排序方式: 共有32条查询结果,搜索用时 15 毫秒
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Ina Vollmer Michael J. F. Jenks Mark C. P. Roelands Robin J. White Toon van Harmelen Paul de Wild Gerard P. van der Laan Florian Meirer Jos T. F. Keurentjes Bert M. Weckhuysen 《Angewandte Chemie (International ed. in English)》2020,59(36):15402-15423
Increasing the stream of recycled plastic necessitates an approach beyond the traditional recycling via melting and re‐extrusion. Various chemical recycling processes have great potential to enhance recycling rates. In this Review, a summary of the various chemical recycling routes and assessment via life‐cycle analysis is complemented by an extensive list of processes developed by companies active in chemical recycling. We show that each of the currently available processes is applicable for specific plastic waste streams. Thus, only a combination of different technologies can address the plastic waste problem. Research should focus on more realistic, more contaminated and mixed waste streams, while collection and sorting infrastructure will need to be improved, that is, by stricter regulation. This Review aims to inspire both science and innovation for the production of higher value and quality products from plastic recycling suitable for reuse or valorization to create the necessary economic and environmental push for a circular economy. 相似文献
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Residual Monomer Reduction in Polymer Latex Products by Extraction with Supercritical Carbon Dioxide
Marijke Aerts Jan Meuldijk Maartje Kemmere Jos Keurentjes 《Macromolecular Symposia》2011,302(1):297-304
Summary: Extraction of residual monomer from a latex product with supercritical carbon dioxide ((sc)CO2) in a column was studied. Operating conditions were chosen at 35 °C and 100 bar. For reducing the residual styrene level in a polystyrene latex from 104 ppm to 100 ppm and from 104 ppm to 10 ppm, a countercurrent bubble column with latex as continuous and (sc)CO2 as dispersed phase is suggested. Monomer partitioning was demonstrated to be a key parameter in the equipment design. Monomer transport was found to be governed by the shuttle effect, caused by Brownian motion of the latex to and from the H2O/CO2 interface. The drift-flux approach was followed to determine the column flooding conditions. Small column volumes are obtained. (sc)CO2 is a promising extraction medium for residual monomer reduction in latex products. Performance towards steam stripping is better as the final residual monomer level becomes lower. 相似文献
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It is well known that sonochemistry is less efficient at high acoustic intensities. Many authors have attributed this effect to decoupling losses and shielding of the acoustic wave. In this study we investigate both phenomena for a 20 kHz ultrasound field with an intensity ranging from 40 to 150 W/cm2. Visualization of the bubble cloud has demonstrated that the void fraction below the ultrasound horn increases more than proportional with increasing power input. Nevertheless, the energy coupling between the horn and the liquid remains constant; this implies that decoupling losses are not reinforced for larger bubble clouds. On the contrary, microphone measurements have shown that due to the larger bubble cloud a substantial part of the supplied energy is lost at high power inputs. In striving towards more efficient sonochemistry, reduction of shielding appears as one of the major challenges. 相似文献
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Horneman DA Ottens M Keurentjes JT van der Wielen LA 《Journal of chromatography. A》2007,1157(1-2):237-245
In the production of monoclonal antibodies, separate chains of the antibody are often present in the product mixture as well as other contaminating proteins. These fragments should be removed from the whole antibodies. This paper shows the purification of monoclonal immunoglobulin G (IgG) from its heavy chain contaminant. The heavy chain fragment is simulated experimentally using bovine serum albumin (BSA), which has approximately the same molecular weight. The purification is performed using traditional size-exclusion chromatography (SEC) and using surfactant-aided SEC (SASEC), testing two different surfactants (C(12)E(23) and Tween20) and two different gels (Sephacryl S200HR and Sephacryl S300 HR). Pulse experiments show that with SASEC both BSA and IgG are more distributed towards the solid phase than compared to using SEC. This effect is larger on IgG, the largest component than on BSA. As a consequence, azeotropes will be formed at a specific surfactant concentration. Above this concentration the selectivity is reversed and increased to values higher than obtained with conventional SEC. At 7.5% (w/w) of C(12)E(23), BSA actually elutes before IgG. These experiments further show that when using SASEC larger productivity, higher yields and lower solvent consumption can be achieved without loss of purity of IgG when compared to conventional SEC. Mathematical simulation of the separation of BSA and IgG using simulated moving bed (SMB) chromatography indicates a large increase in productivity when applying a surfactant gradient in SASEC SMB compared to conventional isocratic SEC-SMB. Furthermore, solvent consumption reductions with a factor 15 prove possible as well as concentrating the IgG by a factor 2. 相似文献
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Horneman DA Ottens M Keurentjes JT van der Wielen LA 《Journal of chromatography. A》2006,1113(1-2):130-139
The selectivity of size-exclusion chromatography (SEC) can be modified by adding non-ionic micelles to the mobile phase. Surfactant-aided size-exclusion chromatography (SASEC) can therefore very well be performed in a gradient mode on an SMB, as is reported in this paper. A method has been developed for correctly positioning a micellar gradient over an SMB. The method is applied for size-exclusion chromatography with the non-ionic surfactant C12E23 as gradient forming solute, and demonstrated by applying it to a relevant chromatographic protein separation problem. 相似文献
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Computer simulations based on Discrete Element Method have been performed in order to investigate the influence of interparticle interactions on the kinetics of self-assembly and the mechanical strength of nanoparticle aggregates.Three different systems have been considered.In the first system the interaction between particles has been simulated using the JKR (Johnson,Kendall and Roberts) contact theory,while in the second and third systems the interaction between particles has been simulated using van der Waals and electrostatic forces respectively.In order to compare the mechanical behaviour of the three systems,the magnitude of the maximum attractive force between particles has been kept the same in all cases.However,the relationship between force and separation distance differs from case to case and thus,the range of the interparticle force.The results clearly indicate that as the range of the interparticle force increases,the self-assembly process is faster and the work required to produce the mechanical failure of the assemblies increases by more than one order of magnitude. 相似文献
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Maartje F. Kemmere Martijn W.A. Kuijpers Jos T.F. Keurentjes 《Macromolecular Symposia》2007,248(1):182-188
A strong viscosity increase upon polymerization hinders radical formation during an ultrasound-induced bulk polymerization. Since CO2 acts as a strong anti-solvent for most polymers, it can be used to reduce the viscosity of the reaction mixture. In this work, a process for the ultrasound-induced polymerization in CO2-expanded fluids has been developed. Temperature oscillation calorimetry has been applied to study the influence of CO2 on the viscosity during the ultrasound-induced polymerization. In contrast to polymerizations in bulk, the results show that a low viscosity is maintained during polymerization reactions in CO2-expanded methyl methacrylate (MMA). As a consequence, a constant or even increasing polymerization rate is observed when pressurized CO2 is applied. Moreover, the ultrasound-induced polymer scission in CO2-expanded MMA is demonstrated, which appears to be a highly controlled process. Finally, a preliminary sustainable process design is presented for the production of 10 kg/hour pure PMMA (specialty product) in CO2-expanded MMA by ultrasound-induced initiation. 相似文献
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在一系列H模放电条件下,建立了一个旨在研究等离子体温度分布剖面不变性的数据库。介绍了数据库建立过程中要解决的关键问题和所用软件,对等离子体温度分布剖面不变性及芯部约束与边缘参数的关系进行了研究。 相似文献
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