One-compartment Reactor Research Articles

Comparison between an electrochemical reactor with and without membrane for the nor oxidation using novel ceramic electrodes

The electrochemical oxidation of the antibiotic Norfloxacin (NOR) in chloride media on different anodic materials was studied at two different electrochemical reactors. The results were compared with those obtained in sulphate media. The anodes under study were a commercial boron-doped diamond (BBD) and two different ceramic electrodes based on tin oxide doped with antimony oxide in the presence (CuO) and absence (BCE) of copper oxide as sintering aid. The reactors employed were a one-compartment reactor (OCR) and a two-compartment one with a membrane separating both electrodes (EMR). The use of the membrane clearly enhanced both NOR degradation and TOC mineralization for all the anodic materials studied since some parallel reactions were avoided. Additionally, two different pathways for NOR oxidation were observed as a function of the reactor employed. The EMR also favoured the ionic by-products generation and the electrolyte dechlorination. NO3− increased with the oxidation power of the anode employed and it was also enhanced by the EMR use. Chloride media favours ceramic electrodes performance independently of the reactor employed as they did not generate an excess of oxidants as BDD did. The BCE electrode is an interesting alternative to BDD since although its oxidative power was lower, it presented similar current efficiency with lower energy consumption.

Solar CO2 reduction using H2O by a semiconductor/metal-complex hybrid photocatalyst: enhanced efficiency and demonstration of a wireless system using SrTiO3 photoanodes

Solar formate production from CO2 and H2O was achieved with no external electrical bias by combining an InP/[RuCP] semiconductor/metal-complex hybrid photocathode with a reduced SrTiO3 (r-STO) photoanode. The conversion efficiency from solar to chemical energy was improved from 0.03 to 0.14% compared to a previous system utilizing a TiO2 photoanode. Stimulated electron transfer from the photoanode to the photocathode is the main cause for the observed improvement, due to an enlarged difference in the band-energy position between r-STO and InP. Since r-STO showed high H2O oxidation selectivity even in the presence of formate, a r-STO/InP/[RuCP] wireless device successfully performed solar CO2 reduction in a one-compartment reactor with no proton exchange membrane, yielding a solar conversion efficiency of 0.08%.

전기화학적 공정의 운전인자에 따른 산화제 생성과 염료 분해 특성

The purpose of this study is to investigate electro-generation of free Cl, <TEX>$ClO_2$</TEX>, <TEX>$H_2O_2$</TEX> and <TEX>$O_3$</TEX> and degradation of Rhodamine B in solution using Ru-Sn-Sb electrode. Electrolysis was performed in one-compartment reactor using a dimensionally stable anode(DSA) of Ru-Sn-Sb/Ti as the working electrode. The effect of applied current (0.5-3 A), electrolyte type (NaCl, KCl, HCl, <TEX>$Na_2SO_4$</TEX> and <TEX>$H_2SO_4$</TEX>) and concentration (0.5-2.5 g/L), air flow rate (0-3 L/min) and solution pH (3-11) was evaluated. Experimental results showed that concentration of 4 oxidants was increased with increase of applied current, however optimum current for RhB degradation was 2 A. The generated oxidant concentration and RhB degradation of the of Cl type-electrolyte was higher than that of the sulfate type. The oxidant concentration was increased with increase of NaCl concentration and optimum NaCl dosage for RhB degradation was 1.75 g/L. Optimum air flow rate for the oxidants generation and RhB degradation was 2 L/min. <TEX>$ClO_2$</TEX> and <TEX>$H_2O_2$</TEX> generation was decreased with the increase of pH, whereas free Cl and <TEX>$O_3$</TEX> was not affected by pH. RhB degradation was increase with the pH decrease.

Different In Vitro Systems Affect CYPIA1 Activity in Response to 2,3,7,8-Tetrachlorodibenzo- p-dioxin

The induction of cytochrome P450IA1 (CYP1A1) activity in human hepatoma cell lines has been used as a model response for exposure to the environmental contaminant, 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD). CYP1A1 induction is mediated by the intracellular Ah receptor. We have designed a cell culture analogue system to evaluate the effect of low dose continuous exposures to TCDD such that the responses can be compared with traditional static in vitro exposures. The two-compartment model is designed to mimic aspects of time-dependent dose exposure in humans and consists of a ‘liver’ compartment with HepG2 cells and an ‘other tissues’ compartment. Exposure of microcarrier-attached HepG2 cells in spinner flask to a single dose of TCDD resulted in an EC 50 for ethoxyresorufin- o-deethylase (EROD) activity induction of 1.49 n m. Using a one-compartment reactor with continuous TCDD dosing resulted in an EC 50 for EROD induction of 0.69 n m TCDD. Finally, using a two-compartment reactor with continuous TCDD dosing resulted in an EC 50 for EROD induction of about 0.05 n m. Parallel studies using 3H-TCDD were performed to determine the amount of cell associated 3H-TCDD and subsequently to estimate the amount of bound Ah receptor. CYPIA1 mediated EROD activities in both cell lines correlated with the estimated amount of bound Ah receptor. To illustrate how these systems might alter estimates of risk, the data were evaluated to estimate the TCDD level which would increase CYPIA1 mediated EROD activity to 0.01% of the maximal response. The two-compartment reactor data yielded an estimate of allowable TCDD exposure of 1×10 −5 n m for an acceptable ‘risk’ level of 0.01%. In contrast, values were estimated as 4×10 −4 n m from the one compartment reactor and 4×10 −3 n m from spinner flasks. This work demonstrates the importance of design of the in vitro system on risk assessment.

Scale‐down and optimization studies of the gluconic acid fermentation by Gluconobacter oxydans

To simulate production-scale conditions of gluconic acid fermentation by Gluconobacter oxydans, different experimental setups are presented in this study. From the determination of the time constants of a production-scale reactor, it can be concluded that mixing and oxygen transfer are the rate-limiting mechanisms. This results in oxygen concentration gradients which were simulated in a one-compartment reactor in which the oxygen concentration was fluctuated by a fluctuated gassing with air and nitrogen. It could be concluded that only very long periods of absence of oxygen (ca. 180 s) results in lower specific oxygen uptake rates by Gluconobacter oxydans. From scale-down studies carried out in a two-compartment system to simulate a production-scale reactor more accurately, it could be concluded that not only the residence time in the aerated part of the system is important, but the liquid flow in between the different parts of the reactor is also an essential parameter. It could also be concluded that the microorganisms are not influenced negatively by the fluctuated oxygen concentrations with respect to their maximal oxidation capacity. The two-compartment system can also be used for optimization experiments in which the "aerated" compartment was gassed with pure oxygen. From these experiments it was concluded that also a short residence of the cells at high oxygen concentrations diminished the growth and product formation rates. These experiments show the necessity of the scale-down experiments if optimization is carried out. The two-compartment system presented in this study is a very attractive tool for reliable scale-down experiments.