Specific ion effects on the electrokinetic properties of iron oxide nanoparticles: Experiments and simulations

We report experimental and simulation studies on ion specificity in aqueous colloidal suspensions of positively charged, bare magnetite nanoparticles. Magnetite has the largest saturation magnetization among iron oxides and relatively low toxicity, which explain why it has been used in multiple biomedical applications. Bare magnetite is hydrophilic and the sign of the surface charge can be changed by adjusting the pH, its isoelectric point being in the vicinity of pH = 7. Electrophoretic mobility of our nanoparticles in the presence of increasing concentrations of different anions showed that anions regarded as kosmotropic are more efficient in decreasing, and even reversing, the mobility of the particles. If the anions were ordered according to the extent to which they reduced the particle mobility, a classical Hofmeister series was obtained with the exception of thiocyanate, whose position was altered. Monte Carlo simulations were used to predict the diffuse potential of magnetite in the presence of the same anions. The simulations took into account the ion volume, and the electrostatic and dispersion forces among the ions and between the ions and the solid surface. Even though no fitting parameters were introduced and all input data were estimated using Lifshitz theory of van der Waals forces or obtained from the literature, the predicted diffusion potentials of different anions followed the same order as the mobility curves. The results suggest that ionic polarizabilities and ion sizes are to a great extent responsible for the specific ion effects on the electrokinetic potential of iron oxide particles.The authors thank the financial support from the following institutions: (i) ‘Ministerio de Economía y Competitividad, Plan Nacional de Investigación, Desarrollo e Innovación Tecnológica (I + D + i)’, Projects MAT2013-44429-R, MAT2012-36270-C04-04 and -02. (ii) ‘Consejería de Innovación, Ciencia y Empresa de la Junta de Andalucía’, Projects P09-FQM-4698, P10-FQM-5977, and P11-FQM-7074. (iii) European Regional Development Fund (ERDF)

Compositional grading in oil and gas reservoirs

Compositional Grading in Oil and Gas Reservoirs offers instruction, examples, and case studies on how to answer the challenges of modeling a compositional gradient subject. Starting with the basics on PVT analysis, applied thermodynamics, and full derivations of irreversible thermodynamic-based equations, this critical reference explains gravity-modified equations to be applied to reservoirs, enabling engineers to obtain fluid composition at any point of the reservoir from measured data to create a stronger model calibration. Once model-parameters are re-estimated, new sensibility can be acquired for more accurate modeling of composition, aiding engineers with stronger production curves, reserve estimations, and design of future development strategies. Multiple examples and case studies are included to show the application of the theory from very simple to more complex systems, such as actual reservoirs influenced by thermal diffusion and gravity simultaneously. Other example include a layer for which asphaltene precipitation takes place in the reservoir and three –phase flash algorithms for liquid-liquid-vapor equilibrium calculations, detailing the techniques necessary to ensure convergence. The book combines practical studies with the importance in modeling more complex phenomena, filling a gap for current and upcoming reservoir engineers to expand on solutions and make sense of their reservoir’s output results.Fil: Oliveira Espósito, Rogelio. Petrobras; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Alijó, Pedro H. R.. Universidade do Estado de Rio do Janeiro; BrasilFil: Scilipoti, José Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina. Universidade Federal do Rio de Janeiro; BrasilFil: Tavares, Frederico W.. Universidade Federal do Rio de Janeiro; Brasi

Intensificação de processos e química verde: importância para as indústrias farmacêutica, cosméticos, alimentícia e biorrefinarias

Made available in DSpace on 2019-04-18T13:29:01Z (GMT). No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) joao_bruno_valentim_et_all.pdf: 965294 bytes, checksum: c054d7ba5849a116791c9e4bd1547e52 (MD5) Previous issue date: 5Instituto SENAI de Inovação em Biossintéticos. Rio de Janeiro, RJ, Brasil / Universidade Federal do Rio de Janeiro. Escola de Química. Centro de Tecnologia. Rio de Janeiro, RJ, Brasil.Universidade Federal do Rio de Janeiro. Escola de Química. Centro de Tecnologia. Rio de Janeiro, RJ, Brasil.Instituto SENAI de Inovação em Biossintéticos. Rio de Janeiro, RJ, Brasil.Universidade do Estado do Rio de Janeiro. Departamento de Físico-Química. Instituto de Química. Rio de Janeiro, RJ, Brasil.O conceito de intensificação de processos (PI) foi inicialmente colocado visando minimizar os custos operacionais e de capital sem comprometer as metas de produção, através apenas da redução na escala. Os benefícios associados incluem alguns princípios da Química Verde, como a segurança intrínseca, baixo impacto ambiental e o menor consumo material, energético e hídrico. Entretanto, para alcançar drásticas reduções de tamanho são necessárias novas abordagens para o projeto dos equipamentos e processos. Os riscos associados à falta de regulamentação e de um histórico que comprove a eficácia e baixos índices de falhas têm comprometido a aceitação destas tecnologias pelo mercado. Ademais, muitas soluções em infraestrutura e no modelo conceitual dos processos intensivos ainda são necessárias para torná-los mais eficientes, flexíveis e verdes. A superação dessas barreiras permitirá que o Brasil estruture um modelo econômico altamente competitivo, baseado na comercialização de produtos de origem biológica. Dessa forma, o principal objetivo do artigo é descrever a importância da inclusão da PI na política de pesquisa, desenvolvimento e inovação nacional. Com isso, espera-se favorecer a diversificação da indústria farmacêutica, de química fina, de alimentos, e de outras indústrias de base biológica, bem como a estruturação das biorrefinarias a longo prazo.The concept of process intensification (PI) was initially aimed at minimizing operational and capital costs without compromising production targets by reducing the scale of processes. The associated benefits also include some principles of Green Chemistry, such as intrinsic safety, low environmental impact and lower material, energy and water consumption. However, in order to achieve drastic size reductions, new approaches to the design of equipment and processes are needed. The risks associated with a lack of regulation and a track record of efficiency and low failure rates have compromised the market's acceptance of these technologies. Moreover, many infrastructure solutions and the conceptual model of the intensive processes are still needed to make them more efficient, flexible and green. Overcoming these barriers will allow Brazil to structure a highly competitive economic model, based on the commercialization of biobased products. Thus, the main objective of this article is to describe the importance of the inclusion of IP in national research, development and innovation policy. Therefore, one expects to favor the diversification of the pharmaceutical industry, fine chemicals, food, and others biobased industries, as well as the structuring of biorefineries in the long term