André Luiz Fiquene de Brito

Avaliação da integridade e da retenção de metais pesados em materiais estabilizados por solidificação

As the quantity of hazardous industrial wastes increases significantly owing to rapid industrialization, its appropriate management is required to reduce adverse impacts on humans and ecosystems. This work evaluated the integrity and retention of heavy metals in materials stabilized by solidification. It was adopted a completely randomized design with a single factor, that is, the averages of four treatments were compared (A, B, C and D) with 0, 40, 50 and 60% respectively contaminants and three repetitions. Portland cement, bentonita and lime-fly ash binders were used to solidify a synthetic heavy metal sludge containing oxides of Cd2+, Pb2+ e Cu2+. It can be concluded that the treatment influenced the result of leaching of cadmium, lead and copper. The treatments showed that the concentrations of solubilized and leachate extract increase with the amount of cadmium, lead and copper added. The highest price was found in the material from the treatment D, that presented leaching equal to 32.815 mg.kg-1 for cadmium and 29.769 mg.kg-1 for the lead. For the tests of integrity/durability, it was found that increasing the absorption of water has caused resistance to compression decreased. The use of cement, calcium hydroxide and sodium bentonite were ideal for retention of heavy metals, avoiding leaching and solubilization for its the environment.

Loss on drying, calcium concentration and pH of fluoride dentifrices

Introduction: Fluoride dentifrices containing calcium carbonate have advantages such as control of dental plaque and progression of dental caries, also contributing to oral hygiene, represent most dentifrices marketed in Brazil. Aim: To evaluate the physicochemical properties of seven fluoride dentifrices containing calcium carbonate in relation to hydrogen potential (pH), loss on drying and calcium concentration. Materials and Methods: Data collection was performed using the potentiometric method for pH ranges, gravimetric analysis for loss on drying and atomic absorption spectrometry for the concentration of calcium ions. All tests were performed in triplicate and the analysis was performed entirely at random according to one-way analysis of variance at 5% significance level. Results: The pH values were alkaline and ranged from 8.67 (Oral-B 123®) to 10.03 (Colgate Máxima Proteção Anticáries®). The results of loss on drying ranged from 33.81% (Oral-B 123®) to 61.13% (Close Up®), with significant differences between brands tested. In relation to the calcium content, the highest and lowest concentrations were found in dentifrices Even® (155.55 g/kg) and Colgate Ultra Branco® (129 g/kg), respectively, with significant difference (P < 0.05). Conclusion: Fluoride dentifrices analyzed showed alkaline pH and high levels of loss on drying and calcium concentration. However, these physicochemical characteristics differed according to the different brands tested.

Study of the Stabilization/Solidification of Oily Sludge of Oil through of Scanning Electron Microscopy and Diffraction of X-Rays

The objective of this study was to evaluate materials stabilized by solidification after incorporation of oily sludge of oil in a ordinary Portland cement matrix through analysis tests Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The research was divided into two main stages. In the first step the preparation of the specimens composed of cement, sand and oily sludge of oil and the second step was to evaluate the stabilization/solidification material via SEM and XRD analysis. The results of the XRD identified the characteristic peaks of portlandite, calcium silicate and ettringite. The same occurred with the SEM that detected the presence of the main products of the reactions of cement hydration. The results showed that the oily sludge of oil did not interfere with cement hydration reactions.

Characterization of National Clays after Acid Treatment and Thermal

The clay types, kaolinite and smectite, are the most used industrially, mainly due to its sorption characteristics. There have been several attempts to improve the quality and characteristics of the clays, modifying them with different techniques. Two of the common techniques are thermal activation and acid activation. For acid activation, hydrochloric acid was used with a reaction time of 1 hour while the thermal activation the samples calcined at 300oC for 24 hours. This work aims to characterize the gray clay (supplied by Süd-Chemie LTDA) and Brasgel (provided by Bentonit), both in its natural form, as well as in the acid and thermal activation form (300°C). Natural and treated clays were characterized by X-ray Spectroscopy Energy Dispersive (EDX), X-ray diffraction (XRD) and nitrogen adsorption (BET). The results showed a reduction of impurities in the samples and did not comprise changes in the structure of the constituent minerals.