Abstract
Hexavalent Cr(VI) found in industrial wastewater is a proven carcinogen which causes serious health issues in humans around the world. This study presents a novel method to enhance the Cr(VI) oxyanion removal from wastewater by polyacrylonitrile (PAN) nanofibers through incorporation of a guanidinium-based ionic covalent organic framework (BT-DG) in the nanofibers structure. Simple electrospinning technique was employed to produce PAN nanofibers and BT-DG was synthesized through condensation between benzene-1,3,5-tricarbaldehyde and N,N'-diaminoguanidine monohydrochloride. In-situ polymerization of BT-DG onto PAN nanofibers resulted in generation of hybrid PAN-BT-DG nanofibers. This modified PAN-BT-DG was characterized by obtaining its point of zero charge (PZC), differential scanning calorimeter (DSC), scanning electron microscopy (SEM) morphology and surface elements and oxidation states by X-ray photoelectron spectroscopy (XPS). PAN-BT-DG exhibited positive surface charge below pH 4, making it an outstanding adsorbent, for Cr(VI) removal. Cr(VI) adsorption onto PAN-BT-DG followed pseudo second order kinetics and adsorption data fitted well to Freundlich isotherm model. Highest Cr(VI) removal was obtained at 55 ℃ with a maximum Langmuir adsorption capacity of 173 mg/g at pH 3. Kinetic studies revealed that Cr(VI) adsorption onto PAN-BT-DG is endothermic and thermodynamically feasible. Desorption studies were conducted on PAN-BT-DG using 1 M NaOH as the stripping solvent and PAN-BT-DG exhibited excellent regeneration after five consecutive cycles.
| Original language | English |
|---|---|
| Article number | 128167 |
| Journal | Journal of Hazardous Materials |
| Volume | 427 |
| DOIs | |
| State | Published - Apr 5 2022 |
Funding
Study reported in this paper was supported by the University of Memphis Division of Research and Innovation through the Office of Technology Transfer. The authors thank Dr. Felio Perez and Dr. Omar Skali in the Integrated Microscopy Center of the University of Memphis for assistance with FE-SEM imaging and XPS analysis and Donya Sharafoddinzadeh for conducting some preliminary experiments. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (S. J.-P.). The authors also thank Dr. Tomoko Fujiwara for providing access to the DSC instrument.
| Funders | Funder number |
|---|---|
| University of Memphis Division of Research and Innovation | |
| U.S. Department of Energy | |
| Office of Science | |
| Basic Energy Sciences | |
| Chemical Sciences, Geosciences, and Biosciences Division |
Keywords
- Chromium (VI)
- Nanofibers
- Organic Framework
- Polyacrylonitrile (PAN)
- Wastewater
