Role of Biosurfactants in Heavy Metal Removal and Mineral Flotation

Surfactants are chemical compounds produced from petroleum feedstock, agro-based waste materials and microbial fermentation having wide variety of use in industries, pharmaceutical, agriculture, cosmetics, etc. These are amphiphilic moieties and chemically synthesised. These chemical compounds are toxic and are responsible for various harmful environmental problems. Recently, biosurfactants have gained lots of interest worldwide, because they are green-alternatives for surfactants. Biosurfactants are produced naturally from microorganisms like yeast, fungi and bacteria. These have both hydrophobic and hydrophilic groups which makes its unique and important in different industries. These organisms produce surface active metabolites or secondary metabolites and grow on water immiscible or oily surface. The surface active molecules help them to absorb, emulsify, wetting, solubilise and disperse the water immiscible substances. Biosurfactants are in demand and commercially promising due to their properties, i.e., low toxicity, higher biodegradability, environmental compatibility, foaming properties, shows stable activity at extreme pH, temperature and salinity, etc. Biosurfactants play very crucial role in mineral flotation. Heavy metal removal and mineral flotation is a very crucial process for industries (which commercially separates metals from ores by collecting them on the surface/froth layer—so the metals can be used commercially) and also for the environment. Biosurfactant mediated mineral floatation and heavy metal removal involves the metal ion sorption to sorbent material followed by floatation and floatation product collection. Using biosurfactants in replacement of surfactants for heavy metal removal and mineral floatation are actually effective, low cost, recyclable, reusable and environmental friendly. This chapter emphasises on removal of some metals from their respective ores using different biosurfactants. A probable mechanism of flotation by biosurfactant is also discussed.