Photo-assisted sondegradation of hydrogels in the presence of TiO2 nanoparticles

Author(s): Rajabali Ebrahimi, Hossein Ghasemzadeh Mohammadi

The degradation of one of the commercially important hydrogel based on acrylic acid and acryl amide, (acrylic acid-co-acryl amide) hydrogels, by means of ultrasound irradiation and its combination with heterogeneous (TiO2) was investigated. 24 kHz of ultrasound irradiation was provided by a sonicator, while an ultraviolet source of 16Wwas used for UVirradiation. The extent of sonolytic degradation increased with increasing ultrasound power (in the range 30–80 W). TiO2 sonophotocatalysis led to complete (acrylic acid-co-acryl amide) hydrogels degradation with increasing catalyst loading, while, the presence of TiO2 in the dark generally had little effect on degradation. Therefore, emphasis was totally on the sonolytic and sonophotocatalytic degradation of hydrogels and a synergy effect was calculated for combined degradation procedures (Ultrasound and Ultraviolet) in the presence of TiO2 nanoparticles. TiO2 sonophotocatalysis was always faster than the respective individual processes due to the enhanced formation of reactive radicals as well as the possible ultrasoundinduced increase of the active surface area of the catalyst.Akineticsmodel based on viscosity data was used for estimation of degradation rate constants at different conditions and a negative order for the dependence of the reaction rate on totalmolar concentration of (acrylic acid-co-acryl amide) hydrogels solution within the degradation process was suggested.

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