Nickel, copper and zinc removal from waste water by a modified clay sorbent

The use of a sorbent produced by the chemical treatment of a locally available clay for the removal of some heavy metals from waste water has been investigated. The modification of the natural clay was performed by treatment with hydrochloric acid and subsequent neutralisation of the resultant solution by sodium hydroxide. The chemical and structural characteristics of the natural and modified clays were determined. The amount of iron, aluminium and magnesium compounds increased in the modified sorbent. Acidic treatment led to the decomposition of the montmorillonite structure. Sorption studies were carried out by both batch and column methods. The uptake capacity of the modified clay for nickel, copper and zinc did significantly increase. Batch and column sorption methods enabled the removal of nickel, copper and zinc ions till the permissible sewerage discharge concentration. The sorption process is reflected by Langmuir-type isotherm. The release of presorbed metals by water at pH 5 was negligible.