Relationship between the structure of chitosan-based flocculants and their performances in the treatment of model azo dyeing wastewater

Chitosan-based flocculants are efficient and biodegradable, possessing the potential application in water treatment . A chitosan-based flocculant, CTS-g-PAM, was prepared via grafting copolymerization . Two main structures of CTS-g-PAM were detected by X-ray photoelectron spectroscopy (XPS), and they related to the different performances of CTS-g-PAM in the treatment of model azo dyeing wastewater in terms of removal efficiency, floc size and zeta potential . CTS-g-PAM with the optimal ratio of C N to –NH– owned the best performance. C N reinforced the interaction between CTS-g-PAM and azo dyes and charge neutralization while the flocs formed in the case were large and compacted. However, excessive C N accelerated itself hydrolysis and leaded to the decomposition of CTS-g-PAM, deteriorating the performance of the flocculant.