Silver Removal from Aqueous Solution by Adsorption on Concrete Particles

The major industrial use of silver is as silver halide in the manufacture of photographic film. In 1983, approximately 44% of silver was used in the manufacturing of chemicals for photographic products in the USA. Other industrial uses of silver include the production of electrical contacts and switching gear, batteries, catalysts and mirrors. It has also been used for jewelry, coins and indelible inks. These industries emit discharges, which not only contribute to water deterioration but also adversely affect the aquatic ecosystem. Sorption is considered the dominant process in silver partitioning in water and its mobility in soils and sediments. Silver accumulations in marine algae have been reported mainly because of adsorption rather than uptake. Free silver ion is hazardous to representative species of sensitive aquatic plants and invertebrates. In humans, serious toxic effects have resulted only from overdoses of medicines containing silver. However, skin contact with silver compounds can cause allergic reactions such as rashes, burning and swelling. Very little is known about the chemical interactions between silver and concrete in the aqueous system. Published data concerning the interaction of silver with soil are rare. However, silver is very ∗Contribution from the Department of Civil and Environment engineering, University of Delaware, Newark, DE 19716, USA.