Abstract
Mineral systems of kaolinite, montmorillonite, goethite and their mixtures were investigated to determine their effect on arsenite removal. Experimental studies include characterization and batch mode experiments. This study was in relation to solution composition and ageing relevant to streams and groundwater impacted by arsenic. Sorption isotherms indicated that sorption capacities of the different clay minerals, goethite and their mixtures were dependent on particle size, pH, particle concentration, arsenic concentration and residence time. Batch mode studies at room temperature revealed increase in sorption as pH was increased. All mineral systems exhibited increase in sorption as initial arsenic concentration increased. All mineral systems exhibited both promotive and non-promotive Cp effects. The complex behavior of mineral systems over the range of residence time investigated may be attributed to increased hydroxylation of the mineral surface and availability of thiol (≡S-H) and hydroxyl (≡Me-OH) functional groups and reactive sites.
Highlights
The environmental concern on arsenic is related to its anomalous concentration in surface and ground waters and its availability to living beings [1]
The aim of this study is to explore the effect of particle size of single and mixed mineral systems of kaolinitemontmorillonite, kaolinite-goethite and montmorillonitegoethite injected with zinc sulfide on sorption behavior of arsenite in relation to solution composition and ageing
In this study under sulfidic-anoxic condition and over the range of particle sizes investigated, sorption capacity increases with pH increase and in a sinusoidal pattern in some cases as shown in Figure 1. pH effect decreases with increase in particle size for all mineral systems
Summary
The environmental concern on arsenic is related to its anomalous concentration in surface and ground waters and its availability to living beings [1]. Arsenic pollutants discharged by anthropogenic and natural could result in degraded surface and ground water chemistry [2]. Immobilization of arsenic in the environment occurs through precipitation of low-solubility salts and adsorption on soils and sediments [3]. Remediation processes will follow the same principles, and the most common techniques are based on precipitation and adsorption phenomena [4]. Adsorption may decrease as particle concentration increases (outer sphere complexation) or not be significantly affected as particle concentration increases Increase in adsorption as particle concentration increases defines promotive particle concentration effect. The solid concentration effect is an anomalous adsorption phenomenon (i.e., the adsorption isotherm declines as particle concentration increases)
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