Erhong Duan

Efficient capture of SO2 by a binary mixture of caprolactam tetrabutyl ammonium bromide ionic liquid and water.

The solubility of SO(2) in a binary mixture of water and caprolactam tetrabutyl ammonium bromide ionic liquid (CPL-TBAB IL) was investigated. Though the ionic liquid and water were fully miscible, a phase separation occurred when SO(2) was introduced into the mixture. The SO(2) concentrated in the lower layer, and it could be released by heating the solution under reduced pressure (382.2K, 10.1 kPa). After desorption, the mixture could be reused to absorb SO(2). It was found that SO(2) acts as a switch to cause the water and CPL-TBAB IL to phase separate, and the mechanics of this phase separation process was studied by gas chromatography-mass spectrometry, fourier transform-infrared spectroscopy and Karl-Fisher titration. The absorption and desorption of SO(2) in the CPL-TBAB/water mixtures were reversible.

Struvite Precipitation for Ammonia Nitrogen Removal in 7-Aminocephalosporanic Acid Wastewater

7-Aminocephalosporanic acid wastewater usually contains high concentrations of ammonium (NH4+-N), which is known to inhibit nitrification during biological treatment processes. Chemical precipitation is a useful technology to remove ammonium from wastewater. In this paper, the removal of ammonium from 7-aminocephalosporanic acid wastewater was studied. The optimum pH, molar ratio, and various chemical compositions of magnesium ammonium phosphate (MAP) precipitation were investigated. The results indicated that ammonium in 7-aminocephalosporanic acid wastewater could be removed at an optimum pH of 9. The Mg2+:NH4+-N:PO43−-P molar ratio was readily controlled at a ratio of 1:1:1.1 to both effectively remove ammonium and avoid creating a higher concentration of PO43−-P in the effluent. MgCl2·6H2O + 85% H3PO4 was the most efficient combination for NH4+-N removal. Furthermore, the lowest concentration of the residual PO43−-P was obtained with the same combination. Struvite precipitation could be considered an effective technology for the NH4+-N removal from the 7-aminocephalosporanic acid wastewater.

Characteristics of penicillin bacterial residue.

Implications: During the production of penicillin, a mass of waste bacterial residue is generated. In the past, the bacterial residues have been used for food additives. Unfortunately, doubts of their suitability as a feedstock have been raised because of the small amount of antibiotics and the degradation products remaining in the bacterial residues. So, penicillin bacterial residue is one of the hazardous wastes. Therefore, penicillin bacterial residue should be managed in accordance with the hazardous waste. To get a right method, the penicillin bacterial residue was characterized.

Absorption of NO and NO2 in Caprolactam Tetrabutyl Ammonium Halide Ionic Liquids

ABSTRACT To explore environmentally benign solvents for the absorption of NO and NO2, a series of caprolactam tetrabutyl ammonium halide ionic liquids were synthesized. The solubility of NO and NO2 was measured at temperatures ranging from 298.2 to 363.2 K and atmospheric pressure, and the following trend in the solubility of NO and NO2 in ionic liquids with various halide anions was observed, respectively: F > Br > Cl and Br > Cl > F. Moreover, as the temperature increased from 308.15 to 363.15 K and the mole ratio of caprolactam increased from 2:1 to 6:1, the solubility of NO increased. Alternatively, the solubility of NO2 decreased as the temperature increased from 298.15 to 363.15 K, and the mole ratio of caprolactam increased from 2:1 to 6:1. The absorption and desorption of NO and NO2 was practically reversible in the ionic liquids, which was characterized by nuclear magnetic resonance. The method, which is at least partially reversible, offers interesting possibilities for the removal of NO and NO2. IMPLICATIONS Basic ionic liquids with amino groups were synthesized and used to capture CO2, SO2, and H2S, and to promote hydrogenation of CO2. In this paper, the authors used caprolactam tetrabutyl ammonium halide ionic liquid (IL) as absorbing medium in which NOx could be absorbed. NOx desorbed from the absorbent could be efficiently reduced by right catalysts at high temperature. The absorbed NO and NO2 gas could be desorbed at higher temperature, allowing the ionic liquids to be reused several times without loss of capability. It was believed that caprolactam tetrabutyl ammonium bromide (CPL-TBAB) ILs may be useful for NOx removal reagent for pollution control.

Preparation, characterization, and phenol adsorption of activated carbons from oxytetracycline bacterial residue

The oxytetracycline bacterial residue–activated carbon (OBR-AC) prepared from oxytetracycline bacterial residue with K2CO3 under chemical activation was studied. The effects of activation temperature, activation time, and activation ratio on the specific surface area (SSA) and methylene blue adsorption (MBA) were studied. Characterization of the optimum OBR-AC was performed by using scanning electron microscopy (SEM), pore structure (PS,) and Fourier-transform infrared spectroscopy (FT-IR). The optimum parameters were as follows: 800°C activation temperature, 3 hr activation time, and 1:3 activation ratio. The SSA and MBA under optimum conditions were 1593.09 m2/g and 117.0 mg/g, respectively. Adsorption equilibrium and kinetics data were determined for the adsorption of phenol from the synthetically prepared phenol solution. The results showed that the Langmuir model gave the best fit for equilibrium isotherm, whereas the kinetics data were well fitted by the pseudo-second order model. Implications In the past, the bacterial residues have been used for feed additives in China. Unfortunately, doubts of its suitability as a feedstock have been raised because of the small amount of antibiotics, a large number of the fermentation by-products and metabolic products and by-products remaining in the bacterial residues. So Oxytetracycline Bacterial Residue (OBR) is one of hazardous wastes in China. In order to solve the problem of OBR, the preparation of OBR-AC is studied, and OBR-AC under optimum operation parameters is characterized by Scanning Eldctron Microscopy (SEM), Pore Structure (PS) and Fourier Transfer-Infra Red (FT-IR). Moreover, the phenol adsorption isotherms and kinetics models for OBR-AC under optimum operation parameters are studied.

