| 1891. |
- Holgersson, Stellan, 1964, et al.
(författare)
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Analysis of the metal content of small-size Waste Electric and Electronic Equipment (WEEE) printed circuit-boards part 1: Internet routers, mobile phones and smartphones
- 2018
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Ingår i: Resources, Conservation and Recycling. - : Elsevier BV. - 0921-3449 .- 1879-0658. ; 133, s. 300-308
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Tidskriftsartikel (refereegranskat)abstract
- The metal content of printed circuit boards from three types of Waste Electric and Electronic Equipment (WEEE) products were analysed. The products disassembled to retrieve the printed circuit boards (PCBs) were 10 Internet routers, modems and hubs; 30 mobile phones; and 30 smartphones. The collected boards of each product type were milled to 2-3 mm fractions, cryo-milled further and then leached with aqua regia. Leaching solutions were analysed for Ag, Al, As, Au, Be, Bi, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Pd, Pt, Rh, Sb, Sn and Zn. The leaching residues were pyrolysed, fused with LiBO2 and analysed for Al, Ba, Be, Ca, Co, Cr, Fe, K, Mg, Mn, Mo, Na, Nb, P, Sc, Si, Sr, Ti, V, W, Y, Zr and Zn. The results gave a PCB weight of the total product weight of 43% for the routers and 21% for the two phone types. The main constituents of the PCBs were carbon polymers with a concentration of 34%, 30% and 25% for routers, mobile phones and smartphones, respectively and Cu, with a concentration of 22%, 34% and 40% for routers, mobile phones and smartphones, respectively. The concentrations of precious metals, Ag, Au and Pd, in PCBs were found to be 1213 ppm, 199 ppm and 20 ppm for the routers; 2640 ppm, 1051 ppm and 119 ppm for mobile phones; and 2773 ppm, 1083 ppm and 55 ppm for the smartphones, respectively. The concentrations of toxic metals, As, Be, Cr and Pb, in the PCBs were <70 ppm, 0.3 ppm, 506 ppm and 3413 ppm for routers; 93 ppm, 99 ppm, 953 ppm and 3747 ppm for mobile phones; and 141 ppm, 115 ppm, 1306 ppm and 260 ppm for smartphones, respectively. The results demonstrate that for toxic metals, the Pb content is lower in more modern smartphones compared with older mobile phones while the content of other toxic metals are fairly constant. For the routers, the Pb content was similar to the mobile phones, despite the later production year span (2004-2010) compared with the mobile phones (1999-2010). Regarding precious metals the contents of Ag and Au remain at same level when comparing older mobile phones with newer smartphones. Internet routers, modems and hubs are shown to also be a potential source for precious metals, with comparable concentrations to the two phone types if the total product weight is considered.
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| 1892. |
- Howlett-Downing, Chantelle, et al.
(författare)
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PM2.5 Chemical Composition and Geographical Origin of Air Masses in Pretoria, South Africa
- 2022
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Ingår i: Water, Air, and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 233
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Tidskriftsartikel (refereegranskat)abstract
- In Africa, there is a paucity of studies that reported on PM2.5, soot, BC, UV-PM (organic carbon) and trace element levels in rural and urban regions. PM2.5 samples were collected over 24 h and every third day during 19 April 2018 and 28 February 2020. The mean PM2.5 level was 24.1 μg.m−3 (range: 2.9–139 μg.m−3). PM2.5 levels exceeded the yearly World Health Organization (WHO) air quality guideline (5 μg.m−3). The daily WHO guideline (15 μg.m−3) was exceeded on 151 of the 228 days. The mean soot, black carbon and organic carbon levels were 1.43 m−1 × 10−5, 2.7 μg.m−3 and 2.1 μg.m−3, respectively. Twelve PM2.5-bound trace elements (Br, Ca, Cl, Cu, Fe, K, Ni, S, Si, Ti, U and Zn) were analysed. The geographical origin of air masses that passed the study site was estimated using the Hybrid Single-Particle Lagrangian Integrated Trajectory software. Four air masses were identified. The observed PM2.5, soot, BC, UV-PM and trace element levels at this urban background study site could potentially pose a significant risk to human health.
