Easy Synthesis of Surface-Tunable Carbon-Encapsulated Magnetic Nanoparticles: Adsorbents for Selective Isolation and Preconcentration of Organic Pollutants

Abstract

We have prepared core/shell structured carbon-encapsulated magnetic nanoparticles (CMNPs) with a simple method by using inorganic iron salt and glucose solution as precursor substance. The synthetic procedure does not require the use of organic solvents. We have utilized X-ray photoelectron spectroscopy, infrared spectroscopy, X-ray diffraction, and Raman analysis to examine the surface properties of CMNPs prepared at different temperature. The specific surface areas, magnetization and contents of graphitized carbon on carbon shell of CMNPs increase with heat treatment temperature. The obtained CMNPs are used to adsorb or preconcentrate bisphenol A (BPA), 4-n-nonylphenol (4-NP), 4-tert-octylphenol (4-OP), diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP) dicyclohexyl phthalate (DCHP), dioctyl phthalate (DOP), sulfonamide, tetracyclines, and quinolones antibiotics organic compounds from water samples. The adsorption of analytes is mainly based on π-π stacking interaction, hydrophobic interaction and hydrogen bonds between analytes and graphitic carbon. As a result, the adsorption or extraction behaviors of CMNPs to analytes are controlled by the content of oxygen-containing species and graphitized carbon on carbon shell of CMNPs. CMNPs prepared at 200 °C have ample oxygen-containing species (80%) on surface and favor the adsorption and extraction of quinolones antibiotics. CMNPs heated at 300-500 °C with the graphitization efficiency of carbon shell lower than 50% exhibit great preconcentration performance to BPA, 4-NP, 4-OP, DBP, DCHP, DOP, tetracyclines, and quinolones antibiotics. CMNPs prepared at 850 °C are highly graphitized (80%) and have strong adsorption affinity to all model analytes; however, they can quantitatively extract only highly polar sulfonamide antibiotics and moderately polar DEP, DPP because of hard desorption of other model analytes. We suggest that the appropriate adsorbent to certain organic contaminants can be obtained with this technique just by tuning the heat temperature without any post-treatment.

Preparation of polydopamine coated Fe3O4 nanoparticles and their application for enrichment of polycyclic aromatic hydrocarbons from environmental water samples

“…Nowadays, magnetic solid-phase extraction (MSPE), a novel SPE method, has been developed based on the use of magnetic nanoparticles since its high extraction efficiency and rapid extraction kinetics [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The magnetic adsorbents are usually devised on the basis of Fe 3 O 4 nanoparticles.…”

“…The magnetic adsorbents are usually devised on the basis of Fe 3 O 4 nanoparticles. Due to the highly hydrophilic property of Fe 3 O 4 , a layer of hydrophobic coat or adlayer such as hemimicelles/admicelles of ionic surfactant or alkyl carboxylates groups [2][3][4][5][6], phenyl or C 18 groups [7][8][9][10][11][12][13], carbon [14][15][16], or polymers [17][18][19][20], must be immobilized on the surface of Fe 3 O 4 MNPs, which involves toxic reagents or high temperature, and multiple, complicated procedures. With regard to MSPE method established with mixed hemimicelle modified magnetic nanoparticles, the extraction efficiency is strongly dependent on certain extraction condition and the adsorbed ionic surfactant is coeluted with targets, which interferes with determination of analytes.…”

Facile synthesis of novel flowerlike magnetic mesoporous carbon for efficient chlorophenols removal

“…The adsorption peak at 1400 cm À1 is related to the vibration of COO À groups from citrate modified on Fe 3 O 4 surface, and the broad peak at 1626 cm À1 is corresponding to the vibration of overlapping COO À and O-H groups [34]. The peak at 3434 cm À1 can be assigned to the surface-sorbed water and hydroxyl groups [35]. The Fe-O vibration is observed in all the other as-prepared materials, but the intensity of this peak decreases clearly due to the immobilization of SiO 2 , LDH and carbon coat.…”

Nanomaterials for analysis and monitoring of emerging chemical pollutants

“…In core-shelled structures of MNPs, different functional groups have been employed as the outer layer to offer good selectivity for the analytes, such as polymers [39,40], metal oxide [41], carbon [42], organic groups [43][44][45][46], surfactants [47][48][49], and b-cyclodextrin (b-CD) [50].…”

“…Niu et al [42] prepared core-shell structured carbon-coated MNPs by using glucose as a carbon source (Fig. 1).…”