Feather Keratin Derived Sustainable Biosorbents for Adsorption of Heavy Metal Ions from Water
Creators: Zubair, Muhammad
Publisher: name: University of Alberta Library
Year: 2023

<p>Water is the epicenter of sustainability and has an essential part of the existence and development of the ecosystem and socioeconomic pillars. However, one in every three humans does not have access to clean drinking water around the globe and heavy metal ions pollution is the major contributor. This study aimed to develop keratin derived biosorbents for the removal of heavy metals from contaminated water. <br>
    Poultry feathers, an underutilized poultry industry by-product with high keratin protein contents, can be used as a sustainable biomass for biosorbents production to clean heavy metals contaminated water. However, keratin itself has a low biosorption efficiency for heavy metals, which can be improved by exposing the active sites of the feather keratin through effective modifications. This research focused on the synthesis of biosorbents from chicken feathers keratin (CFK), i.e., the extraction and nanomodification of keratin with graphene oxide (GO), nanochitosan (NC) and surface modified graphene oxide (SMGO) to transforms into biosorbents for water remediation from heavy metals. <br>
    In the first study, a facile method was used to synthesize keratin derived biosorbents using water dispersed graphene oxide. To develop the biosorbents, feathers were washed with anti-bacterial soap, dried at 50 °C and defatted with hexane followed by the dissolution of keratin with a mixture of urea, tris-base and sodium sulfite. The keratin was modified using different ratios of graphene oxide (1, 3 and 5%) to enhance its biosorption efficiency. The nanomodification of keratin was carried out by cross-linking with the graphene oxide predominantly via an esterification reaction. The nanomodified biosorbents were then tested against a synthetic wastewater solution containing 600 μgL−1 of 8 trace metals, i.e., NiII, CoII, PbII, CdII, ZnII, AsIII, SeVI and CrVI. The 10 ml solution of multi-metals was amended with 0.1g of each prepared biosorbents and incubated for 24 hours, followed by centrifugation and analyzed using inductively coupled plasma-mass spectrometer (ICP-MS). Among synthesized biosorbents CFK modified with GO (1%) exhibited ≥99.04 and ≥99. 11 and ≥97.84% removal efficiency for  NiII SeVI, and AsIII, respectively<br>
    In the second study, the biosorbents were prepared by first unraveling and then cross-linking keratin with NC. The nanomodifications were carried out using different concentrations of NC (1, 3 and 5%) in the keratin solution. The mixtures were treated at 75 °C overnight which predominantly promoted the formation of ester bonds between the hydroxyl groups of nanochitosan and the carboxylic groups of the keratin biopolymer. The ICP-MS results indicated that CFK modified with NC (3%) showed better removal efficiency than CFK containing 1 and 5% nanochitosan.  CFK having 3% NC had removal efficiencies of ≥98.80, ≥98.44, ≥92.96% for SeVI AsIII and  PbII, respectively.<br>
In the third study, graphene oxide was modified first with acryl amide to introduce the acrylic groups on the graphene oxide surface. Introducing acrylic groups on the graphene oxide facilitates the grafting or graft copolymerization with keratin biopolymer. GO was modified with acryl amide under alkaline conditions using N, N′-dicyclohexylcarbodiimide and hydroxy benzotriazole as coupling agent. The surface modified GO was then graft-copolymerized with the keratin in the presence of potassium persulfate and sodium thiosulfate as radical initiators. The successful grafting of SMGO onto the CFK resulted in better metal cations removal efficiencies than oxyanions i.e. ≥99.21 ≥99.03 and ≥96.34% for PbII, CdII and  CoII, respectively</p>

<pre><code>Overall, this research study has demonstrated that modification of feather keratin with GO, NC and SMGO effectively improves its biosorption efficiency for removing multiple trace metal ions from synthetic wastewater in a single treatment. Among synthesized biosorbents CFK-GO, CFK-NC, CFK-SMGO derived biosorbents exhibited biosorption of metals upto 99, 98 and 99%, respectively. Furthermore, insights into the biosorption mechanism revealed that the electrostatic interaction, chelation and complexation primarily contributed to the removal of multiple heavy metal ions from synthetic wastewater in a single treatment. The chemical/physical interaction of the protein biopolymers with the nanoparticles led to the improved surface functionalities of the keratin with substantial morphological changes, uncovering surface functional groups which enhanced the biosorption efficiency of keratin for heavy metals. Moreover, environmentally friendly keratin derived biosorbents will help treat industrially contaminated water and minimize poultry feather related environmental pollution. 
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