Encapsulation technique efficiency in high zinc chloride concentration clayey soil with traditional agents

• Published in: Engenharia Sanitaria e Ambiental 2022
• Main Authors: Perez, Isabel Amado, Ferreira, José Wilson dos Santos, Malko, José Adriano Cardoso, Silva, Maria Isabel Pais, Casagrande, Michéle Dal Toé
• Format: Article
• Language: Portuguese
• Subjects: WATER RESOURCES
• ISSN: 1809-4457
• DOI: 10.1590/s1413-415220200241

ABSTRACT Although the encapsulation technique has been used in environmental remediation for over three decades, there are few studies evaluating its efficacy for high contaminant concentrations. Therefore, this study aims to evaluate the encapsulation technique efficiency of clayey soil contaminated with 5% and 10% of zinc chloride, using lime and cement. Chemical, mechanical, mineralogical, and microscopic analyses were performed for pure, contaminated, and encapsulated soil, based on X-ray fluorescence (XRF/EDX), unconfined compression strength (UCS), atomic absorption spectrometry (AAS), scanning electron microscopy/energy dispersive X-ray spectrometer (SEM/EDS), and X-ray micro-computed tomography (micro-CT) tests. Although chemical interactions between zinc and lime negatively affected the gains when compared to cement, both encapsulating agents increased the strength over the curing periods of 7, 28, and 60 days. The leachates presented a significant reduction in the contaminant concentration, above 77% for critical experimental conditions. The contaminant reduced the presence of chemical elements that compose the soil matrix, consequently causing the voids to increase; in contrast, pozzolanic reactions promoted by the addition of lime and cement resulted in homogeneous voids distribution, enhancing the mechanical behavior and the capability of zinc chloride retention.