Biosorption of Heavy metals from Aqueous Solutions by Chlorophyta (Green Algae) isolated from rivers in Penang, Malaysia

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Date
2012
Authors
Wan Maznah Wan Omar
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Biosorption is an aptitude of certain types of biomass to bind and concentrate heavy metals from aqueous solutions. This study evaluated the potential of green algae Chlorella sp., Chlamydomonas sp. and Scenedesmus sp. to remove copper, cobalt, manganese, and zinc from aqueous solutions. Factors that affect metal uptake were pH, temperature, initial concentration of metals, light intensity, sorbent concentration, and contact time. The uptake of metal per unit mass of sorbent decreased with an increase in the concentration of the sorbent. Increasing the initial metal concentration in the solution resulted in a decrease in uptake per unit mass of sorbent. The kinetic of metal uptake by green algae were studied, showing that the sorption occurred mainly at the surface of the biosorbents. The kinetics of metal biosorption studies could be described by the Lagergren second-order kinetic model. Batch experiments showed that the biomass immobilized in the form of sodium alginate beads was able to remove copper, cobalt, manganese, and zinc from aqueous solutions. The beads had a higher metal biosorption capacity than unimmobilized biomass. Biosorbed metal could also be eluted from the beads with low concentration (0.1 M) of nitric acid and EDTA. Single, binary, and quaternary metal systems of eu, Co, Mn, and Zn were considered. In a mixture of metal, the adsorption of one metal was affected by the presence of the others. Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) and Calcein blue staining revealed that metal were sorbed mainly at the cell wall and only a small amount of ions diffused into cells.
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