Prediction of Bromate Removal in Drinking Water Using Artificial Neural Networks

In treatment of natural water resources, bromide transforms into carcinogenic bromate, especially during the ozonation process. Adsorption was used in the experimental part of this study to remove this harmful compound from drinking water. For this purpose, technically, HCl-, NaOH-, and NH₃-modified activated carbons were used. Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET) analyses were carried out within the characterization study. Moreover, the effects of diameters and heights of adsorption columns, flowrate, and particle size of adsorbent were investigated on the removal amounts of bromate. Optimum conditions were obtained from the experiments, and regional/real samples were collected and analyzed. After the experiments, an artificial neural network (ANN) was used to predict bromate removal percentage by using the observed data. Within this context, a feed-forward back-propagation ANN was chosen in this study. Additionally, the transfer function was selected as tangent sigmoid and 3 neurons were used in the hidden layer. Particle size and amount of the activated carbon, height and diameter of the column, volumetric flowrate, and initial concentration were selected as the input variables. Bromate removal percentage was selected as the output. It was found that the model an R value of 0.988, RMSE value of 3.47 and mean absolute percentage error (MAPE) of 5.19% in the test phase.     

Activity Patterns for the ‘‘Water Gas Shift Reaction Over Supported Precious Metal Catalysts’’

Activity patterns for the high temperature water gas shift reaction over oxide catalysts promoted by precious metals show that the performance of iron oxide–chromia catalysts can be significantly improved by promotion with small amounts of rhodium. The results suggest that reactions of hydrogen at the promoter–catalyst interface are the rate controlling process.     

Effects of Pretreatments of Cu/ZnO-Based Catalysts on Their Activities for the Water–Gas Shift Reaction

The effects of the pretreatments of Cu/ZnO-based catalysts prepared by a coprecipitation method on their activities for the water–gas shift reaction at 523K were investigated. The activity of a Cu/ZnO/ZrO₂/Al₂O₃ catalyst for the water–gas shift reaction was less affected by calcination at temperatures ranging from 673-973K and by H₂ treatment at 573 or 723K than that of a Cu/ZnO/Al₂O₃ catalyst. The catalyst activity could be correlated mainly to the Cu surface area of the catalyst.     

Prediction of Bromate Formation Using Multi-Linear Regression and Artificial Neural Networks

The main objective of this study was to develop simple models for the prediction of bromate formation in ozonated bottled waters, using rapidly and practically measurable raw water quality and/or operational parameters. A total of 6 multi-linear regression (MLR) with or without principal component analysis (PCA) and 2 artificial neural networks (ANN) models with multilayer perceptron architecture were developed for the prediction of bromate formation. PCA was employed to better identify relations between variables and reduce the number of variables. Experimental data used in modeling was provided from the ozonation of samples from 5 groundwater sources at various applied ozone dose and contact time. MLR models#1 and #2 well-predicted bromate formation although correlations (i.e., the signs of regression constants) among pH (as input variable) and bromate concentrations did not agree with the chemistry. MLR model#6, containing practical input parameters that are measured on-line in full-scale treatment plants, adequately predicted bromate formation and agreed with the chemistry, although fewer input parameters were used compared to MLR#1 and #2. Although both of the ANN models exhibited high regression coefficients (R²) (0.97 for both) ANN#1 was found to provide better prediction of bromate formation based on mean square error (MSE) values. However, since ANN#2 included easily measurable input parameters it may be practically used by water companies employing ozonation. Results overall indicated that ANN models have stronger prediction capabilities of bromate formation than MLR models. ANN modeling appears to be a strong tool in situations where the relations between variables are non-linear, interactive and complex, as in the bromate formation by ozonation.     

