ABSTRACT Chemically-modified in natura collage was prepared under acidic catalysis for using in sorption of Cd(II) from aqueous solutions. Simultaneous determination of the quantity and energetic parameters of Cd(II) sorption on PGA-scale at pH 8.0 were determined using solution microcalorimetry (SM). The calorimetric enthalpies of Cd(II) sorption on PGA-scale are all exothermic, and Cd(II) adsorption energies decrease as temperature increases. The maximum sorption capacity of PGA-scale for Cd(II) (438 μmol g-1) is superior with many sorption data reported in the literature. Characterization and SM indicate that the main sites for Cd(II) sorption are located in the collagen structure of PGA-scale. It was found that the interactions PGA-scale/Cd(II) are mainly due to chemisorption and diffusion may occur at the PGA-scale/Cd(II) interface. The results of this study underline the good features of PGA-scale as a promising material for sorption of Cd(II) from aqueous media.

ABSTRACT It is known that wastewaters containing dyes are very difficult to treat, since many dyes are stable and recalcitrant molecules. In this way, sorption may suitable for effectively remove dyes in this specific application field. In this work, a first approach for using polymeric membranous collagen of fish scales for sorption of saline methylene blue dye (MB) solution found in subsurface procedures of oil well industry. From structural characterization, the sorbent was found to be a composite of fibrillar type I collagen and apatites. The MB sorption amounts decreased with temperature increasing, with maximum MB sorbed of 2.18 mmol g-1 at 25 0C. In most sorption tests, residual MB in saline water was undetectable within 200 min of contact time. The sorption kinetic data were well adjusted to a three-parameter multi-step exponential function. The good fitting of such function were only obtained taking into account the presence of time-dependent kinetic parameters. The proposed multi-step sorption mechanism involved surface interaction and diffusion of MB into the membranous collagen. The interaction of positively charged MB ions with the collagenous adsorbent occurred through electrostatic forces. The results point out the collagenous adsorbent for effective procedures of sorption of MB dyes from high-saline wastewaters.

Characterization of fish scales of Leporinus elongatus and their application in the removal of Cu(II) from aqueous solutions are described. It was observed that the scales are mainly formed by hydroxyapatite and type I collagen. Adsorption of Cu(II) was performed using batch experiments at 25 0C. The ANOVA statistical results have shown that the Langmuir model was successful applied to determine the maximum adsorption capacity of 2.686 x10-4 mol g-1 and the Langmuir equilibrium parameter (b) of 168.8 L mol-1. The Langmuir separation parameter, R L, has shown favorable adsorption of Cu(II) on the scales.