Adriana de Souza Forster Araújo

Modeling the Transport Phenomena of TiO2 Nanoparticles into Leachate of Municipal Waste Landfills

Several nanomaterials have been currently developed and new applications has became possible due to the special materials performance requirements. The TiO2 nanoparticles are of special interest due to the wide range of applications from cosmetics to paint and new applications have continuously been searched. However, the effect of these particles into the environment need detailed investigation since some deleterious effects on the ecosystems have been observed. This paper deals with the mechanism of nanoparticles absorption/desorption by soil landfills. A long term simulation of the nanoparticles motion and contamination plume is carried out in the Volta Redonda Municipal Waste landfill and main transport parameters are determined. The model is used to predict the concentration of TiO2 nanoparticles in suspension on the leachate of Municipal Waste landfills and the rate of particles dynamically attached into the soil particles

Application of Nanoparticle Tracking Analysis (NTA) in Aqueous Solutions of TiO2

The study of nanoparticles involves a new field of research in various areas of technology, whose production and use have been recognized as multiple benefits to the society. However, the uncontrolled emission to the environment of nanoparticles is growing exponentially over the last decade. Thus, knowledge of the influence of nanoparticles and how they can modify the ecosystem is extremely importantand demand specific studies. Therefore, it is of fundamental importance to increase the knowledge of the interactions and transport of nanoparticles in soil, in particular this research will study the TiO2 nanoparticles (TiNPs). Aiming to improve such knowledge, this paper addressed tests on columns with soil collected in the landfill Volta Redonda located in the state of Rio de Janeiro, Brazil. Aliquots of TiO2-nanoparticle suspensions in soil were collected periodically after their preparation, and analyzed the aggregate of particles distribution and Ti concentration. Experimental results suggest that the higher stability of TiO2 suspensions resulted in a higher mobility of TiO2 through soil layers with lower retention rate.

Effects of the silica nanoparticles (NPSiO2) on the stabilization and transport of hazardous nanoparticle suspensions into landfill soil columns

This study evaluates the stability and transport behaviors of hazardous nanoparticles into soil landfills using experimental procedures to simulate the effects of natural silica nanoparticle suspensions during their percolation into the soil layers of municipal waste landfills. For this, we prepared stabilized suspensions of nanoparticle oxides containing silicon (NPSiO2), titanium (NPTiO2), copper (NPCuO) and zinc (NPZnO), which are recognized as hazardous to the environment, and we conducted leaching experiments within the soil column by simulating landfills layers and simulating the capture and attenuation of nanomaterials into municipal waste landfills. The results demonstrated that the presence of NPSiO2 in suspensions increases the stable concentrations of copper, zinc and titanium oxides and strongly decreases soil layer effectiveness. In contrast, NPZnO improves effectiveness due to its ability to promote agglomeration and setting conditions, allowing further complexation.

ESTUDO EXPERIMENTAL E NUMÉRICO DO COMPORTAMENTO DO ÍON CÁLCIO EM SOLO DO ATERRO MUNICIPAL DE VOLTA REDONDA

O presente trabalho consiste no estudo da previsao da dinâmica do ion calcio atraves do solo do Aterro Municipal de Volta Redonda, situado no Estado do Rio de Janeiro. O estudo se baseia no movimento do liquido contaminante (solucao) no meio poroso (solo), com a determinacao da sua taxa de sorcao. Para tanto, foram realizados ensaios em colunas de PVC, contendo solo do Aterro, onde ocorre o processo de transferencia do ion calcio entre a solucao contaminante e o solo. Utilizaram-se como solucao contaminante o lixiviado do Aterro e a solucao de gesso agricola. Foram realizados ensaios de laboratorio para determinar parâmetros de interacao do solo com o ion calcio e simulacoes computacionais para prever o comportamento do transporte do ion apos periodo de 5 dias. O modelo utilizado foi o MPHMTP ( Multi Phase Heat and Mass Transfer Program ) desenvolvido pelo programa de Pos-Graduacao em Engenharia Metalurgica de Volta Redonda (PPGM/EEIMVR/UFF). A simulacao computacional determina numericamente os parâmetros de transporte no sistema solo-chorume. Os resultados obtidos durante a realizacao deste trabalho mostraram que a migracao do calcio pode ser explicada atraves da acao simultânea de tres fenomenos, que sao: difusao, sorcao e adveccao. Palavras-chave : difusao, sorcao, mecanismos de transporte, lixiviado ABSTRACT Experimental and numerical study of the behavior of Calcium ion in the Volta Redonda municipal solid waste landfill. The present work aims to study the dynamics of calcium ion within the soil of Volta Redonda Municipal Solid Waste (MSW) landfill, located in Rio de Janeiro state, Brazil. The study is based on the movement of fluid contaminant (solution) into the porous matrix (soil) and determination of the sorption rate of calcium. The experimental procedure was carried out in PVC columns containing soil from the Landfill, with both, the leachate of the MSW and synthetic solutions with controlled concentrations of calcium ion. The experimental results were carried out for 5 days and the concentrations of the liquid were recorded. A computer software (MPHMTP), developed by the Graduate Program on Metallurgical Engineering of Volta Redonda (PPGM/EEIMVR/UFF) was used to determine the transport parameters and the ion concentration on liquid and solid for same conditions of the experiment. The computational simulation determines numerically the parameters of transport in the system soilleachate. Based on the experimental and numerical simulations carried out in this investigation, it is concluded that the migration of calcium can be explained by the simultaneous action of phenomena which are diffusion, advection in the liquid solution and sorption/desorption in the soil particles. Key words : diffusion, sorption, transport mechanisms, leachate