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Sand filters are used as a filter bed in many ground water treatment plants to remove the physical contaminants and oxidation products. A build-up of radioactivity may take place on the granules, where iron and manganese oxides are deposited and form thin films on the surface of sand filter. The oxides of iron and manganese play an important role in adsorbing radium from ground water. The disposal of those granules makes a significant problem. A batch technique is used for solubilization of radium from sand filters in the presence of some organic acids, which act as reducing agents. These acids are formic acid, acetic acid, benzoic acid, succinic acid, oxalic acid, phthalic acid, and adipic acid. The data were obtained as a function of acidity, temperature, contact time and liquid/solid ratio particle size and shaking speed. It was found that oxalic acid was the best for radium removal. The effectiveness of these acids on radium removal was as follows: oxalic acid > phthalic acid > adipic acid > succinic acid > formic acid > acetic acid. The maximum removal obtained was 69.9% at 1M oxalic acid at 8 ml/g ratio. Reaction kinetics and mechanism parameters of the dissolution process were studied and compared with other published data. [ABSTRACT FROM AUTHOR]

Sand filters are used in water treatment stations to remove particulate matter from underground water, where iron and manganese are collected forming thin oxide films. These oxides of iron and manganese adsorb radium from underground water. Radium concentration increases in time on the filters, and consequently the level of radioactivity increases in the station. The removal of adsorbed radium on sand using inorganic acids was studied. Good efficiency of radium removal was obtained by controlling different parameters like temperature, time, pH, addition of competitive cations and anions. It was found that hydrochloric acid is the best for radium removal from sand filters. Maximum removal obtained was about 60% at 5M BaCl2 and 2M HCl at 50 °C for 180-minute contact time. Kinetic parameters of the removal process were studied and compared with literature data. [ABSTRACT FROM AUTHOR]