中孔材料Cu-Zn-Al2O3的合成及其在CO水煤气变换反应中的应用

前言聚合物电极燃料电池（PEFC）系统在固定式发电装置和车载发电装置中得到广泛应用。在聚合物电极燃料电池中作为燃料的氢气．是通过甲醇或烃类的部分氧化反应以及蒸汽重整反应而产生的。目前存在的问题是重整氢气中含有大约1％～3％的CO．而这部分CO在使用温度下（大约80℃）不可逆的吸附在聚合物燃料电池（PEFC）的Pt电极上并阻止电化学反应^[1-3]。     

Chemical and Physical Properties of Copper-Based Catalysts for CO Shift Reaction and Methanol Synthesis

The modern low-pressure methanol synthesis catalysts are based on copper-containing systems such as Cu/ZnO/Al₂O₃ and Cu/ZnO/Cr₂O₃ with various compositions. These catalysts are also highly active for the low-temperature CO shift reaction. For both reactions the nature of the active sites is still an open question.     

Chemical and Physical Properties of Copper-Based Catalysts for CO Shift Reaction and Methanol Synthesis

The modern low-pressure methanol synthesis catalysts are based on copper-containing systems such as Cu/ZnO/Al₂O₃ and Cu/ZnO/Cr₂O₃ with various compositions. These catalysts are also highly active for the low-temperature CO shift reaction. For both reactions the nature of the active sites is still an open question.     

高压变换气气提法尿素用于大型氨厂改扩的商榷

高压变换气气提法生产尿素与ＣＯ２气提法相似,但可取代合成氮的脱除ＣＯ２和再生及尿素的ＣＯ２压缩工序。本文介绍我国高压变换气气提法尿素工艺,以及采用此工艺将３００ｋｔ／ａ合成氨改扩至５００ｋｔ／ａ,并增产３００ｋｔ／ａ尿素的设计。     

等温变换与绝热变换在高水气比粗煤气变换中的应用对比

不少新建合成氨装置采用粉煤加压气化工艺,其粗煤气中水气比高、CO含量高,介绍了与其配套的等温变换和绝热变换2种变换工艺,分别从工艺流程、占地面积、关键设备、公用工程消耗、催化剂用量和经济投资等方面对二者进行了对比。结果表明,等温变换在高水气比粗煤气变换中应用具有一定的优势,但也存在应用业绩不多、运行年限较短的问题。     

Pt and/or Pd Supported/Incorporated Catalyst on Perovskite-Type Oxide for Water Gas Shift Reaction

Catalytic properties of Pd and/or Pt supported/incorporated on/in perovskite-type oxides for water gas shift (WGS) reaction have been investigated. We found that the dominant reaction mechanism over these catalysts was redox mechanism by CO and steam, and their redox properties were controllable by the bulk structure of perovskite.     

工艺条件对耐硫变换催化剂COS转化活性以及甲硫醇生成量的影响

模拟工业装置的工艺条件,考察了原料气中CO和H2S含量、温度和水气比等因素对耐硫变换催化剂COS转化活性和甲硫醇生成量的影响。结果表明,当原料气中CO和H2S含量较高时,会有甲硫醇生成,且其生成量随着CO和H2S含量增加而增加;受平衡的影响,原料气中H2S含量升高时,COS转化率降低;增加反应温度,可以提高COS的氢解反应活性,并减少甲硫醇的生成,但不利于COS的水解反应。水气比具有提高COS转化活性并减少甲硫醇生成的双重作用:水气比较低时,其值从0增加到0.2,COS转化率从89.65%增加到97.82%,表明COS的水解反应比氢解反应更容易进行;当水气比为0.3时,反应后的尾气中只有微量甲硫醇生成,当水气比大于0.4时,反应后几乎无甲硫醇生成。     

Rapid Hydrogen Generation from the Reaction of Aluminum Powders and Water Using Synthesized Aluminum Hydroxide Catalysts

