Arsenopyrite weathering under conditions of simulated calcareous soil

Abstract

Mining activities release arsenopyrite into calcareous soils where it undergoes weathering generating toxic compounds. The research evaluates the environmental impacts of these processes under semi-alkaline carbonated conditions. Electrochemical (cyclic voltammetry, chronoamperometry, EIS), spectroscopic (Raman, XPS), and microscopic (SEM, AFM, TEM) techniques are combined along with chemical analyses of leachates collected from simulated arsenopyrite weathering to comprehensively examine the interfacial mechanisms. Early oxidation stages enhance mineral reactivity through the formation of surface sulfur phases (e.g., S n (2-)/S(0)) with semiconductor properties, leading to oscillatory mineral reactivity. Subsequent steps entail the generation of intermediate siderite (FeCO3)-like, followed by the formation of low-compact mass sub-micro ferric oxyhydroxides (α, γ-FeOOH) with adsorbed arsenic (mainly As(III), and lower amounts of As(V)). In addition, weathering reactions can be influenced by accessible arsenic resulting in the formation of a symplesite (Fe3(AsO4)3)-like compound which is dependent on the amount of accessible arsenic in the system. It is proposed that arsenic release occurs via diffusion across secondary α, γ-FeOOH structures during arsenopyrite weathering. We suggest weathering mechanisms of arsenopyrite in calcareous soil and environmental implications based on experimental data.

Carrier-microencapsulation of arsenopyrite using Al-catecholate complex: nature of oxidation products, effects on anodic and cathodic reactions, and coating stability under simulated weathering conditions

“…The XPS spectra of Fe 2p 3/2 , As 3d 5/2 , S 2p 3/2 , O 1s, and Al 2p 3/2 are shown in Figure 4 and the corresponding curve fitting parameters are summarized in Table 1. The Fe 2p 3/2 spectrum (Figure 4a) shows one strong peak at 707.3 eV, which could be attributed to Fe(II)-AsS in mineral lattices (Corkhill and Vaughan, 2009;Lara et al, 2016;Nesbitt et al, 1995;Zhu et al, 2014). There is another broad peak centered at around 711 eV, which when deconvoluted revealed multiple peaks of Fe , SO 3 2-, and SO 4 2-) (Figures 4b and c).…”

Suppression of arsenopyrite oxidation by microencapsulation using ferric-catecholate complexes and phosphate

“…The Fe 2p 3/2 spectrum (Fig. 4a) suggests that the outermost surface of treated arsenopyrite consists of (1) arsenopyrite (Fe (II) -(AsS) at 707.6 eV), (2) partly oxidized arsenopyrite (Fe (III) -(AsS) at 709.2 eV), (3) ferric-oxyhydroxide (Fe (III) -O at 710.7 eV), and (4) ferric sulfate (Fe (III) -SO 4 at 714.3 eV) (Corkhill and Vaughan, 2009;Grosvenor et al, 2004;Lara et al, 2016;Liu et al, 2020;Nesbitt et al, 1995;Zhu et al, 2014). These assignments are supported by the As 3d 5/2 and S 2p 3/2 spectra (Figs.…”

Estudio teórico de cupratos de litio como posibles materiales catódicos para baterías

“…Dentro de las actividades mineras, la extracción de metales libera al medio ambiente cantidades significantes de arsenopirita (FeAsS) y otros minerales de azufre que contienen elementos tóxicos tales como As, Pb, Cr y Cd [115]. La arsenopirita es la principal fuente mineral de As en la litósfera [116] y parte de su estudio ha sido dirigido a comprender:…”

“…El mecanismo de liberación de As al ambiente mediante el desgaste (oxidación) de arsenopirita, con el propósito de encontrar soluciones para reducir el riesgo de contaminación y poder proteger la salud humana así como la integridad del medio ambiente [115].…”

“…Lara y colaboradores [115] estudiaron la oxidación de arsenopirita bajo condiciones de suelo calcáreo simulado y concluyeron que en el paso inicial de oxidación de arsenopirita, se forma un compuesto tipo Fe 1−x As 1−y S en conjunto con As soluble, S y especies ferrosas, esto sugiere que la oxidación de arsenopirita involucra la oxidación de Fe como de As, por lo que resulta de interés conocer desde el punto de vista teórico, los estados electrónicos más susceptibles a ser oxidados, todo esto mediante la DOS-p así como la s(r) y comparar con lo reportado por estudios experimentales. En la FeAsS obtenida con HSE06, en la cual, se indican los intervalos sobre los cuales se pierde uno y dos electrones.…”