Synthesis of porous chitosan–polyaniline/ZnO hybrid composite and application for removal of reactive orange 16 dye

•This method is simple and time saving process compare to conventional method.•Addition of small zinc chloride increases porosity and dye adsorption.•Higher dye absorption with curve fitting of Langmuir and Freundlich isotherms. For the first time, chitosan–polyaniline/ZnO hybrids were prepared through a polymerization of aniline hydrochloride in the presence of ZnCl2 and chitosan. The hybrid materials were characterized by FT-IR, BET, SEM, UV–vis spectra and XRD analysis. From the BET and SEM micrographs, the introduction of ZnO nanoparticles into chitosan–polyaniline hybrid could obviously increase the porosity due to good possibility for dye adsorption. Adsorption experiments were carried out as a function of contact time, concentration of dye, adsorbent dosage and pH using reactive orange 16 as a model pollutant. The adsorption equilibrium data were fitted well to the Langmuir isotherm equation, with maximum adsorption capacity value was found to be 476.2mgg−1. Adsorption kinetics was best described by the pseudo-second-order model agreed well with the experimental data and good correlation (R2>0.999). Photocatalytic degradation of dye under UV irradiation at pH 5.8 has also been examined. FT-IR spectrum clearly indicates that before adsorption of hybrid showed the functional groups of chitosan and polyaniline, whereas the dye adsorbed hybrid only present the dye molecules and ZnO. Based on the results of present investigation, the introduction of ZnCl2 into chitosan–polyaniline hybrid will enhance the adsorption of reactive dyes and photocatalytic degradation.