Synthesis and characterization of quaternized Cassia tora gum using Taguchi L'16 approach

Galactomannans are branched natural biopolymers possessing good biocompatibility, biodegradability and sustainability leading to diverse industrial applications. In the present study, quaternization of galactomannan derived from Cassia tora gum was investigated by adopting Taguchi's approach of robust design of experiments using 3-chloro-2-hydroxypropyltrimethylammonium chloride under alkaline heterogeneous conditions. The effect of reaction time, temperature, amount of NaOH and CHPTAC on DS of the derivatised products were investigated using Taguchi L₁₆ (4⁵) orthogonal array. The optimised conditions for preparation of the quaternized galactomannan with DS 0.114 were: reaction temperature 30 °C, reaction time 2 h, amount of sodium hydroxide, 0.0125 mol, amount of CHPTAC, 0.00319 mol and Gum-liquor ratio 1:15. The study demonstrated that Taguchi's approach is statistically sound for optimization of reaction conditions to achieve quaternization of Cassia tora gum. The structure of quaternised derivatives was characterized by FTIR, ¹H NMR spectroscopy, FESEM, X-ray powder diffraction (XRD) and thermal analysis.