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Chen X, Vanangamudi A, Wang J, Jegatheesan J, Mishra V, Sharma R, Gray SR, Kujawa J, Kujawski W, Wicaksana F, Dumée LF. Direct contact membrane distillation for effective concentration of perfluoroalkyl substances - Impact of surface fouling and material stability. Water Res 2020; 182:116010. [PMID: 32544734 DOI: 10.1016/j.watres.2020.116010] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/22/2020] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
Polyfluoroalkyl and perfluoroalkyl substances (PFAS) are ecotoxic amphiphilic compounds containing alkyl-fluorinated chains terminated with weak acid moieties, and hence difficult to be degraded or removed from water sources. Direct contact membrane distillation (DCMD) was used for concentrating and removing of perfluoropentanoic acid (PFPeA) compounds from model contaminated water using commercially available poly (tetrafluoroethylene) (PTFE) membranes. The membranes were characterised for surface morphology, roughness, contact angle and pore size distribution before and after the DCMD test to investigate and evaluate membrane fouling. During the DCMD test performed for 6 h using 10 ppm PFPeA solution, the membrane exhibited progressive increased flux (from 17 to 43 kg m-2 h-1) and decreased PFPeA rejection (from 85 to 58%), as the feed temperature was increased from 50 to 70 °C. Further, the feed/retentate side showed a 1.8, 2.1 and 2.8-fold increase in PFPeA concentration tested at feed temperatures 50, 60, and 70 °C, respectively. The permeate side contained less than 1 ppm of PFPeA revealing that the PFPeA moved across the PTFE membrane during DCMD, which is attributed to progressive surface diffusion over time. This study opens a new route to concentrate and remove amphiphilic molecules, such as PFAS, from source points, relevant to landfill leachates or surface waters. The study also points at gaps in materials science and surface engineering to be tackled to deal with PFAS compounds efficiently.
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Affiliation(s)
- Xiao Chen
- Deakin University, Geelong Institute for Frontier Materials, 75 Pigdons Road, Waurn Ponds, 3216, Victoria, Australia.
| | - Anbharasi Vanangamudi
- Deakin University, Geelong Institute for Frontier Materials, 75 Pigdons Road, Waurn Ponds, 3216, Victoria, Australia
| | - Jingshi Wang
- Deakin University, Geelong Institute for Frontier Materials, 75 Pigdons Road, Waurn Ponds, 3216, Victoria, Australia
| | | | - Vandana Mishra
- Bioresources and Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi, 110007, India
| | - Radhey Sharma
- Bioresources and Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi, 110007, India
| | - Stephen R Gray
- Victoria University, Melbourne Institute for Sustainability and Innovation, P.O. Box 14428, Victoria 8001, Australia
| | - Joanna Kujawa
- Nicolaus Copernicus University in Toruń, Faculty of Chemistry, 7 Gagarina Street, 87-100, Toruń, Poland
| | - Wojciech Kujawski
- Nicolaus Copernicus University in Toruń, Faculty of Chemistry, 7 Gagarina Street, 87-100, Toruń, Poland
| | - Filicia Wicaksana
- University of Auckland, Department of Chemical and Materials Engineering, Auckland, 1142, New Zealand
| | - Ludovic F Dumée
- Deakin University, Geelong Institute for Frontier Materials, 75 Pigdons Road, Waurn Ponds, 3216, Victoria, Australia.
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Álvarez-Martos I, Møller A, Ferapontova EE. Dopamine Binding and Analysis in Undiluted Human Serum and Blood by the RNA-Aptamer Electrode. ACS Chem Neurosci 2019; 10:1706-1715. [PMID: 30605601 DOI: 10.1021/acschemneuro.8b00616] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Specific analysis of such neurotransmitters as dopamine by the aptamer electrodes in biological fluids is detrimentally affected by nonspecific adsorption of media, particularly pronounced at positive charges of the electrode surface at which dopamine oxidizes. Here, we show that dopamine analysis at the RNA-aptamer/cysteamine-modified electrodes is strongly inhibited in undiluted human serum and blood due to nonspecific interfacial adsorption of serum and blood components. We demonstrate that nonspecific adsorption of serum proteins (but not of blood components) could be minimized when analysis is performed in a flow and injections of serum samples are followed by washing steps in a phosphate buffer solution (PBS) carrier. Under those conditions, the dopamine-aptamer binding affinity in whole human serum of (1.9 ± 0.3) × 104 M-1 s-1 was comparable to the (3.7 ± 0.3) × 104 M-1 s-1 found in PBS, and the dopamine oxidation signal linearly depended on the dopamine concentration, providing a sensitivity of analysis of 73 ± 3 nA μM-1 cm-2 and a LOD of 114 ± 8 nM. The flow-injection apatmer-electrode system was used for direct analysis of basal levels of dopamine in undiluted human serum samples, without using any physical separators (membranes) or filtration procedures. The results suggest a simple strategy for combatting biosurface fouling, otherwise most pronounced at positive electrode potentials used for dopamine detection, and assist in designing more efficient antifouling strategies for biomedical applications.
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Affiliation(s)
- Isabel Álvarez-Martos
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Arne Møller
- PET-Centre, Aarhus University Hospital, Aarhus, Denmark
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Elena E. Ferapontova
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark
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