Colloidal particle deposition on microchannel walls, for attractive and repulsive surface potentials

Autor(es)

Porto Santos, Tatiana ^{[1, 2]} ; Cunha, Rosiane Lopes ^[2] ; Tabeling, Patrick ^[1] ; Cejas, Cesare M. ^[1]

Afiliação do(s) autor(es)

^[1] PSL Res Univ, ESPCI Paris, Inst Pierre Gilles Gennes IPGG, Nanostruct Lab, Microfluid, MEMS, CNRS, Chim Biol Innovat CBI, UMR 82, 6 Rue Jean Calvin, F-75005 Paris - France

^[2] Univ Estadual Campinas, Fac Food Engn, Dept Food Engn, Rua Monteiro Lobato 80, BR-13083862 Campinas - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Physical Chemistry Chemical Physics; v. 22, n. 30, p. 17236-17246, AUG 14 2020.
• Citações Web of Science: 1

Resumo

Surface interactions are an interplay of van der Waals adhesion forces with electrostatic charges. In colloidal deposition, at low ionic strengths, the Debye layer is sufficiently large to prevent particles from approaching the surface. It is only with the addition of higher salt concentrations, typically above 0.1 M, that surface charges are screened for interactions to take placeviavan der Waals-adhesion forces. This is true for repulsive charges, when both surfaces have similar charges and signs of the zeta potential are the same. However, with attractive charges, where zeta potential signs are opposite, the result is also opposite. By combining microfluidic experiments, theory, and numerical simulations, results show that when charges are attractive, particle deposition instead increases at low ionic strengths (at greater Debye lengths), at rates controlled by van der Waals forces but assisted by electrostatic forces. We propose a mechanism where particles approach the wall, mobilized by electrostatic attraction, up to a distance where van der Waals forces come into play, collecting the particles at the wall, which electrostatic forces alone are unable to achieve, owing to hindered diffusion. The present work thus allows us to understand the different mechanisms that govern deposition in the case where surface charges are opposite. (AU)

• Processo FAPESP: 17/18109-0 - Desenvolvimento de um analisador de estabilidade de emulsões utilizando microfluídica
• Beneficiário: Tatiana Porto dos Santos
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 19/07744-1 - Utilização de dispositivos microfluídicos para avaliação de estabilidade de emulsões
• Beneficiário: Rosiane Lopes da Cunha
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 18/18103-4 - Estudo sistemático da coalescência em emulsões óleo-em-água e água-em-óleo em dispositivos microfluídicos
• Beneficiário: Tatiana Porto dos Santos
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado