Exploring the Sorption Mechanism of Ni(II) on Illite: Batch Sorption, Modelling, EXAFS and Extraction Investigations

Abstract

The sorption mechanism of nickel (Ni) at the illite/water interface was investigated using batch, sorption modelling, extended X-ray absorption fine structure (EXAFS), and extraction approaches. The results showed that Ni(II) sorption on illite was strongly dependent on pH, contact time, temperature, and initial Ni(II) concentration. At a low initial Ni(II) concentration, the ion exchange species of ≡X2Ni° and the inner-sphere complexes including ≡SsONi+, ≡SwONi+ and ≡SwONiOH° species are observed on the sorption edges of Ni(II) on illite. As the initial Ni(II) concentration increased to 1.7 × 10−3 mol/L, precipitates including surface-induced precipitation of s-Ni(OH)2 and amorphous Ni(OH)2 became more significant, especially under neutral to alkaline conditions. EXAFS analysis confirmed that Ni-Al layered double hydroxide (LDH) can gradually form with an increase in the contact time. At pH 7.0, α-Ni(OH)2 was produced in the initial stage and then transformed to the more stable form of Ni-Al LDH with increasing contact time because of the increased Al3+ dissolution. With an increase in temperatures, α-Ni(OH)2 phase on illite transformed to Ni-Al LDH phase, indicating a lower thermodynamic stability compared to Ni-Al LDH phase. These results are important to understand the geochemical behaviors to effectively remediate soil contaminated with Ni(II).

Comparison of Chemical Speciation of Lead, Arsenic, and Cadmium in Contaminated Soils from a Historical Mining Site: Implications for Different Mobilities of Heavy Metals

“…The cation exchange capacity (CEC) and N 2 -Brunauer−Emmett− Teller specific area were approximately 20.0 mequiv/100 g and 28.0 m 2 /g, respectively. More details of the mineralogical characteristics of the illite may be found in Zhao et al 41 The HA used in this study was Aldrich humic acid, which we purified following Kim et al 42 Details of the characteristics of the HA may be found in Yamamoto et al 43 Ferrihydrite was synthesized following the procedure described by Schwertmann and Cornell. 44 The Cd on illite, ferrihydrite, and HA standards were prepared with 1 mM Cd in 0.01 M NaNO 3 at pH 6.5 under a N 2 atmosphere for 48 h. The Cd on the CaCO 3 standard was prepared by adding a solution of CdCO 3 into a CaCO 3 suspension at pH 6.5 with a Cd/Ca molar ratio of 1:140.…”

Thermodynamic and crystallographic model for anion uptake by hydrated calcium aluminate (AFm): an example of molybdenum

“…Understanding, and thus being able to model the mechanisms controlling these retention properties, requires a sound description of the sorption process from crystallographic to macroscopic (aqueous geochemistry) scales. This methodological approach, which has been used successfully to study the mechanisms of ion adsorption by clay minerals 32 – 36 , iron and manganese (hydr)oxides 37 – 40 , and Mg-Al LDH 41 , has to date been seldom applied to cement phases. One noticeable exception is the case of Ca uptake by C-S-H (the main cement component), for which the geochemical and crystallographic studies, although conducted separately 42 – 46 , could be combined to propose a coherent model.…”

Trace Element Geochemistry of Sulfides from the Ashadze-2 Hydrothermal Field (12°58′ N, Mid-Atlantic Ridge): Influence of Host Rocks, Formation Conditions or Seawater?

“…The TEs in associations I-III are closely associated and all metals from association II exhibit high correlations with U, V, Mg, Ca, Al, and Tl. This fact, and elevated contents of Mg, Ca, Al and Si in covellite relative to primary sulfides, indicate the assemblage of covellite with phyllosilicates, which can be a good sink for heavy metals (e.g., [50][51][52][53]), as well as for seawater-derived U and V [54,55]. A close link between U and phyllosilicates is also supported by the finding of numerous uraninite grains in sepiolite of the Ashadze-2 gossans [26].…”