Influence of polymer structural parameters and experimental conditions on metal anion sorption by chitosan

Chitosan is effective at removing molybdate from acidic solutions, especial ly when it is stabilized by crosslinking treatment. The influence of struct ural and physicochemical properties of chitosan and the glutaraldehyde cros slinking step on molybdate has been studied. This study shows that the maxi mum sorption capacity mainly depends on the crystallinity and degree of dea cetylation. Hydration and accessibility to internal sites are controlled by these parameters, which may explain the intraparticle diffusion control on mass transfer. Chitosan gel beads can be used instead of flaked particles to decrease sorbent crystallinity. These sorbents were used in column syste ms, and the breakthrough curves obtained under several experimental conditi ons (flow velocity and column depth) were modelled using numerical analysis . Molybdate-impregnated chitosan beads (MICB) can be used for As(V) removal : sorption isotherms show high sorption levels even at low arsenic concentr ations, and at pH 2-3, arsenic removal is optimal and molybdenum release is minimal. The desorption and regeneration of the sorbent was effective usin g phosphoric acid solutions. (C) 1999 Society of Chemical Industry.