Microalgae are well known to be an effective biosorbent for removal of heavy metals in aqueous solutions because of its high adsorption capacity. However, improved knowledge is still needed on the sorption property of algal biomass with regard to cell surface characteristics. The objective of this study is to enhance the performance of Chlorella vulgaris on removal of heavy metals in aqueous solutions by modifying the cell surface by addition of nutrient sources to growth medium and by chemically pretreatment of the biomass. Live and dead C. vulgaris was purchased from Korean Collection for Type Cultures and Jarrow Formulas(USA), respectively. Live C. vulgaris was cultured in BG-11 medium with the addition of one of four nutrient sources - glucose, ammonium sulfate, ammonium phosphate, and cysteine. Dead C. vulgaris was pretreated using NaOH, HCl, CaCl2, or Na2CO3. Heavy metal solutions containing Cu, Pb, Zn, Ni, or Cd at a concentration of 1 mM were prepared. Each algal biomass was harvested, dried, ground, and sieved with 250 μm mesh after cultivation or pretreatment and was added at a dose of 1 g/L to the heavy metals solutions. After agitating the solution for 2 h, heavy metals in the solutions were analyzed. The adsorption capacities of the live biomass were significantly increased by the addition of ammonium phosphate for all targeted heavy metals, showing factors of 1.79-4.00 higher adsorption capacities in comparison with the biomass grown without any additional nutrient supply. Pretreatment of dead biomass showed significantly different adsorption capacities for each heavy metals, showing factors of 1.77-3.77 higher with an optimum pretreatment method. The results show that the removal of targeted heavy metals can be substantially enhanced by adding nutrient source or chemical pretreatments. Studies are underway to further investigate the distribution of functional groups on the surface of the biomass.

Enhancement of heavy metal sorption to Chlorella vulgaris by modification of growth medium and chemical pretreatment

256th National Meeting (2018)

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