Mathematical modeling for operative improvement of the decoloration of Acid Red 27 by a novel microbial consortium of Trametes versicolor and Pseudomonas putida: A multivariate sensitivity analysis.

In this work, it is presented a first approach of a mathematical and kinetic analysis for improving the decoloration and further degradation process of an azo dye named acid red 27 (AR27), by means of a novel microbial consortium formed by the fungus Trametes versicolor and the bacterium Pseudomonas putida. A multivariate analysis was carried out by simulating scenarios with different operating conditions and developing a specific mathematical model based on kinetic equations describing all stages of the biological process, from microbial growth and substrate consuming to decoloration and degradation of intermediate compounds. Additionally, a sensitivity analysis was performed by using a factorial design and the Response Surface Method (RSM), for determining individual and interactive effects of variables like, initial glucose concentration, initial dye concentration and the moment in time for bacterial inoculation, on response variables assessed in terms of the minimum time for: full decoloration of AR27 (R1 = 2.375 days); maximum production of aromatic metabolites (R2 = 1.575 days); and full depletion of aromatic metabolites (R3 = 12.9 days). Using RSM the following conditions improved the biological process, being: an initial glucose concentration of 20 g l-1, an initial AR27 concentration of 0.2 g l-1 and an inoculation moment in time of P. putida at day 1. The mathematical model is a feasible tool for describing AR27 decoloration and its further degradation by the microbial consortium of T. versicolor and P. putida, this model will also work as a mathematical basis for designing novel bio-reaction systems than can operate with the same principle of the described consortium.

GHG and black carbon emission inventories from Mezquital Valley: The main energy provider for Mexico Megacity.

The greenhouse gases and black carbon emission inventory from IPCC key category Energy was accomplished for the Mezquital Valley, one of the most polluted regions in Mexico, as the Mexico City wastewater have been continuously used in agricultural irrigation for more than a hundred years. In addition, thermoelectric, refinery, cement and chemistry industries are concentrated in the southern part of the valley, near Mexico City. Several studies have reported air, soil, and water pollution data and its main sources for the region. Paradoxically, these sources contaminate the valley, but boosted its economic development. Nevertheless, no research has been done concerning GHG emissions, or climate change assessment. This paper reports inventories performed by the 1996 IPCC methodology for the baseline year 2005. Fuel consumption data were derived from priority sectors such as electricity generation, refineries, manufacturing & cement industries, transportation, and residential use. The total CO2 emission result was 13,894.9 Gg, which constituted three-quarters of Hidalgo statewide energy category. The principal CO2 sources were energy transformation (69%) and manufacturing (19%). Total black carbon emissions were estimated by a bottom-up method at 0.66 Gg. The principal contributor was on-road transportation (37%), followed by firewood residential consumption (26%) and cocked brick manufactures (22%). Non-CO2 gas emissions were also significant, particularly SO2 (255.9 Gg), which accounts for 80% of the whole Hidalgo State emissions. Results demonstrated the negative environmental impact on Mezquital Valley, caused by its role as a Megacity secondary fuel and electricity provider, as well as by the presence of several cement industries.

Novel CdCl2 and HgCl2 complexes with 3-monosubstituted and 3,3-disubstituted 1-furoylthioureas: IR and Raman spectra.

