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.
Department of Agriculture Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Sci Total Environ. 2023 Sep 15;891:164288. doi: 10.1016/j.scitotenv.2023.164288. Epub 2023 May 20.
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 (Cd, Co, Ni) and oxyanions (Cr, As, 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 Ni (q = 2.2 mg g), Cd (q = 2.4 mg g), and Cr (q = 2.8 mg g) best described by Langmuir model with the coefficient of determination (R) values >0.95 while As (K = 6.4 L/g) was fitted well to the Freundlich model with R value >0.98. Based on these findings, we anticipate that keratin adsorbents have the potential to employ at a large scale for water remediation.
角蛋白由于其环境友好的性质、独特的化学结构和结合能力，已成为一种很有前途的吸附材料，可用于从受污染的水中去除重金属。我们使用鸡毛开发了角蛋白生物聚合物（KBP-I、KBP-IV、KBP-V），并在不同温度、接触时间和 pH 值下评估了它们对含金属合成废水的吸附性能。最初，用每种 KBP 孵育含有阳离子（Cd、Co、Ni）和含氧阴离子（Cr、As、V）的多金属合成废水（MMSW）。温度结果表明，KBP-I、KBP-IV 和 KBP-V 在 30°C 和 45°C 时对金属的吸附率更高。然而，所有 KBP 孵育 1 小时后，对选择性金属的吸附达到平衡。对于 pH 值，由于 KBP 缓冲了 pH 值，因此在 MMSW 中观察到吸附没有明显差异。为了最小化缓冲作用，进一步在两个不同的 pH 值（即 5.5 和 8.5）下用 KBP-IV 和 KBP-V 测试了单金属合成废水。选择 KBP-IV 和 KBP-V 是因为它们具有缓冲能力和对含氧阴离子（pH 5.5）和二价阳离子（pH 8.5）的高吸附能力，这表明化学修饰改变并增强了角蛋白的功能基团。X 射线光电子能谱分析用于证明从 MMSW 中去除二价阳离子和含氧阴离子的机制（络合/螯合、静电吸引或化学还原）。此外，KBPs 对 Ni（q=2.2 mg g）、Cd（q=2.4 mg g）和 Cr（q=2.8 mg g）的吸附行为最好用朗缪尔模型描述，决定系数（R）值>0.95，而 As（K=6.4 L/g）则很好地符合弗伦德利希模型，R 值>0.98。基于这些发现，我们预计角蛋白吸附剂有可能在大规模水修复中得到应用。
