41 research outputs found
Real time Takagi-Sugeno fuzzy model based pattern recognition in the batch chemical industry
No full textExploring the Use of Molecular Docking to Identify Bioaccumulative Perfluorinated Alkyl Acids (PFAAs)
No full textMethods to predict the bioaccumulation
potential of per- and polyfluorinated
alkyl substances (PFAS) are sorely needed, given the proliferation
of these substances and lack of data on their properties and behavior.
Here, we test whether molecular docking, a technique where interactions
between proteins and ligands are simulated to predict both bound conformation
and interaction affinity, can be used to predict PFAS binding strength
and biological half-life. We show that an easy-to-implement docking
program, Autodock Vina, can successfully redock perfluorooctanesulfonate
(PFOS) to human serum albumin with deviations smaller than 2 Å.
Furthermore, predicted binding strengths largely fall within one standard
deviation of measured values for perfluorinated alkyl acids (PFAAs).
Correlations with half-lives suggest both membrane partitioning and
protein interactions are important, and that serum albumin is only
one of a number of proteins controlling the fate of these chemicals
in organisms. However, few data are available for validation of our
approach as a broad screening tool, and available data are highly
variable. We therefore call for collection of new data, particularly
including proteins other than serum albumin and substances beyond
perfluorooctanoic acid (PFOA) and PFOS. The methods we discuss in
this work can serve as a framework for guiding such data collection
Mass Integration for Rigorous Process Modelling: A Sequential Approach for Direct Recycling
No full textSequential Ordering Algorithm for Mass Integration: The Case of Direct Recycling
No full textIn the last three decades much effort has been devoted in process integration as a way to improveeconomic and environmental performance of chemical processes. Although the established frameworkshave undergone constant refinement toward formulating and solving complicated processintegration problems, less attention has been drawn to the problem of sequential applications ofmass integration. This work addresses this problem by proposing an algorithm for optimal orderingof the process sinks in direct recycling problems, which is compatible with the typical massintegration formulation. The order consists in selecting the optimal sink at a specific integrationstep given the selection of the previous steps and the remaining process sources. Such order isidentified through a succession of preemptive goal programming problems, namely of optimizationproblems characterized by more objectives at different priority levels. Indeed, the target foreach sink is obtained by maximizing the total flow recycled from the available process sources tothis sink and then minimizing the use of pure sources, starting from the purest one; the hierarchyis respected through a succession of linear optimization problems with a single objective function.While the conditional optimality of the algorithm holds always, a thorough statistical analysis includingstructured to random scenarios of process sources and process sinks shows how frequentlythe sequential ordering algorithm is outperformed with respect to the total recycledamount by a different selection of process sinks with the same cardinality. Two more case studiesproving the usefulness of ordering the process sinks are illustrated. Extensions of the algorithmare also identified to cover more aspects of the process integration framework
Nonlinear model predictive control of an industrial batch reactor subject to swelling constraint
No full textSwelling Constrained Control of an Industrial Batch Reactor Using a Dedicated NMPC Environment: OptCon
No full textHazard assessment of fluorinated alternatives to long-chain perfluoroalkyl acids (PFAAs) and their precursors : Status quo, ongoing challenges and possible solutions
No full textBecause of concerns over the impact of long-chain perfluoroalkyl acids (PFAAs) on humans and the environment, PFAAs and their precursors are being substituted by alternative substances including fluorinated alternatives that are structurally similar to the substances they replace. Using publicly accessible information, we aimed to identify the status quo of the hazard assessment of identified fluorinated alternatives, to analyze possible systemic shortcomings of the current industrial transition to alternative substances, and to outline possible solutions. Fluorinated alternatives, particularly short-chain PFAAs and perfluoroether carboxylic and sulfonic acids (PFECAs and PFESAs), possess high environmental stability and mobility implying that they have a high global contamination potential. In addition to their potential for causing global exposures, certain fluorinated alternatives have been identified as toxic and are thus likely to pose global risks to humans and the environment. Various factors, particularly the information asymmetry between industry and other stakeholders, have contributed to the current lack of knowledge about the risks posed by fluorinated alternatives. Available cases show that a non-fluorinated substitution strategy (employing either chemical or functionality substitutions) can be a possible long-term, sustainable solution and needs to be further developed and assessed.</p
On-line model based control of a safety constrained batch reactor subject to recipe uncertainties
No full textPolybrominated Diphenyl Ether (PBDE) Accumulation in Farmed Salmon Evaluated Using a Dynamic Sea-Cage Production Model
No full textUsing COSMOtherm to predict physicochemical properties of poly- and perfluorinated alkyl substances (PFASs)
No full textRecently, there has been concern about the presence of poly- and perfluorinated alkyl substances (PFASs) in the environment, biota and humans. However, lack of physicochemical data has limited the application of environmental fate models to understand the environmental distribution and ultimate fate of PFASs. We employ the COSMOtherm model to estimate physicochemical properties for 130 individual PFASs, namely perfluoroalkyl acids (including branched isomers for C(4)-C(8) perfluorocarboxylic acids), their precursors and some important intermediates. The estimated physicochemical properties are interpreted using structure-property relationships and rationalised with insight into molecular interactions. Within a homologous series of linear PFASs with the same functional group, both air-water and octanol-water partition coefficient increase with increasing perfluorinated chain length, likely due to increasing molecular volume. For PFASs with the same perfluorinated chain length but different functional groups, the ability of the functional group to form hydrogen bonds strongly influences the chemicals' partitioning behaviour. The partitioning behaviour of all theoretically possible branched isomers can vary considerably; however, the predominant isopropyl and monomethyl branched isomers in technical mixtures have similar properties as their linear counterparts (differences below 0.5 log units). Our property estimates provide a basis for further environmental modelling, but with some caveats and limitations.</p
