Abstract
An amino-functionalized magnetic macroporous copolymer of glycidyl methacrylate (GM) and ethylene glycol (E) dimethacrylate (m-poly(GME)-deta) was synthesized, fully characterized, and used to investigate the adsorption of vanadium (V) oxyanions from aqueous solutions (Ci = 0.5 mM) in a batch system at room temperature (298 K). Pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich, and intra-particle diffusion (IPD) models were used to analyze the kinetic data. The study showed that sorption is rapid, i.e., the sorption half-time is approximately one minute. Initially, the sorption process primarily involved surface sorbent particles, and it was best described by the PSO model. However, after saturation of the surface active sites is attained, the sorption rate decreases significantly because of limitations of the diffusion rate, which is then primarily controlled by the IPD process. The sorption process is favorable in the pH range of 3–6 due to the strong electrostatic interactions between the absorption centers of copolymer and vanadium (V) oxyanions. In the stated pH range, deta absorption centers with two and three protonated N atoms are in equilibrium as studied by quantum chemical modeling. Among V(V) species present in diluted aqueous media, the adsorption of H2VO4− ions dominates.
Highlights
Vanadium occurs in nature in the form of 65 different minerals, mostly vanadinite, descloisite, carnotite, and patronite
The sorption process is favorable in the pH range of 3–6 due to the strong electrostatic interactions between the absorption centers of copolymer and vanadium (V) oxyanions
The porosity parameters for sample m-Si-poly(GME)-deta, i.e., the values of specific pore volume, Vs, and pore diameter corresponding to half of pore volume, DV/2, were read from the pore size distribution curves determined by mercury porosimetry, while the specific surface area, Ss,Hg, was calculated as the sum of incremental specific surface areas from the pore size distribution curves as described in the literature [16]
Summary
Vanadium occurs in nature in the form of 65 different minerals, mostly vanadinite, descloisite, carnotite, and patronite. Several studies showed that amino-functionalized GM-based copolymers possess a significant affinity for the sorption metal ions [7,8]. These polymers are characterized by thermal and chemical stability [9,10]. It was shown that the metal ion sorption process on the surface of macroporous polymer nanocomposites depends on various parameters, such as the properties of the sorbent (chemical structure, porosity, specific surface area, particle size), ion properties (chemical nature and charge), and sorption conditions, such as ion concentrations in solution, pH, temperature, presence of other competing species, and contact time. An amino-functionalized magnetic macroporous copolymer of GM and E dimethacrylate synthesized by in situ suspension copolymerization in the presence of Fe3O4 (m) nanoparticles coated with 3-aminopropyltrimethoxysilane (APTMS) through a silanization process, functionalized with diethylene triamine (deta), m-Si-poly(GME)-deta, was fully characterized in terms of its structural properties and tested as a sorbent of vanadium (V) oxyanions
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