This paper reports the development of calibration models for quality control in the production of ethylene/propylene/1-butene terpolymers by the use of multivariate tools and FT-IR spectroscopy.
...1-Butene concentration prediction is achieved in terpolymers by coupling FT-IR spectroscopy to multivariate regression tools. A dataset of 26 terpolymers (14 coming from a constrained experimental design for mixtures, plus 12 terpolymers used for external validation) was analysed by FT-IR spectroscopy. An internal method of “Polimeri Europa” plant, based on
13C NMR spectroscopy is used to determine the percentage of 1-butene in the samples. Then, different multivariate tools are used for 1-butene concentration prediction based on the FT-IR spectra recorded. Different multivariate calibration methods were explored: principal component regression (PCR), partial least squares (PLS), stepwise OLS regression (SWR) and artificial neural networks (ANNs). The model obtained by back-propagation neural networks turned out to be the best one. The performances of the BP-ANN model were further improved by variable selection procedures based on the calculation of the first derivative of the network.
The proposed approach allows the monitoring in real time of the polymer synthesis and the estimation of the characteristics of the product attainable from the concentration of 1-butene.
This paper describes the design, realisation and test of a power unit based on a polymer electrolyte fuel cell, operating at room temperature, for portable application. The device is composed of an ...home made air breathing fuel cell stack, a metal hydride tank for H
2 supply, a dc–dc converter for power output control and a fan for stack cooling. The stack is composed by 10 cells with an active surface of 25
cm
2 and produces a rated power of 15
W at 6
V and 2
A. The stack successfully runs with end-off fed hydrogen without appreciable performance degradation during the time. The final assembled system is able to generate 12
W at 9.5
V, and power a portable DVD player for 3
h in continuous. The power unit has collected about 100
h of operation without maintenance.
Lithium ion can be added as a denaturing agent to wines unsuitable for consumption. Accuracy of flame atomic emission spectroscopy with direct nebulization, which is commonly adopted for discovering ...illegal use of denatured wines, was found to be compromised by Na
+, K
+, NH
4
+, Mg
2+, Ca
2+ and ethanol contained in wine. Ion chromatography (IC) was tested in order to propose an alternative method for legal controls. Experimental design was used to investigate the influence on the accuracy of the determination of Li
+ at ppb levels, of Na
+ and ethanol content of wine and of fluctuations of eluent flow-rate and composition. It turned out that IC quantification of Li
+ can be affected by eluent parameters rather than by wine composition. Since the former can be maintained under the operators control, while the latter cannot, IC was judged preferable to AES for legal controls of Li
+ in wines.
The aim of the study was to analyse BTEX compounds (benzene, toluene, ethylbenzene, xylenes) in air by solid phase micro-extraction/gas chromatography/mass spectrometry (SPME/GC/MS), and this article ...presents the features of the calibration method proposed. Examples of real-world air analysis are given. Standard gaseous mixtures of BTEX in air were generated by dynamic dilution. SPME sampling was carried out under non-equilibrium conditions using a Carboxen/PDMS fibre exposed for 30 min to standard gas mixtures or to ambient air. The behaviour of the analytical response was studied from 0 to 65 microg/m3 by adding increasing amounts of BTEX to the air matrix. Detection limits range from 0.05 to 0.1 microg/m3 for benzene, depending on the fibre. Inter-fibre relative standard deviations (reproducibility) are larger than 18%, although the repeatability for an individual fibre is better than 10%. Therefore, each fibre should be considered to be a particular sampling device, and characterised individually depending on the required accuracy. Sampling indoor and outdoor air by SPME appears to be a suitable short-delay diagnostic method for volatile organic compounds, taking advantage of short sampling time and simplicity.
Five noncommercial and four commercially available cyclodextrin (CD) derivatives were tested as chiral auxiliaries for the capillary electrophoretic (CE) resolution of racemic 1,1’‐bi‐(2‐naphthol) ...(BN), 1,1’‐binaphthyl‐2,2’‐diyl hydrogenphosphate (BNHP), and 1,1’‐binaphthyl‐2,2’‐diamine (BNA) at pH 4.0, 6.5, and 8.6. The noncommercial CDs were ethyloxycarbonyl‐γ‐CD (ethylcarbonate‐γ‐CD), dimethylamino ethyloxycarbonyl‐β‐CD, a mercaptosuccinic acid derivative of β‐CD, a maleic acid derivative of β‐CD and heptakis(6‐deoxy‐6‐amino)‐β‐CD derivative with one amino group on the C‐6 carbon of each glucose unit. Except for the latter, the remaining derivatives were synthesized for this work. Also commercially available methyl‐β‐CD, hydroxypropyl‐β‐CD and the native β‐ and γ‐CDs were examined. Among the nine CDs tested, the maleic acid derivative of β‐CD gave the most interesting performances, since it resolved the atropisomers of BNA and BNHP in the same electrophoretic run at pH 4.0. It resolved the BNA racemate also at pH 6.5. Both the negatively charged CD tested were found to resolve anionic BNHP enantiomers, while positively charged CDs did not with cationic BNA. Several of the CDs investigated in this work were found to resolve the BNHP racemate, although at nonoptimal concentration. None of the experimented CDs was found to resolve the electrically neutral BN atropisomers pair at the three pHs considered, while some among these nine, experimented in a previous work, did so at higher pH.