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| 1893. |
- Lexén, Jenny, et al.
(författare)
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Concentrations of potentially endocrine disrupting chemicals in car cabin air and dust : effect of temperature and ventilation
- 2024
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 947
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Tidskriftsartikel (refereegranskat)abstract
- Materials in car cabins contain performance-enhancing semi-volatile organic compounds (SVOCs). As these SVOCs are not chemically bound to the materials, they can emit from the materials at slow rates to the surrounding, causing human exposure. This study aimed at increasing the understanding on abundance of SVOCs in car cabins by studying 18 potential endocrine disrupting chemicals in car cabin air (gas phase and airborne particles) and dust. We also studied how levels of these chemicals varied by temperature inside the car cabin along with ventilation settings, relevant to human exposure. A positive correlation was observed between temperature and SVOC concentration in both the gas and the particle phase, where average gas phase levels at 80 °C were a factor of 18–16,000 higher than average levels at 25 °C, while average particle phase levels were a factor of 4.6–40,000 higher for the studied substances. This study also showed that levels were below the limit of detection for several SVOCs during realistic driving conditions, i.e., with the ventilation activated. To limit human exposure to SVOCs in car cabins, it is recommended to ventilate a warm car before entering and have the ventilation on during driving, as both temperature and ventilation have a significant impact on SVOC levels.
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| 1894. |
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| 1895. |
- Niinipuu, Mirva, 1988-, et al.
(författare)
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The influence of inorganic components and carbon-oxygen surface functionalities in activated hydrothermally carbonized waste materials for water treatment
- 2020
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Ingår i: Environmental Science and Pollution Research. - : Springer Berlin/Heidelberg. - 0944-1344 .- 1614-7499. ; 27:30, s. 38072-38083
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we have examined how the activation of hydrothermally carbonized sewage sludge and horse manure influences the inorganic component of these materials and surface chemistry. This was examined through statistical correlations between kinetic tests using trimethoprim, fluconazole, perfluorooctanoic acid, and copper, zinc, and arsenic and physicochemical properties. Yield and inorganic content varied considerably, with potassium hydroxide-activated materials producing lower yields with higher inorganic content. Phosphoric acid activation incorporated inorganically bound phosphorus into the material, although this showed no statistically relevant benefit. A maximum surface area of 1363 m(2)g(-1)and 343 m(2)g(-1)was achieved for the horse manure and sewage sludge. Statistical analysis found positive correlations between carbon-oxygen functionalities and trimethoprim, fluconazole, perfluorooctanoic acid, and copper removal, while inorganic content was negatively correlated. Conversely, arsenic removal was positively correlated with inorganic content. This research provides insight into the interactions with the organic/inorganic fraction of activated waste materials for water treatment.
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| 1896. |
- Riddell, Nicole, 1979-, et al.
(författare)
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Examination of technical mixtures of halogen-free phosphorus based flame retardants using multiple analytical techniques
- 2017
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 176:June 2017, s. 333-341
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Tidskriftsartikel (refereegranskat)abstract
- The application of phosphorus based flame retardants as replacements for commonly used halogenated flame retardants has been gaining interest due to the possibility that these compounds may have a less significant impact on human and environmental health. Unfortunately, little is known about the chemical compositions of many of the technical products (which often are mixtures) and a single separation technique for concurrent analysis of these types of compounds has not been identified. This paper reports the results of an investigation into the constituents of three halogen free organophosphate flame retardants (OPFRs), resorcinol bis(diphenyl phosphate) (RDBPP), bisphenol A bis(diphenyl phosphate) (BPA-BDPP), and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The major components of commercial samples of RDBPP and BPA-BDPP were isolated by preparative TLC and characterized by NMR. A commercial sample of DOPO was found to be essentially pure, but its analysis is complicated by the fact that it can exist in ring-open and ring-closed forms. With the structures of the components confirmed by NMR, multiple analytical separation techniques (gas chromatography (GC), liquid chromatography (LC), and packed column supercritical fluid chromatography (pSFC)) were investigated for the analysis of these three technical products. Packed column supercritical fluid chromatography allows the separation of the components of all three OPFRs, including the two forms of DOPO, in a single run.
