Depolymerization of guar gum solution using different approaches based on ultrasound and microwave irradiations

• Intrinsic viscosity reduction of guar gum solutions using irradiations.
• Novel use of sequential combination based on ultrasound and microwave for polymers.
• Role of temperature and initiator (KPS) has been established.
• Comparison of different approaches in terms of kinetic parameters.
• Ultrasound in combination with KPS is the best treatment approach.

The present work investigates the application of ultrasound and microwave operated individually or in combination for depolymerization of aqueous solution of guar gum. In addition, intensification aspects due to the use of an initiator, potassium persulfate (KPS), has been investigated. The extent of depolymerization has been analyzed in terms of the reduction in intrinsic viscosity. Also, the effectiveness of treatment approach has been analyzed on the basis of kinetic rate constant, limiting intrinsic viscosity and the time required for the desired extent of viscosity reduction. The kinetic rate constant has been found to increase with an increase in the temperature and KPS loading. For the individual operation involving irradiations, the rate was found to be higher in the case of ultrasound as compared to the microwave irradiations. In the case of sequential approach, microwave followed by ultrasound was more effective as compared to the approach of ultrasound followed by microwave. The obtained results clearly established that ultrasound in combination with KPS was the most effective approach for depolymerization. The work has also enabled to understand the effective role of KPS and operating temperature in intensifying the viscosity reduction of guar gum polysaccharides.