Comparison Between Washed and Unwashed Ninivite on the Removal Efficiency of Mercury from Aqueous Solutions

Ninivite is a silica rich rock, which has a very high surface area, that may exceed (800g/m2). Low grad ninivite is characterized by high absorption, adsorption ability and may act as an ion exchange to remove heavy metals. Efforts of applications under study are in the field of waste water treatment. Washing operation of ninivite with distilled water to reduce impurities; such as gypsum; and increasing silica ratio rendered it to be inefficient to removing mercury from its effluents. In the mean time the adsorptive materials such as alum and iron sulfate, are also washed out. It was found that the unwashed, raw, low grade, ninivite was outweighing washed one, using different concentrations of mercury(0-200mg/L) and at different pH values (1.6, 7.4, 9.5, and 10.6). Optimum removal efficiency of mercury concentrations of 75mg/L and 175 mg/L were at a pH of 9.5 and7.5 respectively.