RESUMO Polyols as solvents are widely and successfully used in various methodologies to obtain zinc oxide nanostructures. One of the main reasons of using polyols is related to its capacity to prevent the agglomeration of ZnO nanoparticles during the synthesis and to promote a more stable colloidal solution of it. In this work it is presented, for the first time, the obtaining of nanostructured ZnO by a polyol mediated solvothermal synthesis using zinc nitrate as precursor. The combination of the zinc source with sodium hydroxide in a polyol medium with PVA as dispersing agent provided a simple process for obtaining nanostructured ZnO. The zinc oxide nanostructures obtained were characterized by UV-visible, XRD, FESEM, TEM, DLS and BET. As result, was obtained a wurtzite phase with hexagonal structure with crystallite size of 12 nm and, according to TEM micrographs, an average size of 14 nm, which was corroborated to other analyses.

Abstract The clay minerals have characteristics and properties that allow their applicability in the cosmetic area, being incorporated into formulations as an active principle. Therefore, the aim of this work is characterizing and evaluating the influence of a clay from Miracema do Norte, Tocantins, Brazil, named Clay V, on the physicochemical characteristics of a hydrophilic gel of Aristoflex®, a copolymer of the neutralized acryloyldimethyltaurate and vinylpyrrolidone sulphonic acid. Clay V was decontaminated and characterized through microbiological evaluation, crystalline phases present by X-Ray Diffraction (XRD), chemical composition by X-Ray Fluorescence (XRF), thermogravimetric analysis (TGA) and granulometric distribution by sieving. Gels were prepared using Clay V with particles in the range ≤ 180 μm in three different concentrations: 1%, 3% and 5% (w/w) and a standard gel without clay. The formulations were evaluated according to organoleptic characteristics, pH, viscosity, spreadability and the centrifugation test. The microbiological evaluation showed that the clay sample is in compliance with the parameters established by the legislation. The following mineral phases were identified by XRD: kaolinite, illite, vermiculite and quartz, mainly composed of silica and alumina according to XRF. Thermal analysis showed that the clay has two thermal decomposition reactions, the largest being 547.6°C. The granulometric analysis identified that the largest fraction (63.22%) was of particles with sizes greater than 710 μm. The organoleptic characteristics presented by the formulations were suitable, with characteristic gel odor, homogeneous appearance, soft and refreshing texture and staining based on the concentration of Clay V used. The obtained pH values were within the range between 5.5 and 6.5, and it was verified that the gel has high spreadability, distributing evenly on the skin. The values obtained for viscosity showed that the formulations are non-Newtonian fluids with pseudoplastic behavior. The centrifugation test showed that the formulations are stable, with no phase separation. The results obtained with the tests showed that the natural clay V material is beneficial in cosmetic products and can be used for incorporation in cosmetic gel formulations of Aristoflex® type.

The silicon alkoxides-based coating is an alternative to control the release of cytotoxic ions through metal implants. This study evaluated the influence of the number of layers of a hybrid coating on the surface of austenitic stainless steel AISI 316L on the corrosion resistance. This coating was produced from the precursors of silicon alkoxides 3-(trimethoxysilyl)propyl methacrylate (MAP) and tetraethoxisylane (TEOS) obtained by sol-gel process, and easily applied by dip-coating. Results indicated that a single layer of coating in the substrate showed a better protection than two layers. This single layer developed by the combination of the precursors TEOS-MAP was enough to create a compact and uniform film with good adherence to AISI 316L and higher electrochemical development. A single layer of TEOS-MAP coating is more adequate as a protective coating for the AISI 361L than the sample subjected to two layers and the non-coated substrate, because this film ensures its integrity in an aggressive environment.

Oil is a major pollutant of water resources, affects aquatic life, causing environmental degradation. Currently there is an increase in studies of membrane applied to separation of oil-water. Among these membranes, there are composite membranes, which show as main characteristic an association of organic and inorganic membrane properties. In a tangential flow process, the ceramic tube (support) is responsible for the mechanical strength of the membrane and the selective barrier property of the membrane is established by the polymer. The aim of this work is the application of α-alumina/polyamide 66 composite membrane in the retention of sunflower oil from oil-water emulsions and the study of resistance of such membranes in ultrafiltration processes. The α-alumina ceramic tubes were impregnated internally with a solution of polyamide 66 (PA66) (5% w/v) and tested with distilled water and sunflower oil solutions at concentrations of 50, 100 and 200 mg·L-1. Membranes impregnated with PA66 showed a sunflower oil retention between 53.5 and 99.5% and superior membrane resistance (MR) to the permeate flux (1.92 x 1013 a 5.52 x 1013) which explains the decrease in the permeate volume.

Many polymers have been used as biomaterials due to their physicochemical characteristics and structural versatility. However, usage on the human body requires sterilization in order to prevent microbial contamination and diminish the risk of rejection or inflammation. This study presents the use of thermogravimetric analysis (TGA) as an alternative to monitor the presence of residual ethylene oxide from polymers sterilization processes. This is a simple technique and does not require sample preparation stages which can imply in some ethylene oxide loss. Ethylene oxide has been used to sterilize polymeric biomaterials, but with restrictions in the amount used due to the difficulty in removing the toxic waste after the sterilization procedure. Samples of commercial (PEEKc) and medical (PEEKm) grade poly(ether ether ketone) (PEEK) were manufactured in the form of cylindrical tubes, hygienized and sterilized with ethylene oxide. PEEKs showed no chemical changes, but exhibited thermal changes by TGA, which evidenced weight loss between 100 and 500ºC that was attributed to the removal of residual ethylene oxide, so this technique, at a 10ºC‧min-1 heating rate, can be used to monitor the sterilization processes.

This paper aims the morphological and structural characterization of ceramic membranes of mullite and their application in the removal of Escherichia coli. A complex irregular structure presented by the pores of the membrane was verified by scanning electron microscopy (SEM). The average pore size and distribution were determined by mercury intrusion porosimetry. The average pore size of the material presented was 0,39 µm. Microfiltration tests resulted in a protein retention of 46, 76 and 89% for trypsin (TR), egg albumin (EA) and bovine serum albumin (BSA), proving the efficiency of the membrane microfiltration tests for molecular weight of 69 kDa. The application of the membranes on the retention of gram-negative bacterium E. coliresulted in a 66% efficiency at a pressure of 200 kPa and a 98% efficiency when applied a pressure of 50 kPa. Therefore, the use of mullite membranes show limited efficiency towards bacteria retention. Nevertheless, they present fluxes similar to other materials proposed in the literature.

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.

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.

Polymers are often used to coat tablets for controlled drug release. The purpose of this study is to evaluate the solubility of the HPMC and PVA blend compared to isolated polymers in solutions with a pH of biological fluids (6 and 1.2) and the dissolution of capsules obtained using theophylline granules produced with the HPMC/PVA 25/75 blend as a matrix and as coating. HPMC is completely solubilized in the medium that simulates the pH of the stomach and intestine, and PVA is the polymer that allows controlling the solubility of the blend in the medium, with a differents pH. The dissolution time was monitored by UV absorbance with maximum theophylline at 269 nm. The theophylline was released immediately in the granules, and in the capsules 78.4% after 30 minutes and 97.4%, after 120 minutes. Thus, PVA can potentially control the drug solubilization, contributing to obtaining modified release systems.