Removal of heavy metal ions from wastewaters: A review

Application of low-cost adsorbents for dye removal – A review

The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

/pdf/the-environmental-protection-agency-3gx4opzrjm.pdf

The Environmental Protection Agency

A review on biodiesel production using catalyzed transesterification

羟氨苄青霉素引起大疱性类天疱疮样疹

Catalytic activity of active carbons impregnated before activation of pinewood sawdust and nutshells to be used on the control of atmospheric emissions.

The objectives of this work were: (1) to identify an isotherm model to relate the contaminant contents in the gas phase with those in the solid and non-aqueous liquid phases; (2) to develop a methodology for the estimation of the contaminant distribution in the different phases of the soil; and (3) to evaluate the influence of soil water content on the contaminant distribution in soil. For sandy soils with negligible contents of clay and natural organic matter, contaminated with benzene, toluene, ethylbenzene, xylene, trichloroethylene (TCE), and perchloroethylene (PCE), it was concluded that: (1) Freundlich’s model showed to be adequate to relate the contaminant contents in the gas phase with those in the solid and non-aqueous liquid phases; (2) the distribution of the contaminants in the different phases present in the soil could be estimated with differences lower than 10% for 83% of the cases; and (3) an increase of the soil water content led to a decrease of the amount of contaminant in the solid and non-aqueous liquid phases, increasing the amount in the other phases.

/pdf/estimation-of-pollutant-partition-in-sandy-soils-with-y3weh1xmne.pdf

Estimation of pollutant partition in sandy soils with different water contents.

This study aims to predict the next day hourly average tropospheric ozone (O"3) concentrations using genetic programming (GP). Due to the complexity of this problem, GP is an adequate methodology as it can optimize, simultaneously, the structure of the model and its parameters. It is an artificial intelligence methodology that uses the same principles of the Darwinian Theory of Evolution. GP enables the automatic generation of mathematical expressions that are modified following an iterative process applying genetic operations. The inputs of the models were the hourly average concentrations of carbon monoxide (CO), nitrogen oxide (NO), nitrogen dioxide (NO"2) and O"3, and some meteorological variables (temperature -T; solar radiation - SR; relative humidity - RH; and wind speed - WS) measured 24h before. GP was also applied to the principal components (PC) obtained from these variables. The analysed period was from May to July 2004 divided in training and test periods. GP was able to select the most relevant variables for prediction of O"3 concentrations. The original variables, T, RH and O"3 measured 24h before were considered significant inputs for prediction. The selected PC had also important contributions of the same variables and of NO"2. GP models using the original variables presented better performance in training period and worse performance in test period when compared with the models obtained using PC. The results achieved using the GP methodology demonstrated that it can be very useful to solve several environmental complex problems.

Prediction of tropospheric ozone concentrations: Application of a methodology based on the Darwin's Theory of Evolution

https://recipp.ipp.pt/bitstream/10400.22/2993/1/ART_MariaFerraz_2006_GRAQ.pdf

Soil remediation time to achieve clean-up goals I: Influence of soil water content.

Impregnated active carbons were prepared to be used as catalysts for complete oxidation, aiming at the reduction of atmospheric emission of volatile organic compounds. Good dispersion of the catalyst is required, as it regulates the conversion efficiency in the pores where pollutants can access to be converted. When impregnation is performed on the raw material or after activation, the influence of impregnated species on the structure and on the catalyst dispersion is already well studied. This paper aims to analyze the influence of impregnated species on the structure and on the catalyst dispersion when the impregnation step is performed after carbonization, as this knowledge is yet very scarce. Olive stones were used as raw material. In order to evaluate the influence of the methodology of impregnation with CoO, Co 3 O 4 , and CrO 3 , the impregnation step was completed after activation and between carbonization and activation. In the first sequence, the impregnated oxides must be deposited on the internal surface, blocking part of the initial microporous structure. When impregnation is conducted after carbonization, metal species act as catalysts during the activation step. The structure developed strongly depends either on the chemical state of the catalyst or on its distribution in the carbonized material. A well-developed pore structure can appear just where metal species can access, remaining a micropore structure with pores of very small sizes. The better efficiency of Co 3 O 4 as a catalyst of the activation step is conditioned by a worse distribution of the carbonized material, related to the bigger size of its crystals. CrO 3 is the least efficient catalyst for the activation step.

Maria C.M. Alvim-Ferraz

Papers

Catalytic activity of active carbons impregnated before activation of pinewood sawdust and nutshells to be used on the control of atmospheric emissions.

Estimation of pollutant partition in sandy soils with different water contents.

Prediction of tropospheric ozone concentrations: Application of a methodology based on the Darwin's Theory of Evolution

Soil remediation time to achieve clean-up goals I: Influence of soil water content.

Impregnated active carbons to control atmospheric emissions: I. Influence of the impregnated species on the porous structure