Multivariate Optimization for Preconcentration and Separation of Brilliant Green using Magnetite Nanoparticles Functionalized by Cetyltrimethylamonium Bromide

Abstract

Adsorptive removal and preconcentration of Brilliant Green (BG) on Fe₃O₄ magnetic nanoparticles functionalized with cetyltrimethylamonium bromide (CTAB) was investigated in a batch system. The method was based on the analyte adsorption and direct determination by UV–visible spectrophotometry. Various experimental factors such as pH, adsorbent dose (m) and initial concentration (c_d) were evaluated and optimized using Box-Behnken design through adsorption of BG on the modified adsorbent. The optimized conditions for maximum removal efficacy (99%) were: pH 9; amount of nanoparticles, 7.1 mg; CTAB, 5.4 mg and c_d = 100 mg/L. Under optimum conditions, preconcentration of BG with enrichment factor of 35, LOD = 4 µg/L and RSD = 2.7% (n = 10) for 10 µg/L sample were achieved. The maximum monolayer adsorption of BG onto nano-Fe₃O₄‒CTAB through running Langmuir isotherm was obtained as 416 mg/g. The morphology and characteristics of the prepared nano-Fe₃O₄‒CTAB were investigated by scanning electron microscopy, X-ray diffraction, vibrating sample magnetometer, Fourier transform infrared spectroscopy and thermogravimetric analysis.