Neutral Red Adsorption onto Modified Chitosan: Effect of pH and Temperature

The purpose of the research was to investigate the effects of temperature, initial pH, initial concentration, and contact time on the biosorption of neutral red (NR) 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 NR sorption process was evaluated at 25 degrees C, 35 degrees C, and 45 degrees C. Results showed that the modified chitosan had a good capacity for biosorption of NR. The kinetic behavior was described by the pseudo-second-order model. The experimental isotherms obtained were fit better with the Langmuir model than with the Freundlich model. Thermodynamic parameters triangle H degrees and triangle S degrees were calculated using the Van't Hoff equation, and the results showed that NR sorption by modified chitosan was an endothermic and spontaneous process.