Arsenic removal from the leachate of a chromated copper arsenate (CCA) contaminated soil using iron-copper oxide nanoparticles

Yassaman Babaee, Catherine N. Mulligan, Md Saifur Rahaman

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Geoenvironmental Engineering

ABSTRACT: Arsenic contamination of groundwater is a widespread problem. Arsenic, from natural or anthropogenic sources, can adsorb onto the soil and leach into the groundwater so it is necessary to treat the leachate of arsenic contaminated soils. There are many technologies to reduce arsenic contamination in liquid phase. Arsenic adsorption by iron nanoparticles is one of the most recent solutions. Due to high adsorption capacity and the strong reduction potential of iron nanoparticles, arsenic immobilization can be highly effective. In this study an iron-copper oxide nano-composite was synthesized and evaluated for its effectiveness to remove arsenic from ground water. A series of batch experiments was performed using a synthetic arsenic contaminated water at three concentrations of 100, 500 and 1000 µg/L. The result showed that more than 70% removal is possible by using 50 mg/L of nanoparticles.

RÉSUMÉ: Contamination par l'arsenic des eaux souterraines est un problème répandu. Arsenic, à partir de sources naturelles ou anthropiques, peut adsorber sur le sol et la lixiviation dans les eaux souterraines il est donc nécessaire de traiter le lixiviat de l'arsenic des sols contaminés. Il existe de nombreuses technologies pour réduire la contamination par l'arsenic dans la phase liquide. L'arsenic par adsorption des nanoparticules de fer est l'une des solutions le plus récente. En raison de la capacité d'adsorption élevée et le potentiel des nanoparticules de fer de réduction solide, l'arsenic immobilisation par eux peuvent être très efficaces. Dans cette étude, un fer-oxyde de cuivre nano-composite a été synthétisé et évalué pour son efficacité à éliminer l'arsenic de l'eau du sol. Une série d'expériences a été effectuée en utilisant eau contaminée par l'arsenic synthétique à trois concentrations de 100, 500 et 1000 mg/L. Le résultat a montré que plus de 70% d™enlèvement est possible à l'aide de 50 mg/L de nanoparticules. 1 INTRODUCTION Arsenic is a widely dispersed element in the nature and its increasing concern is due to its high toxicity and non-biodegradability. Intake of inorganic arsenic over a long period can lead to chronic arsenic poisoning. Effects, which can develop through the years depending on the level of exposure, include skin lesions, peripheral neuropathy, gastrointestinal symptoms, diabetes, renal system effects, cardiovascular disease and cancer (IPCS 2001). Arsenic is released to the environment from a variety of natural and anthropogenic sources. In the earth™s crust average concentrations is reported to range from 1.5 to 5 mg/kg (Cullen and Reimer 1989). In some igneous and sedimentary rocks, higher concentrations of arsenic can be found, particularly in iron and manganese ores (Welch et al., 1988). Man-made sources of arsenic include its use in agriculture, livestock, medicine, pesticides wood preservative material and general industries (EPA-815-D00-001, 2000). CCA (chromated copper arsenate) is a commonly used wood preservative material which may contribute to arsenic contamination of subsurface soil. Most arsenic compounds are readily dissolved in water from the soil matrix and can reach a water body or groundwater which creates an elevated health risk. Therefore, it is necessary to treat arsenic contaminated soils before it leaches out to groundwater (Jang et al. 2005). Several remediation methods such as coagulation and flocculation, adsorption, ion exchange and membrane filtration have been employed to mitigate arsenic contamination in groundwater (EPA 2002; Shih 2005; Choong et al. 2007). Adsorption is among the most widely used technology for arsenic removal (Chen et al. 1999). Different types of adsorbent materials include activated alumina (AA), activated carbon (AC), copper-zinc granules, granular ferric hydroxide, ferric hydroxide coated newspaper pulp, iron oxide coated sand, iron filings mixed with sand, greensand filtration (KMnO4 coated glauconite), proprietary media, and surfactant modified zeolite (EPA 2002). Very recently nanoscale zero-valent iron (nZVI) has been used for removal or degradation of different contaminants, such as chlorinated solvents (Choe et al. 2001), chlorinated pesticides (Elliott et al. 2009), transition metals (Klimkova et al., 2011; Li and Zhang 2007), metalloids (Klimkova et al. 2011), etc. The successful application of nZVI in dissolved metal removal was

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