Physicochemical interactions of spiculisporic acid based biosurfactant with metal ions and colloidal particles

Abstract

In this thesis, physicochemical interactions of a biosurfactant, sodium salt of tricarboxylic acid (DCMA-3Na), derived from spiculisporic acid with metal ion and colloidal particles were investigated. First, the precipitation phase boundary diagrams of DCMA-3Na and divalent metal ions, $Ca^{+2},\ Mg^{+2},\ Zn^{+2}$ and $Cu^{+2}$, and trivalent ion $Al^{+3}$ consisted of two branches which were surfactant precipitation equilibrium line with negative slope and micelle saturation equilibrium line with infinite slope, respectively, in all the cases considered here except the precipitation boundary diagrams for DCMA-Cu and DCMA-Al systems. Secondly, DCMA-metal precipitates were observed through optical microscope. The precipitates of a few m in size clumped together to form aggregates. Thirdly, using biosurfactant-based ultrafiltration, effects of metal species, the molar ratios of biosurfactant to metal ion and filtration time on the relative fluxes through ultrafiltration membrane, and rejection efficiencies for both the metal ions and biosurfactant were investigated. Finally, adsorption isotherms of DCMA-3Na on $TiO_2$, zeta potential, and changes of particle size as a function of biosurfactant concentration, solid-liquid ratio and pH were systematically investigated.