A synthesized and nano-sized Al(OH)₃ powder that promotes the generation of hydrogen from a Al/water reaction is demonstrated. In this study, aluminum hydroxides are synthesized using sodium aluminate NaAlO₂, distilled water and ethanol. The mole ratio of ethanol/water and the concentration of sodium aluminate in solution affect the crystal structure, morphology and sizes of the Al(OH)₃ powders significantly. These Al(OH)₃ powders contain both gibbsite and bayerite phases and exhibit excellent catalytic power on the hydrogen generation of Al/water system. It is proposed that two major characteristics of Al(OH)₃ powders dominate the catalytic power. That is, the surface area and the high-energy sites of Al(OH)₃. When mole ratio of ethanol/water is between 0.3–0.6 and the concentration of NaAlO₂ is higher than 0.0167 g/ml, the synthesized Al(OH)₃ powders are in a more gibbsite-oriented and plate-like structure. Other than above conditions result in a more bayerite-oriented and particulate-like structure. The plate-like structure exhibits strong catalytic power due to the existence of high-energy sites on the edge of plates even its surface area is not so high. The particulate-like structure may also have strong catalytic power when it has a high surface area. By taking advantage of the exothermic reaction, ~?100% yield of hydrogen can be produced from 1 g Al/10 g water system within 30 s using 3 g synthesized Al(OH)₃. A aluminum waste scrap can also react with water using these effective catalysts and generate?~?95% yield of hydrogen within 8 min.     

中变锅炉给水预热器变换气出口弯头爆裂的原因分析及措施

简要介绍了CO变换工序的工艺流程,分析了中变锅炉给水预热器变换气出口弯头爆裂的原因,最终确定冲刷腐蚀是导致管线弯头发生爆裂的主要原因。对爆裂的弯头、壁厚减薄的管道进行更换,并将材质更换为不锈钢,同时对相应的管道及弯头定期进行壁厚分析、加强工艺操作与管理,变换工序运行正常。     

用人工神经网络预测聚乙烯及其共混物机械性能

人工神经网络专家系统具有学习、记忆和泛化推广功能.MATLAB软件可根据用户的要求自动生成人工神经网络程序.本文应用BP模型人工神经网络对聚乙烯及其共混物的机械性能进行预测研究.结果表明,所建立的网络程序具有高速、容错和自适应等特点,在本领域的应用性能良好,预测准确率较高,达到预期的效果.     

Artificial Neural Networks Modeling of Ozone Bubble Columns: Mass Transfer Coefficient,Gas Hold-Up,and Bubble Size

This study aims at applying artificial neural network (ANN) modeling approach in designing ozone bubble columns. Three multi-layer perceptron (MLP) ANN models were developed to predict the overall mass transfer coefficient (k_La, s^?1), the gas hold-up (? _G , dimensionless), and the Sauter mean bubble diameter (d_S , m) in different ozone bubble columns using simple inputs such as bubble column's geometry and operating conditions. The obtained results showed excellent prediction of k_La, ? _G , and d_S values as the coefficient of multiple determination (R² ) values for all ANN models exceeded 0.98. The ANN models were then used to determine the local mass transfer coefficient (k_L , m.s^?1). A very good agreement between the modeled and the measured k_L values was observed (R² ?=?0.85).     

Significant Improvement in Activity and Stability of Pt/TiO2 Catalyst for Water Gas Shift Reaction Via Controlling the Amount of Na Addition

Na promoted Pt/TiO₂ catalysts have been studied under high severity, near equilibrium, conditions for use as a single stage WGS catalyst. Addition of 3 wt% Na to a 1 wt% Pt/TiO₂ catalyst has been found to improve water gas shift activity significantly compared to Pt/TiO₂, Pt/CeO₂, and Pt–Re/TiO₂ catalysts. This catalyst is stable when the reaction temperature is higher than 250 °C. Deactivation occurred when the reaction temperature was lower than 250 °C, however, returning the temperature to higher than 250 °C fully recovered activity. TEM observations revealed that addition of Na inhibited Pt particle sintering. These results suggest that Na promoted Pt/TiO₂ is a promising single stage water gas shift catalyst for small scale hydrogen production.