1
|
Ramos P, Singh Kalra S, Johnson NW, Khor CM, Borthakur A, Cranmer B, Dooley G, Mohanty SK, Jassby D, Blotevogel J, Mahendra S. Enhanced removal of per- and polyfluoroalkyl substances in complex matrices by polyDADMAC-coated regenerable granular activated carbon. Environ Pollut 2022; 294:118603. [PMID: 34861330 DOI: 10.1016/j.envpol.2021.118603] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 08/25/2021] [Revised: 11/19/2021] [Accepted: 11/27/2021] [Indexed: 06/13/2023]
Abstract
Granular activated carbon (GAC) has been used to remove per- and polyfluoroalkyl substances (PFASs) from industrial or AFFF-impacted waters, but its effectiveness can be low because adsorption of short-chained PFASs is ineffective and its sites are exhausted rapidly by co-contaminants. To increase adsorption of anionic PFASs on GAC by electrostatic attractions, we modified GAC's surface with the cationic polymer poly diallyldimethylammonium chloride (polyDADMAC) and tested its capacity in complex water matrices containing dissolved salts and humic acid. Amending with concentrations of polyDADMAC as low as 0.00025% enhanced GAC's adsorption capacity for PFASs, even in the presence of competing ions. This suggests that electrostatic interactions with polyDADMAC's quaternary ammonium functional groups helped bind organic and inorganic ions as well as the headgroup of short-chain PFASs, allowing more overall PFAS removal by GAC. Evaluating the effect of polymer dose is important because excessive addition can block pores and reduce overall PFAS removal rather than increase it. To decrease the waste associated with this adsorption strategy by making the adsorbent viable for more than one saturation cycle, a regeneration method is proposed which uses low-power ultrasound to enhance the desorption of PFASs from the polyDADMAC-GAC with minimum disruption to the adsorbent's structure. Re-modification with the polymer after sonication resulted in a negligible decrease in the sorbent's capacity over four saturation rounds. These results support consideration of polyDADMAC-modified GAC as an effective regenerable adsorbent for ex-situ concentration step of both short and long-chain PFASs from real waters with high concentrations of competing ions and low PFAS loads.
Collapse
Affiliation(s)
- Pia Ramos
- Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA
| | - Shashank Singh Kalra
- Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA
| | - Nicholas W Johnson
- Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA
| | - Chia Miang Khor
- Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA
| | - Annesh Borthakur
- Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA
| | - Brian Cranmer
- Department of Environmental and Radiological Health Sciences, Colorado State University, 1680 Campus Delivery, Fort Collins, CO, 80523, USA
| | - Gregory Dooley
- Department of Environmental and Radiological Health Sciences, Colorado State University, 1680 Campus Delivery, Fort Collins, CO, 80523, USA
| | - Sanjay K Mohanty
- Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA
| | - David Jassby
- Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA
| | - Jens Blotevogel
- Department of Civil and Environmental Engineering & Center for Contaminant Hydrology, Colorado State University, 1320 Campus Delivery, Fort Collins, CO, 80523, USA
| | - Shaily Mahendra
- Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA.
