Leonardo Martins da Silva

Study of the Effects of SiO2 Nanoparticles Concentration on the TiO2 Nanoparticles Suspensions Stabilization

TiO2 nanoparticles (NPTiO2) suspensions are in several ecosystems and residue treatment processes or disposal systems due to their large industrial use and handling. The interactions of the NPTiO2 with NPSiO2 have special interest due to their strong ability to maintain high TiO2 nanoparticles concentration in suspension and promote nanoparticles clustering. These characteristics are used either in cleaning systems or in production of nanoparticles solution for several applications in the food industry or medicine. In this study, suspensions of NPTiO2 and NPSiO2 are synthetized and their stabilizations are discussed. A base TiO2 nanoparticles suspension was synthetized and the initial concentrations of SiO2 nanoparticles (NPSiO2) were changed in order to determine the effects of presence of SiO2 nanoparticles on the stabilization and clustering size. Zeta potential and concentrations measurements were carried out throughout the time and correlated with the initial concentrations of the base suspensions. In this study, the concentrations, zeta potential and pH are measured to estimate the stability of the suspensions. The clustering size, obtained by nanoparticle tracking analysis (NTA), are also monitored and discussed. Results of column soil experiments are discussed and compared under similar conditions with literature data.

Analysis of the Microwave Heating Effect in the Comminution Efficiency of Iron Ore Particles

Heating iron ore fine particles using microwave energy has been effective due to the different interactions between minerals and gangue in the magnetic field generated by the microwave. In this way, this paper proposes to use microwave energy to heat the particles of iron ore to promote micro cracks and fissures, which would facilitate the comminution and pulverization process to produce pellet feed. It was analyzed different conditions of heating and cooling in the comminution step. By using techniques of scanning electron microscopy (SEM) and image analysis it was possible to assess and quantify the micro cracks and subsequent analysis of the energy and size fragmentation in the comminution step of ultrafine particles.

Predictions of Xylene Adsorption on Agglomerated Activated Carbon Pellets in a Fixed Bed Column

Volatile organic compounds (VOCs) are an important category of air pollutants and adsorption has been widely recognized as an effective means of controlling emissions to the atmosphere. The current study used theoretical model to analyze the rate of xylene adsorption from inert gaseous stream on the granular activated carbon in a fixed bed column under varying operating conditions. The model considers the inner diffusion of VOC into the activated carbon particles. Experimental results of another author study were used to validate the present model and the methodology proposed to determine the xylene concentrations at the outlet of the column and corresponding inner particles.

Evaluation of Heat Absorption in Iron Ore Using Microwave Energy Source

The phosphorus content has significant effect on the steels quality and their applications. The iron ore resources around the world has continuously increased the amount of phosphorous due to the increase of the mining volume with less sterile generation aiming at the efficient utilization of the mining resources, as consequence larger amount of materials with high iron content but with higher phosphorous has been incorporated in the mining body. An alternative to enhance the mining efficiency is to perform a pre treatment of part of the mining body and subsequent blending to attain the acceptable phosphorous in the steelmaking. A viable alternative for reducing the phosphorus content of these residue is to use the acid leaching process which is considered an economical process for the dephosphorization of the iron ore, however, depending on the way the element phosphorus is contained in the ore it will demand additional energy. The objective of the present paper is to study the effective heating and cooling rates of iron ore using microwave energy and its subsequent cooling effect in a short period (thermal shock). Through the X-ray diffraction analysis and applying the Rietveld method it has been possible to demonstrate the mineralogical composition of the iron ore samples and the effect of rapid heating and cooling suitable to promote the fissure formation, thus enhancing the leaching efficiency. The scanning electron microscopy (SEM) was used to analyze the structure of ore due to the effect of its heating and cooling rates.