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11.
Determination of alcohols and volatile organic acids in anaerobic bioreactors for H2 production by near infrared spectroscopy 总被引:1,自引:0,他引:1
Maurílio Gustavo Nespeca Caroline Varella Rodrigues Kamili Oliveira Santana Sandra Imaculada Maintinguer José Eduardo de Oliveira 《International Journal of Hydrogen Energy》2017,42(32):20480-20493
In recent years, near infrared (NIR) spectroscopy has been investigated as a tool for monitoring anaerobic digesters, but several adversities in its application have been reported. This study proposes the application of NIR for the determination of alcohols and volatile organic acids from H2 production bioreactors and evaluates different approaches to optimize the prediction models. Partial least squad (PLS) models were developed using samples from anaerobic batch reactors fed with crude glycerol for wastewater treatment. The analytes predicted were: methanol, ethanol, 1-butanol, acetic, propanoic, butyric, isocaproic and total volatile organic acids (VFA). The optimization of the predictive capacity of the models was achieved through the orthogonal signal correction (OSC) preprocessing and the selection of variables performed by the genetic algorithm (GA). The application of the proposed models were based on the following figures of merit: accuracy, precision, linearity, limits of detection and quantitation, measurement interval, sensitivity, selectivity, signal-to-noise ratio and bias. Despite the low selectivity (maximum of 0.12%), the models presented high sensitivity [γ?1 = 0.19 (mg L?1)?1], low LOQ (1 mg L?1) and correlation between reference and predicted values (r) at least 0.93, except for propanoic acid (rpred = 0.85). The F-test revealed that the selection of variables by GA significantly improved the accuracy and linearity of the prediction models for methanol, acetic acid, isocaproic acid and VFA. NIR spectroscopy has proved to be a powerful tool for monitoring H2 production bioreactors since provides fast, low cost and multicomponent information. 相似文献
12.
The fragmentation of a liquid layer to form a fine droplet mist by high frequency ultrasonic atomization of liquids has been applied to a range of industrial applications such as fine chemical manufacturing, pharmaceutical production, and food processing. A recent development is the separation of alcohol from miscible alcohol‐water mixtures using ultrasonic atomization. In this work, the effect of high frequency ultrasonic atomization at 1.6 MHz on the enrichment of ethanol from ethanol‐water feed mixtures has been studied. Experiments for evaluating this enrichment process were conducted in batch and continuous feed processing systems. The continuous enrichment process generated product concentrations that were higher than the equivalent vapor‐liquid equilibrium curve at feed concentrations greater than 40 mol.‐% in a single stage. The role of the ultrasonic jet formed at the surface of the feed solution combined with the ethanol separation characteristics has been discussed. 相似文献
13.
Innocenzo G. Casella 《Electrochimica acta》2009,54(15):3866-3871
Palladium film can be deposited on gold polycrystalline electrodes, from a deoxygenated alkaline solution containing 50 mM NaOH plus 0.5 mM K2Pd(CN)4. A multipulse sequence of potentials of equal amplitude and duration was used for the palladium deposition process. In particular, an optimized waveform of potentials of E1 = 1.0 V vs. SCE and E2 = −1.0 V vs. SCE for the relevant pulse duration of t1 = 0.05 s and t2 = 0.05 s, for 30 s, was used. Cyclic voltammetry and scanning electron microscopy (SEM) were employed to characterize the gold-palladium modified electrode (Au-Pd) towards the electrooxidation of aliphatic alcohols in alkaline solutions. The voltammetric study suggests that the kinetics involved in the alcohol electrooxidation at the Pd-Au electrode are sensibly higher than those observed on the bare Pd and Au electrodes. In addition, the most interesting aspect of the electrooxidation of aliphatic alcohols at the Au-Pd electrode was that as the number of methylene groups on the homologous series of aliphatic alcohols increased, the molar response also increased. Under pulsed chronoamerometric conditions (PCC), using an optimized triple pulse waveform of potentials the modified electrode exhibits interesting catalytic currents without any apparent poisoning effects during the oxidation of aliphatic alcohols. 相似文献
14.
A new method for nitric oxide (NO) removal was developed by combining dielectric barrier discharge (DBD) and negative pulse corona (NPC). The effects of gas composition (O2, CO2, and H2O) on NO removal were investigated with this method, and the effect of alcohols (methanol and ethanol) addition on NO removal was also investigated as well as the reaction mechanisms to enhance the NO removal efficiency. The experimental results showed that O2, CO2, and H2O had obvious inhibition effects on NO removal, and the negative effects were in the following order:O2 > CO2 > H2O. The addition of methanol or ethanol in the reaction system could mitigate the negative effects of O2, CO2, and H2O on NO removal, and also eliminated the production of NO2. The positive effect of alcohols addition with DBD-NPC denitration method was also validated in the simulated flue gas, in which the NOx (NO, NO2) was mainly converted into N2. 相似文献
15.
In heterogeneous catalytic processes, the relationship between bubble size and various process parameters is important in determining interfacial area, hence mass transfer rate. This paper presents the results of an experimental study of bubble sizes in air-alcohol dispersions with and without the presence of catalyst particles in a batch stirred reactor at different agitation speeds and mean specific energy dissipation rates. Factors investigated include catalyst type, particle size and concentration. It has been found that:
- •
- Since there are large differences in the viscosity of the various alcohols used, by dividing them into two groups based on the flow type (turbulent or transitional), a consistent correlation has been found for mean bubble size as a function of Weber number, We, for each region, though neither correlation agrees with the precise relationship suggested by Kolmogoroff's theory of locally, homogeneous, isotropic turbulence.
