Removal of divalent cations and oxyanions by keratin-derived sorbents: Influence of process parameters and mechanistic studies

Irum Zahara; Muhammad Faisal Irfan; Muhammad Zubair; Tariq Siddique; Aman Ullah

doi:10.1016/j.scitotenv.2023.164288

Removal of divalent cations and oxyanions by keratin-derived sorbents: Influence of process parameters and mechanistic studies

Sci Total Environ. 2023 Sep 15:891:164288. doi: 10.1016/j.scitotenv.2023.164288. Epub 2023 May 20.

Authors

Irum Zahara¹, Muhammad Faisal Irfan¹, Muhammad Zubair², Tariq Siddique³, Aman Ullah⁴

Affiliations

¹ Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2E3, Canada; Department of Agriculture Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
² Department of Agriculture Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
³ Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2E3, Canada. Electronic address: tariq.siddique@ualberta.ca.
⁴ Department of Agriculture Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada. Electronic address: ullah2@ualberta.ca.

PMID: 37211135
DOI: 10.1016/j.scitotenv.2023.164288

Abstract

Keratin has become a promising adsorbing material for the removal of heavy metals from polluted water due to its environmentally benign nature, unique chemical structure, and binding ability. We developed keratin biopolymers (KBP-I, KBP-IV, KBP-V) using chicken feathers, and assessed their adsorption performance against metal-containing synthetic wastewater at varying temperatures, contact times, and pH. Initially, a multi-metal synthetic wastewater (MMSW) containing cations (Cd²⁺, Co²⁺, Ni²⁺) and oxyanions (Cr^VI, As^III, V^V) was incubated with each KBP under different sets of conditions. Temperature results exhibited that KBP-I, KBP-IV and KBP-V showed higher metals adsorption at 30 °C and 45 °C, respectively. However, the adsorption equilibrium was achieved for selective metals within 1 h of incubation time for all KBPs. For pH, no significant difference was observed in adsorption in MMSW due to buffering of pH by KBPs. To minimize buffering, KBP-IV and KBP-V were tested further for single-metal synthetic wastewater at two different pHs i.e. 5.5 and 8.5. KBP-IV and KBP-V were selected due to their buffering capacities and high adsorption abilities for oxyanions (pH 5.5) and divalent cations (pH 8.5), respectively indicating that chemical modifications changed and enhanced the functional groups of the keratin. X-ray Photoelectron Spectroscopy analysis was performed to demonstrate the adsorption mechanism (complexation/chelation, electrostatic attraction, or chemical reduction) for the removal of divalent cations and oxyanions by KBPs from MMSW. Furthermore, KBPs exhibited adsorption behavior for Ni²⁺ (q_m = 2.2 mg g^-1), Cd²⁺ (q_m = 2.4 mg g^-1), and Cr^VI (q_m = 2.8 mg g^-1) best described by Langmuir model with the coefficient of determination (R²) values >0.95 while As^III (K_F = 6.4 L/g) was fitted well to the Freundlich model with R² value >0.98. Based on these findings, we anticipate that keratin adsorbents have the potential to employ at a large scale for water remediation.

Keywords: Adsorption efficiencies; Adsorption isotherms; Field-collected wastewater; Incubation conditions; Keratin biopolymers; Synthetic wastewater.