SORPTION OF COPPER(II) FROM AQUEOUS SOLUTION BY PEAT Y. S. HO and G. MCKAY ∗ Department of Chemical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong ( ∗ author for correspondence, e-mail: kemckayg@ust.hk) (Received 21 February 2003; accepted 5 April 2004) Abstract. The use of peat for removal of copper(II) from aqueous solution has been investigated at various initial copper ion concentrations and masses of peat. The equilibrium sorption study can be described by the Langmuir equation and defined in terms of the operating lines for each batch contacting system. The mechanisms of the rate of sorption of copper(II) were analysed using the Elovich equation and a pseudo-second-order model. Both rate mechanisms provided a very high degree of correlation of the experimental sorption rate data suggesting either model could be used in design applications. Keywords: copper, kinetics, peat, sorption 1. Introduction Since copper is an essential metal in a number of enzymes for all forms of life, problems arise when it is deficient or in excess. However, the carcinogenic character of copper is accepted and epidemiological evidence, such as the higher incidence of cancer among coppersmiths, suggests a primary carcinogenic role for copper (Luckey and Venugopal, 1977). In addition, copper is phytotoxic and, indeed, has been used as an algicide to control algal blooms. It can, therefore, cause plant damage if, for example, it is present at too high a concentration in sewage sludge that is applied to agricultural land. There are many routes by which metals can enter the air, water and soil as a result of man’s activities. A principal source of copper in industrial waste streams is metal cleaning and plating baths, and rinses, as brass, boiler pipe, cooking utensils, fertilizers, and from copper metal working, which requires periodic oxide removal by immersing the metal in strong acid baths. Solution adhering to the cleaned metal surface is rinsed from the metal and contaminates the waste rinse water. Similarly, plated metal parts are also rinsed and produce wastewater. For humans, copper is an essential element and the body can regulate its level haemostatically, although large, acute doses can have harmful, even fatal, effects. There is evidence to suggest that copper may be carcinogenic. In addition, copper can cause damage to a variety of aquatic fauna (fish and invertebrates). During the past 20 years, most research work on peat has been focused on metal and organic removal from industrial waste streams. Indeed, even earlier, Water, Air, and Soil Pollution 158: 77–97, 2004. C  2004 Kluwer Academic Publishers. Printed in the Netherlands.