Project Details
Projekt
Continuous classification of nanoparticles by selective agglomeration according to size, composition and surface properties
Applicant
Professorin Dr.-Ing. Doris Segets
Subject Area
Mechanical Process Engineering
Term
since 2017
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 382100499
Aim of this project is the development of a scalable, continuously operated process for the multidimensional separation of colloidal nanoparticles (NPs) below 20 nm via selective agglomeration. Selective agglomeration is based on the gradual flocculation of less stable NPs by the addition of an appropriate non-solvent (poor liquid) and subsequent flock isolation, while more stable NPs stay as well-dispersed primary particles in solution. By combining distinct steps of selective agglomeration, multidimensional fractionation according to size, composition and surface properties is achieved. The focus of the second funding period will be threefold. First, multidimensional separation will be demonstrated on lab-scale via the serial connection of different selective agglomerations in batch mode. Central challenge is to identify the best sequence of individual separation steps to achieve true 2D fractionation according to size and composition or size and surface properties. In addition, appropriate combinations with other separation strategies, that are available via the collaboration partners of this PP, will be analyzed as well. Then, at least one serial batch procedure will be selected and scaled up to a truly continuous process. This comes with the challenge of adopting concentrations, residence times and flow rate ratios in such a way that individual separation steps by selective agglomeration can be combined with each other in one continuous operation line. Process control is compulsory to automatically realize the switch between alternatingly operated membrane modules during flock isolation when selective agglomeration is applied. Finally, the concepts developed for phase-pure materials will be generalized and made accessible to more complex, however technically highly relevant organic-inorganic hybrid materials. Here graphene hybridized TiO2 particles (photocatalysis) and carbon functionalized Si particles (anode material in batteries) will be used as benchmark materials. They have in common that during processing, in particular during dispersion, new surface is created that in parts strongly deviates from the surface properties of the target material. Thus, after the sequence of powder synthesis, powder suspension and dispersion, 2D separation by size and surface properties must be realized for high performance photocatalysts or battery anodes, while particles not matching the specifications need to be sorted out and recycled. At the end of this PP, selective agglomeration will have been established as a powerful method for the scalable, multidimensional classification of colloidal NPs. Moreover, new standards for multidimensional NP characterization will have been developed and suitable combinations with other separation strategies (centrifugation, (di)electrophoreses, flotation) will have been identified and evaluated with regard to their limitations and opportunities together with the collaboration partners.
DFG Programme
Priority Programmes
