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Articles 31 - 60 of 62

Full-Text Articles in Nanoscience and Nanotechnology

Toxicological Assessment Of Coated Versus Uncoated Rubber Granulates Obtained From Used Tires For Use In Sport Facilities, João F. Gomes Dec 2009

Toxicological Assessment Of Coated Versus Uncoated Rubber Granulates Obtained From Used Tires For Use In Sport Facilities, João F. Gomes

João F Gomes

Reuse of tire crumb in sport facilities is currently a very cost-effective waste management measure. Considering that incorporation of the waste materials in artificial turf would be facilitated if the rubber materials were already colored green, coatings were specifically developed for this purpose. This paper presents an experimental toxicological and environmental assessment aimed at comparing the obtained emissions to the environment in terms of polycyclic aromatic hydrocarbons (PAHs), heavy metals, and ecotoxicity for coated and noncoated rubber granulates. This study is a comprehensive evaluation of the major potential critical factors related with the release of all of these classes of ...


Endargement Of Undeveloped Areas Of Serbia By Forest Fires, João F. Gomes Jan 2009

Endargement Of Undeveloped Areas Of Serbia By Forest Fires, João F. Gomes

João F Gomes

Considering the significance of discovering the causes of forest fires, the hypothesis on the solar activity is presented (i.e. physical–chemical characteristics of the solar wind) as the possible cause of these natural disasters. The empirical confirmation of the mentioned hypothesis was disabled by the non existence of an adequate data base on the (regional) distribution of the number of fires and burned areas on the level of Serbia. Therefore an emphasis is put on theoretical explanations, but also on the characteristic situations in which there is an agreement between the processes occurring on the Sun and fire phenomena ...


2008 Report Of Crerg Research Activities, João F. Gomes Jan 2009

2008 Report Of Crerg Research Activities, João F. Gomes

João F Gomes

No abstract provided.


Assessment Of The Impact Of The European Co2 Emissions Trading Scheme On The Portuguese Chemical Industry, João F. Gomes Dec 2008

Assessment Of The Impact Of The European Co2 Emissions Trading Scheme On The Portuguese Chemical Industry, João F. Gomes

João F Gomes

No abstract provided.


Estimating Local Greenhouse Gas Emissions - A Case Study On A Portuguese Municipality, João F. Gomes Jan 2008

Estimating Local Greenhouse Gas Emissions - A Case Study On A Portuguese Municipality, João F. Gomes

João F Gomes

This paper describes the study that led to the development of a carbon dioxide emissions matrix for the Oeiras municipality, one of the largest Portuguese municipalities, located in the metropolitan area of Lisbon. This matrix takes into account the Greenhouse Gases (GHG) Emissions, due an increase of electricity demand in buildings as well as solid and liquid wastes treatment, from the domestic and services sectors. Using emission factors that were calculated from the relationship between the electricity produced and amount of treated wastes, the GHG emissions in the Oeiras municipality, were estimated for a time series of 6 years (1998 ...


Dynamic Simulation Of Co2 Absorption From Post Combustion Gases, João Gomes Jan 2008

Dynamic Simulation Of Co2 Absorption From Post Combustion Gases, João Gomes

João F Gomes

CO2 capture from combustion flue gases is currently an issue of main interest due to the high taxes being imposed on industrial companies as a measure to achieve CO2 emissions abatement. CO2 capture can be efficiently achieved by gas absorption using amines, namely Monoethanolamine (MEA). Based on henrys law, validated with previously published experimental work, this study considers the development of a dynamic model of an absorption column for post combustion CO2 capture. A dynamic model of the temperature swing de-absorption process was developed with the integration of both models for absorption and de-absorption (with the introduction of heat exchangers ...


Reflexions On The Use Of Renewable Power Sources And Nuclear Energy In Portugal, João F. Gomes Jan 2008

Reflexions On The Use Of Renewable Power Sources And Nuclear Energy In Portugal, João F. Gomes

João F Gomes

This paper analyses the current energy balance of Portugal, considering the actual sources which are mainly traditional fossil fuels, hydroelectric power and renewables. Other potential sources are discussed also and taken into consideration in view of the previewed evolution of the country in energetic terms. Among these, nuclear power, once regarded as an option, is now being re-considered. This paper also sums up the main issues to be considered in a future debate on the subject.


Emissions Of Polyciclic Aromatic Hidrocarbons And Polyciclic Carbonyl Bifenils From Electric Arc Furnaces, João F. Gomes Dec 2007

Emissions Of Polyciclic Aromatic Hidrocarbons And Polyciclic Carbonyl Bifenils From Electric Arc Furnaces, João F. Gomes

João F Gomes

This paper describes work done in order to determine the emissions of highly toxic organic micropollutants from electric arc furnaces used in the production of carbon steel from scrap. The study will be allowing to derive relationships between the levels of airborne micropollutants and the operational parameters of the production process so that an abatement of pollution could be achieved. By using the European standard method CEN 1948 for dioxin like compounds sampling and measurement, it was possible to determine the characteristic fingerprint of micropollutants such as polycyclic aromatic hydrocarbons (PAHs) and PCBs emitted by this particular stationary source.


Assessing The Possibility Of Corrosion Occurrence In Metallic Stacks Caused By Hydrochloric Acid, João F. Gomes Jan 2007

Assessing The Possibility Of Corrosion Occurrence In Metallic Stacks Caused By Hydrochloric Acid, João F. Gomes

João F Gomes

This article presents a simple method to estimate the possibility of corrosion in metallic stacks and surfaces due to hydrochloric acid deposition from stack gases, based on the HCl content in gases and also the flue gas temperature


New Technologies For Effective Forest Fire Fighting, João Gomes Jan 2007

New Technologies For Effective Forest Fire Fighting, João Gomes

João F Gomes

Efficient fire extinction with water could be greatly improved by using superabsorbent polymers, added to the water used for fire fighting, or sprayed over surfaces of combustible materials in order to protect them from fire. Specially developed superabsorbent polymers such as acrylamide/2-acrylamide-2-methyl-propane-sulphonate (AA/AMPS) seem to be particularly efficient for this purpose. In terms of water absorption, the experimental tests performed, showed that the optimal composition of this polymer is 30:70 AMPS versus AA, using 0.5% of bis-acrylamide (BA) as crosslinking agent.


Deriving An Indoor Environmental Index For Portuguese Office Buildings, João F. Gomes Jan 2007

Deriving An Indoor Environmental Index For Portuguese Office Buildings, João F. Gomes

João F Gomes

The EC issued a Directive in 2002 aiming to reduce the energy consumption of buildings, which was adopted by the EU member states and came into force in 2006. Portugal adopted it by issuing law decrees in 2006 which considered not only the energy saving aspects but also additional specific measures aiming to protect indoor air quality (IAQ). This new legislation is now being enforced and it will be necessary to define compliance acceptance levels for the prescribed indoor air limits. The use of comfort or environmental indexes could be of considerable help in order to ameliorate the evaluation of ...


The Importance Of Considering Building Downwash When Assessing The Need To Heighten Stacks Of Existing Small And Medium Sized Industries, João F. Gomes Jan 2007

The Importance Of Considering Building Downwash When Assessing The Need To Heighten Stacks Of Existing Small And Medium Sized Industries, João F. Gomes

João F Gomes

No abstract provided.


Measurements Of Indoor Air Pollutant Levels In A University Office Building, João F. Gomes Jan 2007

Measurements Of Indoor Air Pollutant Levels In A University Office Building, João F. Gomes

João F Gomes

This work consisted of a series of determinations performed in typical rooms of a building belonging to the Technical University of Lisbon, which is located in a central urban area of Lisbon. The main objective was to evaluate the Indoor Air Quality (IAQ) of the rooms so that further corrective measures could be taken if unsatisfactory IAQ levels were to be found. Correlations were derived, between indoor and outdoor pollutant concentrations, in order to assess the existence of contaminations coming from outside. Also, correlations were derived between total volatile organic compounds (VOC) concentrations and specific individual organic species measured in ...


Reflections On The Use Of The Mccabe And Thiele Method, João F. Gomes Jan 2007

Reflections On The Use Of The Mccabe And Thiele Method, João F. Gomes

João F Gomes

This paper reflects on the continuity of teaching the McCabe and Thiele method on chemical engineering courses for understanding the vapour-liquid equilibrium phenomena involved in distillation. Some exercises comparing the results obtained by this method as well as by other accurate analytical methods are presented and solved, as they are taught in ISEL courses. Because of its accuracy and easiness of use, and also because of the fact as this method allows an easy visualisation of the whole operation itself, the McCabe and Thiele method continues to be widespread used and students show a remarkable adherence to it.


Forest Fires In Portugal: How They Happen And Why They Happen, João F. Gomes Jan 2006

Forest Fires In Portugal: How They Happen And Why They Happen, João F. Gomes

João F Gomes

Forest fires are recurrent phenomena in Southern European countries, due to the nature of Mediterranean forest and climatic characteristics. However, in Portugal, in the last years, forest fires attained the dimension of public calamity and are now endangering sustainability of forest itself, as well as several derived economic activities. This paper reviews the past and current situation of forest fires in Portugal, analyses its main causes and consequences and derives recommendations to effectively overcome this problem.


Leaching Of Heavy Metals From Steelmaking Slags, João F. Gomes Jan 2006

Leaching Of Heavy Metals From Steelmaking Slags, João F. Gomes

João F Gomes

Leaching tests with EAF and Ladle slags were performed, using a flow through test and the standard batch test DIN 38414-S4. The previous method was used to simulate the leaching behaviour of steel slags under landfill. The chemical analysis of the leachates during this period shows, in general, for both types of slag, an increase of heavy metal releases with ageing. Standard test method DIN 38414-S4 was used to evaluate leachability of heavy metals by water in unprocessed slags. After more than one year of trials, slag samples submitted to these trials presented very low total leaching levels. The most ...


Estimation Of Uncertainty In The Determination Of Nitrogen Oxides Emissions, João F. Gomes Jan 2006

Estimation Of Uncertainty In The Determination Of Nitrogen Oxides Emissions, João F. Gomes

João F Gomes

This paper presents a methodology for estimation of uncertainty on a reference test method for determination of nitrogen oxides concentration in gaseous emissions from stationary sources. As a first stage for identification of uncertainty sources, the test method is carefully reviewed in detail. Afterwards, these sources are quantified, bearing in mind its partial uncertainty, allowing the determination of the combined uncertainty and, finally, the expanded uncertainty. The calculation procedure was implemented into an excel calculation file. Using this file and considering several numerical applications from real situations, uncertainities around 15 mg/Nm3 over determined concentrations of 350 mg/Nm3 of ...


Fume Emissions During Metal Arc Welding, João F. Gomes Jan 2006

Fume Emissions During Metal Arc Welding, João F. Gomes

João F Gomes

No abstract provided.


Avoid Sulfuric Acid Corrosion In Metallic Stacks, João F. Gomes Jan 2005

Avoid Sulfuric Acid Corrosion In Metallic Stacks, João F. Gomes

João F Gomes

Acidic gaseous effluents frequently cause corrosion on metallic stacks. This paper presents a method for prevision of probability of corrosion occurrence caused by gaseous effluents containing sulphur oxides which is based on the sulphur trioxide and moisture content measured in stack


Emissions Of Dioxin And Dibenzofuran From Electric Arc Furnaces, João F. Gomes Jan 2005

Emissions Of Dioxin And Dibenzofuran From Electric Arc Furnaces, João F. Gomes

João F Gomes

This paper describes work done in order to clarify the formation mechanism of highly toxic micropollutants, such as dioxins and dibenzofurans, from electric arc furnaces used in the production of carbon steel from scrap. The study is allowing to derive relationships between the levels of airborne micropollutants and the operational parameters of the production process so that an abatement of pollution could be achieved. By using the European standard method CEN 1948 for dioxin like compounds sampling and measurement, it was possible to determine the characteristic fingerprint of micropollutants emitted by this particular stationary source.


Analysis Of Welding Fumes: A Short Notice On The Comaprison Between Two Sampling Techniques, João F. Gomes Dec 2004

Analysis Of Welding Fumes: A Short Notice On The Comaprison Between Two Sampling Techniques, João F. Gomes

João F Gomes

No abstract provided.


Air Quality Regulation Policy In Portugal, João F. Gomes Jan 2004

Air Quality Regulation Policy In Portugal, João F. Gomes

João F Gomes

Ten years after the publication of first air quality laws in Portugal, and seven years after the publication of the respective emission limits, it seems appropriate to analyse the degree of law enforcement by the Portuguese manufacturing industry. Therefore, based on the emission measurements made regularly by ISQ, as the only officially accredited laboratory, a set of about 400 sources is analysed in terms of the compliance with the emission limits regarding total suspended particulate, sulphur dioxide, nitrogen oxides and VOCs. The compliance is evaluated through a non-dimensional parameter and plotted versus the emission flow rate to derive conclusions: it ...


Emission And Odour Control In Kraft Pulp Mills, João F. Gomes Jan 2003

Emission And Odour Control In Kraft Pulp Mills, João F. Gomes

João F Gomes

This paper describes systematic work done in the field of atmospheric emissions from Portuguese Kraft pulp mills, focused mainly on the gaseous emissions responsible for its characteristic odour. These mal-odorous gases, which were identified as hydrogen sulphide, methyl mercaptan, deimethyl mercaptan and dimethyl-disulphide, were experimentally quantified and classified into groups so that alternatives for abatement could be devised. The considered abatement techniques were evaluated economically and it was concluded that the costs to be incurred by pulp mills for an efficient abatement of TRS gases are not dramatic and could be easily covered by this industry, resulting in an evident ...


