Preparation of silica-magnetite nanoparticle mixed hemimicelle sorbents for extraction of several typical phenolic compounds from environmental water samples

• Published in: Journal of Chromatography A 2008-04, Vol.1188 (2), p.140-147
• Main Authors: Zhao, Xiaoli, Shi, Yali, Wang, Thanh, Cai, Yaqi, Jiang, Guibin
• Format: Article
• Language: English
• Subjects: Analysis methods; Analytical chemistry; Applied sciences; Cetrimonium Compounds - chemistry; Cetylpyridinium - chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Drinking water and swimming-pool water. Desalination; Environmental Restoration and Remediation - methods; Exact sciences and technology; Ferrosoferric Oxide - chemistry; Hydrogen-Ion Concentration; Isoelectric Point; Magnetics; Micelles; Mixed hemimicelles; Nanoparticles - chemistry; Natural water pollution; Other chromatographic methods; Other wastewaters; Phenolic compounds; Phenols - isolation & purification; Pollution; Silica-coated magnetite nanoparticles; Silicon Dioxide - chemistry; Solid Phase Extraction; Solubility; Solutions; Surface-Active Agents - chemistry; Time Factors; Wastewaters; Water Pollutants, Chemical - isolation & purification; Water treatment and pollution
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2008.02.069

A novel type of superparamagnetic silica-coated (Fe 3O 4/SiO 2 core/shell) magnetite nanoparticle modified by surfactants has been successfully synthesized and was applied as an effective sorbent material for the pre-concentration of several typical phenolic compounds (bisphenol A (BPA), 4- tert-octylphenol (4-OP) and 4- n-nonylphenol (4-NP)) from environmental water samples. Compared with pure magnetic particles, a thin and dense silica layer would protect the iron oxide core from leaching out in acidic conditions. In order to enhance their adsorptive tendency towards organic compounds, cetylpyridinium chloride (CPC) or cetyltrimethylammonium bromide (CTAB) were added, which adsorbed on the surface of the Fe 3O 4/SiO 2 nanoparticles (Fe 3O 4/SiO 2 NPs) and formed mixed hemimicelles. Main factors affecting the adsolubilization of analytes were optimized and comparative study on the use of CPC and CTAB-coated Fe 3O 4/SiO 2 NPs mixed hemimicelles-based SPE was also carried out. CPC-coated Fe 3O 4/SiO 2 NPs system was selected due to lower elution volume required and more effective adsorption of the target compounds. Under selected conditions, concentration factor of 1600 was achieved by using this method to extract 800 mL of different environmental water samples. The detection limits obtained for BPA, 4-OP and 4-NP with HPLC-FLD were 7, 14, and 20 ng/L, respectively.