钛基二氧化铱涂层电极的节能分析

随着社会的快速发展,能源问题日益严峻。简述了钛基二氧化铱涂层电极的特征和进展,并对冶金工业和化学工业中金属锌（铜）电积过程的电能节约进行了深入的理论分析和量化计算。结果表明,Ti/IrO2- SnO2电极、Ti/结晶IrO2- Ta2O5电极、Ti/IrO2- RuO2电极、Ti/非晶IrO2- Ta2O5电极等新型二氧化铱涂层电极比Pb- Ag电极、Pb- Sb电极等传统铅基合金电极节电10%以上。另外,展望了钛基二氧化铱涂层电极的应用前景。     

溶剂对Ti/SnO2-Sb-Nd电极性能的影响

分别以乙醇、异丙醇、正丁醇为溶剂配制涂液,采用刷涂热分解法制备了稀土Nd共掺杂的Ti/SnO2 -Sb-Nd电极.采用SEM、XRD、伏安电荷、电化学孔隙率、分形维数、降解苯酚实验等研究了溶剂对电极微观形貌、晶体结构和电化学性能的影响.结果表明:随着所用醇类溶剂的与羟基相连的碳链复杂化和延长,制得电极涂层的微观表面趋于平整,物理比表面积变小.碳链最长的正丁醇溶剂体系制得了结晶最好的SnO2电极涂层,并且有效的阻止了钛基体被氧化.按照乙醇、异丙醇、正丁醇顺序,相应的3种电极的伏安电荷分别为1.783,2.074,2.884 mC·cm-2,这表明电极的电化学活性面积依次增大;电极涂层的电化学孔隙率分别为97.78％,53.11％,51.68％;电极涂层的分形维数分别为1.892,1.978,1.968;当累积通电量为4.783 Ah ·L-1时,苯酚降解率分别达到87.49％,90.04％,91.50％,在此过程中槽压分别升高了3.94,1.48,1.44V.伏安电荷、电化学孔隙率和分形维数的变化规律有效地反映了电极的电催化氧化活性和稳定性的变化.     

Preparation of Ti-based Yb-doped SnO2–RuO2 electrode and electrochemical oxidation treatment of coking wastewater

In this study, the Ti/SnO₂–RuO₂ electrodes with different Yb contents were prepared by sol–gel method and thermal decomposition method, and the surface morphology and crystal structure of the electrodes were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD), the electrochemical properties of the electrodes were tested by linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The electrochemical oxidation device was constructed with Yb-doped Ti/SnO₂–RuO₂ electrode as the anode and titanium plate as the cathode, and the electrochemical oxidation effect and product changes of the anode on coking wastewater were investigated. The results show that the surface of the electrode is flat with high crystallinity of SnO₂ and RuO₂ crystals at 1.5% Yb doping, and the LSV and CV curves indicate that the Yb doping of 1.5% increases the oxygen precipitation potential and electrocatalytic oxidation activity of the electrode. When the electrode with Yb doping of 1.5% is the anode with current density of 10 mA/cm² electrochemical oxidation time of 30 min, the electrode can remove chemical oxygen demand (COD) up to 85.06%, total organic carbon (TOC) up to 60.59% and UV₂₅₄ from 1.594 to 0.507 for coking wastewater. Gas chromatography (GC–MS), UV–vis and three-dimensional fluorescence results of coking wastewater before and after treatment show that large toxic substances in coking wastewater are degraded to low toxic organic substances, and most soluble organic substances are degraded and transformed. This study provides the possibility of basic research for the engineering practice of electrochemical oxidation for the treatment of coking wastewater.     

Preparation and application of pharmaceutical wastewater treatment by praseodymium doped SnO2/Ti electrocatalytic electrode

Praseodymium was selected as a promoter for SnO2/Ti electrode to improve the electrocatalytic performance by electrodeposition in pharmaceutical wastewater treatment; the micrograph and the structure were characterized by SEM and XRD. Mixture uniform design was used in the optimization of the electrolytic conditions; mathematical model was established according to the rate of wiping COD off, which revealed the relationship between the current intensity, time of electrolysis, the amount of doped Pr, and the ratio of area （SnOJTi：Al）. On the basis of the analysis of the empirical model, the optimized parameters had been obtained; the rate of wiping COD off was up to 94.9%, it decreased from 392 to 20 mg/L. Experimental results showed that the electrocatalytic performance of the electrode doped with Pr was superior for the treatment of pharmaceutical wastewater.     

