuals still illegally use RDB as a food additive. Therefore, a simple and accurate method is needed to determine RDB in real samples such as food or cosmetic products. In this study, the magnetic solid phase extraction (MSPE) method was used to measure very low amounts of RDB dye in water samples. The advantages of this method include simplicity, good repeatability, high preconcentration factor, higher extraction efficiency, low organic solvent volume requirement, rapid separation, low cost, high sensitivity, and interference removal compared to other methods. Within this approach, iron oxide nanoparticles underwent synthesis, followed by the application of tetra ethoxy silane (TEOS) and polydopamine (PDA) coatings on the nanoparticle surface, resulting in the creation of Fe3O4@SiO2@PDA nano-sorbent. This nano-sorbent was then utilized as the magnetic solid phase in MSPE. The characteristics of compounds synthesized were investigated by various methods such as infrared Fourier transform spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and vibrating sample magnetometer (VSM). Response surface methodology (RSM) and Box-Behnken (BB) design were used to optimize the variables affecting the adsorption process and achieved high recovery percentages. In optimal experimental conditions, the detection limit and quantification limit of the method were found to be 0.73 and 2.42 µg/L of RDB, respectively, with RSDs of ±0.32% and ±0.67%. Furthermore, the linear concentration range of the proposed method for solid phase extraction of RDB was determined to be 10.0-900.0 µg/L. Moreover, the recovery rates for tap water, lake water, and well water samples ranged from 96.9% to 98.6%.