Adsorption, desorption and condensation of nitrobenzene solution from active carbon: a comparison of two cyclodextrins and two surfactants

The adsorption of nitrobenzene on active carbon was researched. The experimental results shown the adsorption of nitrobenzene on active carbon can be described by Freundlich's adsorption model. On the other hand, beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) can react with nitrobenzene to form inclusion complex, which will enhance the aqueous solubility of nitrobenzene. By using different concentrations of beta-CD and HP-beta-CD as extractants, nitrobenzene on active carbon has been desorbed statically. As a comparison, surfactant CTAB and SDS were also selected as extractants. The desorbing of mechanism has been discussed. The low concentration of NB was effectively condensed by enrichment of active carbon and desorption of HP-beta-CD. HP-beta-CD is regarded as a potential extractant to deal with soil, sediment or active carbon.     

Isolation and characterization of a nitrobenzene degrading yeast strain from activated sludge

Strain Z1 was isolated from nitrobenzene-contaminated sludge. Strain Z1 was able to utilize nitrobenzene as a sole source of carbon, nitrogen, and energy under aerobic condition. Based on the morphology, physiological biochemical characteristics, and 26S rDNA D1/D2 domain sequence, strain Z1 was identified as Rhodotorula mucilaginosa. Strain Z1 mineralized up to 450mg L(-1) nitrobenzene. Kinetics of nitrobenzene degradation was described using the Andrews equation. The kinetic parameters were as follows: q(max)=1.50h(-1), K(s)=31.31mg L(-1), and K(i)=101.34mg L(-1). Strain Z1 had a high-salinity tolerance. It degraded nitrobenzene effectively in 5% NaCl (quality concentration). Even in the presence of aniline or phenol, strain Z1 degraded nitrobenzene efficiently. Strain Z1 therefore could be an excellent candidate for the bio-treatment of nitrobenzene industrial wastewaters.     

Low-energy electron interaction with nitrobenzene: C6H5NO2

Low-energy electron attachment to C₆H₅NO₂ (nitrobenzene) in the gas phase is reported in the electron energy range from about 0 up to 10 eV with an energy resolution of 120 meV. Dissociative and nondissociative electron attachment to nitrobenzene were observed. From the numerous ions observed, the two most abundant were NO₂⁻ and C₆H₅NO₂⁻. Based on comparison of the abundance of studied ions with Cl⁻ in the dissociative electron attachment to CCl₄ at 0.8 eV, estimates of cross sections for the all observed ions were obtained for the first time (e.g. σ(NO₂⁻)=4.6×10⁻²⁰ m² and σ(C₆H₅NO₂⁻)=3.8×10⁻²¹ m²).     

Heterogeneous Photocatalysis in Microreactors for Efficient Reduction of Nitrobenzene to Aniline: Mechanisms and Energy Efficiency

Aniline was synthesized from nitrobenzene through photo‐induced reduction in microreactors under UV irradiation. Nitrobenzene solution and the nanofluid prepared by a TiO₂ nanocatalyst, PEG‐400, and deionized water were mixed in a capillary microreactor. The effects of catalyst composition, residence time, and substrate concentration on the reaction performance were systematically investigated. The conversion of nitrobenzene and the yield of aniline reached high values under optimized conditions. The excellent reusability of the photocatalyst was realized for four runs. A mechanism was proposed for this photocatalytic reduction process based on reaction kinetics. Both photo‐induced electrons and ^?CO₂^? could reduce nitrobenzene to aniline. The photonic efficiency in the microreactor was still much higher than that obtained in batch reactors, which was mainly attributed to the much larger effective radiation area of the microreactor.     

Kinetic Description of Industrial Wastewater Ozonation Processes

Literary and experimental data on the ozonation kinetics of aqueous solutions and wastewater were analyzed. COD was suggested to be used as a kinetic parameter from the solution side. On the basis of the results obtained from the ozonation of model solutions and wastewater, the rate coefficient by COD of the reaction was shown to be constant during separate stages of the process. Due to the consumption of fast-reacting components and entering into the reaction of more slowly reacting intermediate products, the rate coefficient changed spasmodically with transition from one stage to another. The reaction order with respect to the COD of the solution was shown to be equal to the reaction order with respect to the pure component.     

