Figure 2.

Adsorption isotherms for HA on chitosan, DEAE-cellulose, chitin and activated charcoal at 37 °C. A fixed amount (0.1 g) of DEAE-cellulose, activated charcoal, chitin, and chitosan was added to 50 mL of HA (40 µg/mL) in 0.1 M HCl. After the incubation at 37 °C for 2 h, the reaction was stopped by 0.2 M Na₂HPO₄. After the centrifugation, the mixture supernatants were measured the concentration of remaining humic acid by spectrophotometer at 230 nm. The adsorption isotherms, q_e as the amount of HA adsorbed per gram of adsorbent and C_e as the concentration of HA remaining in the solution, were calculated and the representative results were shown (N = 3).