Leachate composition of lead and cadmium ions from solidified mortar mixed with Nanosilica

Abstract

Soils contaminated with Cd and Pb ions are a great problem that affects human health and the environment. Intending to decrease the environmental risk. Solidification/ stabilization (S/S) is one of the commonly used and economic remediation technologies to treat contamination by heavy metals in soils compared with other remediation technology. To understand the leaching mechanism from the (S/S) process, the EPA Semi-dynamic Tank Leaching method 1315 and unconfined compressive strength test was carried out to test the effectiveness and performance of the solidification process of contaminated sands with Pb and Cd ions by using ordinary Portland Cement locally produced and nanomaterial. Tow mix designs were performed on the contaminated sands at three different pollution concentrations and three ratios of synthesized Nanosilica from rice husk as additive replacement of cement. The Nanosilica as-prepared has amorphas form, average diameter equal to 52.83 nm and surface area around 618 m2/g. This paper discusses the effects of Nanosilica on leaching contamination from solidifying samples and compressive strength. The leaching rate of lead and cadmium ions from the test specimens demonstrated the effectiveness of nanoparticles in reducing the release of contaminant. Diffusion studies from the S/S matrixes indicated low and very low mobility of lead and cadmium ions respectively. For all test specimens, the mean leachability index was found to be higher than 9.