Degradation of Nitrobenzene-Containing Wastewater with O_3 and H_2O_2 by High Gravity Technology

Nitrobenzene-containing industrial wastewater was degraded in the presence of ozonecoupled with H2O2 by high gravity technology. The effect of high gravity factor, H2O2 concentration, pH value, liquid flow-rate, and reaction time on the efficiency for removal of nitrobenzene was investigated. The experimental results show that the high gravity technology enhances the ozone utilization efficiency with O3 /H2O2 showing synergistic effect. The degradation efficiency in terms of the COD removal rate and nitrobenzene removal rate reached 45.8% and 50.4%, respectively, under the following reaction conditions, viz.: a high gravity factor of 66.54, a pH value of 9, a H2O2 /O3 molar ratio of 1:1, a liquid flow rate of 140L/h, an ozone concentration of 40mg/L, a H2O2 multiple dosing mode of 6mL/h, and a reaction time of 4h. Compared with the performance of conventional stirred aeration mixers, the high gravity technology could increase the COD and nitrobenzene removal rate related with the nitrobenzene-containing wastewater by 22.9% and 23.3%, respectively.

Degradation of Wastewater Containing Nitrobenzene by High Gravity-Ultrasonic/Ozonation/Electrolysis Technology

The integrated high gravity-ultrasonic/ozonation/electrolysis technology was applied in the pretreatment of wastewater containing nitrobenzene.The effect of pH value,high gravity factor,liquid flow-rate and electric current density on removal of COD and nitrobenzene compounds was investigated.Experimental results have determined the optimal process regime involving a high gravity factor of 100,an electric current density of 20mA/cm2,a liquid flow-rate of 100L/h,and an initial liquid pH value of 11.After the wastewater had been treated for 180 min,the degradation of nitrobenzene and COD reached 99% and 80%,respectively,with the biochemical coefficient(BOD/COD) equating to 0.64,and the subsequent treatment of wastewater could be carried out by conventional biochemical means.Compared with traditional aerationozone contactors,a rotating packed bed with high mass transfer characteristics could be used to increase the ozonation treatment efficiency.

Treatment of Phenol Wastewater Using High Gravity Electrochemical Reactor with Multi-concentric Cylindrical Electrodes

A novel high gravity electrochemical reactor with multi-concentric cylindrical electrodes was used in the electrochemical treatment of 5 000 mg/L phenol-containing wastewater at a petrochemical plant, which can operate continuously and process in a large scale. The results show that the high gravity technology used in electrochemical treatment of phenol-containing wastewater can shorten the electrolysis time, decrease the electrolysis voltage, and reduce the energy consumption. The COD removal efficiency was high in the high-gravity field, and reached up to about 48%, which was about 2 times the value achieved in the normal gravity field at a processing capacity of 6 L, a high gravity factor of 80, a voltage of 12 V, an electrolysis time of 40 min, and a wastewater flowrate of 80 L/h.

Comparison of Mass Transfer Characteristics between Countercurrent-Flow and Crosscurrent-Flow Rotating Packed Bed

The rotating packed bed(RPB), mainly including the countercurrent-flow RPB(Counter-RPB) and the crosscurrentflow RPB(Cross-RPB) that are classified from the perspective of gas-liquid contact style, is a novel process intensification device. A significant measurement standard for evaluating the performance of RPB is the mass transfer effect. In order to compare the mass transfer characteristics of Counter-RPB and Cross-RPB with the same size, the liquid volumetric mass transfer coefficient(k_La_e) and effective interfacial area(a_e) were measured under identical operating conditions. Meanwhile, the comparison of comprehensive mass transfer performance was conducted using the ratio of ΔP(pressure drop) to kLae as the standard. Experimental results indicated that kLae and ae increased with the increase in liquid spray density q, gas velocity u, and high gravity factor β. Furthermore, compared with the Cross-RPB, the Counter-RPB has higher liquid volumetric mass transfer coefficient and slightly larger effective interfacial area. The experimental results of comprehensive mass transfer performance showed that the Counter-RPB had higher ΔP/k_La_e than the Cross-RPB with changes in liquid spray density and high gravity factor, and there exists a turning point at 0.71 m/s accompanied by a variation with gas velocity. Moreover, the relative error of experimental value to calculated value, which was computed by the correlative expressions of kLae, was less than 5 %. In conclusion, the mass transfer characteristics of RPB are deeply impacted by the manner in which the flows are established and the Cross-RPB would have a great potential for industrial scale-up applications.

