A evolução da indústria petroquímica brasileira

The Brazilian Petrochemical Industry is about to turn fifty years old, and endures profound changes. In less than four years, it has moved from a system of centralized decisions and a national lever of planning, to another which is spread, without massive actions and with less integration with the raw material supplying company. On this issue it is presented, briefly, a small history of the development of this industrial type, including issues on how the growth of this activity, so important to the development of Brazil, shall be lead.

As primeiras vinte reuniões anuais da SBQ: uma visão da evolução da química no Brasil

An analysis of the different activities carried out during the first twenty annual meetings (1978-1997) of the Brazilian Chemical Society (SBQ) is presented. The number of papers in the abstract book increased from around 300 in the biennium 78/79 to around 1230 in 96/97. The papers contained in the different sections of the abstract book in the 1st (1978), 10th (1987) and 19th (1996) annual meetings were grouped according to the regions of Brazil the authors' institutions were from, or abroad, and also considering whether the paper came from one institution or was a collaboration between two or more institutions. The relative contribution of the southeastern and northern regions decreased from 77% and 3.0% of the total in 1978 to 63% and 1.2% in 1996, respectively, while those of the northeastern, southern and midwestern regions increased from 12%, 4.8% and 0.6% to 15%, 13%, and 2.6%, respectively; the relative contribution of institutions from abroad also increased from 2.4% to 4.0%. Chemistry of Natural Products and Organic Chemistry decreased their relative contribution from around 55% in 1978 to around 28% in 1996, an evolution towards a more balanced development of the different areas of chemistry in Brazil.

Detectores potenciométricos para sistemas de análise por injecção em fluxo, evolução e aplicação

The field of flow injection potentiometry (FIP) is reviewed and its current status assessed. The research development and application of electrodes in flow injection systems are presented and discussed.

Propagação da poluição atmosférica por flúor nas águas subterrâneas e solos de regiões próximas às indústrias de fertilizantes (Rio Grande, RS)

Fluoride concentration was determined in rainwater, ground water and soil in the zone of fertilizer industry in the city of Rio Grande. In contaminated rainwater fluorine concentration was registered up to the value of 4,4 mg.L-1. Fluorine concentration in the shallow ground water in general reflects its distribution in the atmosphere, but cannot be used as marker of atmosphere contamination in the urban area due to dissolving influence of residential effluents. The 0,01% HCl extracts from the set of surface soil samples demonstrates fluoride distribution in the zone of influence of industrial emissions, which coincides to the numerical simulation of fluorides dispersion in the air.

Redução de poluentes de efluentes das indústrias de papel e celulose pela floculação/coagulação e degradação fotoquímica

The abatement of recalcitrant lignin macromolecules from effluents of pulp and paper industry was investigated by combined process. Flocculation and coagulation with aluminum sulfate and natural polyelectrolytes extracted from cactus Cereus peruvianus were used in the first step. After separation of solid residues by filtration, the photochemical methods using TiO2 as catalyst were employed for photocatalytic degradation of lignin compounds from solution. The abatement of lignin compounds after flocculation and coagulation was 46%, and after the overall process, the pollutants reduction observed were 66%. The remaining organic compounds may be removed by any biological treatment.

A história, evolução e crescimento da Eletroquímica: Eletroanalítica nestes últimos 25 anos

This text describes the development of Electrochemistry and Electroanalytical Chemistry in Brazil from the pioneers at the IQ/USP in the 70's to the present day status. It explains how the members of the scientific community organized themselves before the establishment in 1993 of a specific division within the Brazilian Chemical Society (SBQ) through bi-ennial meetings (Brazilian Symposium of Electrochemistry and Electroanalytical Chemistry - SIBEE). Those SIBEE meetings, in a present number of 12, are described individually giving some emphasis on their organizers, the invited speakers and the statistics and overall structure of the event. The activities of the Electrochemistry and Electroanalytical Chemistry Division of the SBQ from 1993 are also briefly discussed as well as some considerations are made on the present and future of these fields.

