Depolymerization of carboxymethyl cellulose using hydrodynamic cavitation combined with ultraviolet irradiation and potassium persulfate.

In the present work, hydrodynamic cavitation (HC) has been used for the depolymerization of sodium salt of carboxymethyl cellulose (CMC) solution. Use of two different cavitating devices as slit and circular venturi has been investigated along with the combination of HC with potassium persulfate (KPS) and ultraviolet (UV) irradiation for understanding the process intensification benefits. The effect of operating parameters as inlet pressure (HC) and power dissipation (UV based treatment) on the degree of polymerization has been studied initially. The combined approaches of HC + UV, HC + KPS and HC + UV + KPS have been then investigated under optimized conditions of pressure and power dissipation. Depolymerization was favored in the case of slit venturi in HC and at higher power dissipation for UV based approach as well as at higher KPS loading for the combined approach of HC + KPS. For the combined approach of HC + UV + KPS, maximum viscosity reduction obtained was 75% under the optimized conditions (slit venturi, 3 bar as the pressure, 8 W as UV power and KPS loading of 0.4 g/L) in 180 min of treatment. The chemical structure of the native CMC and processed CMC using all approaches was analyzed using FTIR spectra and it was clearly established that any significant changes in the chemical structure are not observed.