• biosorption;
  • methylene blue;
  • chitosan;
  • modification

The purpose of the research was to investigate effects of temperature, initial pH, initial concentration, and contact time on the biosorption of methylene blue (MB) by modified chitosan using a batch technique. The modified chitosan was prepared by grafting poly (amic acid), which was obtained via reaction of pyromellitic dianhydride (PMDA) and l-arginine, onto the surface of cross-linked chitosan. The MB sorption process was evaluated at 25, 35, and 45°C. Results showed that the modified chitosan had a good capacity for biosorption of MB. The kinetic behavior was described by pseudo-second-order model. The experimental isotherms obtained were fitted better with Langmuir model than Freundlich model. According to the Langmuir equation, the maximum uptake capacity (qm) for MB was 392.16 mg g−1. Thermodynamic parameters inline imageand inline imagewere calculated using the Van't Hoff equation, and results showed that MB sorption by modified chitosan was an exothermic and spontaneous process. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1180–1186, 2014