A novel approach on leaching study for removal of toxic elements from thermal power plant-based fly ash using natural bio-surfactant

The plant extract like Saponin obtained by both chemical and aqueous methods from the fruits of Sapindus laurifolia (S. laurifolia) was adopted as an economical low cost leaching agent for removal of toxic elements from thermal power plant-based coal fly ash (FA). The leaching investigation the elements including Cr, As, Ni, Pb, Zn and Cu from FA particles was systematically carried out and reported. The role of the critical factors such as saponin concentration, time, temperature, and pH of lixiviant was examined. The leaching results of sapoin isolated by aqueous extraction and chemical extraction were compared and reported. The change in FA phase like the appearance of surface roughness from the regular phases of the FA after leaching obtained by SEM analysis was well ascribed due to the leaching of metals out of FA. The interaction mechanism due to the adopted saponin with the FA surface phase during the leaching of these metals based on the hydrophobic and hydrophilic character was derived and proposed based on the leaching results.