An electrochemical method is proposed for the degradation of an industrial effluent from a chemical industry, containing sulfonate- and phenol- derivatives.
A model solution simulating the ...composition of the waste was prepared and the degradation kinetics of each component was followed. For this purpose an ion-interaction HPLC method was developed, able to simultaneously separate phenol- and sulfonate- derivatives. The method is essentially based on the formation of ion-pairs in a mobile phase of octylamine o-phosphate at pH=8.0
The degradation process was then applied in the analysis of the waste. Both for the model solution and for the waste, the electrochemical process led to about 80% degradation.
An ethylcarbonate derivative of β-cyclodextrin (β-CD) with three substituents per molecule, hydroxypropyl-β-CD and native α-CD have been tested as resolving agents in the capillary zone ...electrophoresis (CZE) separation of the four enantiomers of the herbicides mecoprop and dichlorprop. The performances of the three compounds have been quantified by means of two-levels full factorial design and the inclusion constants were calculated from CZE migration time data. Possible structure of inclusion complexes have been proposed, on the basis of molecular mechanics simulations.
Native β‐ and γ‐cyclodextrin (CD), neutral β‐CD derivatives and ethylcarbonate derivatives of β‐ and γ‐CD were used as stereoselective additives for CD‐capillary zone electrophoresis (CZE) resolution ...of atropisomers of 1,1′‐bi‐(2‐naphthol) (BN). CZE experiments at variable CD concentration allowed calculating binding constants from electrophoretic mobility data, corrected for electroosmotic flow (EOF) and running buffer viscosity variations. The CDs were chosen on the basis of geometric examination of molecular models of BN and CDs that suggested the possibility of inclusion complexes formation. Optimum concentrations, with aqueous 25 mM phosphate running buffer at pH 10.5, 36 cm×50 νm capillary and 10 kV applied potential, were 3.6, 3.9, 2.1, 2.2, 1.9 mM for β‐CD, γ‐CD, ethylcarbonate‐β‐CD, methyl‐β‐CD and hydroxypropyl‐β‐CD, respectively.
BACKGROUND AND INTENTION: Aromatic sulphonates other than surfactants and their hydroxy and amino-derivatives are important intermediates for the production of azo dyes. Their production on a large ...scale can be detrimental for the environment, if the by-products of their synthesis are not disposed of appropriately. An industrial waste, the organic components of which were mainly amino and hydroxy-substituted aromatic sulphonates, seriously endangers the environment close to an dismissed Italian industrial site. Inorganic sulphates and chlorides contained in the waste seriously hinder its disposal by incineration, since they corrode furnace walls. In this work, preliminary exploration of aqueous-phase electrochemically and photochemically induced oxidation techniques have been performed as possible alternatives to incineration.
Electrochemically-induced oxidation was experimented on individual aromatic sulphonates and on an industrial waste by electrolysing them between smooth platinum electrodes at low temperature (5 degrees C) and high current densities (0.4 A/cm2) with aqueous 0.5 M NaHSO4 electrolyte. Photochemically-induced oxidation was performed by irradiating individual aromatic sulphonates or industrial waste with a 500 W mercury lamp in the presence of sodium peroxydisulphate.
After 200 min electrodegradation, 90% of the original compounds disappeared, while 50% Total Organic Carbon (TOC) of an industrial waste was removed from solution after 10 hours. After 180 min UV-photodegradation, 90% of two test aromatic sulphonates disappeared, while 65% of TOC of industrial waste was removed after 5 hours.
Two methods, electrochemical and UV-persulphate oxidation of an industrial waste, were used in order to propose a disposal procedure alternative to incineration. Electrodegradation with smooth Pt anode in 0.5 M NaHSO4 at 5 degrees C halved TOC concentration within 10 hours, while persulphate-assisted UV-photochemical oxidation with a 500 W high pressure Hg lamp abated two-thirds of TOC concentration after 5 hours. Energetic consumption of electrodegradation was 0.33 kWh/g TOC, while that of photooxidation was larger than 2 kWh/g TOC. Although both techniques can be considered efficient from a purely chemical point of view, since both are capable of wet-oxidising the aromatic sulphonates and the industrial waste, electrodegradation seems more promising than a photochemical degradation if economical considerations are also taken into account. Considering also that neither cell design nor catalyst were optimised in this preliminary study, the energy yield of electrodegradation seems likely to be largely improved.
