Boron Removal from Aqueous Solutions by Synthetic MgAlFe Mixed Oxides

Abstract

The boron removal capacity from an aqueous solution using MgAlFe mixed oxides from layered double hydroxides (LDH) was studied. They were synthesized by the coprecipitation method at 70 °C and were characterized as potential filter materials. The Fe3+ analyzed by X-ray photoelectron spectroscopy and UV–visible diffuse reflectance showed their tetrahedral and octahedral coordination. Scanning electron microscopy micrographs and thermogravimetric and differential scanning calorimetry analysis evidenced the presence of clusters and particles aggregates and decreased dehydroxylation temperature when the iron content increased. Mixed oxides and boron solution in a ratio of 20:1 Mg/B were put in a batch reactor at different contact times. The borate removal process was due to the memory effect of the mixed oxides and superficial adsorption by electrostatic attraction. This fact is directly related to the specific surface area, Fe content, and surface charge. The maximum boron removals were achieved with the CS25 and CS50 samples with values higher than 85%.

Effective Removal of Boron from Aqueous Solutions by Inorganic Adsorbents: A Review

“…The research of De la Fuente et al [58] showed that the removal rate improved as the pH increased, presenting a maximum adsorption capacity at a pH value between 9.5 and 10.5. For an initial concentration of 50 mg/L, the maximum adsorption capacity was obtained after 30 min of stirring and 6 h of repose at 70 • C. Under these optimum conditions, a boron removal rate of around 95% was obtained; however, this value decreased to 75% at 30 • C. In a subsequent article [78], they demonstrated that the adsorption process followed a pseudo-second-order kinetic model and the Langmuir isotherm model. Nevertheless, the reaction process between boron and magnesium compounds was found to be irreversible, and neither pH nor temperature adjustment could be used to regenerate the adsorbents.…”

“…Under these optimum conditions, a boron removal rate of around 95% was obtained; however, this value decreased to 75% at 30 °C. In a subsequent article [ 78 ], they demonstrated that the adsorption process followed a pseudo-second-order kinetic model and the Langmuir isotherm model. Nevertheless, the reaction process between boron and magnesium compounds was found to be irreversible, and neither pH nor temperature adjustment could be used to regenerate the adsorbents.…”

“…In other works, tertiary mixed oxides were studied. Heredia et al [ 78 ] studied boron removal capacity from aqueous solutions utilizing MgAlFe mixed oxides. They achieved a maximum boron removal exceeding 85%, equivalent to 9.08 mg/g.…”

Facile synthesis of core-shell magnetic Fe3O4@SiO2-NH2 nanoparticles and their application for rapid boron removal from aqueous solution

“…Among of which, adsorption has become one of the most effective methods due to its simple operation, high selectivity and low energy consumption. Currently, Study on boron adsorption has being focused on various absorbents, such as ion exchange resins, activated carbon, metal oxides and hydroxides, polymers, metal-organic frameworks (MOFs) and magnetic adsorbents [14][15][16][17][18], and each kind of these absorbents has its own advantage and disadvantage during boron removal process. The magnetic nanoparticles (MNPs) and their functional composites had embodied high boron adsorption e ciency, simple magnetic separation and easy regeneration because of their large surface area, strong magnetic property, low cost and environmentally friendly.…”