EVALUATION OF TREATMENT TECHNIQUES FOR INCREASING THE UPTAKE OF METAL-IONS FROM SOLUTION BY NONLIVING SEAWEED ALGAL BIOMASS

The effects of several different treatments on subsequent uptake of se veral metal ions from solution by six strains of seaweed algae and a s ea plant were investigated. Samples of Gracilaria conferta, Eisenia bi cyclis, Ulva lactuca, Sargassum fluitans, Cladophora prolitera, Padina pavonica, and Zostera marina were treated with one or more of the fol lowing: 1 M HCl, 1 M HNO3, 0.1 M NaOH, 1 M NaOH, acetone, and 60-degre es-C water at times from 15 to 60 min and temperatures of 25 and 60-de grees-C. Results obtained demonstrate that a treatment time of 15 or 3 0 min is usually sufficient to produce maximum subsequent metal uptake . Temperature of treatment had little effect. The percentages of Pb, C u, Zn, Cd, Cr, Mn, Ni, Co, TI, Hg, Au, and Ag subsequently removed fro m standard metal solutions at a pH of 2-6 by each treated biomass were compared with the percent removal by untreated biomass under the same conditions. All treatments increased the ability of the biomass types studied to bind metals relative to untreated biomass. In addition, pH binding dependence was altered to some extent with a greater degree o f binding observed at low pHs by biomass treated with acid. For certai n strains of seaweed algae, 0.1 M NaOH treatment produced subsequent u ptake of Pb, Cu, Zn, and Cd at levels reaching 100% of initial metal a vailable. Both acidic and basic treatment increased the uptake of Au, Ag, and Hg by four strains of seaweed to nearly 100%.