An internal circulation iron-carbon micro-electrolysis reactor for aniline wastewater treatment:Parameter optimization,degradation pathways and mechanism

Aniline is a vital industrial raw material.However,highly-toxic aniline wastewater usually deteriorated effluent quality,posed a threat to human health and ecosystem safety.Therefore,this study reported a novel internal circulation iron-carbon micro-electrolysis(ICE)reactor to treat aniline wastewater.The effects of reaction time,pH,aeration rate and iron-carbon(Fe/C)ratio on the removal rate of aniline and the chemical oxygen demand were investigated using single-factor experiments.This process exhibited high aniline degradation performance of approximately 99.86% under optimal operating conditions(reaction time=20 min,pH=3,aeration rate=0.5 m3·h^(-1),and Fe/C=1:2).Based on the experimental results,the response surface method was applied to optimize the aniline removal rate.The Box–Behnken method was used to obtain the interaction effects of three main factors.The result showed that the reaction time had a dominant effect on the removal rate of aniline.The highest aniline removal rate was obtained at pH of 2,aeration rate of 0.5 m^(3)·h^(-1)and reaction time of 30 min.Under optional experimental conditions,the aniline content of effluent was reduced to 3 mg·L^(-1)and the removal rate was as high as 98.24%,within the 95% confidence interval(97.84%-99.32%)of the predicted values.The solution was treated and the reaction intermediates were identified by high-performance liquid chromatography,ultraviolet-visible spectroscopy,Fourier-transform infrared spectroscopy,gas chromatography-mass spectrometry,and ion chromatography.The main intermediates were phenol,benzoquinone,and carboxylic acid.These were used to propose the potential mechanism of aniline degradation in the ICE reactor.The results obtained in this study provide optimized conditions for the treatment of industrial wastewater containing aniline and can strengthen the understanding of the degradation mechanism of iron-carbon micro-electrolysis.

Treatment of naphthalene derivatives with iron-carbon micro-electrolysis

The degradation of five naphthalene derivatives in the simulated wastewater was investigated using the iron-carbon micro-electrolysis method.The optimal initial pH of solution and adsorption of iron-carbon and removal efficiency of the total organic carbon(TOC)were investigated.The results show that the removal efficiency of the naphthalene derivatives can reach 48.9%?92.6% and the removal efficiency of TOC is 42.8%?78.0% for the simulated wastewater with 200 mg/L naphthalene derivatives at optimal pH of 2.0?2.5 after 120 min treatment.The degradation of five naphthalene derivatives with the micro-electrolysis shows the apparent first-order kinetics and the order of removal efficiency of the naphthalene derivatives is sodium 2-naphthalenesulfonate,2-naphthol,2,7-dihydroxynaphthalene,1-naphthamine,1-naphthol-8-sulfonic acid in turn.It is illustrated that the substituents of the naphthalene ring can affect the removal efficiency of naphthalene due to their electron-withdrawing or electron-donating ability.

Micro-electrolysis technology for industrial wastewater treatment

Experiments were conducted to study the role of micro-electrolysis in removing chromaticity and COD and improving the biodegradability of wastewater from pharmaceutical, dye-printing and papermaking plants. Results showed that the use of micro-electrolysis technology could remove more than 90% of chromaticity and more than 50% of COD and greatly improved the biodegradability of pharmaceutical wastewater. Lower initial pH could be advantageous to the removal of chromaticity. A retention time of 30 minutes was recommended for the process design of micro-electrolysis. For the use of micro-electrolysis in treatment of dye-printing wastewater, the removal rates of both chromaticity and COD were increased from neutral condition to acid condition for disperse blue wastewater; more than 90% of chromaticity and more than 50% of COD could be removed in neutral condition for vital red wastewater.

