Purpose The purpose of this paper is to model the corrosion rate behavior for two ferrous materials, carbon steel AISI 1020 and stainless steel AISI 304, immersed in ferric sulfate and ferric chloride solutions using D-optimal design with response surface methodology. Design/methodology/approach Experimental design addresses two factors (concentration and contact time) with multilevel categories, in order to predict and compare the corrosion rates of the studied materials immersed in flocculants solutions. A corrosion rate of specimens was calculated from mass loss determinations. Findings The authors used a polynomial model to fit the experimental values, thereby predicting significantly higher corrosion rates in ferric chloride solutions, as compared to ferric sulfate. Originality/value The authors propose a high fidelity model of the corrosion rate of each carbon steel and stainless steel material using D-optimal design with a response surface method (RSM).

Today's requirements in the art field have challenged researchers to create artistic paintings with attractive appearance and long‐term color stability. Alkyd‐based art mediums have become an important group in the art field, because of their similar characteristics to traditional oils and exceptional drying properties. In this work, high solid alkyd‐based art mediums have been synthesized by the monoglyceride and acidolysis processes. Multifunctional polyols and high unsaturated fatty acid sources were compared and used for alkyd synthesis. The use of a non‐traditional oil of Peruvian origin is proposed. Resins have been characterized according to their physicochemical (acid number, viscosity, color and density) and drying properties. Drying tendencies were verified with the use of quartz crystal microbalance. Also, the behavior of the art mediums mixed with commercial oil paintings and a dry pigment, have also been evaluated. Results indicate that resins containing the polyol with the highest functionality are more viscous and have fewer tendencies to yellowing, while non‐traditional Peruvian oil is the best option for creating light‐colored art mediums. Alkyd mediums prepared by the monoglyceride method gave to oil paintings better characteristics and drying behavior on canvas.

PurposeThe goal of this paper is to model the activated carbon adsorption capacity of cadmium using a polynomial regression model. The properties that influence the removal of heavy metals by activated carbon must be taken into consideration in order to synthesize materials specific to the characteristics of the pollutant.Design/methodology/approachMultivariable analysis applications allow a comprehensive description of the relationship between activated carbon surface properties and heavy metal adsorption.FindingsThe authors use a second-grade polynomial regression model to determine the influence of porosity and surface acidity in cadmium adsorption by activated carbon.Originality/valueThe authors propose a statistic analysis to correlate the carbon properties with its cadmium adsorption capacity. Model coefficient analysis will give a better comprehension of the influence of activated carbon porosity and surface acidity of cadmium removal.