Chemistry

The suspended particulate matter (PM10) breathable fraction is one of the biggest pollutants in the cities atmospheres being of special interest because it passes directly to the lungs in the breathing process and it is deposited in the lung alveoli.-The PM10 contain great variety of metals whose origin can be natural or anthropogenic. The governorship environment departement, since couple years is monitoring the concentration of PM10 in the air of the city. The present work proposes the measure of the metals concentration( contents in this particulate matter breathable fraction.The monitoring of breathable fraction was carried in the High Volume sampling for PM 10(Hi Vol PM 10) on microfibre quartz filters in sampling collections during 1997,1998 and January to April of 1999 in four sampling stations located in different points of the city of Bucaramanga. The samples were subjected to acid digestion and in the remaining solutions the metals were measured by atomic absorption espectroscopy. The Kennedy and Juventud stations(to the north of the city), present the highest PM10 and metals concentrations in every period. The Gaitan stations presents the smaller PM 10 and metals concentration. However, the metals concentration found are for below the maximum permissible values in Europe and the United States.

El objetivo del proyecto es extraer bromelina de la piña perolera y estudiar su comportamiento cinético. La bromelina es una glicoproteína del grupo de las cisteíno proteasas, actúa sobre los aminoácidos básicos y aromáticos de las proteínas. En la industria alimentaria, se utiliza como ablandador de carne; hidroliza proteínas solubles de la cerveza. La pulpa de la fruta se llevó a refrigeración ( ≤ 4ºc), agregando benzoato de sodio, se realizó la extracción con dos solventes: etanol y acetona (75% y 50%) v/v en agua. El extracto se centrifugó a 4000 rpm por 20 min. La mezcla total se dejo en reposo durante 50 horas manteniendo la temperatura entre 5 y 10ºc y se centrifugo a 4000 rpm por 25 min, se obtuvo un precipitado amarillo oscuro que se dejó secar a temperatura ambiente. Se realizó la cuantificación de proteína, utilizando el método de biuret. Se realizó una electroforesis para encontrar el peso molecular aproximado de la proteína extraída. La eficiencia catalítica de la bromelina se determinó usando caseína como sustrato. Se obtuvo como resultado que, la acetona a una concentración de 75% v/v es la más eficaz para la extracción (243,2mg) que supera aproximadamente en 100mg a la cantidad obtenida con el etanol al 50% v/v (146,0mg). El análisis electroforético muestra que el peso molecular de la bromelina es de 35000 dalton. El comportamiento cinético de la bromelina se ajusta al modelo de michaelis-menten en el cual se determinan la Vmax 3.38e-3 mm/seg y el valor de kM de 4,19e-3 mm.

The equilibrium liquid-liquid (ELL) of ternary systems benzene + (hexane, heptane and cyclohexane) with the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate (EMIM-EtSO4) at 308.15 K, selectivity (S) and the distribution coefficient (β) are calculated from experimental data. The ability of ionic liquid as solvent for separation of the aromatic from their mixtures with aliphatic hydrocarbons is analyzed. The region of immiscibility increased in the following order: cyclohexane < hexane < heptane. The consistency of the experimental data of ELL is evaluated using the equation of Othmer-Tobias. The composition of the phases in equilibrium is correlated with the models for the activity coefficient NRTL and UNIQUAC.

"The excess molar volumes of 38 binary mixtures containing alcohol: (methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol,
heptan-1-ol, octan-1-ol, decan-1-ol, propan-2-ol, butan-2-ol, pentan-2-ol, 2-methylpropan-1-ol and 3-methylbutan-1-ol) with different solvents:
(pentane, hexane, heptane, octane, cyclohexane, methyl cyclohexane, 1,1,2,2-tetrachloroethane, acetonitrile, ethyl benzene, o-xylene, m-xylene,
p-xylene, 2-butanone, ethyl acetate, 1-ethyl-3-methylimidazolium ethyl sulfate and water), were predicted from the refractive index data, using 3 types of methods coupled with several different mixing rules for refractive index
calculations: Lorentz-Lorenz, Dale-Gladstone, Eykman, Arago-Biot, Newton and Oster. In these systems, molecular interactions and intermolecular forces during mixing produce positive or negative deviations from ideal behavior. The results are analyzed in terms of the nature of the components and the influence of alcohol chain length."

