Cross linked Sago Starch Phosphate as a Bioadsorbent for the Heavy Metal Pb(II)

Abstract

A cross linked sago starch phosphate (SgP) was successfully synthesized from sago starch (Sg) and a mixture of Na₂HPO₄-NaH₂PO₄ in an acidic solution. The synthesized SgP was then used as a bioadsorbent of Pb(II) in an in vitro simulation of the human digestion system. The optimized synthesis condition was reached at an acidic pH 6, at a temperature of 30° C, with a reaction time of 10 minutes, and a mixing rate of 100 rpm. Analysis of Sg and SgP using XRD did not show major differences. An absorption band with a wave number of 2345 cm-1 was observed on the IR spectra of SgP and is a characteristic of a phosphate diester bonding (RO-PO3-R’), indicating a successful cross-linking process. It was found that the adsorption of Pb(II) by SgP follows the second order kinetics and Langmuir equation with adsorption capacity of 23.67 mg/g. It was also found that SgP is resistant to digestive enzymes and changes in pH and temperature, making it suitable for use as a bioadsorbent of Pb(II) under varied conditions.