Diagnostic Of Critical Circuits Of Kraft Pulp Production Process Considering The Environmental Aspects, João F. Gomes Jan 2002

Diagnostic Of Critical Circuits Of Kraft Pulp Production Process Considering The Environmental Aspects, João F. Gomes

João F Gomes

This paper describes systematic work done in the field of atmospheric emissions from Portuguese Kraft pulp mills. This study led to the determination of emission factors from stationary sources that proved to be an important tool to assess the need for investment on air pollution abatement equipment, namely in what concerns mal-odorous gases.


Characterisation Of Non-Condensable Sulphur Containing Gases From Kraft Pulp Mills (2), João F. Gomes Jan 2001

Characterisation Of Non-Condensable Sulphur Containing Gases From Kraft Pulp Mills (2), João F. Gomes

João F Gomes

This paper describes work performed on the sampling and analysis of non-condensable gases (NCG) emitted from diffuse sources of a Portuguese Kraft pulp mill, which is the background information for a NCG collection, treatment and disposal system. The variability found in the composition of the gaseous compounds showed the existence of gaseous streams other than typical total reduced sulphur (TRS) compounds as usually described. From the measured TRS concentrations and the gas flow rate from each source it was possible to calculate the emission flow rate, E, of each source. These emission flow rates were then divided into 3 categories ...


Practical Determination Of Efficiency Of Electrostatic Precipitators, João F. Gomes Jan 1999

Practical Determination Of Efficiency Of Electrostatic Precipitators, João F. Gomes

João F Gomes

Electrostatic precipitators are one of the most efficient particulate pollution control equipments used mainly for the treatment of gaseous effluents at high flow rates. Consequently electrostatic precipitators are widely used in thermal power plants, cement plants and pulp mills. Apart from a high efficiency other advantages are related with the fact that this type of equipment has a considerable low payback time in industrial plants where the particulate recovered from the gases has commercial value and can be recycled within the industrial process itself or even sold to other industrial companies. Where sulphate (Kraft) pulp mills are concerned an electrostatic ...


Characterisation Of Non-Condensable Sulphur Containing Gases From Kraft Pulp Mills, João F. Gomes Jan 1998

Characterisation Of Non-Condensable Sulphur Containing Gases From Kraft Pulp Mills, João F. Gomes

João F Gomes

This paper describes work performed on the sampling and analysis of non-condensable gases (NCG) emitted from diffuse sources of a Portuguese kraft pulp mill, which is the background information for a NCG collection, treatment and disposal system. The variability found in the composition of the gaseous compounds showed the existence of gaseous streams other than typical total reduced sulphur (TRS) compounds as usually described.


A Simple Way To Measure Particle Size, João F. Gomes Jan 1998

A Simple Way To Measure Particle Size, João F. Gomes

João F Gomes

The size range of particles is an important parameter for subsequent dispersion estimates and sometimes is quite useful for analysing the performance of combustion equipment as well as dedusting equipment efficiency. So far, no standard method has been developed but several laboratories use laser-beam techniques which are usually quite expensive ones. In this paper a method is presented where the particles are collected isokinetically in a filter from gases circulating in a stack as described in USEPA method 5. Afterwards particles are observed at an optical microscope and measured. In spite of some limitations this appears to be an inexpensive ...


Assessment Of Opacimeter Calibration On Kraft Pulp Mills, João F. Gomes Dec 1997

Assessment Of Opacimeter Calibration On Kraft Pulp Mills, João F. Gomes

João F Gomes

This paper describes the methodology and specific techniques for calibrating automatic on-line industrial emission analysers, specifically equipments that measure total suspended dust installed in pulp mills within the scope of Portuguese Regulation Nº 286/93 on air quality. The calibration of opacimeters is a multi-parameter relationship instead of the bi-dimensional calibration which is used in industrial practice. For a stationary source from a pulp mill such as the recovery boiler stack, which is subjected to significant variations, the effects of parameters such as the humidity and gas temperature, deviations on isokinetism, size range of particles and characteristic transmitance of equipment ...


Pollutant Atmospheric Emissions From Portuguese Kraft Pulp Mills, João F. Gomes Jan 1997

Pollutant Atmospheric Emissions From Portuguese Kraft Pulp Mills, João F. Gomes

João F Gomes

This paper describes systematic work done in the field of atmospheric emissions from Portuguese Kraft pulp mills. This study led to the determination of emission factors from stationary sources that proved to be an important tool to assess the need for investment on air pollution abatement equipment.