Novel Magnetic Nanostructured Beads for Cadmium(II) Removal

Abstract

This study presents an effective magnetic separation method for cadmium removal, based on the use of a novel nanostructured material as an adsorbent. This adsorbent involves the incorporation of magnetite nanoparticles (Fe3O4-NPs), synthesized by the reverse coprecipitation method, into sodium alginate and activated carbon to form spherical structures by crosslinking Ca2+ ions with the charged alginate chains, referred to as magnetic alginate activated carbon (MAAC) beads. The effect of the experimental parameters, such as pH, contacting time, adsorbent dosage, agitation type, and rotating speed were investigated and optimized for an efficient removal of Cd(II) ions at an initial concentration of 250 mg/L. The amount of adsorbed Cd(II) by MAAC beads increased at a pH of 6 with a removal efficiency over 90%. The maximum adsorption capacity reached was 70 mg/g of adsorbent at an initial Cd(II) concentration of 150 mg/L, whereas at 250 mg/L the adsorption capacity lowered until 60 mg/g. Sorption isotherms were calculated using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich equations, and were better described by the Freundlich and Temkin models. These results proved the removal efficiency and the potential use under real environmental conditions of the MAAC beads, due to their easy recovery from contaminated aqueous solutions.

Tribological Behavior of Nanolubricants Based on Coated Magnetic Nanoparticles and Trimethylolpropane Trioleate Base Oil

“…In this case, the ∆ of 77 cm −1 is ascribed to a chelating bidentate interaction between the COO − group and the Fe or Nd atoms. This result is in concordance with previous works, in which a strong chemical bond between carboxylic acid and the amorphous iron oxide or neodymium alloy nanoparticles' surface has been shown [36,37].…”

“…In this case, the ∆ of 77 cm −1 is ascribed to a chelating bidentate interaction between the COO − group and the Fe or Nd atoms. This result is in concordance with previous works, in which a strong chemical bond between carboxylic acid and the amorphous iron oxide or neodymium alloy nanoparticles' surface has been shown [36,37]. Also, thermogravimetric analysis (TGA) was used to estimate the oleic acid content in the synthesized nanoparticles as well as the number of oleic acid molecules per surface area of each nanoparticle (Table 1).…”

“…This fact is in accordance to that expected for the reduction of magnetization caused by a dead magnetic layer in small magnetic nanoparticles and the Additionally, crystallinity and the phase structures of coated Fe 3 O 4 nanoparticles were also characterized by X-ray powder diffraction (XRD) using a Philips PW1710 diffractometer (Cu Kα radiation source, λ = 1.54186 Å) with a step size of 0.02 • and counting time of 2 s per step from 10 to 80 • (2θ). In Figure 4, the diffractograms of both samples S1 and S2, show a set of peaks corresponding to those of the crystalline Fe 3 O 4 phase (Joint Committee on Powder Diffraction Standards, JCPDS 79-0417) [36]. Moreover, the widening of the peaks, indicate the ultra-fine nature and small crystallite size of the particles [37].…”

Extraction and Characterization of Alginate from an Edible Brown Seaweed (Cystoseira barbata) Harvested in the Romanian Black Sea

“…For instance, including magnetite has enhanced the recovery of biosorbents. In this case, adsorption of Cd 2+ ions was improved by also including activated carbon in the alginate matrix leading to an improved material in terms of adsorption capacity and costs [48]. Another approach is to obtain a compressive alginate sponge where the contaminant is recovered after adsorption simply by compressing the biosorbent before reuse.…”

Facile Synthesis and Reuse of Magnetic Black Carbon Magnetite (BC-Mag) for Fast Carbamazepine Removal from Water

“…These particles typically contain a core-shell structure where the exposed carbon shell provides available sorption sites and the protected iron oxide core (typically magnetite, Fe 3 O 4 ) is sensitive to applied magnetic fields [11,17,18]. This combination of physical properties allows retrieval of the nanoparticles for regeneration and reuse [19,20]. Carbon-coated magnetic iron oxides are typically formed within hydrothermal conditions where dissolved organic molecules (e.g., glucose) become charred upon pre-formed nanomagnetite particles [21].…”