2-Hydroxy-1, 4-napthoquinone solubilization, thermodynamics and adsorption kinetics with surfactant

Abstract

• Lawsone-surfactant interactions established for the first time. • Lawsone deposited on the surface of glass with silver ions, CTAB in alkaline media. • Dye adsorption kinetics discussed with various adsorptions kinetic models. • Our findings would be helpful to enhance color fastness of dye in textile processes. 2-Hydroxy-1, 4-napthoquinone (lawsone) natural red–orange dye was extracted from fresh henna (Lawsonia inermis) leaves in an alkaline media. The lawsone-surfactant solubilization constants ( K LS ) were calculated for the first time by using cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium dodecyl sulphate (SDS). The standard free energy, concentration of solubilized lawsone and number of lawsone molecules solubilized into micelles were calculated and discussed. Surface excess, minimum surface area per molecule, surface pressure, free energy (adsorption and aggregation) and equilibrium constants of different states were determined from tensiometry. Different metal ions (Ag + , Co 2+ , Cu 2+ , Ni 2+ , Fe 3+ , Zn 2+ and Al 3+ ) were used to determine the complex forming ability with lawsone. Out of these, Ag + ions have strong binding capacity with lawsone. The adsorption of lawsone on the surface of glass with silver ions in presence of CTAB was also observed at pH ≥ 9.0. The pseudo-first, second-order kinetic equation, intraparticles diffusion and Elovich models were used to determine the kinetics of lawsone adsorption onto the surface of glass and a probable mechanism has been discussed. Lawsone adsorption followed second-order kinetic equation ( k 2 = 0.019 g·mg −1 ·min −1 ).