Characterization of Copper Adsorption onto an Alginate Encapsulated Magnetic Sorbent by a Combined FT-IR, XPS, and Mathematical Modeling Study

Abstract

Copper adsorption onto calcium alginate encapsulated magnetic sorbent is studied in this paper. The objective of this study was to qualitatively and quantitatively elucidate the copper binding onto the sorbent. The adsorption increases from around 0 to almost 100% as the initial pH is increased from 2 to 5. A maximum adsorption capacity of 0.99 mmol g -1 is achieved. The FT-IR and XPS studies show that the CsO in carboxyl group of alginate directly attaches to the copper ion that leads to most of the adsorption. A mathematical model is developed, and it includes ion exchange between the calcium and the copper, coordination reaction between the functional group and the copper, as well as surface complex formation between the iron oxide and the copper. The model is capable of describing and predicting effects of various key operational parameters on the adsorption process, such as initial pH, metal concentration, and dosage of sorbent.

Barium alginate caged Fe3O4@C18 magnetic nanoparticles for the pre-concentration of polycyclic aromatic hydrocarbons and phthalate esters from environmental water samples

“…This indicates that the C 18 chain is successfully attached to the magnetic nanoparticles by reactions with the hydroxyl groups on the surface of Fe 3 O 4 . Once Fe 3 O 4 @C 18 are encapsulated into the Ba 2+ -ALG vesicles, the hydroxyl group absorption appears again, and a carboxylic group adsorption at 1413 and 1598 cm −1 can also be observed [18,21]. These groups are introduced by the alginate polymer, indicating successful functionalization of alginate on the surface of the Fe 3 O 4 @C 18 nanoparticles.…”

“…2(d [14]. The stretching vibrations of hydroxyl groups (OH) usually form a broad band region at 3100-3700 cm −1 [21]. As shown in Fig.…”

“…So it is quite desirable to cage Fe 3 O 4 @C 18 into barium alginate (Ba 2+ -ALG) polymers to enhance the dispersibility and stability of sorbents in aqueous solution. In the published studies, a special encapsulation system, electrostatic extrusion equipment which is unavailable in most laboratories, has been required to prepare cross-linked alginate microvesicle, and the size of the obtained magnetic bead is about hundreds of micron scale [18][19][20][21] In the present study, we reported the preparation of Fe 3 O 4 @C 18 @Ba 2+ -ALG and their potential applications in the enrichment of organic contaminations from environmental water samples. To examine the feasibility of this approach, we selected four polycyclic aromatic hydrocarbons (PAHs) and four phthalate esters (PAEs) as model compounds.…”

“…Moreover, the polymer cage allows bidirectional diffusion of small molecules but restricts the access of large molecules [18,19]. Magnetite nanoparticles have also been encapsulated into calcium alginate for heavy metal removal from contaminated water [20,21]. So it is quite desirable to cage Fe 3 O 4 @C 18 into barium alginate (Ba 2+ -ALG) polymers to enhance the dispersibility and stability of sorbents in aqueous solution.…”

Improvement of metal adsorption onto chitosan/Sargassum sp. composite sorbent by an innovative ion-imprint technology

“…At 2 < pH < 4, the amine groups on the surface of the sorbent could be easily protonated, which induces an electrostatic repulsion of copper ion. Competition between protons and Cu ions for sorption sites greatly decreases the sorption capacity (Chen and Wang, 2001;Lim et al, 2008). As pH is increased, the functional groups become more available for metal ion binding, and hence the biosorption is enhanced.…”