Optimization of the N2 generation selectivity in aqueous nitrate reduction using internal circulation micro-electrolysis

The reduction of nitrate using internal circulation micro-electrolysis te chnology(ICE)was investigated.The effect of the reaction time,initial pH,Fe/C ratio,and aeration rate on the nitrate reduction was investigated using a single factor experiment.Based on the results of the single factor experiment,a response surface methodology(RSM)was applied to optimize the N2 generation selectivity.The effects and interactions of three independent variables were estimated using a Box-Behnken design.Using the RSM analysis,a quadratic polynomial model with optimal conditions at pH=8.8,Fe/C=1:1,and an aeration rate of 30 L·min-1 was developed by means of the regre ssion analysis of the experimental data.Using the RSM optimization,the optimal conditions yielded a N2 generation selectivity of 72.0%,which is in good agreement with experimental result(73.2%±0.5%)and falls within the 95%confidence interval(IC:66.8%-77.3%)of the model results.This indicates that the model obtained in this study effectively predicts the N2 generation selectivity for nitrate reduction by the ICE process,thus providing a theoretical basis for process design.

Nitrogen removal efficiency of iron-carbon micro-electrolysis system treating high nitrate nitrogen organic pharmaceutical wastewater

The nitrate nitrogen removal efficiency of iron-carbon micro-electrolysis system was discussed in treating pharmaceutical wastewater with high nitrogen and refractory organic concentration. The results show that the granularity of fillings,pH,volume ratios of iron-carbon and gas-water,and HRT. have significant effects on the nitrogen removal efficiency of iron-carbon micro-electrolysis system. The iron-carbon micro-electrolysis system has a good removal efficiency of pharmaceutical wastewater with high nitrogen and refractory organic concentration when the influent TN,NH4+-N,NO3--N and BOD5/CODCr are 823 mg/L,30 mg/L,793 mg/L and 0.1,respectively,at the granularity of iron and carbon 0.425 mm,pH 3,iron-carbon ratio 3,gas-water ratio 5,HRT 1.5 h,and the removal rates of TN,NH4+-N and NO3--N achieve 51.5%,70% and 50.94%,respectively.

Structural parameter optimization for novel internal-loop iron–carbon micro-electrolysis reactors using computational fluid dynamics

It is generally recognized that internal-loop reactors are well-developed mass and heat-transfer multiphase flow reactors. However, the internal flow field in the internal-loop reactor is influenced by the structure parameter of the reactor, which has a great effect on the reaction efficiency. In this study, the computational fluid dynamics simulation method was used to determine the influence of reactor structure on flow field, and a volume-offluid model was employed to simulate the gas–liquid, two-phase flow of the internal-loop micro-electrolysis reactor. Hydrodynamic factors were optimized when the height-to-diameter ratio was 4:1, diameter ratio was9:1, draft-tube axial height was 90 mm. Three-dimensional simulations for the water distributor were carried out, and the results suggested that the optimal conditions are as follows: the number of water distribution pipes was four, and an inhomogeneous water distribution was used. According to the results of the simulation,the suitable structure can be used to achieve good fluid mechanical properties, such as the good liquid circulation velocity and gas holdup, which provides a good theoretical foundation for the application of the reactor.

Degradation of Nitrobenzene Wastewater via Iron/Carbon Micro-electrolysis Enhanced by Ultrasound Coupled with Hydrogen Peroxide

The zero valent iron/granular active carbon(ZVI/GAC) micro-electrolysis enhanced by ultrasound(US) coupled with hydrogen peroxide(H_2O_2) was investigated for the deep degradation of nitrobenzene-containing wastewater. The results of scanning electron microscopy-energy dispersive X-rays analysis(SEM-EDS) demonstrated that continuously accelerated regeneration of ZVI and GAC in situ by US could improve the process for converting nitrobenzene(NB) to aniline(AN). H_2O_2 was decomposed catalytically by the byproduct Fe^(2+) ions generated in the micro-electrolysis process to hydroxyl radicals and the organic pollutants in the wastewater were finally mineralized to CO2 and H2O. Effects of the ZVI dosage, the ZVI/GAC mass ratio, the initial pH value and the H_2O_2 dosage on the efficiency for degradation of NB were studied in these experiments. The optimal operating conditions covered a ZVI dosage of 15 g/L, a ZVI/GAC mass ratio of 1:2,an initial pH value of 3 and a H_2O_2 dosage of 4 mL. In this case, the NB removal efficiency reached 97.72% and the total organic carbon(TOC) removal efficiency reached 73.42% at a NB concentration of 300 mg/L. The reduction of NB by USZVI/GAC followed the pseudo-first-order kinetics model, and the pseudo-first-order rate constants were given at different initial pH values. The reaction intermediates such as AN, benzoquinonimine, p-benzoquinone, p-nitrophenol and other organic acids were detected and a probable pathway for NB degradation has been proposed.

