Synthesis of poly-amidoxime resin from grafted millet husk cellulose for adsorption of Congo red

Abstract

Poly-amidoxime ligand was synthesized from grafted millet husk for adsorption of Congo red dye from aqueous solution; the grafting process was carried out using Acrylonitrile and Ceric ammonium nitrate as an initiator. The functional group, thermal degradation and morphology of the adsorbent was investigated by Fourier transform infrared (FT-IR), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM) respectively. The Initial concentration, adsorbent dosage and contact time were taken as independent variables. The adsorption process was optimized by central composite design (CCD) in Response surface methodology (RSM). The FT-IR results showed that grafting was successful due to the presences of 2244 cm^-1 for cyno group (CN) and also band at 1640 cm-1 and 1380 cm^-1 that replaced 2244 cm^-1 which successful confirmed the synthesis of poly(amidoxime) functional group. The TGA showed two stages of thermal degradation. About 12 % weight loss observed in amidoxime at 240 ⁰C which is due degradation of amidoxime functional group then it reduces to 2 % in second stage at 530 ⁰C which revealed the improved thermal stability of the material. The predicted value is in good agreement with experimental value and also the ANOVA result showed that all the independent variables have significant impact with the adsorbent. The optimum condition achieved in the experiment was at initial concentration of 60mg/L, adsorbent dosage of 0.3g and contact time of 45 min with percentage removal of 95.9 % predictably and 94.89 % experimentally. Finally, it can be concluded that, poly-amidoxime ligand can be efficiently used in treatment of waste water contaminated with dyes.