METAL ION BINDING BY ALGAE AND HIGHER PLANT TISSUES: A Phenomenological Study of Solution pH Dependence

Several biomaterials derived from blue-green algae and cells and tissues from some higher plants were tested for their potential to remove metal ions from solutions at different pH. Most biomaterials displayed pH-dependent binding profiles for Cu(II), Al(III), and Au(III). However, fragments of cultured Datura cells showed pH-independent binding of Au(III) binding of over 97%. Other biomaterials also showed high affinity for Cu(II) and Au(III) at pH 5.0. These included freeze dried roots and stems of cattail plants (Typha latifolia), the leaves of tumble weeds (Salsola spp.). alfalfa sprouts (Medicago sativa), and sphagnum peat. Al(III) binding by most biomaterials was low. An exception to this observation was Al(III) binding to alfalfa sprouts. The highest binding capacities for copper were exhibited by sphagnum peat moss and alfalfa sprouts with 30 and 18 mg Cu/g biomaterial, respectively. The reduction of Au(III) to Au(O) by several of these biomaterials was observed.