Hyperbranched polymer modified collagen fiber was used as a novel absorbent to remove hexavalent chromium from simulated chrome solution. Various factors influencing the uptake of Cr(VI), namely, quantity of absorbent, pH, the concentration of the simulated chrome solution and the duration of treatment had been studied. The experimental result indicated that the modified collagen fiber was very effective for removing Cr(VI) from simulated chrome solution. The removal of Cr(VI) increased with the decrease of solution pH values. The maximum rate of removal was attained at pH 3.0. The increase of absorbent dosage would raise the removal efficiency, but it would simultaneously reduce the adsorption capacity. Moreover, the removal rate of Cr(VI) was found to decrease with the increasing of initial concentration of Cr(VI). At pH 3.0, the temperature of 30 ℃, 4.0 g·L^-1 modified collagen fiber, the rate of removal could reach 99.57%. Whereas, the Cr(VI) uptake capacity increased with the increase of Cr(VI) initial concentration until reaching saturation, which was found to be 38.94 mg·g^-1 at pH 3.0, 30 ℃ and the initial concentration of 400 mg·L^-1. Several desorption solutions were used to analyze the desorption process while the 0.18 mol·L^-1 NaOH solution was the best. Furthermore, X-ray photoelectron spectroscopy (XPS) as well as scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analysis were employed to characterize hyperbranched polyamide amino modified collagen fiber (CF-HBPN), and further to elucidate the adsorption mechanism involved in the process. XPS analysis revealed that the Cr(VI) combined on the surface of modified collagen fiber and the protonation amino groups were the functional groups in the adsorption process because of the electrostatic power. SEM analysis revealed that the surface of modified collagen fiber was rough and it had three-dimensional network structures. EDS analysis indicated that the adsorption process included ion exchange.

Key words: collagen fiber, Cr(VI), adsorption, characterization, mechanism