Effect of competing ligands on the sorption/desorption of arsenite on/from Mg–Fe layered double hydroxides (Mg–Fe-LDH)

Synthesis and arsenic adsorption performances of ferric-based layered double hydroxide with α-alanine intercalation

“…Since iron oxides or hydroxides have a high affinity to arsenic, the iron based LDHs are promising materials for arsenic removal and several researches have been reported [31][32][33][34][35]. The amino acid intercalation in the interlayer region changes the properties of LDHs, and provides the useful information for the effect on drug release from LDHs in the life body.…”

Formation, properties and reactivity of coprecipitates and organomineral complexes in soil environments

“…on Mg-Fe-LDH; greater percentages of As(III) than As(V) were replaced by the competing ligands, except P. To describe the latter observation, Caporale et al (2013) hypothesized that, when P was added to the LDH on which As(V) was previously sorbed, it competed with As(V) for common sites. Vice versa, since As(III) did not occupy all the sites occupied by…”

Chemical Processes Affecting the Mobility of Heavy Metals and Metalloids in Soil Environments

“…Some studies were carried out by Violante et al [54][55][56] on samples formed by coprecipitating arsenate with aluminum and/or iron. These authors demonstrated that less ) of arsenite and arsenate in absence and presence of competing anions (initial anion/arsenite or arsenate molar ratio of 1.0), at pH 6.0 and 20°C, and efficiency (%) (i.e., efficiency of the anions in inhibiting arsenite or arsenate sorption on sorbent surfaces) on ferrihydrite (A) [52], noncrystalline Al oxides (B) [53], and MgFe-LDH (C) [26,27] Arsenite Arsenate Anion Sorption (mmol kg arsenate was replaced by phosphate from arsenate iron and/or aluminum coprecipitates than from previously formed iron and/or aluminum oxides on which arsenate was sorbed [57]. Low amounts of arsenate coprecipitated with aluminum and/or iron oxides at pH 7.0 were removed by phosphate (5-25 %), attributed to the formation of strong inner-sphere complexes, metal-arsenate precipitates, and partial occlusion of arsenate into the coprecipitates.…”

“…In contrast, on noncrystalline Al oxides, higher sorption of arsenate versus arsenite was always evidenced in a wide range of pH, both in the absence or presence of organic ligands. Caporale et al [26,27] evaluated the arsenite and arsenate sorption capacity of a Al-Mg and a Fe-Mg layered double hydroxide at varying pH values in the presence of many anions. They also observed that Fe-Mg-LDH sorbent was able to hold a much higher amount of arsenate than arsenite and noted that the sorption of the former was much more pHdependent than the latter.…”

“…In the last decade, many studies have shown that at high metal loadings (also below the theoretical metal-monolayer coverage of sorbent surfaces) sorption of some cations, such as Ni, Co, Cr, and Zn, on the surfaces of Al-oxides and Al-bearing phyllosilicates may promote the formation of precipitates such as double layered hydroxides (LDHs) at pH values below the pH where the formation of metal hydroxide precipitate is expected according to the solubility product [3,7,8] 4 , and ClO 4 which are present in the interlayers of the mineral [26,27]. The formation of metal surface precipitates can sequester heavy metals with a consequent reduction of metal release and bioavailability for plants and microorganisms [8].…”