Preparation of TiO2/Hydroxyapatite Composite and Its Photocatalytic Degradation of Methyl Orange

A TiO2/hydroxyapatite composite (Ti-HAP) was prepared by a hydrothermal method with hydroxyapatite and titanium sulfate and tested for photocatalytic degradation of methyl orange with an 8?W ultraviolet (UV) lamp irradiation. The properties of Ti-HAP were characterized by X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy (FT-IR) analysis. The effect of the Ti/(Ca+Ti) mole ratio on the photocatalytic degradation efficiency of methyl orange by Ti-HAP and the photocatalytic degradation dynamics were investigated. The results show that the addition of Ti slightly changes the structure of HAP. A higher Ti/(Ca+Ti) mole ratio results in the generation of anatase in Ti-HAP and higher removal efficiency of methyl orange by Ti-HAP under UV irradiation. The removal efficiency decreases with the initial content of methyl orange increasing from 10–200??mg/L. The photocatalytic degradation process of methyl orange by Ti-HAP and HAP follow the Langmuir-Hinshelwood kinetics model.     

PEM水电解用多层钛网析氧阳极制备及性能研究

以钛网为扩散层基体,氯铱酸为前驱体,采用浸渍-热解法制备了IrO₂/Ti 析氧阳极,进一步采用热压法制备膜电极.综合扫描电镜尧循环伏安尧交流阻抗尧单池性能曲线测试及阳极寿命强化测试,研究了不同层数钛网析氧阳极对性能及寿命的影响.结果表明院与单层钛网析氧阳极比较,采用双层钛网析氧阳极,积分电荷由84.27 mC/cm2 增至153.12 mC/cm2,电极电化学反应阻抗由7.38 Ω·cm2 降低至3.03 Ω·cm2,单池性能得到提升.寿命强化测试表明,采用双层钛网析氧阳极在稳定性及寿命方面有显著提升,稳定运行时间由30 h 增加到了53 h.      

Electrochemical Pretreatment of Wastewater from Bulk Drug Manufacturing Industry

The present study involves the treatment of high strength Bulk Drug Industry Wastewater by electrochemical method. The treatability studies were carried out with four different electrodes made of mild steel, aluminum, carbon, and stainless steel. The treatment efficiencies for chemical oxygen demand (COD)/biochemical oxygen demand (BOD), color, and heavy metal removals were assessed at different electrolysis time. A comparative study for heavy metal removal between chemical precipitation using aluminum and electrocoagulation with aluminum electrode has shown electrocoagulation to be more effective. Carbon electrode has shown COD removal of 34.0% and high BOD5f/CODf ratio of 0.581 at 120-min exposure time. Among all electrodes, aluminum was found as the most efficient in removal of color, suspended solids, and heavy metals with the least energy consumption of 95.83?Wh?kg?1?CODr and anode efficiency of 5.76?kg?COD?A?1?m?2?h?1. After electrochemical treatment, certain increase in BOD/COD ratio attributed to increase in biodegradability of wastewater. The study reveals that the wastewater could be effectively pretreated by electrochemical method.     

Phenol Degradation in a Bipolar Trickle Tower Reactor Using Boron-Doped Diamond Electrode