活性炭吸附法处理含苯胺、硝基苯废水的实验研究

本文探讨活性炭吸附法处理以苯胺硝基苯为主要污染物的酸性废水的可能性,通过实验证实该方法是可行的。     

Degradation of Refractory Organic Pollutants by Catalytic Ozonation—Activated Carbon and Mn-Loaded Activated Carbon as Catalysts

A novel catalyst for the ozonation process was prepared by loading manganese on the granular activated carbon (GAC). Nitrobenzene was used as a model refractory organic micropollutant in this study. The catalytic activity of GAC and the Mn-loaded GAC were studied respectively. The removal efficiency of nitrobenzene by Mn-loaded GAC catalyzed ozonation could reach 34.2–49.9%, with the oxidation efficiency being about 1.5–2.0 times higher than that achieved in GAC catalyzed ozonation and 2.0–3.0 times higher than that achieved by ozonation alone. The effect of pH and the t -butanol on the GAC/ozone process was discussed. The optimum condition for preparing the catalyst was studied.     

Study of the hypophosphite effect on the electrochemical reduction of nitrobenzene on Ni

The effect of the hypophosphite ion on the electrochemical reduction of nitrobenzene on Ni was evaluated from a cyclic voltammetric study and from constant potential electrolysis in an aqueous-ethanol alkaline medium. The results were compared with the data obtained in an hypophosphite-free solution. It was found that in an hypophosphite containing solution an unusual selective reduction of nitrobenzene to nitrosobenzene occurs. It is the first time that nitrosobenzene is detected as the reaction product of the nitrobenzene electrochemical reduction in an aqueous-ethanol solution. It is proposed that the Ni modified surface which is formed upon hypophosphite oxidation is responsible for the non reducibility of nitrosobenzene. The effect of the electrode potential on the nitrobenzene electrolysis on a Ni modified electrode was analysed. It was concluded that the highest nitrosobenzene yield (33%) and selectivity (82%) is achieved at −1.1 V. It was also found that the formation of nitrosobenzene leads to an electrode poisoning effect in the electrolysis process.     

Methodology Of Ozone Introduction Into Water And Wastewater Treatment

Theoretical basis and methodology for calculation and modeling of ozonation processes and contact equipment have been elaborated. Methodology of determination of reaction rate constant, stoichiometric coefficient, optimum values of pH, intermediate and final products, regimes of chemisorption, etc., for certain typical fast and slow reacting organic compounds (aniline, toluidine, humic acids, nitrobenzene, glyoxalic, oxalic and acetic acid) and wastewaters have been proposed. For calculation of the wastewater ozonation process, the value of chemical oxygen demand (COD) was suggested to be as a kinetic parameter from the solution side. On the basis of kinetic information, recommendations for the choice of the construction of contact equipment for the different chemisorption regimes of ozonation have been presented. Some new contact apparatuses have been proposed.     

Multi-objective optimization of aniline and hydrogen production in a directly coupled membrane reactor

A numerical study of aniline production by hydrogenation of nitrobenzene (NBH) and hydrogen production by steam methane reforming (SMR) in a directly coupled membrane reactor is developed. This membrane reactor was proposed aiming to decarbonize heating in SMR and to favor the recovery of all products. Aniline recovery is improved in this reactor as water, a byproduct in NBH, is consumed in SMR. The simulation is performed using a heterogeneous-one dimensional model (Dusty gas model) and results are compared against the homogeneous model. The operating conditions of the reactor were selected using a multi-objective optimization method, genetic algorithms. The aims of the optimization were: methane conversion maximization, minimum membrane area, minimum reactor size, hydrogen yield maximization, nitrobenzene conversion maximization and the maximization of hydrogen recovery. This process was able to achieve complete conversion of methane and nitrobenzene. The hydrogen yield achieved can be as high as the maximum (～4). 35% of this hydrogen was used as a reactant for aniline production. 99% of the unreacted hydrogen was recovered and purified. As the steam flow was minimized, aniline was obtained with a molar composition (70%), 2.1 times higher than that obtained in a conventional process for aniline production (33%). CO₂ was obtained with a purity of 97%, hence, CO₂ carbon capture and storage techniques were also favored. In addition, the energy requirements of heating of feedstock, reaction and recovery system of this novel process was 2.7 times lower than that of conventional processes carried out independently.