Synthesis and characterization of chitosan/polyacrylamide hydrogel grafted poly(N-methylaniline) for methyl red removal.

Chitosan/polyacrylamide hydrogel grafted poly(N-methylaniline) (CS/PACM-gr-PNMA) was good synthesized by chemical oxidative radical polymerization using potassium persulphate (KPS). The obtained polymer samples are characterized using IR and Uv-visible spectroscopy. Both surface properties and thermal stability were studied using XRD, SEM, BET and TGA techniques respectively. The characterized polymeric samples were used as a new sorbent for methyl red (MR). MR as an example of azo-dyes presence as pollutants in industrial wastewater which cause physiological damages was chosen to uptake. The influence of contact time, adsorbent dose, and temperature on the efficiency of CS/PACM-gr-PNMA towards the removal of MR was investigated. The efficacy was equal to 98% through 120 min at room temperature. The obtained data show that, ∆H = -21.478 kJ mol-1, so adsorption process is physically spontaneous and follow Freundlich isotherm. The sorption process of MR on the surface of CS/PACM-gr-PNMA is proceed via the Lagergren pseudo-second order reaction. This confirms the removal mechanism by both chemical and physical adsorption of MR with both unpaired and π electrons present in polymer structure on NH, NH2, and benzene or quinoid units respectively. In addition, it can explain the chemical adsorption type which occurs through sharing between the used adsorbent materials and the dissolved materials beside the physical adsorption.