Electrochemical oxidation of phenol was studied in a bipolar trickle tower reactor using Raschig ring shaped boron-doped diamond (BDD) electrodes in recirculated batch mode. The model wastewater was prepared with phenol using distilled water. The effects of initial phenol concentration, concentration of Na2SO4 as a supporting electrolyte, current density, flow rate, and initial pH on the removal efficiency were investigated. The removal of phenol of 200?mg/L and chemical oxygen demand (COD) of 480?mg/L were achieved with efficiencies of 99.85 and 88.89%, respectively. In the same study, specific energy consumption of 0.676?kWh/g phenol removed was determined at the current density of 5?mA/cm2. On the other hand, for the initial phenol concentration of 500?mg/L and COD of 1,200?mg/L, 99.69 and 90.83% removal efficiencies were obtained at the current density of 5?mA/cm2, respectively. Microtox toxicity tests were performed to investigate the toxicity reduction potential of BDD anodes, and relatively good toxicity reductions were obtained with respect to the initial values. After determining optimum experimental conditions, petroleum refinery wastewater was also studied by monitoring the destruction of phenol and COD. In this study, phenol removal of 99.53% and COD removal of 96.04% were achieved at the current density of 5?mA/cm2. Chemical oxidation studies were also carried out and the results were compared with the electrochemical oxidation studies. According to the whole results, it can be said that Raschig ring shaped BDD anodes exhibited an excellent performance for the degradation of phenol and COD and for the reduction of toxicity.     

Modeling the Transformation of Chromophoric Natural Organic Matter during UV/H2O2 Advanced Oxidation

This research developed a differential kinetic model to predict the partial degradation of natural organic matter (NOM) during ultraviolet plus hydrogen peroxide (UV/H2O2) advanced oxidation treatment. The absorbance of 254?nm UV, representing chromophoric NOM (CNOM) was used as a surrogate to track the degradation of NOM. To obtain reaction rate constants not available in the literature, i.e., reactions between the hydroxyl radical (?OH) and NOM, experiments were conducted with “synthetic” water, using isolated Suwannee River NOM, and parameter estimation was applied to obtain the unknown model parameters. The reaction rate constant for the reaction between ?OH and total organic carbon (TOC), k?OH,TOC, was estimated at 1.14(±0.10)×104??L?mg-1?s-1, and the reaction rate constant between ?OH and CNOM, k?OH,CNOM, was estimated at 3.04(±0.33)×104??L?mol-1?s-1. The model was evaluated on two natural waters to predict the degradation of CNOM and H2O2 during UV/H2O2 treatment. Model predictions of CNOM degradation agreed well with the experimental results for UV/H2O2 treatment of the natural waters, with errors up to 6%. For the natural water with additional alkalinity, the model also predicted well the slower degradation of CNOM during UV/H2O2 treatment, owing to scavenging of ?OH by carbonate species. The model, however, underpredicted the degradation of H2O2, suggesting that, when NOM is present, mechanisms besides the photolysis of H2O2 contribute appreciably to H2O2 degradation.     

TiO2-SiO2复合气凝胶的常压干燥制备及光催化降解含油污水活性

以钛酸四丁酯和正硅酸乙酯为原料,利用溶胶凝胶工艺制备出不同硅含量的TiO₂-SiO₂复合醇凝胶.结合老化液浸泡和小孔干燥工艺,在常压下干燥得到完整的TiO₂-SiO₂复合气凝胶块体.采用扫描电子显微镜、BET比表面积测试、X射线粉末衍射等测试手段对复合气凝胶的微观结构和物化性能进行了测试和表征.测试结果表明,复合气凝胶具有良好的性能,Ti和Si元素在气凝胶中分布均匀.随着SiO₂含量的增加,复合气凝胶的密度逐渐变小,比表面积增大,孔隙率增加,转变为锐钛矿相的相变温度升高.经高温煅烧晶化处理,复合气凝胶转变为锐钛矿相结构.以乳化后的渤海原油水溶液作为含油污水模拟溶液,测试了复合气凝胶对含油污水的催化降解性能.污水降解结果显示复合气凝胶对渤海原油污水具有较好的催化降解活性.在SiO₂摩尔分数低于30%时,随着硅含量的增加,复合气凝胶的光催化降解率升高;但当SiO₂摩尔分数高于30%后,继续增加SiO₂掺入量,反而造成复合气凝胶催化能力下降.对于SiO₂摩尔分数为30%的复合气凝胶,获得了最佳的催化降解效果,90 min催化降解率达95%.      

