| 1. |
- Arvidsson, Rickard, 1984, et al.
(författare)
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Life cycle assessment of Biodiesel - Hydrotreated oil from rape, oil palm or Jatropha
- 2008
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Ingår i: Annual Poster Exhibition at the Department of Chemical and Biological Engineering, Chalmers University of Technology, Mars 6th, 2008, Göteborg, Sweden.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There is a need for fuels based on renewable resources that have acceptable emission profiles and that are functional for truck engines used in heavy vehicles. Volvo has participated in the CONCAWE/EUCAR/JRC WTW study, which analyzed a number of candidate fuels, several process routes to produce each fuel as well as different raw material choices. However, the CONCAWE study did not include any second generation hydrogenated vegetable oil type biodiesel. In the present study, Volvo and Chalmers investigate and benchmark hydrogenated vegetable oils. Different production routes from different proposed raw materials are investigated using life cycle assessment modeling. Raw materials considered are oil from rape seed (grown in Germany), palm oil (grown in Malaysia) and oil from the fruits of Jatropha curcas (grown in India). The raw material is converted into hydrogenated oil at a production site in northern Europe and used at the European market. Results regarding life cycle global warming potential and energy use are presented.
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| 2. |
- Fröling, Morgan, 1966, et al.
(författare)
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Life Cycle Assessment of Second Generation Biodiesel: Biomass to Liquid
- 2008
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Ingår i: Designing Pathways for a Sustainable World: At Scale, in Time, and for All, AGS Annual Meeting, MIT, Cambridge, MA. USA, January 28-30 2008. ; , s. abstract in proceedings-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Arvidsson, Rickard, 1984, et al.
(författare)
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Environmental Impact of Titanium Dioxide Nanoparticles – Applying Life Cycle Thinking and Risk Assessment for Swedish Conditions
- 2008
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Ingår i: 3rd International Conference on the Environmental Effects of Nanoparticles and Nanomaterials, Birmingham University, Birmingham, UK, September 15-16, 2008.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The risks of nanoparticles have been issued by several different groups, e.g. The Royal Society (2004) and Friends of the Earth (2006), and the concept nanotoxicology has been introduced to underline the distinctive toxicological features of nanoparticles (Oberdörster et al. 2005). Some nanoparticles, such as carbon nanotubes, have been outlined as hazardous and great caution has been suggested before introducing carbon nanotubes into the market (Poland et al. 2008). According to a risk assessment performed by Mueller and Nowack (2007), titanium dioxide nanoparticles had higher predicted environmental concentration compared with the predicted no effect concentration than both silver nanoparticles and carbon nanotubes, and further detailed studies regarding titanium dioxide nanoparticles were suggested. However, no sensitivity analysis was performed in Mueller and Nowack (2007), and a crude model was used to model environmental faith of the titanium dioxide nanoparticles. Our study applied substance flow analysis in order to facilitate a comprehensive environmental risk assessment of titanium dioxide nanoparticles (see e.g. Tsunemi and Wada (2008) and Fuster et al. (2002)). A detailed investigation of the production of titanium dioxide nanoparticles and their application in society was performed facilitating hazard identification according to Hansen et al. (2007). Emissions were calculated based on use assumptions and a modelling of the environmental faith of the titanium dioxide nanoparticles was attempted including the particle aggregation and interaction with natural organic substances that modify bioavailability. Predicted environmental concentrations were calculated and compared with predicted no effect concentrations according to several ecotoxicological studies and in order to assess the uncertainty a sensitivity analysis was performed for input parameters.
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| 4. |
- Arvidsson, Rickard, 1984, et al.
