This was the preliminary finding of researchers of the Los Baños-based Department of Science and Technology-Forest Products and Development Institute (FPRDI).
The laboratory-scale study was the first to be conducted at FPRDI on the barks of local tree species for such application, researcher Jennifer Tamayo reported.
Tamayo found that the barks of five tree species–acacia or raintree (Samanea saman), kamachile (Pithecellobium dulce), yemane (Gmelina arborea), gubas (Endospermum peltatum), and river red gum (Eucalyptus camaldulensis)–successfully removed metal ions from solutions of lead (Pb) with 92-100 percent efficiency; copper (Cu), 60-92 percent; chromium (Cr), 17-52 percent; and zinc (Zn), 2-6 percent.
Also, the results were comparable with those of the commercial carboxyl type synthetic resin, with 100 percent removal of lead, 92 percent of copper, 56 percent of chromium, and seven percent of zinc.
In the study, the barks were treated with formaldehyde to prevent leaching of color.
The treatment did not diminish their capacity to remove heavy metal ions from the solutions.
Yemane, raintree, and kamachile barks need formaldehyde treatment to scavenge the four metal ions. However, river red gum and gubas barks can be used without treatment. – Rudy A. Fernandez