Abstract:

The copper adsorption capacities of the manganese nodule powder were 13mg Cu/g at solution pH 1.5, 40mg Cu/g at pH 4.5, and 45mg Culg at pH 5.5, respectively. The adsorption of copper ions was found to be an endothermic process and increased with temperature between 20 and 80°C from 39.9mg Cu/g to 48.7mg Cu/g. The adsorption of copper on the nodule powder increased with the decreasing particle size and was not influenced by the addition of sodium ions and different kinds of anions. The amount of copper adsorbed on the nodule powder descreased with the increasing heat treatment temperature of the nodule powder.(Without heat treatment: 40mg Cu/g, with heat treatment at 500°C: 22.8mg Cu/g).

Introduction

Manganese nodules are comprised mainly of oxides of manganese and iron containing minor metals such as copper, nickel and cobalt (Fuerstenau and Han, 1983). It is mainly because of these valuable metal elements that nodules have attracted attention in recent years as a potential mineral resource. The major phases in these nodules have been identified as todorokite and goethite (Fuerstenau, Herring and Hoover, 1973). Other metals are not present as separate minerals, but are associated with mangnaese and iron containing minerals. The most remarkable physical characteristics of manganese nodules are their high porosity and specific surface area. Nodules are filled with extremely fine pores of the order of 100 Adiameter which results in porosites of near 60% by volume and surface areas of about 200 m2/g (Han, 1976, Agarwal, 1976). It has been also reported that manganese is present in nodules as &-Mn02 which has excellent adsorption capacity for heavy metal ions(Murray, 1967). These properties of manganese nodules has led to consideration of their use as an adsorbent, but only a few works on this field have been reported till now (Nishiyama, 1984).

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