Adsorption of C.I. Reactive Blue 19 from aqueous solutions by porous particles of the grafted chitosan

• Chitosan was modified by graft copolymerization with Poly(methyl methacrylate).
• The grafted chitosan remains the C2-NH2 groups and is almost amorphous.
• Porous particles of the grafted chitosan were prepared.
• They have strong affinities for the C.I. Reactive Blue 19 dissolved in water.
• The adsorption process is pH controlled.

Chitosan (CTS) was modified by graft copolymerization with Poly(methyl methacrylate) on the premise that its C2-NH2 groups were remained. Porous particles of the grafted CTS were prepared by emulsification together with wet phase inversion and evaluated as a new adsorbent for decolorizing the C.I. Reactive Blue 19 solutions. The chemical composition, thermal stability and amorphous structure of the grafted CTS were demonstrated by FT-IR, TGA and WXRD characterizations. Porous particles of the grafted CTS were observed in SEM images. For the given adsorbent/dye system, the data from equilibrium sorption experiments are well fitted to the Langmuir isotherm. The maximum dye uptake (1498 mg/g) is attained at 30 °C and pH 3. Besides, the pseudo-second-order sorption kinetics indicates that chemisorption controls the process. The dominant role for adsorption mechanism is electrostatic attraction. When the initial pH of dye solution is above 3, higher pH induces higher and faster dye uptake.

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