Pyromellitic Dianhydride-Modified Chitosan Microspheres for Enhancement of Cationic Dyes Adsorption

Pyromellitic dianhydride (PMDA) grafted chitosan microspheres (PMDA-GLA-CTS) were prepared, and characterized by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). Due to the presence of a large number of carboxyl groups, the adsorption capacity of the PMDA-GLA-CTS for methylene blue (MB) and neutral red (NR) showed a significant increase compared with the unmodified microspheres. The maximum adsorption capacities were 935 and 909 mg g(-1) for MB and NR, respectively, according to the Langmuir equation. Kinetics studies showed that the sorption rate was controlled by the chemisorption process. Sample analysis showed that the adsorbent can effectively remove the cationic dyes in printing and dyeing wastewater.