Effect of Micro-electrolysis and Micro-nano Bubbles Coupled with Peroxymonosulfate Treatment of Rural Domestic Sewage

With the continuous deepening of rural revitalization strategy and the increasingly strict sewage discharge standards,rural domestic sewage treatment technology is facing higher challenges and requirements.The combined process of micro-electrolysis+micro-nano bubbles coupled with peroxymonosulfate was constructed in this study,and the treatment effect and application value of this technology were explored with the actual rural domestic sewage as the treatment object.The experimental results showed that under the conditions of HRT of 120 min,PMS dosage of 0.15 mmol/L,pH=7,MBs air intake of 15 ml/min,current intensity of 15 A,and Fe/C mass ratio of 1:1,the removal rates of COD,ammonia nitrogen and total phosphorus can reach 88.55%,77.18%and 74.67%,respectively.Under the condition that the pH value of sewage was not adjusted,the non-biochemical simultaneous decarbonization,denitrification and phosphorus removal of rural domestic sewage can be achieved by micro-electrolysis and micro-nano bubbles coupled with peroxymonosulfate.The concentrations of effluent COD,ammonia nitrogen and total phosphorus met the requirements of the first level standard of the Discharge Standard of Water Pollutants for Rural Domestic Sewage Treatment Facilities(DB45T2413-2021).And the comprehensive operating cost was about 1.15 yuan/m 3.

一种用于配电系统谐振抑制及谐波治理的新型PAPF控制方法

针对配电系统中时有发生的并联电容器与电网阻抗之间谐振的现象,该文首先分析了传统的负载电流检测方式下并联型有源电力滤波器(parallel active power filter,PAPF)对系统谐振的抑制情况。分析表明,由于无功补偿电容器的影响,传统控制策略下的PAPF对系统谐振的抑制效果不理想,同时当检测的负载电流中包括无功补偿电容器电流时,系统还有可能出现不稳定的现象。针对这种情况该文提出了一种新的PAPF控制策略,该控制策略可以在进行谐波治理的同时有效抑制负载谐波电流或者系统谐波电压造成的并联电容器与电网阻抗之间的谐振。最后给出了实验验证结果。

氰化尾渣制备微电解填料及降解甲基橙研究

以氰化尾渣为原料,采用煤基直接还原工艺制备铁碳微电解填料,并将填料用于处理甲基橙等模拟废水.研究了焙烧温度、焙烧时间、煤用量等制备条件对填料降解甲基橙的影响.结果表明,在焙烧温度为1250°C,焙烧时间为60min,煤用量为30%的条件下制备的微电解填料对甲基橙废水的脱色效果最好.提高填料用量和降低溶液初始pH值有利于去除甲基橙.用于处理400mL浓度为100mg/L的甲基橙溶液,在填料用量为2g,溶液初始pH值在3～6的范围内,当降解时间为30min时,甲基橙脱色率均接近100%.XRD分析表明,最佳条件下制备的填料中主要结晶物相为零价铁.SEM显示填料中的零价铁颗粒粒度均在50μm以下,零价铁与残碳构成微电解填料.