Nitrogen Removal in Recirculating Sand Filter Systems with Upflow Anaerobic Components

Septic systems can present a risk to human health by releasing highly soluble nitrate–nitrogen into the groundwater. A research and demonstration study undertaken in Black River Falls, Wisconsin, evaluated several promising biofilter technologies for on-site nitrogen removal. Duplicate recirculating sand filter-upflow anaerobic systems with a design hydraulic loading rate of 954?L/day (250?gal/day) were used to treat septic tank effluent from a correctional institution and produced a treated wastewater with a total nitrogen concentration of 15.2?mg/L for System 1 and 18.2?mg/L for System 2, or 72.0 and 63.0% nitrogen removal, respectively. The differences between the two systems appear to have been the result of process configuration changes made over the duration of the study. This paper evaluates the nitrogen removal performance of the recirculating sand filter-upflow anaerobic systems and the effect of operational and environmental factors, including the recirculation ratio, BOD5/NO3?, and temperature. Nitrogen removal was limited by the recirculation ratio with the maximum total nitrogen removal of 70.1% when the recirculation ratio = 3. Improved performance was also noted for temperatures ≥ 20°C and BOD5/NO3? ≥ 8. Low temperatures adversely affected nitrification and low BOD5/NO3? adversely affected denitrification. The relationships among nitrogen removal, recirculation ratio, BOD5/NO3?, and temperature are also discussed.     

Fecal Coliform Removal within a Marshland Upwelling System Consisting of Scatlake Soils

The marshland upwelling system (MUS) was installed on private camps in the Grand Bay National Estuarine Research Reserve, Moss Point, Mississippi. The system was evaluated for its effectiveness in removing fecal coliforms from settled, raw wastewater. A suite of studies was performed at flow rates of 1.9, 2.8, and 5.5 L/min and an injection frequency of 30 min every 3 h to investigate fecal coliform removal. An additional study was performed at a flow rate of 2.8 L/min and an injection frequency of 15 min every hour. Overall, the MUS consistently maintained fecal concentrations below effluent regulatory standards for shellfish harvesting waters (14 most probable number of colonies per 100 mL). Mean influent concentrations of 55,269±2,218,016 colony forming units (CFU)/100 mL were reduced to effluent counts of 2.7±14.07 CFU/100 mL (observed in the 1.5 m wells). Three- to four-log reductions in influent counts were observed over the initial 1.4 vector?m from the injection well. The overall removal followed a first-order decay relationship with respect to vector distance, resulting in removal rate constants ranging from 5.6 to 6.6/m and predicted surface concentrations approaching 0 CFU/100 mL. The 2.8 L/min for 30 min every 3 h treatment provided the best effluent quality.     

Lactate Transport in Soil by DC Fields

Electrokinetic injection of lactate, a negatively charged biodegradable organic, in homogeneous soils is evaluated. Net lactate migration rate on the order of 5?cm2/V?day is measured in sand from cathode towards the anode. The ionic injection in sand was dependent on current density; however, the increase in electric current did not result in an equivalent increase in lactate transport due to development of an appreciable electroosmotic (EO) flow from the anode to the cathode. While high EO flow (ke on the order 10?6 to 10?5?cm2/V?s) occurred in clay samples, ion migration from cathode to anode is the dominant transport process under relatively high current density (5.3?A/m2 in this study) and can be used as an effective transport mechanism for negatively charged additives. An effective lactate reactive transport rate of more than 3?cm/d (under 1?V/cm) can be achieved in clays, which is at least two orders of magnitude greater than hydraulic injection under unit hydraulic gradient. Even though lactate concentrations in the clay were below 10% of the boundary value due to biological transformation, these concentrations (few 100?s?mg/L) are high enough to maintain microbial activities capable of degrading organic contaminants. At the same time, control experiments showed that, while lactate adsorption was negligible, hydraulic injection under a unit gradient was ineffective because of the low hydraulic conductivity of clay and the biodegradation of lactate.     