- •
- At the same We number, the size is bigger in transitional flow than in turbulent. The functionality of the correlation of d32/D versus We is similar whether particles are present or not.
- •
- In fully developed turbulent flow, the bubble size is slightly reduced when catalyst particles are present, independent of catalyst size or type.
- •
- In transitional flow, the effect of catalyst particles on bubble size is much stronger, the size being reduced by approximately 30%.
16.
Vinyl groups in phenyl-terminated polybutadiene (1a) containing 99% unsaturation (27% vinyl group, 73% internal olefin), and for which the average Mn is 3400, were simultaneously hydrogenated and hydroacylated with various aromatic or heteroaromatic primary alcohols in the presence of the catalytic system RhCl3.H2O, PPh3 and 2-amino-4-picoline. Sterically less hindered alcohols, such as benzyl alcohol, showed greater reactivity than sterically more hindered alcohols, such as 2-naphthylmethanol and heteroaromatic primary alcohols. Vinyl groups in phenyl-terminated polybutadiene (1b) containing 99% unsaturation (45% vinyl group, 55% internal olefin) and for which the average Mn is 1300 also showed similar reactivity toward various primary alcohols under identical reaction conditions. 相似文献
17.
A. Iriondo V.L. Barrio M. El Doukkali J.F. Cambra M.B. Güemez J. Requies P.L. Arias M.C. Sánchez-Sánchez R. Navarro J.L.G. Fierro 《International Journal of Hydrogen Energy》2012
In this paper the steam reforming of bioalcohols over Ni and Pt catalysts supported on bare Al2O3 and La2O3 and CeO2-modified Al2O3 to produce H2 was studied. Catalytic activity results showed that the glycerine and the intermediate liquid products may hinder the ethanol adsorption on metal active sites of the catalysts, especially at temperatures below 773 K. In fact, ethanol conversion was lower than glycerine conversion in the steam reforming reaction at low temperatures. H2 chemisorption revealed that La2O3 doping of the Ni/Al2O3 catalyst improved the metal dispersion providing a better behaviour to the Ni/Al2O3-O2 catalyst towards H2 production. In the case of Pt catalysts, the good reducibility and the H2 spillover effect provided to the Pt/Al2O3-O1 catalyst the capacity to produce higher H2 yields. 相似文献
18.
Volatile components of the enzyme-ripened sufu, a Chinese traditional fermented product of soy bean 总被引:2,自引:0,他引:2
In the present study, sufu, a soft cheese-like oriental fermented food, was prepared by ripening the salted-tofu cubes in Aspergillus oryzae-fermented soybean-rice koji at 37°C for 16 days (16-day sufu). Sufu was further held at room temperature for another 30 days (46-day sufu). The volatile components of the non-fermented tofu cubes and the sufu products were identified and quantified by GC and GC-MS. A total of 70 volatile compounds including 20 aldehydes, 18 alcohols, 16 esters, 5 ketones, 5 acids and 6 other compounds were identified. Sufu products contained more volatile compounds than non-fermented tofu cubes qualitatively and quantitatively. After 16-days of ripening, fatty acid, aldehyde and ester were noted to be the dominant volatile fractions. In contrast, the 46-day sufu contained ester, and alcohol as the major volatile fractions. They comprise approximately 63.9% of the total volatile components. 相似文献
19.
In recent years, a number of direct coal liquefaction processes have been developed. All processes use a slurry type reactor. Although for lab-scale reactors of large length-to-diameter ratio the use of highly sophisticated slurry reactor model may be justified, simple considerations can meaningfully elucidate the behavior of industrial reactors. A simple analysis shows that the coal liquefaction is controlled by intrinsic kinetics. Both gas and slurry phases can be assumed to be completely backmixed in large diameter reactors. A simple analysis of the thermal behavior revealed multiplicity for a fairly wide range of operating conditions. In most cases, the intermediate unstable steady state is close to the temperature observed in adiabatic coal liquefaction reactors (with and without quench). Due to the unstable character of the operation, point pathological phenomena like runaway may be possible and a close feedback control of the commercial reactor may be required. 相似文献
20.
Kabir-ud-Din Mohammed D. A. Al-Ahmadi Andleeb Z. Naqvi Mohd. Akram 《Chemical Engineering Communications》2013,200(8):948-957
The work focuses on the clouding and dye solubilization phenomena in an amphiphilic drug, nortriptyline hydrochloride (NOT), which is a tricyclic antidepressant. A 30 mM drug solution prepared in 10 mM sodium phosphate buffer (pH: 7.07) showed CP at 45°C, which was found to decrease with the addition of long-chain alcohols and cyclohexanol but remained almost constant with short-chain alcohols. The behavior is explained on the basis of their nature: short-chain alcohols are water soluble and partition very little in micelles, whereas long-chain alcohols are hydrophobic and solubilize in drug aggregates. Diols decreased the CP. Addition of cationic surfactants increased the CP, whereas sugars caused a decrease. Dye solubilization results indicate micellar growth with fixed concentrations of surfactants. 相似文献