机织滤布的堵塞及单丝滤布的开发应用

从机织滤布的材料性质、孔隙结构及加工工艺等方面出发，讨论了机织滤布的堵塞机理及规律，在此基础上，充分论证了单丝滤布是减轻滤布堵塞，延长滤布过滤周期，提高过滤指标和经济效益的最有效的措施之一。

空地反辐射导弹制导方案研究

论述了以宽频带被动雷达导引头和捷联惯导系统组成的空地反辐射导弹复合制导方案。选取了导引规律,给出了控制方程。并采用广义卡尔曼滤波(EKF)解决了目标雷达关机情况下的制导问题。给出了空地反辐射导弹的全空间弹道仿真结果。

基于超级电容储能的有源电力滤波器的研究

重点介绍了主电路的设计方案、工作原理,并利用Matlab仿真平台,对装置进行了仿真分析。结果表明,该装置克服了传统有源电力滤波器功能单一的局限,使有源电力滤波器在进行谐波和无功补偿的同时还可以解决电压跌落、短时停电等多种电能质量问题。

改进自适应算法研究

基于对 LMS 算法的分析,本文提出一种滤波改进算法。分析表明,该算法是无条件收敛的,其性能失调量也远较 LMS 算法为优。

格雷码色标微机检测系统

介绍了一种基于单板微型计算机的格雷码色标检测方法。该方法用于对规格化的书帖毛本的出错检测获得成功。文中对该系统的脉冲红外光电探测部分和单板微机的智能检测部分作了较为详细的介绍。

组合导航的自校正滤波控制

本文介绍了一种新的组合导航自校正滤波与控制方法，它是将卡尔曼滤波、参数辨识与自校正控制结合起来，从而提高了适应能力与误差补偿精度，文中分别讨论了误差模型、自校正滤波与自校正控制，并把它们统一起来，得到了封闭解。

多片TMS32010构成的全双工模数模语音置乱系统

本文介绍的全双工模数模语音置乱系统采用一种无需帧同步的置乱算法置乱语音信号,并以自适应回波抵消技术消除系统中的回波干扰。文中研究了语音置乱处理对自适应滤波算法性能的影响,导出了回波抵消的理论性能与自适应滤波器阶数的关系,对系统样机进行了实际性能测试。这种全双工模拟语音置乱系统可望用于移动通信网络和普通电话网络。

模糊控制器在并联有源滤波器(PAPF)中的应用

通过分析有源滤波器直流电容电压控制的不确定因素,采用模糊控制理论,对PAPF直流电 容电压的控制进行了研究.实验结果表明了该方法的有效性,并取得了良好的效果.

Treatment of oilfield produced water by anaerobic process coupled with micro-electrolysis

Treatment of oilfield produced water was investigated using an anaerobic process coupled with micro-electrolysis （ME）, focusing on changes in chemical oxygen demand （COD） and biodegradability. Results showed that COD exhibited an abnormal change in the single anaerobic system in which it increased within the first 168 hr, but then decreased to 222 mg/L after 360 hr. The biological oxygen demand （five-day） （BOD5）/COD ratio of the water increased from 0.05 to 0.15. Hydrocarbons in the wastewater, such as pectin, degraded to small molecules during the hydrolytic acidification process. Comparatively, the effect of ME was also investigated. The COD underwent a slight decrease and the BOD5/COD ratio of the water improved from 0,05 to 0.17 after ME. Removal of COD was 38.3% under the idealized ME conditions （pH 6.0）, using iron and active carbon （80 and 40 g/L, respectively）. Coupling the anaerobic process with ME accelerated the COD removal ratio （average removal was 53.3%）. Gas chromatography/mass spectrometry was used to analyze organic species conversion. This integrated system appeared to be a useful option for the treatment of water produced in oilfields.

克拉申“情感过滤假设”在英语听力课堂教学活动中的运用

20世纪80年代初,美国语言学家S.D.Krashen提出了情感过滤假说。根据情感过滤假说,情感主要在学习动机、自信心、焦虑等三个方面对学习者的第二语言习得具有重要影响。而学习者听力习得又是语言习得的一个重要方面,如何在课堂教学中运用该假说来提高听力外语课堂教学的效果则是我们外语教师所关心的问题。本文以克拉申第二语言习得理论中的情感过滤假说为理论基础,,提出了在课堂教学活动环节中如何具体运用这一理论、降低学习者情感过滤作用、从而有效提高其听力技能。