Absorption of Sulphur Dioxide with Sodium Citrate Buffer Solution in a Rotating Packed Bed

Absorption of SO2 from a SO2/air mixture with sodium citrate buffer solution was investigated using a rotating packed bed(RPB) in laboratory scale.The effects of operating parameters,such as the rotation speed of RPB,liquid-gas ratio,inlet gas flow rate,inlet concentration of SO2 in flue gas,sodium citrate buffer concentration and initial pH of absorption solution,on the SO2 concentration in the absorption solution or removal efficiency of SO2 were examined.Incremental rate of sulfate radical ions in the absorption solution was also examined.Experimental results indicate that the efficiency of this regenerative process will be improved by using RPB under appropriate operating conditions,and the generation of SO2-4 will be restrained in the process in RPB.

Characteristics of Fin Baffle Packing Used in Rotating Packed Bed

For an alcohol/water system and with fin baffle packing,continuous distillation experiments were carried out in a rotating packed bed(RPB)system at atmospheric pressure.The effects of the average high gravity factor(β),liquid reflux ratio(R)and feedstock flux(F)on the momentum transfer and mass transfer were investigated. The gas phase pressure drop of RPB increased with the average high gravity factor,liquid reflux ratio and feedstock flux,which was 13.55-64.37 Pa atβof 2.01-51.49,R of 1.0-2.5,and F of 8-24 L·h1for a theoretical tray in the RPB with fin baffle packing.The investigation on the mass transfer in the RPB with different packings showed that the number of transfer units of RPB with a packing also increased with the average high gravity factor,reflux ratio and feedstock flux.It is found that the fin baffle packing(packing III)presents the best mass transfer performance and lowest pressure drop for the height equivalent to a theoretical plate(HETP),which is 6.59-9.84 mm.

Continuous Distillation Experiment with Rotating Packed Bed

旋转的性能与三种包装包装了床(RPB ) 在气压在连续蒸馏条件下面用白酒 / 水答案被调查。平均高严肃因素的效果(尾) ，倒流比率(R) ，和化工物品流动(F) 在上在蒸馏集体转移独立被检验。试验性的结果显示 RPB 的理论单位(NTU ) 的全部的数字与尾， R，和 F 增加了。三种包装，不锈钢(收拾行李的 III )收拾行李的波浪线与约 7.35 公里的一个理论盘子( HETP )的高度等价物有最好的集体转移效率-- 23.58 公里，而不锈钢收拾行李的弄皱的磁盘(收拾行李我)与大约 13.4 mm-48.07 公里的 HETP 有最糟的。关联被开发为包装描述集体转移效率。把试验性的数据与数据作比较由关联计算了，一般水准背离获得了因为分别地，各收拾行李是 0.72% ， 1.98% ，和 2.7% 暗示开发的关联的精确性是合理的。

Mass transfer characteristics in a rotating packed bed with split packing

The rotating packed bed(RPB) with split packing is a novel gas–liquid contactor, which intensifies the mass transfer processes controlled by gas-side resistance. To assess its efficacy, the mass transfer characteristics with adjacent rings in counter-rotation and co-rotation modes in a split packing RPB were studied experimentally.The physical absorption system NH3–H2O was used for characterizing the gas volumetric mass transfer coefficient(kyae) and the effective interfacial area(ae) was determined by chemical absorption in the CO2–NaO H system. The variation in kyaeand aewith the operating conditions is also investigated. The experimental results indicated that kyaeand aefor counter-rotation of the adjacent packing rings in the split packing RPB were higher than those for co-rotation, and both counter-rotation and co-rotation of the split packing RPB were superior over conventional RPBs under the similar operating conditions.

利用一种带有旋转圆筒电极的电化学反应器快速再生络合铁脱硫液(英文)

A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution.The influence of operating parameters,such as the rotation speed of electrode,voltage,and inlet air and liquid flow rates,on the regeneration rate was investigated.Compared with the traditional tank-type reactor,the regeneration rate with the new electrochemical reactor was increased significantly.Under the optimum conditions,the regeneration rate was increased from 45.3%to 84.8%.Experimental results of continuous operation indicated that the new electrochemical regeneration method had some merits including higher regeneration efficiency,smaller equipment size and good stability in operation.

Preparation of one-dimensional nanostructured ZnO

Rod-like ZnO particles were synthesized via a sol-gel method by adding ethylene diamine(EDA) to the reaction system of Zn(Ac)2·2H2O and H2C2O4·2H2O.The crystal phase and morphology of the products were characterized by XRD(X-ray powder diffractometer) and TEM(transmission electron microscope).Rod-like ZnO belongs to the hexagonal Wurtzite system,with diameters and lengths of about 20-200 nm and 0.2-1.5 m,respectively.Experimental results showed that the morphology of nano-ZnO can be controlled by modulating the quantities of EDA added into the reaction system and that EDA plays an important role in the formation of rod-like ZnO particles.The growth mechanism of the rod-like nanoZnO was briefly discussed.The proposed facile,reproducible,effective and low-cost synthesis promises future large-scale preparation of nanostructured ZnO for application in nanotechnology.