A evolução dos reagentes químicos comerciais através dos rótulos e frascos

This work presents an evolution profile of labels and containers of commercial chemicals employed in laboratories since 1870. Most chemicals were made in Germany before the Second World War, after which many other manufacturers arrived on the Brazilian market. North-american products were dominant in the 1940s, but Brazilian chemicals have increased their participation along time. Labels presented increasingly more information, from originally simple names of the compounds at the beginning of the XXth century to the data presented today such as chemical formulae, safety regards and detailed chemical analysis. The raw material for container manufacturing also changed: glass was dominant until the 1950s, but nowadays plastic flasks are preferred whenever possible. Cork covers were replaced by screw caps. The diversity of commercial products also sharply increased with time, especially after the 1950s, following the many new and specific applications of chemicals for research and commercial purposes.

A evolução da balança analítica

This work intends to describe the historical evolution of the balance based on its technical improvement. This instrument has always been used for commercial and industrial purposes, but its value in research and chemistry was only recognized much later. The classical balance was the two-pan model for about 40 centuries, but when its importance in chemistry was established, particularly beginning at the end of the XVIIIth century, many improvements were made in order to increase sensitivity and shorten the weighing procedure. The balance design greatly changed along the XXth century: the classical two-pan models were replaced by one-pan balances that were replaced by electronic instruments.

Indústria química: evolução recente, problemas e oportunidades

Chemical industry underwent a significant upturn in the past few years. In Brazil, the position of this industry has been continuously strengthened as the second largest industrial sector. Current circumstances are discussed, especially the need for increased innovation, the impacts of nanotechnology, biotechnology and information technologies. Some misconceptions on the Brazilian chemical industry are criticized and recent improvements are described, including those related to environmental protection, to conclude that its prospects are very good, considering both the availability of basic raw materials (oil, natural gas, agribusiness products and minerals), the growing demand and increased competitiveness.

70º aniversário do biodiesel em 2007: evolução histórica e situação atual no brasil

Periodically, during petroleum shortages, vegetable oils and their derivatives have been proposed as alternatives to petroleum diesel fuel. Different approaches have been proposed, including the use of pure vegetable oils (or blends) or their derivatives. Indeed, the use of fatty-acid methyl or ethyl esters (usually known as "biodiesel") produced by alcoholysis of triacylglycerides or esterification of fatty acids was initially proposed in Belgium 70 years ago, when the first world patent was deposited. Recently, foreign dependence on diesel fuel and the petroleum crisis have increased the discussion in Brazil on starting to use alternatives to diesel fuel, being biodiesel the alternative of choice for a large petroleum diesel substitution program.

Aromaticidade: evolução histórica do conceito e critérios quantitativos

In this paper the evolution of the concept of aromaticity is discussed. It considers not only historical aspects of the aromaticity concept but also the different criteria (theoretical and experimental) that have appeared to explain the properties of the aromatic compounds. The topics range from the isolation of benzene by Faraday (1825) until the modern criteria based on geometries, magnetic properties, resonance energy (RE), aromatic stabilization energy (ASE), topological analyses, and others. A chronological separation of issues concerning aromaticity was made, splitting the definitions before and after the appearance of the quantum chemistry. This work reviews the concept of aromaticity.

Evolução biomolecular homoquiral: a origem e a amplificação da quiralidade nas moléculas da vida

The fact that biologically relevant molecules exist only as one of the two enantiomers is a fascinating example of complete symmetry breaking of chirality and has long intrigued our curiosity. The origin of this selective chirality has remained a fundamental enigma with regard to the origin of life since the time of Pasteur, 160 years ago. The symmetry breaking processes, which include autocatalytic crystallization, asymmetric autocatalysis, spontaneous crystallization, adsorption and polymerization of amino acids on mineral surfaces, provide new insights into the origin of biomolecular homochirality.

Os semimetais na origem e evolução da vida

Metalloids have characteristics between metals and non-metals which give them, in some cases, specific properties. At least two of this chemical elements, boron and silicon, are essential to a significant number of living organisms and since some years ago it has been observed that the same metalloids may be involved in the synthesis and stabilization of some molecules relevant to the origin of life.