Glycerol is a plasticizer widely used due to its good plasticization efficiency, great availability, biocompatibility and low exudation. It is a renewable raw material that, when introduced in biodegradable films, promotes significant changes in its properties and, thus, guarantees a wide spectrum of application. In this work, corn straw was used to produce cellulose triacetate films from mixtures with glycerol (10%, 20% and 30%). The films were characterized by X-Ray Diffraction, Scanning Electron Microscopy, Thermogravimetric Analysis, Water Vapor Transport Rate and Water Vapor Permeation. The cellulose triacetate films produced with 20% glycerol have high barrier properties, when compared to films with concentrations 0, 10 and 30%.

In order to reduce the total number of experiments for achieving the highest amount of adsorbed Cu2+ (qmax) using pecan nutshells (Carya illinoensis) as biosorbent, a full 2(4) factorial design with two central points was carried out (mass of biosorbent- m, pH, initial metallic ion concentration- C0, time of contact- t). In order to continue the optimization of the system, a central composite surface analysis design with two factors and five central points was carried out. The maximum amount of Cu2+ taken up by the pecan nutshells was 20 mg g-1. These results were confirmed by determining a Cu2+ isotherm using the best conditions attained by the statistical design of experiments.

Neste trabalho foi investigado o uso do Poliestireno sulfonado (PSSNa), produzido a partir de copos plásticos descartáveis de Poliestireno (PS), como aditivo em argamassas e concretos de cimento Portland CPV32. A avaliação do PSSNa como aditivo foi baseada em ensaios de fluidez e resistência mecânica à compressão de corpos de prova. Foi observado, em argamassas com relação água/cimento (a/c) de 0,48, um aumento na fluidez com o aumento das porcentagens de PSSNa (0,25 a 1,00%). A adsorção do PSSNa sobre as partículas de cimento melhora a dispersão dos componentes da argamassa, aumentando a resistência mecânica à compressão dos corpos de prova após a cura. A aplicação do PSSNa em concreto apresentou o mesmo efeito. O abatimento do concreto sem PSSNa foi de 50 mm, atingindo cerca de 200 mm com o uso do polieletrólito. Devido à elevada plasticização observada é possível empregar o PSSNa como aditivo redutor de água. Foi produzido um concreto com o mesmo abatimento da referência sem aditivo reduzindo-se a quantidade de água em 20,8%. O ganho de resistência mecânica à compressão obtido foi de 21,5 e 26,3 %, respectivamente aos 7 e 28 dias de cura. Estes resultados mostraram que soluções de PSSNa podem atuar eficientemente como aditivo superplastificante ou redutor de água em argamassas e concretos.

In this work an investigation was made of the effects from adding PSSNa, obtained from disposable polystyrene (PS) cups, as admixture agent in mortars and concrete with varying ratios from 0.25 to 1.00%. The evaluation of PSSNa as additive was based on results of fluidity and mechanical strength to compression. In mortars with water/cement ratio of 0.48, an increase in flow was observed when the dosage of PSSNa varied from 0.25 to 1.00%. The dispersion of mortar components was improved due to the adsorption of PSSNa on cement particles, which increased the mechanical strength of mortars. Similar results were obtained with the application of PSSNa to concrete. The slump of the concrete taken as reference was 50 mm, while for the concrete with PSSNa it reached about 200 mm. Because of its plasticization of concrete, PSSNa can be used as additive to reduce the amount of water required. For instance, a concrete with the same slump of the reference concrete was produced using PSSNa and a reduction of 20.8% in the volume of water. The increase in mechanical strength was 21.5 and 26.3%, respectively, at 7 and 28 days of curing. These results showed that PSSNa solutions can act as superplasticizer or as admixture to reduce the amount water in mortars and concretes.