(författare)
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Fate modeling of titanium dioxide nanoparticles in the water compartment by colloid chemistry
- 2009
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Ingår i: 1st International Conference on the Environmental Implications and Applications of Nanotechnology, June 9-11, 2009, Amherst, U.S.A..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Titanium dioxide is one of the most produced nanoparticles according to the Project of Emerging Nanotechnologies (www.nanotechproject.org). According to Mueller and Nowack (2008) it is also the nanoparticle that has the largest environmental concentration in the Swiss water compartment, 16 µg/l according to their high estimate. Further, Boxall et al. (2007) estimate a titanium dioxide nanoparticle environmental concentration of 24.5 µg/l in the UK water compartment for a scenario that probably overestimates the current exposure levels. However, neither of these risk models take fate processes such as aggregation and sedimentation into account. Colloid chemistry deals with particles within the size range of 1 nm to 1 µm. Nanoparticles of a size between one nanometer and a few hundred nanometers are thus well within the colloid range. Theories of colloid chemistry suggest that sedimentation of nanoparticles depends mainly on the density and the viscosity of the water and the density and size of the particles. Sedimentation is shown not to be an important factor, since the sedimentation of particles smaller than ~300 nm is negligible. Aggregation is a more complex process which depends on factors such as temperature, salinity, ion valence, pH, point of zero charge, the Hamaker constant, particle size and particle concentration (Elimelech et al. 1995). These factors were estimated for a typical Swedish lake and calculations were performed in MATLAB. The aggregation is modeled by kinetics according to Smoluchowski (1917) but adjusted according to the DLVO theory (see Elimelech et al. 1995). Preliminary results show that aggregation can reduce the predicted environmental concentration significantly in a short time. It would take less than 4 minutes for the initial environmental concentrations predicted by both Mueller and Nowack (2008) and Boxall et al. (2007) to be reduced by 50%. After 24 hours, both predicted environmental concentrations would have fallen below 0.1 µg/l.
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| 5. |
- Arvidsson, Rickard, 1984, et al.
(författare)
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MODELLING ENVIRONMENTAL FATE OF TiO2 NANOPARTICLES IN WATER – IMPLICATIONS FOR EMPIRICAL VALIDATION STUDIES
- 2009
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Ingår i: 4th International Conference on the Environmental Effects of Nanoparticles and Nanomaterials, 6-9 September, Vienna, Austria.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The potential environmental effects of nanoparticles (NPs) require interdisciplinary research to assess the risks. One part of a risk assessment concerns exposure, which builds on knowledge of the environmental fate. In this particular case the fate of TiO2 NPs in the water compartment was modelled by applying a second order kinetic rate equation and the DLVO theory. Assumptions were made regarding water parameters such as pH, salt concentration and temperature, as well as regarding particle properties such as Hamaker constant, primary particle size and point of zero charge. The effect of sedimentation was taken into account, but as one would expect the influence of sedimentation on such small particles is very small. The model was implemented in MATLAB®. Results indicate the importance of agglomeration as an important fate mechanism, and that pH andpoint of zero charge are important parameters with regards to agglomeration. Other parameters such as the Hamaker constant, salt concentration and temperature were shown not to have a significant effect, which is in goodcorrelation with empirical studies. Also, we would like to see our model validated by empirical studies. Important implications then are to include a continuous inflowof NPs in the experimental setup and to work at environmentally relevant water properties. For example is the effect of natural organic matter (NOM) on theagglomeration not modelled, despite that its significance has been pointed out in many studies. This is due to a weak link between mathematical expressions andempirical data for this particular part of the model. It is of importance that this linkage is strengthened both by theoretical and empirical studies on NOM aimingat producing mathematical expressions, and empirical data, that can assist fate modelling of NPs.
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| 6. |
- Arvidsson, Rickard, 1984, et al.
(författare)
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The fate of titanium dioxide nanoparticles in the water compartment
- 2009
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Ingår i: SETAC Europe 19th Annual Meeting, 31 May-4 June, 2009, Göteborg, Sweden.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Environmental risk of nanoparticles has been assessed in several studies. Titanium dioxide has been identified as one of the potentially most problematic nanoparticles. It has been shown that a large amount of the titanium dioxide nanoparticles may end up in the water compartment. These risk assessments constitute first estimates and several fate mechanisms are not taken into account. In this study, we propose a risk model that includes the two fate mechanisms sedimentation and aggregation. The sedimentation rate of titanium dioxide nanoparticles is determined using simple laws of motion. Still water is assumed, which gives optimal conditions for sedimentation. It is shown that despite the optimal conditions for sedimentation, the sedimentation rates of particles with a diameter of 100 nm and 1000 nm are about 8 years and 1 month, respectively. One month can be regarded as a long time from a risk perspective, and thus sedimentation is shown not to be an important factor for the removal of titanium dioxide nanoparticles from the water compartment. However, preliminary results show that aggregation can reduce the predicted environmental concentration significantly in a short time. Hence, equilibrium concentrations could be several orders of magnitude lower than what has been indicated in earlier studies. The aggregation of titanium dioxide nanoparticles is modeled using Smoluchowski kinetics and the DLVO theory, which are commonly used in colloid chemistry. The aggregation is shown to depend mainly on the pH of the water compartment and the zero point charge of the particles.
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