The potential application of TiO2/hydrogel nanocomposite for removal of various textile azo dyes

TiO2/hydrogel nanocomposite has been utilized for investigation of photocatalytic degradation of three different groups of anionic azo dyes in aqueous solutions under solar light simulating source in order to evaluate its potential application for treatment of textile wastewaters. Hydrogel based on chitosan, itaconic and methacrylic acid (monomers ratio Ch/IA/MAA = 1:1.56:10) was modified with synthetized 0.2 M colloidal TiO2 nanoparticles and 0.2 M commercial Degussa P-25. SEM/EDX measurements confirmed the presence of Ti in the hydrogel. TiO2 nanoparticles did not affect already formed covalent bonds within polymer network, nor did they affect its thermal stability. However, network morphology, mechanical properties and swelling behavior were changed in the presence of TiO2 nanoparticles. Under sun-like illumination, nanocomposite with immobilized colloidal TiO2 nanoparticles completely removed C.I. Acid Red 18, C.I. Acid Blue 113, C.I. Reactive Black 5 and C.I. Direct Blue 78, while removal degree of C.I. Reactive Yellow 17 was 55%. After four cycles of illumination removal rate of C.I. Acid Red 18 was 75%, indicating that prepared TiO2/hydrogel nanocomposites could be reused without significant loses of photocatalytic efficiency.