| |
Collapse
|
2
|
Burch JB, Svendsen E, Siegel PD, Wagner SE, von Essen S, Keefe T, Mehaffy J, Martinez AS, Bradford M, Baker L, Cranmer B, Saito R, Tessari J, Linda P, Andersen C, Christensen O, Koehncke N, Reynolds SJ. Endotoxin exposure and inflammation markers among agricultural workers in Colorado and Nebraska. J Toxicol Environ Health A 2010; 73:5-22. [PMID: 19953416 DOI: 10.1080/15287390903248604] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The adverse respiratory effects of agricultural dust inhalation are mediated in part by endotoxin, a constituent of gram-negative bacterial cell walls. This study quantified personal work-shift exposures to inhalable dust, endotoxin, and its reactive 3-hydroxy fatty acid (3-OHFA) constituents among workers in grain elevators, cattle feedlots, dairies, and on corn farms. Exposures were compared with post-work-shift nasal lavage fluid inflammation markers and respiratory symptoms. Breathing-zone personal air monitoring was performed over one work shift to quantify inhalable dust (Institute of Medicine samplers), endotoxin (recombinant factor C [rFC] assay), and 3-OHFA (gas chromatography/mass spectrometry). Post-shift nasal lavage fluids were assayed for polymorphonuclear neutrophils (PMN), myeloperoxidase (MPO), interleukin 8 (IL-8), albumin, and eosinophilic cation protein (ECP) concentrations. The geometric mean (GSD) of endotoxin exposure (rFC assay) among the 125 male participants was 888 +/- (6.5) EU/m(3), and 93% exceeded the proposed exposure limit (50 EU/m(3)). Mean PMN, MPO, albumin, and ECP levels were two- to threefold higher among workers in the upper quartile of 3-OHFA exposure compared to the lowest exposure quartile. Even numbered 3-OHFA were most strongly associated with nasal inflammation. Symptom prevalence was not elevated among exposed workers, possibly due to endotoxin tolerance or a healthy worker effect in this population. This is the first study to evaluate the relationship between endotoxin's 3-OHFA constituents in agricultural dust and nasal airway inflammation. More research is needed to characterize the extent to which these agents contribute to respiratory disease among agricultural workers.
Collapse
Affiliation(s)
- James B Burch
- Department of Epidemiology and Biostatistics, Cancer Prevention and Control Program, and Center for Colon Cancer Research, University of South Carolina, Columbia, SC 29208, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
3
|
McMullin TS, Andersen ME, Tessari JD, Cranmer B, Hanneman WH. Estimating constants for metabolism of atrazine in freshly isolated rat hepatocytes by kinetic modeling. Toxicol In Vitro 2007; 21:492-501. [PMID: 17188835 DOI: 10.1016/j.tiv.2006.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2006] [Revised: 10/09/2006] [Accepted: 10/21/2006] [Indexed: 10/24/2022]
Abstract
This study estimated the kinetic constants for oxidative metabolism of atrazine (ATRA) and its chlorotriazine (Cl-TRI) metabolites, 2-chloro-4-ethylamino-6-amino-1,3,5-triazine (ETHYL), 2-chloro-4-amino-6-isopropylamino-1,3,5-triazine (ISO), and diaminochlorotriazine (DACT), using freshly isolated rat hepatocytes. Hepatocytes were incubated with 1.74, 44, 98, and 266 microM ATRA. Disappearance of ATRA and formation of the Cl-TRI metabolites were quantified over 90 min. At all incubation concentrations, ATRA was preferentially metabolized to ETHYL, producing ETHYL concentrations approximately 6 times higher than those of ISO. DACT concentrations peaked at 44 microM ATRA and decreased with increasing incubation concentrations, indicating non-linear metabolic behavior of ATRA with respect to DACT formation. A series of kinetic models were developed from these data to describe the dose and time-dependent oxidative metabolism of ATRA and the Cl-TRI metabolites. An integrated model for all the chloro-triazines included multi-substrate competitive inhibition of metabolism to describe the non-linear behavior of DACT production in relation to ATRA while simultaneously simulating the time-course behavior of the Cl-TRIs at all four ATRA concentrations. The maximal metabolic rate (V(max)) of ATRA metabolism and the Michaelis-Menten constant (K(M)) for the reaction were 1.6 microM/min and 30 microM, respectively. V(max) and K(M) values for ETHYL and ISO metabolism to DACT were also estimated using this modeling approach.
Collapse
Affiliation(s)
- Tami S McMullin
- Department of Environmental and Radiological Health Sciences, Campus Delivery, 132 Physiology Building, 1680, Colorado State University, Fort Collins, CO 80523, United States
| | | | | | | | | |
Collapse
|