Adsorption Isotherms of Arsenic on Conditioned Layered Double Hydroxides in the Presence of Various Competing Ions

Abstract

Analysis of effluents from various power plants indicates that, in addition to arsenic (As), these effluents also contain such ions as fluorides, nitrates, chlorides, carbonates, sulfates, and phosphates. Adsorption is considered the method of choice for the treatment of waste streams containing As. Of concern, therefore, is the impact of such competing anions on the capacity for As adsorption of the various materials utilized. In this work, we systematically investigated the effects of such ions on the As removal capacity of layered double hydroxides (LDHs), a class of materials investigated by our group and others as effective adsorbents for As and other heavy metals. The adsorption of As in the presence of each of these competing ions on LDH follows the extended Sips isotherm. It is concluded from our study that, of all of these ions, fluorides and nitrates have the least effect on As adsorption, followed by chlorides, carbonates, sulfates, and phosphates. Phosphates, in particular, have a very strong impact.

Controls on arsenate, molybdate, and selenate uptake by hydrotalcite-like layered double hydroxides

“…This finding is consistent with earlier reports on trace metals and anions (e.g., Das et al, 2006;Delorme et al, 2007). The negligible effect of NO 3 − on Se(IV) uptake compared to divalent anions has also been reported (You et al, 2001) and is similar to findings by Yang et al (2005) and Dadwhal et al (2011) on As(V)/Se(IV) and As(V) uptake, respectively, that support the current PO 4 3 − > NO 3 − trend. Higher charge density anions have a stronger affinity for HT-LDHs interlayer, in the order CO 3 2 − > SO 4 2 − > Cl − > NO 3 − (Sato et al, 1993) or…”

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

“…Among various treatment technologies, adsorption technique is considered as one of the most popular, efficient and practical methods, due to its high efficiency, easy operation, low cost and little risk. Owing to the worldwide research efforts, more and more adsorbents have been developed, which include activated carbon [21], activated alumina [22], iron hydroxide and oxide [23], anionic clays [24], zeolites [25], chitosan [26] and others [27,28]. Recently, layered double hydroxides (LDHs), known as a kind of multifunctional materials, have been reported to serve as adsorbents for anionic contaminants removal due to their large surface area, high anion exchange capacity and good thermal stability [29].…”

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

“…Compliance with this strict As standard in drinking water requires cost effective and efficient technologies for better removal of As. Methods that have been investigated include precipitation-filtration, ion exchange, membrane separation, and adsorption [3,6]; the latter technique, in particular, has been found to be superior for water reuse applications, in terms of initial capital costs, simplicity in design, and ease of operation. So far, common adsorbents, such as various clays and naturally occurring minerals [3,[7][8][9], activated [10] and mesoporous alumina [11], Fe-oxides [12], and ferrihydrite [13,14] have all been investigated.…”