Influence of Different Degradation Techniques on the Molecular Weight Distribution of κ -Carrageenan

Carrageenan as an abundant natural carbohydrate could be used as a representative material instead of synthetic polymers. In this work, the degradation of κ-Carrageenan by means of ultrasound irradiation at a frequency of 24 kHz and its combination with heterogeneous Titanium dioxide, followed by a photocatalytic process was investigated. The scission of carrageenan chains induced by a high intensity field of ultrasonic irradiation; result in various molecular weights of carrageenan. The low molecular weight species of carrageenan have biological and pharmaceutical uses that only should be obtained from the degradation method. The ultrasound power not only led to enhanced turbulence and liquid streaming, but also increased the active surface area. Therefore, TiO2 sonophotocatalysis was carried out faster than sonolysis and sonocatalysis processes. The influence of the basic operational parameters such as, ultrasound power and amount of TiO2 on the degradation rate of carrageenan was also studied. The results revealed that the extent of sonolytic degradation was increased with increasing of ultrasound power (in the range 30-80 W) and at higher catalyst concentration, the degradation rate in the solution soared. The degraded carrageenans were characterized by gel permeation chromatography (GPC).