Search results for " Chemical Engineering"
showing 10 items of 2965 documents
Arsenic(III) Removal at Low Concentrations by Biosorption usingPhanerochaete chrysosporiumPellets
2013
As(III) removal from dilute aqueous solutions by biosorption onto pellets of the white rot fungus Phanerochaete chrysosporium was investigated. The As(III) uptake capacity was evaluated at low initial concentrations (0.2–1 mg/L) which revealed that the P. chrysosporium pellets were only slightly less efficient than the well studied adsorbent granular ferric hydroxide. Moreover, its performance was much more superior compared to anaerobic granular sludge, another cheaply available bacterial biosorbent. In the studied pH (5–9) and biomass concentration (0.25–1.5 g/L wet weight basis) ranges, no large differences in As(III) removal efficiency were observed. The influence of different ions, com…
Fixed‐Bed Removal of Free and Complexed Ni from Synthetic and Industrial Aqueous Solutions
2008
Abstract This paper evaluates the application of several biosorbents for Ni removal from aqueous solutions in the absence and in the presence of EDTA. Fixed bed experiments were performed (Ni influent concentration, 2 mg dm−3; EDTA doses, 0, 5, and 10 mg dm−3; pH=7) to study the process feasibility as refining after conventional physicochemical treatment. In absence of EDTA, uptake capacity followed the order peat > Posidonia oceanica > chitosan > chitin ≫ Scharlau AC. Maximum uptakes of 8.95 mg g−1 and 5.10 mg g−1 were found for peat and Posidonia oceanica, respectively. In the presence of EDTA, removal capacity decreased for all biosorbents; Ni was detected in the effluent from the beginn…
Halogen-containing BODIPY derivatives for photodynamic therapy
2019
Abstract Two iodinated (1 and 2) and two brominated (3 and 4) BODIPY-based photosensitizers are prepared and characterized using slightly modified synthetic procedures previously described. 1–4 present intense absorption bands in the 510–540 nm interval and very weak emissions due to the presence of halogen atoms in their structure. Irradiation of aqueous solutions of 1–4 with visible light (wavelength > 475 nm) induce the generation of singlet oxygen with quantum yields of ca. 0.62–0.66 for the photosensitizers containing iodine atoms (1 and 2) and of ca. 0.16–0.21 for the brominated counterparts (3 and 4). In vitro studies carried out with HeLa, SCC-13 and HaCaT cell lines and the four ph…
Some working principles of heterogeneous photocatalysis by semiconductors
1993
The present paper outlines some of the principles which are the working base for the photocatalytic processes: we refer to those photocatalytic processes performed using irradiated semiconductors. The steps related to the photoproduction of electron-hole pairs and their separation are discussed. It is also shown how the step of pair separation induces the formation of various chemical species, some of which are useful for the oxidation reactions. It is also shown that in order to reach a detailed description of photocatalytic processes it is necessary to have the knowledge of both the electronic and the physicochemical features of the semiconductors. The paper finally reports a case study r…
Chromogenic Chemodosimeter Based on Capped Silica Particles to Detect Spermine and Spermidine
2021
A new hybrid organic–inorganic material for sensing spermine (Spm) and spermidine (Spd) has been prepared and characterized. The material is based on MCM-41 particles functionalized with an N-hydroxysuccinimide derivative and loaded with Rhodamine 6G. The cargo is kept inside the porous material due to the formation of a double layer of organic matter. The inner layer is covalently bound to the silica particles, while the external layer is formed through hydrogen and hydrophobic interactions. The limits of detection determined by fluorimetric titration are 27 µM and 45 µM for Spm and Spd, respectively. The sensor remains silent in the presence of other biologically important amines and is a…
Study of the performance of a resolution criterion to characterise complex chromatograms with unknowns or without standards
2017
The search for best conditions in liquid chromatography is routinely carried out with information provided by chemical standards. However, sometimes there are samples with insufficient knowledge about their chemical composition. In other cases, identities of the components are known, but there are no standards available, and in other cases the identities of peaks in chromatograms taken under different conditions are ambiguous. Most resolution criteria used to measure separation performance cannot be applied to these samples. In this work, a global resolution function valid for all situations was developed based on automatic measurements of peak prominences (area fraction exceeding the line …
Influence of annealing atmosphere on photoelectrochemical response of TiO2 nanotubes anodized under controlled hydrodynamic conditions
2021
[EN] The influence of three annealing atmospheres (air, nitrogen and argon) and the use of controlled hydrodynamic conditions (from 0 to 5000 rpm) on morphological, structural, chemical and photoelectrochemical properties of TiO2 nanotubes have been evaluated. For this purpose, different characterization techniques have been used: Field Emission Scanning Electron Microscopy, Raman Confocal Laser Spectroscopy, X-Ray Diffraction, X-Ray Photoelectron Spectroscopy, Incident Photon-to-electron Conversion Efficiency measurements, ultraviolet-visible absorption spectra, Mott-Schottky analysis and photoelectrochemical water splitting tests. According to the results, it can be concluded that both hy…
Contribution to modeling the viscosity Arrhenius-type equation for some solvents by statistical correlations analysis
2014
Abstract Estimation and knowledge of transport properties of fluids are essential for heat and mass flow. Viscosity is one of the important properties which are affected by temperature and pressure. In the present work, based on the use of econometric and statistical techniques for parametric and non-parametric regression analysis and statistical correlation tests, we propose an equation modeling the relationship between the two parameters of viscosity Arrhenius-type equation, such as the Arrhenius energy ( E a ) or the pre-exponential factor ( A s ). In addition, we introduce a third interesting parameter called Arrhenius temperature ( T A ), to enrich the discussion. Empirical validation …
Multilanguage Semantic Interoperability in Distributed Applications
2013
JOSI is a software framework that tries to simplify the development of such kinds of applications both by providing the possibility of working on models for representing such semantic information and by offering some implementations of such models that can be easily used by software developers without any knowledge about semantic models and languages. This software library allows the representation of domain models through Java interfaces and annotations and then to use such a representation for automatically generating an implementation of domain models in different programming languages (currently Java and C++). Moreover, JOSI supports the interoperability with other applications both by …
Biodegradability Prediction of Fragrant Molecules by Molecular Topology
2016
Biodegradability is a key property in the development of safer fragrances. In this work we present a green methodology for its preliminary assessment. The structure of various fragrant molecules is characterized by computing a large set of topological indices. Those relevant to biodegradability are selected by means of a hybrid stepwise selection method to build a linear classifier. This model is compared with a more complex artificial neural network trained with the indices previously found. After validation, the models show promise for time and cost reduction in the development of new, safer fragrances. The methodology presented could easily be adapted to many quasi-big data problems in R…