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| 1897. |
- Riggi, Laura
(författare)
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Effect of the Rearing Substrate Contamination with λ-Cyhalothrin Pesticide on the Growth Performance and Survival of Black Soldier Fly (Hermetia illucens) Larvae: A Study of Biodegradation Kinetics
- 2024
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Ingår i: Chemistry Africa. - 2522-5758 .- 2522-5766. ; 7, s. 833–2844-
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Pesticide residues may be present in fruits and other organic wastes used as rearing substrates for black soldier fly larvae (BSFL, Hermetia illucens). These contaminants are toxic, and their presence in rearing substrates might affect the growth and survival of BSFL as well as the safety of larvae. The present study assesses the effect of lambda-cyhalothrin pesticide present in rearing substrates (mixture of oranges and pineapples) on the growth performance and survival of BSFL. Moreover, the biodegradation kinetics of lambda-cyhalothrin by BSFL and kinetic parameters were determined. Methods Six-day old larvae were reared on the fruit wastes, spiked with known concentrations of lambda-cyhalothrin. The High-Performance Liquid Chromatography (HPLC) technique was used in the determination of residual concentrations of lambda-cyhalothrin in both larvae and substrates. Results By application of the HPLC method, a linear dynamic range of lambda-cyhalothrin was found within the concentration range of 0.625-20 mgL(-1), with a limit of detection and limit of quantification of 0.124 mgL(-1) and 0.820 mgL(-1), respectively. Overall, the presence of lambda-cyhalothrin (concentration >= 30 x Maximum Residual Limit) in the spiked substrate was observed to slow down the development of larvae, but no bioaccumulation of lambda-cyhalothrin was detected in the survived larvae at all developmental stages. No larvae survived on the substrates with lambda-cyhalothrin concentrations of 5 mgL(-1) (A total mortality was observed 48 h after incubation). The development of BSFLs on substrates containing 3 mgL(-1) of lambda-cyhalothrin was weak, but larvae showed an ability to degrade lambda-cyhalothrin and no by-products were identified. The obtained degradation kinetics were found to be of second order, with half lives of 2.00, 8.85 and 9.52 days for lambda-cyhalothrin at 0.5, 1, and 3 mgL(-1), respectively. Conclusion The present approach showed no contamination risk of BSFLs by pesticide residues present in rearing substrates. However, the presence of pesticide residues affects the development of larvae at certain concentrations and therefore could reduce the production. The proposed approach could be an efficient alternative for a quality control analysis of BSFL produced in West Africa.
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| 1898. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Assessment of heavy metals mobility and correlative recovery and decontamination from MSWI fly ash: Mechanism and hydrometallurgical process evaluation
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 768
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Tidskriftsartikel (refereegranskat)abstract
- Fly ash from municipal solid waste incineration (MSWI) enriches many leachable toxic metals which readily migrate into the environment, posing serious risks to the ecosystem and human. In this study, the elements mobility, leaching availability as well as the potential maximum amounts of heavy metals in fly ash were thoroughly evaluated. To decontaminate the toxic elements from resulting fly ash leachates, The aqueous zinc (Zn) was recovered using Cyanex 572, cadmium (Cd) and copper (Cu) were effectively removed through adsorption process by a self-assembled hierarchical hydroxyapatite (HAP) nanostructure. The removal mechanism of Cd, Cu and Zn by leaching, extraction and adsorption was revealed with the results from XRD, ICP-MS and SEM. The results showed that fly ash has a high mobility under maximum availability leaching test (95% of fly ash was dissolved), a recovery rate of 91% for Zn can be obtained using Cyanex 572, and a high adsorption rate (> 95% for both Cu and Cd) was reached using HAP for the pristine fly ash leachate. The outcomes from isothermal and kinetic study revealed that Langmuir isotherm and pseudo-second order model can well describe the Cd and Cu adsorption behavior. Economic assessment suggested that the application of HAP for the removal of Cd and Cu is a technically sound and economically feasible approach. The findings of this study demonstrated that this comprehensive process integrated leaching, solvent extraction and consequential decontamination can be a practical strategy for MSWI fly ash treatment.
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| 1899. |
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| 1900. |
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