An asymmetric membrane of polysulfone (PSf) was synthesized by phase inversion method. Permeation experiments were carried out between 2 to 5 bar pressure, and at temperatures 20 to 45°C. The dense-selective layer of PSf membrane presents regular thickness (about 5 µm), and was not possible to observe the formation of macrovoids in porous layer. The CO₂ permeability through membrane was 18.8 Barrer at 35°C and 2 bar pressure, and this relationship between the pressure and the CO₂ permeability was described adequately by Dual-mode model. The absence of CH₄ permeability at 2 and 3 bar pressure, qualifies the PSf membrane for gases separation with high selectivity in this range.

The objective of this study was to develop non-supported and PET-supported chitosan membranes that were cross-linked with glutaraldehyde, then evaluate their physical–chemical, morphological, and mechanical properties, and evaluate their performance in the separation of ethanol/water and limonene/linalool synthetic mixtures by hydrophilic and target-organophilic pervaporation, respectively. The presence of a PET layer did not affect most of the physical-chemical parameters of the membranes, but the mechanical properties were enhanced, especially the Young modulus (76 MPa to 398 MPa), tensile strength (16 MPa to 27 MPa), and elongation at break (7% to 26%), rendering the supported membrane more resistant. Regarding the pervaporation tests, no permeate was obtained in target-organophilic pervaporation tests, regardless of membrane type. The support layer influenced the hydrophilic pervaporation parameters of the supported membrane, especially in reducing transmembrane flux (0.397 kg∙m⁻²∙h⁻¹ to 0.121 kg∙m⁻²∙h⁻¹) and increasing membrane selectivity (611 to 1974). However, the pervaporation separation index has not differed between membranes (228 for the non-supported and 218 for the PET-supported membrane), indicating that, overall, both membranes had a similar performance. Thus, the applicability of each membrane is linked to specific applications that require a more resistant membrane, greater transmembrane fluxes, and higher selectivity.

Membranas de poliamidas alifáticas são muito utilizadas como barreiras seletivas em processos de microfiltração e ultrafiltração. Neste trabalho membranas de poliamida 66 (PA 66) foram preparadas pelo método de inversão de fases e caracterizadas para aplicação em processos de ultrafiltração. As membranas de PA 66 foram preparadas utilizando dois solventes diferentes, ácido fórmico (AF) e ácido clorídrico (HCl) e água como não-solvente. A análise por Espectroscopia de Infravermelho com Transformada de Fourier (FT-IR) mostrou que a estrutura química da PA 66 não foi alterada com o uso dos solventes na preparação das membranas. O ensaio de compactação com água pura realizado a 1500 kPa de pressão revelou que as membranas preparadas em AF sofreram maior compactação na sua estrutura apresentando fluxo de permeado em torno de 17 L.m-2.h-1 enquanto a membrana preparada em HCl apresentou fluxo de 22,2 L.m-2.h-1. Nos ensaios de ultrafiltração (UF), ambas as membranas apresentaram valores de retenção próximos a 70% para albumina de ovo (45 kDa) e 80% para albumina sérica bovina (69 kDa). Com esse resultado, pode-se concluir que ambas as membranas apresentaram ponto de corte nominal para aplicações em processos de UF.

The presence of metallic ions in raw freshwater is a problem that occurs with greater intensity in periods of drought, due to the intensification of water withdrawal from lower levels of the dams, where there is a higher percentage of organic matter and concentration of metallic ions, including manganese and iron. High levels of these dissolved metals, in addition to altering the organoleptic properties of water, also cause deleterious effects on human and animal health. Given this, the present study aimed to evaluate the use of reverse osmosis in the removal of Mn⁺² and Fe⁺² from raw freshwater, to comply with the MS 5/2017 regulation (Brazilian standard), which establishes the maximum allowable values for Mn⁺² and Fe⁺² ions in drinking water. Three synthetic feed solutions were evaluated to study the retention alone and together of the metals, as well as the water permeability before and after the retention tests with each studied solution. The results showed that the reverse osmosis process retained 99 % of Mn⁺², 93 % of Fe⁺², and 98 % of the two ions together. Regarding the cleaning process, it increased the water permeability of the membrane after exposure to Fe⁺² and the mixture of Mn⁺² and Fe⁺², being reduced after exposure to Mn⁺² only. For the three types of feed, the post-cleaning fouling was estimated at 9.14 − 13.65 % in terms of permeability. Thus, reverse osmosis can be considered a promising process for the treatment of drinking water, and further studies are needed to implement this process in water treatment plants.

Pervaporation is still regarded as an emergent process, with a great potential to be an alternative to classical separation processes, with technical advantages. Chitosan is considered a promising material in next-generation pervaporation membranes, especially hybrid and mixed matrix membranes. This study aimed to evaluate the effect of fillers such as calcium carbonate, kaolinite, graphene, and graphene oxide, added separately at the concentration of 1 wt.%, on the mechanic and physical-chemical properties, microstructure, and hydrophilic pervaporation performance of chitosan membranes cross-linked with glutaraldehyde. The fillers influenced the mechanical and physicochemical properties of the membranes differently. Relative to the hydrophilic pervaporation tests, the presence of calcium carbonate and kaolinite increased membrane efficiency (α_W/E of 1,777 and 1,225 against 611 in the control), whereas graphene reduced the permeate flux (0.341 kg·m⁻²·h⁻¹ against 0.397 kg·m⁻²·h⁻¹ in the control). The addition of graphene oxide increased the flux and permeability of ethanol (0.089 kg·m⁻²·h⁻¹ and 8.66·10⁻¹⁴kg·m⁻¹·s⁻¹·Pa⁻¹ against 0.019 kg·m⁻²·h⁻¹ and 1.74·10⁻¹⁴kg·m⁻¹·s⁻¹·Pa⁻¹ in the control), unlike the other fillers, which had no significant influence on this parameter. Thus, the membranes containing the fillers calcium carbonate and kaolinite were more suited for use in hydrophilic pervaporation (PSI of 842 and 561 against 228 in the control). Graphene did not affect membrane properties (α_W/E of 398 and PSI of 127). Graphene oxide (α_W/E of 174 and PSI of 72) may be considered as an alternative and starting point for the development and research of mixed matrix membranes based on chitosan to be used in target-organophilic pervaporation.