In this study, polymer/ceramic composite membranes were prepared and characterized. The polymer used was polyamide 66 (PA66) deposited by dip coating on the inner surface of α-alumina-based (Al2O3) microporous tube. A coating on the ceramic support surface and the formation of the selective layer was analyzed by scanning electron microscopy (SEM) in membranes with one (PA-1) and two layers (PA-2). The results of mercury porosimetry showed that the deposition of the polyamide layers decreases the average pore size. The PA-1 presented an average pore size of 0.35 μm, while the PA-2 presented two peaks of 0.18 and 0.56 μm. Both showed a superior performance than the ceramic support (pore diameter of 0.65 μm). Although, the permeate flux was higher with an impregnation membrane, the number of layers (one or two) just introduced a slight difference in pore statistical analysis. The order of rejection coefficient values for protein molecules is BSA > egg albumin > trypsin. The permeation tests showed that the composite membrane can be applied in ultrafiltration processes with MWCO of 69 kDa.

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.

In the present study, polyamide 66 (PA 66) membranes were prepared by phase inversion method and characterized in order to verify their potential application in ultrafiltration processes. PA 66 membranes were prepared using two different solvents, formic acid (FA) and hydrochloric acid (HCl), and water as a non-solvent. Fourier-transform infrared spectroscopy (FT-IR) showed that the chemical structure of PA 66 was not altered by the use of solvents in the preparation of membranes. The compaction experiment with pure water performed at a pressure of 1500 kPa revealed that membranes prepared with FA undergo greater compaction of its structure and had a permeate flux value of approximately 17 L.m-2.h-1 whereas the membrane prepared with HCl had a permeate flux of 22.2 L.m-2.h-1. In the ultrafiltration experiment, both membranes had retention values around 70% for egg albumin and 80% for bovine serum albumin. Based on this result, one concludes that both membranes had nominal cut off values for application in ultrafiltration processes.

Polymers are vastly employed for numerous purposes in different industrial segments and generate soaring quantities of discarding in the environment. This research analyzed the degradability/biodegradability of polypropylene films (PP) and Bioriented polypropylene (BOPP) polymers after 11 months interred in the São Giácomo landfill in Caxias do Sul. Comparing the buried PP film to a sample of virgin PP, two peaks of degrading activity appeared at the TG curve as well as structure modification typified by occurrence of new absorption bands at FTIR, which can be credited to changes in crystallinity. Thermal analysis carried out on the buried PP and BOPP showed decreases in the percentage of crystallinity due to chain scission. The major reduction was observed in the PP, since its crystallinity is a consequence of polymerization instead of chain orientation processes, as in BOPP. Cracks and erosion of the polymer surface were detected in both PP and BOPP, indicating degrading processes by microorganisms.

The membranes properties prepared from water/formic acid (FA)/ polyamide 66 (PA66) and water/hydrochloric acid (HCl)/polyamide 66 (PA 66) systems has been studied. The different solvents interact distinctly with the polymer, affecting the membrane morphology. The asymmetric structure of the membranes showed a dense top layer and a porous sublayer. The membranes M-HCl prepared from HCl/PA 66 system showed a larger dense layer (around 23 μm) in compared to those prepared from FA/PA 66 system (M-FA) (around 10 μm). The membrane morphology was a determinant factor in results of water absorption, porosity and pure water flux. The lower thickness of dense layer in M-FA membranes resulted in a higher water absorption and, consequently, porosity, approximately 50%, compared with M-HCl membranes, approximately 15%. The same trend was observed to permeate flux, the lower thickness of dense layer higher pure water flux.

Membranas de polisulfona/poliuretano foram preparadas pelo método de inversão de fases. As membranas preparadas com a adição de fotoiniciador foram irradiadas com lâmpada ultravioleta para aumentar a interação entre os polímeros e o suporte de poliéster utilizado. As membranas com e sem adição de fotoiniciador foram caracterizadas através dos testes de resistência química, capacidade de adsorção de água, determinação de densidade, porosidade, morfologia e fluxo permeado de água. A membrana fotoiniciada apresentou poros com paredes bem definidas e maior estabilidade nos testes de resistência química e fluxo permeado. Ambas as membranas apresentaram valores aproximados na adsorção de água e porosidade.

Polysulfone/polyurethane membranes were prepared by the phase inversion method and irradiated with an ultraviolet light bulb to increase the interaction between polymers and the polyester support. The membranes with and without addition of fotoinitiator were characterized using tests of chemical resistance, water adsorption capacity, density and porosity determination, water permeate flux and membrane morphology. The membrane treated with the fotoinitiator exhibited well defined pores and greater stability in the tests of chemical resistance and water permeate flux. Both membranes had similar values for the water adsorption and porosity.