Efficiency and Kinetics of Catalytic Ozonation of Acid Red B over Cu-Mn/γ-Al2O3 Catalysts

The efficiency and kinetics of catalytic ozonation of Acid Red B over Cu-Mn/γ-Al2O3 catalysts were investigated. Cu-Mn/γ-Al2O3 catalysts were prepared by impregnation and characterized by X-ray diffraction and X-ray fluorescence. The removal efficiencies of Acid Red B and total organic carbon were up to 99.35% and 54.38%, respectively. The Cu-Mn/γ-Al2O3 catalysts were stable and easy to be reused. The interim products were analyzed by means of Vis-UV absorption spectrum. Cu-Mn/γ-Al2O3 catalytic ozonation of Acid Red B conformed to the pseudo–first-order kinetics reaction model.

Adsorption and oxidation of SO2 in a fixed-bed reactor using activated carbon produced from oxytetracycline bacterial residue and impregnated with copper

The SO2 removal ability (including adsorption and oxidation ability) of activated carbon produced from oxytetracycline bacterial residue and impregnated with copper was investigated. The activated carbon produced from oxytetracycline bacterial residue and modified with copper was characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The effects of the catalysts, SO2 concentration, weight hourly space velocity, and temperature on the SO2 adsorption and oxidation activity were evaluated. Activated carbon produced from oxytetracycline bacterial residue and used as catalyst supports for copper oxide catalysts provided high catalytic activity for the adsorbing and oxidizing of SO2 from flue gases. Implications: To improve the SO2 removal efficiency and reduce costs, the pretreatment of activated carbon or activated carbon-based materials has been widely studied. Oxytetracycline bacterial residue is currently a hazardous waste, which has been investigated in terms of an adduct to active carbon (OBR-AC). Unfortunately, the application of OBR-AC was limited due to the absence of several metals in it, such as Fe and K. The OBR-AC was loaded with copper by immersion method to prepared Cu/OBR-AC, which was used to absorb and oxidize SO2. Cu/OBR-AC exhibited significantly greater catalytic activity than OBR-AC.

Formation and investigation of unstable complex hydrides from tetrabutylammonium fluoride, water and SO2

A phase separation occurred when SO2 was introduced into the binary system of tetrabutylammonium fluoride (TBAF) and water system. The mechanics of this phase separation process were studied by Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy and Karl-Fischer titration. A complex hydrides of TBAF–SO2–H2O was formed and the TBAF and SO2 concentrated in the lower layer, and it could be released by heating the solution under reduced pressure (382.2 K, 10.1 kPa). The equilibrium solubility of SO2 in the binary system of tetrabutylammonium fluoride and water was investigated. After desorption, the mixture could be reused to absorb SO2. The effect of temperature and concentration of TBAF on the mole ratio of SO2–TBAF and H2O–TBAF of the triple hydrate was studied. The binary system of TBAF and water could absorb SO2 efficiently.

Process and mechanism of toluene oxidation using Cu 1-y Mn 2 Ce y O x /sepiolite prepared by the co-precipitation method

To achieve efficient degradation of toluene, a series of Cu1-yMn2CeyOx/sepiolite catalysts (y = 0.1, 0.2, and 0.3) with different Cu1-yMn2CeyOx loadings (10%, 20%, and 30%) were prepared via the co-precipitation method. The structure-activity and surficial elemental species of Cu1-yMn2CeyOx/sepiolite were characterized by XRD, TEM, SEM, BET, ICP-MS and XPS. The catalytic activity of the catalysts was tested in the oxidation reaction of toluene, results showed that 20%Cu0.8Mn2Ce0.2Ox/sepiolite remains able to remove toluene completely with high efficiency at a temperature of 289 °C. Two kinetic models have been selected and tested to describe the oxidation of toluene, the Mars-van krevele (MVK) model provided a good fit (R2 ≥ 0.99). And the optimal relation of the surface oxidation activation energy (26.074 kJ mol-1) and surface reduction activation energy (23.591 kJ mol-1) were calculated.

Absorption of methylbenzene in 1-butyl-3-methylimidazolium ionic liquids

The liquid-liquid phase equilibrium of the binary systems, 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) + methylbenzene, were investigated at temperatures ranging from 294 K to 355 K. The solubility of methylbenzene was greater in [Bmim][PF6] than in [Bmim][BF4]. The effects of multiple parameters, such as temperature, gas flow rate and concentration of methylbenzene, were systematically investigated. The removal of methylbenzene in [Bmim][PF6] is up to 83% at 293.15 K, a gas flow rate of 50 mL/min and a gas concentration of 395 mg/m3. The absorption and desorption of methylbenzene in [Bmim][PF6] were reversible.