Effect of non-solvents used in the coagulation bath on morphology of PVDF membranes

Abstract

The aim of this paper was to prepare a poly (vinylidene fluoride) (PVDF) membrane using different non-solvents in the coagulation bath for the phase inversion method. In order to increase the mechanical strength of membranes, facing the pressure of work, was used a macro-porous polyester support. The morphology and structure of the resulting membranes were evaluated by scanning electron microscopy, porosity measurements, water and 1-octanol uptake, contact angle, pure water flux, hydraulic permeability and hydraulic resistance. The morphology and pure water flux changed significantly using ethanol (symmetric membrane) and/or water (asymmetric membrane) as the non-solvent. The symmetric membrane presented a high hydrophobic surface (water contact angle ~136°) and a higher pure water flux and porosity than the asymmetric membrane, which presented a lower hydrophobicity surface (water contact angle ~90°). The morphologies obtained suggest different applications.

Characteristics and Performances of Blended Polyethersulfone and Carbon‐Based Nanomaterial Membranes: Effect of Nanomaterial Types and Air Exposure

“…Porosity is defined as the pore volume divided by the total volume of the membrane. Porosity is determined by the gravimetric method, in which the dry and wet membrane period was measured to estimate the amount of liquid present in the membrane , . Porosity was then calculated by Eq.…”

Polyvinylidene fluoride membranes impregnated at optimised content of pristine and functionalised multi-walled carbon nanotubes for improved water permeation, solute rejection and mechanical properties

“…As a result of higher water (i.e. non-solvent) transfer during membrane formation, higher porosity is hence expected in the CNTs-O/PVDF membrane matrix (Thürmer et al, 2012). However, as shown in Figure 3, CNTs-O/PVDF membranes have a slightly lower porosity than CNTs-P/PVDF membranes.…”

“…The membrane volume porosity (ε) is defined as the ratio between the volume of the pores and the total volume of the porous membrane. The volume of the pores was determined from measurement of the volume of water that occupied the pores of a wetted membrane using a mass difference between a wet and dry membrane (Equation 1) (Thürmer et al, 2012;Zhao et al, 2013).…”

“…The growth of the dense top layer will be halted when sufficient non-solvent medium have diffused into the sublayer solution to create the pores. The porous surface forms when the non-solvent inflow is higher than the solvent outflow (Thürmer et al, 2012). the coagulation process as a result of increased viscosity imparted by CNTs (Table 2).…”

Microdominios lipídicos ricos em fosfatase alcalina em filmes Langmuir-Blodgett para obtenção de uma superfície de Ti osteoindutora

“…Biomineralization. Figura 9 -Imagens de micrografias de monocamadas de DPPC obtidas por: microscopia de fluorescência em subfase de NaCl 0,2 mol L -1 em  = 16,9 mN m -1 (A), microscopia BAM em subfase de tampão fosfato 75 mmol L -1 (pH 7,4) em  = 10 mN m -1 (B) (Modificados das referências [87,88] Figura -Diagrama esquemático das forças entre as interfaces sólido-ar (SV), sólido-líquido (SL) e líquido-ar (LV), responsáveis pelo ângulo de contato da gota do líquido sobre a superfície sólida (Modificado da referência [130] Figura 32 -Variação de  em função do tempo para monocamadas de DMPA em subfase de CaCl2 70 mmol L -1 na ausência e presença de diferentes razões molares de TNAP:DMPA (sem polidocanol) (A) e ciclos de compressão e expansão de isoterma -A de monocamada mista de TNAP:DMPA 1:1400 em subfase de CaCl2 70 mmol L…”