Removal of Hexavalent Chromium from Water by Polyurethane–Keratin Hybrid Membranes

Abstract

The feasibility of employing a porous polyurethane-keratin hybrid membrane for the removal of hexavalent chromium was investigated. Keratin was extracted from chicken feathers and incorporated onto a synthetic polyurethane polymer to synthesize a hybrid membrane. Keratin supply active sites to bioadsorb Cr (VI) and polyurethane play an important role as the support to protein. Also, polyurethane-keratin biofiber membranes were synthesized. Biofibers obtained from chicken feathers were modified to activate their surface. The effective pore in membranes is less than 50 nm, which places these materials in the mesopore range. Scanning electron microscopy (SEM) was used to study the morphology of membranes, and mechanical dynamical analysis (DMA) was used to evaluate the viscoelastic properties. NH, C=O, S-S and C-S were determined via Fourier-transform infrared (FTIR) analysis as functional groups of keratin, which participate in the linking sorption of hexavalent chromium. Adsorption of Cr(VI) was carried out in a filtering system at low contact time in continuous flux; the maximum removal reached was 38% at neutral pH of chromium solution. Results indicate that the isoelectric point of keratin is relevant in the adsorption process. pH of keratin solution above the isoelectric point brings about higher adsorption of heavy metals, whereas lower pH causes minor adsorptions, due to the functional groups' ion charges. Based on the results, keratin extracted from feathers is a natural biosorbent that can be incorporated onto synthetic polymers to develop novel membranes and improve its applications in the heavy metal separation process.

Design and characterization of sustainable bio‐composites from waste chicken feather keratin and thermoplastic polyurethane

“…The utilization of eco‐friendly, “green”, bio‐based composites has been reported in many areas including, but not limited to, the packaging, insulation, automotive, building and roofing industries, as well as for separation membranes for water treatment . To compare the properties of the new bio‐composites with existing similar materials a range of measurements were made in the laboratory and sourced from Polymer Database—PoLyInfo.…”

Keratinous Materials as Novel Absorbent Systems for Toxic Pollutants

“…Hybrid membranes based on chicken feather keratin for removal of toxic metals have been investigated 60,61 . The membrane, consisting of synthetic polyurethane as support matrix and keratin biofiber or resin as active sites, was used to remove Cr 6+ for wastewater treatment 60 .…”

“…The membrane, consisting of synthetic polyurethane as support matrix and keratin biofiber or resin as active sites, was used to remove Cr 6+ for wastewater treatment 60 . It showed good Cr 6+ adsorption (38%) capacity when it had membrane pore size of 5 nm and keratin or biofiber content of 15 wt%.…”

Polyurethane-Keratin Membranes: Structural Changes by Isocyanate and pH, and the Repercussion on Cr(VI) Removal

“…Recently, keratin from chicken feathers has been proposed as biosorbent, considering that it has abundant amino acid groups that have demonstrated good potential to attract heavy metals [4,6]. However, one limitation concerning the use of biosorbents is their handling; this is particularly true for feather keratin fibers, since one of their most important features is their low density [7][8][9].…”