Leaching of Chromium in Red Ceramic Monolith by Immersion and Irrigation

The use of waste to improve sustainability of construction materials has increased in recent years. However, in Brazil no specific official standard has been issued on the solidification/stabilization (S/S) technique for construction materials. Similarly, no leaching methodology to evaluate products that include waste, under common use conditions, has been developed. As a result, both waste and products developed based on the S/S technique are assessed following the same official standard, which considers the landfill as the only final disposal condition. This study presents a leaching methodology to analyze the S/S approach in construction materials. Red ceramic sample blocks were manufactured with the addition of 0.05% Cr2O3. Two leaching approaches were conceived: immersion and irrigation. Tests were carried out in four 7-day cycles. Total experimental time was shorter than the period stipulated in a Dutch standard for this purpose. The results had low coefficient of variation and proved the usefulness of the technique to simulate intense and prolonged contact with a leaching agent, as in floods, and exposure to acid rain.

A New Model for Predicting Sorption Isotherm of Water in Foods

A new model for predicting sorption isotherms of type II and III based on the Polanyi theory is proposed. This model allows the prediction of the sorption isotherms at different temperatures from one experimental isotherm. The theoretical predictions of isotherms and isosteric heat were validated successfully using data from literature for twenty one foods. This method allows total experimental time and operation costs to be reduced.