Densities and refractive indices of binary mixtures of water, methanol and ethanol with 1-Ethyl-3-methylimidazolium Ethylsulfate (EMIM-EtSO4) and ethanol with 1-Methyl-3-methylimidazolium Methylsulfate (MMIM-MeSO4) in the K temperature range (298.15, 308.15 and 318.15) were measured. The excess of molar volumes (V_M^E ) and the deviation of the refractive index (δ_η ), were fitted to an order fourth polynomial equation of Redlich-Kister.

El volumen de exceso molar de 30 mezclas binarias que contienen líquidos iónicos de imidazoliocon diferentes solventes moleculares: (metanol, etanol, 1-propanol, 2-propanol, acetona, 2-butanona, 2-pentanona, acetato de metilo, acetato de etilo, acetato de butilo, carbonato dedimetilo, carbonato de dietilo, nitrometano, 1,3-dicloropropano y etilenglicol),se predice desdedatos de índice de refracción, usando tres tipos de métodos acoplados con diferentes reglas demezcla para el cálculo del índice de refracción: Lorentz-Lorenz, Dale-Gladstone, Eykman, Arago-Biot, Newton y Oster. En estos sistemas, las interacciones moleculares y las fuerzasintermoleculares provocan, durante la mezcla, desviaciones positivas o negativas delcomportamiento ideal. Los resultados obtenidos se analizan en términos de la naturaleza dellíquido iónico y solvente molecular.

Study of LiquidLiquid Equilibria of Toluene + (Hexane, Heptane, or Cyclohexane) with 1-Ethyl-3-methylimidazolium Ethylsulfate at 308.15 K We studied extraction of toluene from hydrocarbons with [EMim][EtSO 4 ] at 308.15 K, the values of the selectivity > 1, show that the toluene extraction is possible. The selectivity values increase as the alkane linear chain increases.

When the United Nations declared that 2011 would be the International Year of Chemistry, it
did so in part because the year 2011 coincided with the 100th anniversary of the Nobel Prize in Chemistry awarded to Madame Marie Curie. Sharing philatelic material between teachers and students is helpful to study the life and work of relevant scientists. In this article forty-six postage stamps issued by different countries from 1938 through 2011 were used to make a didactic description of the biographical aspects of Marie Curie.

The extraction of toluene from heptane was analyzed
by liquid extraction with 1,3-dimethylimidazolium me-
thylsulfate [MMim][MeSO4
] ionic liquid, as a solvent.
The experimental (liquid + liquid) equilibrium (LLE)
data were determined at T= 318.15 K and atmosphe-
ric pressure.  Selectivity and distribution coefficient,
derived from the tie-lines, were used to determine the
ability of this ionic liquid as solvent for the separa-
tion of toluene from its mixtures with heptane. The
degree of consistency of the experimental LLE data
was ascertained using the Othmer–Tobias equation.
The experimental data for LLE of the ternary system
were correlated with the Non-Random Two-Liquid
(NRTL) and UNIversal QUAsi-Chemical (UNI-
QUAC) thermodynamic models.

Diagramas binarios líquido-sólido mostrando la formación de compuestos en mezclas de tetra-cloruro decarbono-dioxano y cloroformo-dioxano con punto de fusión metastables son mostrados. Se observa la formación de un compuesto en la mezcla tetracloruro de carbono-dioxano a 33% molar. Los resultadosson analizados y comparados con datos de literatura. Este experimento introduce al estudiante en el manejo de las bajas temperaturas mediante un montaje de laboratorio simple

"The yellow greases and the vegetable oils used can be converted to biodiesel. The
problem with these sources of low cost oil and fats is that they contain large amounts
of free acids that cannot be converted to biodiesel using an alkaline catalyst. A
pretreatment to avoid the formation of soaps is an acid-catalyzed to esterify the free fatty acids before transesterifying the triglycerides with an alkaline catalyst to complete the reaction. The best production of biodiesel, corresponds to the methyl oleate, with 4.985 kmol/hr, and for the methyl butyrate a production of 4.658 is obtained kmol/hr."

En la presente investigación donde se evalúa el contenido de azúfre  y el calor de combustion en  residuos poscosecha de caña panelera en las variedades CC85-92, CC85-47, CC 84-75, CC 864-5, RD 75 – 11 y de  mazorca en las variedades ICA V-109, ICA V-156, ICA V-304, ICA V-305 E ICA V-507, con contenido de humedad de 0% (p/p), 10% (p/p), 20% (p/p), y 30% (p/p).