Removal of Refractory Organic Compounds in Liquid Swine Manure Obtained from a Biofiltration Process Using an Electrochemical Treatment

Swine wastewaters contain varied and high amounts of organic matter (proteins, antibiotic compounds, organic acids) which are difficult to oxidize biologically or chemically. The discharge of such effluents is undesirable and can cause excessive oxygen demand in the receiving water. In order to produce an effluent suitable for stream discharge, electrochemical techniques have been explored at the laboratory pilot scale, for refractory residual organic compound removal in liquid swine manure (LSM) following a biofiltration process. Two types of electrolytic cells (monopolar and bipolar electrode cells) using aluminum and mild steel electrodes were studied. Effectiveness was measured in terms of chemical oxygen demand (COD) and biological oxygen demand (BOD) reduction. The amount of residue sludge produced and energy consumed have been also considered. Results showed that the best performances of COD and BOD removal from LSM were obtained using either aluminum bipolar (Al-BP) electrodes or mild steel monopolar (Fe-MP) electrodes operated at current intensities of 0.5 and 2.0?A, respectively, through 30?min of treatment. The COD removal yields varied from 65 to 68%, whereas BOD removal reached 87%. The optimal conditions determined for organic compound removal, including energy consumption and metallic sludge disposal, involved a total cost of only $0.24?and?$0.29?United?States/m3 of treated LSM. The treatment using the Fe-MP system was found to be more economical and practical than the chemical treatment using FeCl3 as a coagulating agent.     

Degradation and Mineralization of Simazine in Aqueous Solution by Ozone/Hydrogen Peroxide Advanced Oxidation

Advanced oxidation of simazine in aqueous solution by the peroxone (hydrogen peroxide/ozone) treatment was investigated using Box-Behnken statistical experiment design and response surface methodology. Effects of pH, simazine and H2O2 concentrations on percent simazine and total organic carbon (TOC) removals were investigated. Ozone concentration was kept constant at 45?mg?L?1. The optimum conditions yielding the highest simazine and TOC removals were also determined. Both simazine and peroxide doses affected simazine removal while pH and pesticide dose had more pronounced effect on mineralization (TOC removal) of simazine. Nearly 95% removal of simazine was achieved within 5 min for simazine and peroxide concentrations of 2.0 and 75?mg?L?1, respectively at pH = 7. However, mineralization of simazine was not completed even after 60 min at simazine doses above 2?mg?L?1 indicating formation of some intermediate compounds. The optimum H2O2/pH/Simazine ratio resulting in maximum pesticide (94%) and TOC removal (82%) was found to be 75/11/0.5(mg?L?1).     

柚皮残渣制备活性炭对Cu2+吸附性能

以柚皮为材料,提取柚皮苷后残渣制备柚皮基活性炭（简称PPAB）,研究其在不同pH、投加量、吸附质浓度、时间、温度、粒径、解吸剂条件下对水中Cu2+的吸附性能.结果表明:在pH值为6,PPAB投加量4 g/L,溶液温度35 ℃,Cu2+初始浓度30 mg/L,吸附60 min,PPAB对Cu2+去除率94.47 %,最大吸附容量7.09 mg/g;0.25 mol/L盐酸脱附Cu2+效果较优,回收率98.21 %.吸附过程Langmuir等温式能较好拟合,此工艺下PPAB平均得率36.9 %,比表面积高达1 764 m2/g.柚皮基活性炭作为吸附剂处理低浓度重金属废水具有广阔前景.      

Ir_(1-x)Ru_xO_2/Ti析氧阳极的电催化活性研究

以氯铱酸为主要的前驱体,采用加热分解法制备了不同Ru含量的Ir1-xRuxO2/Ti析氧阳极,并采用扫描电镜,循环伏安,恒电流电解,线性极化等测试手段对电极进行表征和测试。电化学测试结果表明当Ir,Ru的摩尔比为3∶2时,500mA.cm-2恒电流水解电位最低,为1.4V(vs.SCE);循环伏安测试表明,Ir0.6Ru0.4O2/Ti的伏安电量亦达到最高,达到1271mC.cm-2,析氧电催化活性点最多。SEM表面形貌进一步证实了Ru的加入使得电极的表面的多孔结构更加明显,当Ir,Ru摩尔比为3∶2时,电极表面颗粒最小,孔隙率最高,亦表明该电极的电化学活性表面积最大,电催化活性最高。     

