Nanosilica was extracted from rice husk, which was locally collected from the Iraqi mill at Al-Mishikhab district in Najaf Governorate, Iraq. The precipitation method was used to prepared Nanosilica powder from rice husk ash, after treating it thermally at 700°C, followed by dissolving the silica in the alkaline solution and getting a sodium silicate solution. Two samples of the final solution were collected to study the effect of filtration on the purity of the sample by X-ray fluorescence spectrometry (XRF). The result shows that the filtered samples have purity above 98%, while the non-filtered sample purity was around 96 %. The structure analysis investigated by the X-ray diffraction (XRD), found that the Nanosilica powder has an amorphous structure in nature. Also, it shows a broad peak at (2θ = 22.25°-22.55°). The particle size distribution was determined by Atomic force microscope (AFM), the results gave that the average diameter equals 52.83 nm and dimension range in 30-75 nm, while B.E.T. analysis confirms a high surface area around 618 m 2 /g. FT-IR Spectra experimental data showed the presence of hydrogen-bonded silanol group (Si-O-H) and siloxane group (Si-O-Si) which proved the high purity of Nanosilica particles.

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.