A comparative study on silica sands as absorbents for the removal of hexavalent chromium ions from aqueous solutions

摘要

Silica sand is the main material in glass production. It can also be used for water purification. In this work, two types of silica sand used for the glass production were directly applied in the removal of Cr~(6+) from aqueous solutions. The chemical composition, loss-on-ignition, acid solubility and surface area of the two sands are compared. The results indicate that both sands are quite similar in chemical and mineral compositions. However, sand B has a higher organic content, a smaller crystalline grain size, a larger surface area and acid solubility. As a result, sand B shows a larger absorption of Cr~(6+) than sand A. In addition, both sands exhibit declined absorption of Cr~(6+) with increasing the pH of the solution from 1 to 3. No absorption Occurred when the pH was higher than 3.