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- Englund, Sophie, et al.
(författare)
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Removal efficiency of multiple poly- and perfluoroalkyl substances (PFASs) in drinking water using granular activated carbon (GAC) and anion exchange (AE) column tests
- 2017
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 120, s. 77-87
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Tidskriftsartikel (refereegranskat)abstract
- Poly- and perfluoroalkyl substances (PFASs) have been detected in drinking water at relatively high concentrations throughout the world which has led to implementation of regulatory guidelines for specific PFASs in drinking water in several European countries and in the U.S. The Swedish National Food Agency has determined that the drinking water of over one third of the country's municipal consumers is at risk or already affected by PFAS contamination. The present study investigated the effects of perfluorocarbon chain length, functional group and isomer structure (branched or linear) on removal of multiple PFASs using granular activated carbon (GAC, Filtrasorb (R) 400) and anion exchange (AE, Purolite (R) A600) column experiments. The removal of 14 different PFASs, i.e. the C-3-C-11, C-14 perfluoroalkyl carboxylic acids (PFCAs) (PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFTeDA), perfluorooctane sulfonamide (FOSA), and the C-4, C-6, C-8 perfluoroalkyl sulfonic acids (PFSAs) (PFBS, PFHxS, PFOS), was monitored for a 217 day period. The results indicate the selective nature of PFAS removal as the absorbents are loaded with PFASs and dissolved organic carbon (DOC). A clear relationship between perfluorocarbon chain length and removal efficiency of PFASs using GAC and AE was found while PFASs with sulfonate functional groups displayed greater removal efficiency than those with carboxylate groups. Similarly, time to column breakthrough increased with increasing perfluorocarbon chain length and was greater for the PFSAs than the PFCAs for both GAC and AE. Shorter carbon chained PFASs such as PFBA, PFPeA, PFHxA showed desorption behavior and long-chained PFASs showed increased removal towards the end of the experiment indicating agglomeration or micelle development. Linear isomers of PFOS, PFHxS, and perfluorooctane sulfonamide (FOSA) had greater column removal efficiencies using GAC (and also for AE at greater bed volume throughput) than the branched and this difference increased at greater bed volume throughputs. The GAC and AE columns showed a poor correlation between DOC and PFAS removal efficiency. The results indicate that designers and operators of AE and GAC treatment processes must take into consideration the selective nature of PFAS removal and associated desorption of short-chain PFCAs during co-removal of multiple PFASs. (C) 2017 Elsevier Ltd. All rights reserved.
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| 3. |
- Neovius, Erik, et al.
(författare)
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Persistent diplopia after fractures involving the orbit related to nerve injury
- 2015
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Ingår i: Journal of Plastic, Reconstructive & Aesthetic Surgery. - : Elsevier BV. - 1748-6815 .- 1878-0539. ; 68:2, s. 219-225
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Tidskriftsartikel (refereegranskat)abstract
- Background: Fractures in the facial skeleton are common and may lead to orbital sequelae caused by the injury and/or the surgery. In this long-term follow-up, we examined the nature of sequelae after facial fractures involving the orbit and whether a higher complexity of the fractures produced more sequelae compared to simpler fracture patterns, and if so, to what extent. Methods: Patients surgically treated for facial fractures involving the orbit at the Karolinska University Hospital with a follow-up duration of >= 3 years were included in this retrospective study and were examined by a neuro-ophthalmologist. Based on the location and severity of the fractures, the patients were divided into four groups according to fracture complexity: 1) isolated zygomatic fracture, 2) isolated orbital floor blowout fracture, 3) zygomatic fracture combined with blowout fracture and 4) bilateral or multiple fracture patterns. Results: Out of 154 patients, 81 patients (53%) attended follow-up examinations, 65 male (80%) and 16 female (20%). The duration of follow-up was 3.0-7.6 years (mean of 4.9 years). The incidence of diplopia was 3.7%, visual loss 2.5%, dystopia 4.9% and visible enophthalmos (>2 mm) 8.6%. Severe diplopia (2.5%) was due to nerve injuries. Visual loss was encountered only in group 4 with complex fractures. Fracture complexity had an effect on the presence of any sequelae, with group 4 presenting a higher percentage of patients with sequelae than the other three groups. However, no statistically significant effect of group could be found on the individual, quantitative output values of dystopia and enophthalmos. Conclusions: In this study, severe persistent diplopia in patients was due to nerve injuries, which emphasizes the need for preoperative ophthalmologic examinations, in all patients with fractures involving the orbit. A higher fracture complexity was found to lead to a higher percentage of patients presenting sequelae. (C) 2014 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.
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