Synthesis of quaternised guar gum using Taguchi L₍₁₆₎ orthogonal array

Area of Science:

• Polymer Chemistry
• Biopolymer Modification
• Green Chemistry

Background:

• Quaternized polysaccharides offer diverse applications due to the incorporation of quaternary ammonium groups.
• Modifying biopolymers like guar gum enhances their functional properties for various uses.

Purpose of the Study:

• To optimize the quaternization of guar gum using Taguchi's robust design of experiments.
• To achieve a higher degree of substitution (DS) in quaternized guar gum efficiently.
• To establish a statistically sound and environmentally friendly method for reaction optimization.

Main Methods:

• Utilized Taguchi's L16 (4^5) orthogonal array for experimental design.
• Optimized reaction parameters including NaOH and CHPTAC concentrations, reaction time, temperature, and gum:liquor ratio.
• Characterized the modified product using FTIR, 1H-NMR, 13C-NMR, DEPT-135, HSQC, and HMBC spectroscopy.

Main Results:

• Achieved a degree of substitution (DS) of 0.49 under optimized conditions.
• Identified optimal levels: 3.24 mol/AGU NaOH, 2.04 mol/AGU CHPTAC, 2 h reaction time, 30 °C, and a 1:20 gum:liquor ratio.
• Demonstrated Taguchi methodology's efficiency, requiring fewer experiments than classical methods.

Conclusions:

• Taguchi's approach provides a statistically robust and green methodology for optimizing polysaccharide quaternization.
• The optimized conditions yield quaternized guar gum with a significantly improved DS.
• Spectroscopic characterization confirmed the successful modification of guar gum.