Effect of Hg2+ on the microphysical and chemical properties of oil-producing Nannochloropsis sp.

Abstract

The influence of the adsorption of heavy metal Hg2+ on the microphysical and chemical properties of microalgal cells and the content and composition of oil were analysed in this paper. Experimental studies showed that the microalgal cells that adsorbed heavy metals showed grooves and folds on the surface of the cell wall and had 5.8 times increase in specific surface area, 59.09% decrease in pore area in the cell wall, 33.9 times increase in the outer surface area of the cell wall, 52.81% reduction in the average pore size of the cell wall surface and greatly reduced pore volume. The –OH, phenolic carboxylic acid, COO–, amide and phosphorus-containing functional groups on the surface of the cell wall are involved in varying degrees in the Hg adsorption of Nannochloropsis sp. cells. The cell oil content of microalgae enriched with heavy metals increased slightly, because heavy metals inhibited the accumulation of phospho-oils in cells and induced the accumulation of oils. The research showed that the adsorption of Hg2+ influence the microscopic morphology of Nannochloropsis sp. cells. And microalgae can be used to adsorb heavy metals, such as Hg2+, for sewage treatment as an additional commercial value in the process of bioenergy production.