Electrochemical Desulfurization of Waste Gases in a Batch Reactor

To meet the increasing need for reduction of exhaust emissions from stationary sources, many technologies have been developed to remove SO2 from flue gas. In this study the anodic oxidation of sulfur dioxide in aqueous solutions of sulfuric acid with a unique reactor design and electrode configuration has been investigated. An electrochemical absorption column larger than laboratory scale was employed. A titanium rod cathode and platinum expanded mesh anode separated by a cation exchange membrane were used as electrodes in the cylindrical electrochemical reactor. The effects of current densities of 10, 1, and 0.1?Am?2, initial SO2 concentrations of 500, 2,500, and 5,000?ppm, gas flow rates of 0.75, 1.5, and 5?L min?1, sulfuric acid concentrations of 1, 5, and 10%(w), gas composition, and electrolysis time on removal efficiency, current efficiency, energy consumption, and mass transfer coefficient were reported. Removal efficiency of 94% was obtained with a high current efficiency of 94%, energy consumption of 2.22×10?2?kW?hm?3, and mass transfer coefficient of 5.9×10?5?ms?1 without additives or pretreatment. At the current densities of 0.1, 1, and 10?Am?2, the removal efficiencies were 10, 94, and 98%, respectively. Removal efficiency was observed to decrease as inlet SO2 concentration, gas flow rate, and electrolyte concentration increased. The presence of CO2 in the gas mixture led to a decrease in the SO2 removal efficiency. During electrochemical absorption of SO2 into the H2SO4 solution, the concentration of acid is increased from 5 to 10%. At the end of the studies, electrochemical desulfurization succeeded in meeting the regulation requirement, and the absorbing liquid remained in a reusable form.     

Evaluation of Granular Surfactant-Modified/Zeolite Zero Valent Iron Pellets As a Reactive Material for Perchloroethylene Reduction

The use of permeable reactive barriers (PRBs) for groundwater remediation is based on two distinct mechanisms: sorption and transformation. With sorption as the main mechanism, contaminants sorb on the PRB materials and are retarded. With transformation as the main mechanism, the contaminants react with the PRB materials and then converted to less toxic or innocuous substances. In this study, we tested surfactant-modified zeolite/zero valent iron (SMZ/ZVI) pellets as a PRB material to retard and degrade perchloroethylene (PCE), utilizing both sorption and transformation processes. Batch PCE kinetic studies showed instantaneous PCE removal from the aqueous phase due to sorption and subsequent removal with time due to reduction. The separation of sorption from reduction can be used to obtain both the PCE distribution coefficient (Kd) and the pseudofirst-order reduction rate constant (μobs) from a single batch experiment. The calculated Kd and μobs values are 3.0 and 0.5?L/kg and 0.14 and 0.05?h?1 for SMZ/ZVI and Z/ZVI pellets, respectively. Column experiments were performed at linear flow velocities of 0.07, 0.14, and 0.20?cm/min. The results were modeled using the one-dimensional advection–dispersion equation with linear sorption and first-order transformation. The Kd values were 2.3±0.4 and 0.5±0.1?L/kg for SMZ/ZVI and Z/ZVI pellets, respectively, in agreement with those of the batch study. The PCE transformation constants varied between 0.077 and 0.199?h?1 for the SMZ/ZVI pellets and between 0.037 and 0.144?h?1 for the Z/ZVI pellets, indicating that an enhanced transformation of PCE occurred with the sorbing SMZ/ZVI pellets. The PCE reduction rates were faster at slower flow rates, indicating that the reduction was not a mass-transfer-limited process.     

改性黏土的制备及吸附Zn2+的研究

实验室对富镁纤维状硅酸盐黏土进行酸改性和钾盐活化处理,并与聚合羟基铁离子进行聚合反应,制备了一种新型黏土复合絮凝剂.对重金属离子Zn2+的吸附性能试验结果表明:pH值对复合絮凝剂吸附Zn2+影响很大,当pH<2时,Zn2+去除率只有20%左右,当pH>6时,Zn2+去除率达到95%;初始浓度对Zn2+的去除率影响较大,去除率随着初始浓度的上升而下降;而温度、絮凝剂投加量对Zn2+去除率影响相对较小.改性后黏土矿物对Zn2+有较强的去除能力,常温下,当pH为6～8、投加量为0.3 g、500 r/min转速条件下快速搅拌5 min、100 r/min转速条件下慢速搅拌10 min、静置60 min时,Zn2+的去除率可达95%,该方法工艺简单且无二次污染.