Speciation of Hexavalent Chromium in Aqueous Solutions Using a Magnetic Silica-Coated Amino-Modified Glycidyl Methacrylate Polymer Nanocomposite

Abstract

A new magnetic amino-functionalized polymeric sorbent based on glycidyl methacrylate was synthesized and used in the separation of chromium Cr(VI) oxyanions sorption from aqueous solutions in a static batch system. The kinetic and isothermal parameters of the sorption process were determined. The experimental data were best fitted by a pseudo-second-order model with R2 = 0.994 and χ2 = 0.004. The sorption process of Cr(VI) removal by amino-functionalized sorbent was controlled by both intraparticle diffusion and liquid film diffusion. The equilibrium results showed that the sorption process is best described by the Freundlich model, followed closely by the Sips isotherm model, with a maximum sorption capacity of 64 mg/g. Quantum chemical modeling revealed that the sorption sites on the sorbent surface are fragments with diethylenetriamine and aminopropyl silane groups that coated the magnetic nanoparticles. The calculations showed that Cr(VI) oxyanions (Cr2O72−, CrO42− and HCrO4−) bind to both sorption sites, with diethylenetriamine centers slightly favored. The X-ray photoelectron spectroscopy (XPS) spectra demonstrate that the chromium bound to the sorbent in the form of Cr(III), indicating that the Cr(VI) can be converted on the surface of the sorbent to a less harmful form Cr(III) due to the sorbent’s chemical composition.

Fast Gold Recovery from Aqueous Solutions and Assessment of Antimicrobial Activities of Novel Gold Composite

“…Brief analyses of the structural parameters for the [AuCl 4 ] − ion with the structure of the [AuCl 4 ] − anion (Figure S1) are given in the Supplementary Materials. The intra-particle plots (Figure 5b) show three distinct stages: a liquid film diffusion stage, an intra-particle diffusion stage, and a final equilibrium stage [37]. According to the obtained results, the intra-particle plots were linear and deviated from the origin, suggesting that the adsorption of Au onto pGME-en was controlled by both liquid film and intra-particle diffusion.…”

“…In addition, epoxy ring vibrations at 1256, 910, and 847 cm −1 , such as stretching carbonyl vibrations at 1722 cm −1 peaks, were found [37,38]. Compared with the pGME spectrum, the appearance of new absorption bands was observed at 1656, 1561 (N-H bending vibrations), and 754 cm −1 (N-H wagging vibrations), as well as broad bands assigned to the -OH and to the N-H stretching vibrations, with a maximum at ~3400 cm −1 [37,39]. Also, a decreasing intensity of characteristic epoxy vibration peaks was observed.…”

“…The characteristic absorption bands at 2994, 2926, and 2852 cm −1 , assigned to -CH 2 and -CH-stretching vibrations as well as the bands of -CH 2 and -CH-bending vibrations at 1447 and 1386 cm −1 , were observed. In addition, epoxy ring vibrations at 1256, 910, and 847 cm −1 , such as stretching carbonyl vibrations at 1722 cm −1 peaks, were found [37,38]. Compared with the pGME spectrum, the appearance of new absorption bands was observed at 1656, 1561 (N-H bending vibrations), and 754 cm −1 (N-H wagging vibrations), as well as broad bands assigned to the -OH and to the N-H stretching vibrations, with a maximum at ~3400 cm −1 [37,39].…”

Polymeric Materials in Speciation Analysis Based on Solid-Phase Extraction

“…The method was validated by analyzing several CRM-Tibet soil, strawberry leaves and applying it to Cr speciation in food, biological, and soil samples. A new sorbent was prepared following a relatively complicated synthesis procedure: Macroporous magnetic poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) is obtained by in situ suspension copolymerization in the presence of Fe 3 O 4 nanoparticles coated with a silanization agent 3-aminopropyltriethoxysilane (APTES) and further functionalized with diethylenetriamine with the main aim of selective removal of Cr(VI) [ 78 ]. The results indicated that Cr(VI) oxyanions that bind to the sorption sites can be converted on the surface of the sorbent to a less harmful form of Cr(III) due to the sorbent’s chemical composition.…”

Orientation Growth of N-Doped and Iron-Based Metal–Organic Framework and Its Application for Removal of Cr(VI) in Wastewater

“…Among these methods, adsorption effectively concentrates Cr(VI) by two main forces, i.e., electrostatic interactions and coordination interactions, which are recognized as easy, fast, and highly efficient environmental protection techniques without secondary waste [ 18 , 19 , 20 , 21 , 22 , 23 ]. A wide variety of adsorption materials for the removal of Cr(VI) in wastewater have been reported, such as metal hydroxides [ 24 ], silica-based materials [ 25 , 26 , 27 ], biochar [ 28 ], activated carbon [ 29 , 30 , 31 ], various types of clay minerals [ 32 , 33 ], chitin and chitosan [ 34 , 35 , 36 ], zeolites [ 37 ], graphene oxide [ 38 , 39 , 40 ], amino-functionalized silica [ 41 ], amino-functionalized magnetic polymers [ 42 ] and metal–organic frameworks (MOFs) [ 43 , 44 , 45 , 46 ]. Among these adsorption materials, MOFs are a novel class of crystalline porous material with periodic network structure formed by the interconnection of inorganic metal centers (metal ions or metal clusters) and bridging organic ligands through self-assembly [ 43 , 44 , 45 ].…”