Two series of coordination complexes of CdCl(2) and HgCl(2) with 3-monosubstituted and 3,3-disubstituted 1-furoylthioureas were prepared and characterized. These complexes were obtained with a medium to high yield from ethanolic solutions of both ligand and salt. The formed complex results from the salt-ligand interaction with participation of both the salt anion and cation. Information on the coordination chemistry of these complexes was derived from thermal stability data, and IR, Raman and (13)C CPMAS NMR spectra. On coordination the electronic structure of these ligands changes as a whole, affecting practically all their vibrational pattern, however, within that complex pattern some vibrations provide valuable information on the nature of the studied complexes. These thiourea derivatives behave as neutral ligands, which coordinate the metal ion through the sulfur atom of the thiocarbonyl group. This fact is supported by the observed frequency shift, to lower values, in the nu(CS) vibration on the coordination and the appearance of a low frequency Raman line which was assigned to the metal-sulfur stretching, nu(M-S), in the formed complex. The frequency of the nu(CO) vibration always increases on complex formation, which discards the participation of the carbonyl group in the coordination process. The complexation takes place preserving the free ligand conformation, established from intra-molecular interactions, particularly in 3-monosubstituted ligands. Such features of the studied ligands and their complexes are also supported by (13)C CPMAS NMR spectra. This spectroscopic information correlates with the reported behavior of the ligands in ion selective electrodes.

A Raman and infrared study of 1-furoyl-3-monosubstituted and 3,3-disubstituted thioureas.

Raman and IR spectra of two series of 1-furoylthiourea derivatives (19 compounds) were recorded and compared in order to identify the vibrations, which involve contributions from motions within the thioureido (NCSN) core. This procedure allowed an unequivocal identification of the nu(CS) vibration in these spectra. In 3-monosubstituted furoylthioureas (Series 2) the carbonyl group and the proton on N(3) are engaged in a strong hydrogen bond interaction. This leads to an "S"-shaped conformation of the CO and CS groups where these donor sites reach a maximum separation. In this conformation, the nu(CO) vibration is not influenced by the substituent. In the absence of that hydrogen bridge, in 3,3-disubstituted thiourea derivatives (Series 1), the CO and CS groups adopt an "U"-shaped conformation. In this conformation, the nu(CO) vibration shows a pronounced substituent dependence. These thiourea derivatives have been tested as ionophores for heavy-metal ion selective electrodes and their behavior in that sense correlates with the observed Raman and IR absorptions. The best performance in that application corresponds to compounds of Series 2, which showed the highest frequency values of the nu(CS) vibration. This fact was related to an appropriated nucleophilic character of the sulphur atom. From these data, Raman and IR spectra of these thiourea derivatives could be used as a predictor on their expected behavior in analytical applications as ionophores.

Aroylthioureas: new organic ionophores for heavy metal ion selective electrodes. A nuclear magnetic resonance study.

The 1H and 13C NMR spectra of four series of 1-aroylthiourea derivatives in DMSO-d6 are reported. The NH signals for 3-alkyl substituted aroylthioureas are identified by their multiplicity and by homonuclear irradiation experiments. Correlation analyzes are made for NH, CO and CS signals in order to determine the best way to modulate the nucleophilic character of the CS group, as thioureas are well-known ionophore groups. Almost all 1,3-substituted thioureas (Series 2-4) show the reported chelated structure with the exception of those with CF3, CN and NO2 groups. Pyridine group promote a different equilibrium in solution. The fragment -CO-NH- transmits poorly the electronic effects of substituents in the aroylgroup.

Response mechanism of a neutral carrier Hg(II) polymeric membrane ion-selective electrode. SEM and EDAX study.

Scanning electron microscopy (SEM) and energy dispersive atomic X-ray spectrometry (EDAX) were used to study the response mechanism of a previously reported new Hg membrane ion-selective electrode (ISE) based on 1,3-diphenylthiourea. These techniques allowed the study of the membrane surface characteristics, such as the morphological homogeneity and chemical composition. A 'twice Nernstian' response at pH > or = 7 was explained by the detection of the Hg(OH)+ cation. A normal Nernstian response was found at acidic pH values. Using these techniques, both coordination compounds, [Ligand-Hg-OH] at pH 7 and [Ligand-Hg-Ligand] at pH 4.5, were confirmed on the electrode membrane surface activated with Hg(NO3)2 solution at both pH values. These methods provide results which are independent of the potential measurement data and in agreement with them. A successful response model has explained both independent and unbiased sets of results. These conclusions confirm the proposed response mechanisms for this new Hg membrane sensor.