Synergistic adsorption/photodegradation effect for effective removal of crystal violet dye and acetamiprid pesticide using Fe3+ cross-linked ternary carboxymethyl cellulose/polyaniline/TiO2 photocomposites

Abstract

In this paper, a new series of cross-linked carboxymethyl cellulose (CMC) based photocomposite hydrogels incorporating polyaniline (PANI) as semi-interpenetrating chains and titanium oxide (TiO2) as inorganic filler were prepared to effectively remove crystal violet (CV) and acetamiprid pollutants (AC) by adsorption/photodegradation under solar light. The structural, textural, thermal and optical properties of these hydrogels were analyzed using; Fourier-transform infrared spectroscopy (FTIR), X-Ray diffraction analysis (XRD), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and UV–visible diffuse reflectance spectra. The performance of CMC-based hydrogels for CV adsorption was evaluated through batch experiments using multi-variable parameters reactor. The results revealed that the adsorption kinetics was consistent with the pseudo-second order model (with values of R2 > 0.99) and the adsorption isotherm followed the Langmuir model (R2 > 0.99 and a maximum Langmuir adsorption capacity of 159.08 mg g−1 obtained for the optimized hydrogel CP5). Meanwhile, it was observed that a better photocatalytic activity was generated by combination of TiO2-PANI systems with an almost complete removal (99 %) of dye molecules in 80 min of irradiation duration, suggesting a synergy between these two systems. Separately, the AC degradation study revealed good catalytic activity of hydrogels against this pollutant from both demineralised and real water. Lastly, the regeneration study of photocomposite beads revealed a good stability of these hydrogels in water by retaining their photoactivity over five cycles of reuse.