Arsenic Adsorption onto Minerals: Connecting Experimental Observations with Density Functional Theory Calculations

Abstract

A review of the literature about calculating the adsorption properties of arsenic onto mineral models using density functional theory (DFT) is presented. Furthermore, this work presents DFT results that show the effect of model charge, hydration, oxidation state, and DFT method on the structures and adsorption energies for As (oxyhydr)oxide cluster models were calculated using planewave and cluster-model DFT methods.

Density Functional Theory Study of Arsenate Adsorption onto Alumina Surfaces

“…This type of configuration will be referenced as bidentate binuclear (BB) throughout this paper. Arsenate adsorption onto iron oxide surfaces is also found to be more favorable in a bidentate binuclear configuration [15][16][17]. In a comprehensive study done by Watts and colleagues, the adsorption of arsenic atop mineral substrates and its current state in the literature has been reviewed.…”

“…In their study, two tetrahedral metal atoms were linked by one bridging oxygen atom, and different configurations of bicarbonate were modelled. Another study by Watts et al employed a tri-nuclear Fe cluster structure, to model As adsorption [15]. In this Fe structure, two Fe atoms are octahedrally coordinated, while one Fe atom only has five bonds.…”

“…In a comprehensive study done by Watts and colleagues, the adsorption of arsenic atop mineral substrates and its current state in the literature has been reviewed. Part of this work is devoted to systematically analyzing the influence of surface charge, hydration, and oxidation states on adsorption geometries and energetics of arsenic onto iron-(oxyhydr)oxide models [15]. The work has concluded that properties such as reaction rates, thermodynamics, and structural results are biased towards the choice of the DFT method and should be further validated.…”

“…Building on earlier work on clean single-crystal mineral surfaces studied under ultra-high vacuum conditions [3][4][5][6], experimental studies of hydrated surfaces have emerged to address questions, such as how exposed surfaces transform under geochemical conditions [7][8][9][10]. Experimental studies of Al and Fe (hydr)oxide surfaces are prolific [11][12][13][14][15][16][17], as these materials have a natural abundance and reactivity towards aqueous contaminants. As an example, numerous studies conducted by Catalano and co-workers can be mentioned [18][19][20][21].…”

Interlayer Structures and Dynamics of Arsenate and Arsenite Intercalated Layered Double Hydroxides: A First Principles Study

“…Numerous studies have been carried out to investigate As adsorption on various minerals, such as clay minerals [9][10][11][12][13][14][15][16][17] and (hydr)oxides [18][19][20][21][22][23][24][25][26][27]. Adsorption of As onto clay can occur directly on edge surfaces and indirectly through cation bridging on basal surfaces [17], which has been shown to be highly dependent on pH [9,10,12,13].…”