负载型颗粒活性炭催化过硫酸钠氧化降解橙黄G

通过在颗粒活性炭(GAC)上负载氧化铁,并以此作为催化剂(Fe/GAC)在常温常压下催化过硫酸钠(PS)产生硫酸根自由基降解偶氮染料橙黄G。研究了体系pH、氧化剂浓度、催化剂浓度对橙黄G去除率的影响,并且对催化剂的重复使用性能进行了测试。结果表明,在Fe/GAC/PS体系中,[OG]0=0.2 mmol/L,[GAC]=1 g/L,[PS]0=2 mmol/L,降解2 h后OG去除率为99%,且有较高的矿化率;随着氧化剂浓度和催化剂浓度的增加,OG的去除效率提高;催化剂有较好的重复使用性。利用扫描电镜(SEM)对催化剂进行了表征,可以看出在活性炭上成功负载氧化铁。利用化学分子探针竞争实验鉴定催化反应中的活性物种SO4-·和OH·。     

曝气条件对浸没式膜生物反应器内流场的影响

为深入研究流场动力学特性对浸没式膜生物反应器系统内膜面污染的控制,应用fluent软件对浸没式膜生物反应器内气液两相流动进行了三维数值模拟研究。采用标准k-ε湍流模型和欧拉多相流模型,考察了改变曝气条件对膜面气液速度场及气含率分布的影响。模拟结果表明,在相同曝气强度下,1 mm曝气孔径下膜面气液两相的速度增加较孔径2 mm、3 mm的快;曝气孔径为1 mm时,膜面的液相速度随着曝气强度的增加逐渐增大;曝气孔径为1 mm时,曝气量为5.5 m3/h所形成的漩涡区较大,膜面气含率值较高且分布较均匀,气液两相接触面积较大,膜面冲刷效果较好;模拟观察到反应器底部靠近壁面局部气含率较低,不利于活性污泥中微生物的生长,需要进一步优化曝气和反应器结构。     

Stand-alone wind power system with battery/supercapacitor hybrid energy storage

This paper presents a stand-alone wind power system with battery/supercapacitor hybrid energy storage. A stand-alone wind power system mainly consists of a wind turbine, a permanent magnet synchronous generator, hybrid energy storage devices based on a vanadium redox flow battery and a supercapacitor, an AC/DC converter, two bidirectional DC/DC converters, a DC/AC converter and a variable load. Several control strategies for the stand-alone wind power system are involved such as a maximum power point tracking (MPPT) control, a vanadium redox flow battery charge/discharge control and a supercapacitor charge/discharge control. The proposed MPPT control combines a sliding mode control with an extreme search control to capture maximum wind energy. This strategy avoids the necessity of measuring wind velocity, obtaining models or parameters of the wind turbine and calculating the differentials of the power generated from the wind power system and from the speed of the generator. The battery charge/discharge control maintains a constant DC bus voltage. When the battery charging/discharging current reaches the setting threshold, the charge/discharge control of the supercapacitor is triggered to limit the charging/discharging current of the battery. The simulation results show that the proposed method can rapidly respond to variations in wind velocity and load power.     

Adsorption of 2-mercaptobenzothiazole from aqueous solution by organo-bentonite

The adsorption behavior of 2-mercaptobenzothiazole onto organo-bentonite was investigated.Natural bentonite from Gaozhou in Guangdong Province,China was collected.Organo-bentonite was prepared by intercalation of cetyltrimethyl ammonium bromide into the natural bentonite.The physicochemical properties of the prepared organo-bentonite were characterized by X-ray diffraction,N2 adsorption-desorption isotherm and Fourier transform infrared spectroscopy.The results showed that montmorillonite is the main component of the natural bentonite.The basal spacing of the natural bentonite is 1.47 nm,which increased to 1.98 nm on intercalation with cetyltrimethyl ammonium bromide.Moreover,both the surface area and pore volume increased with intercalation.Clear CH2 stretching(3000-2800 cm-1) and scissoring(1480-1450 cm-1) modes of the intercalated surfactants were observed for organobentonite.Compared with the pseudo first-order kinetic model,the pseudo second-order kinetic model is more suitable to describe the adsorption kinetics of 2-mercaptobenzothiazole onto organo-bentonite.The adsorption capacity of 2-mercaptobenzothiazole onto organo-bentonite increased with increasing initial concentration of 2-mercaptobenzothiazole,but decreased with increasing adsorbent dosage.The adsorption isotherm of 2-mercaptobenzothiazole onto organo-bentonite fits well with the Langmuir model.The maximum adsorption capacity of organo-bentonite for 2-mercaptobenzothiazole was 33.61 mg/g,indicating that organo-bentonite is a promising adsorbent for 2-mercaptobenzothiazole.     

保护层分析应用规则研究

为了确保保护层分析(LOPA)结果的客观性和可靠性,对LOPA的应用规则进行了探讨.按照LOPA应用的基本程序,对场景筛选、确定初始事件、独立保护层评估、场景频率计算、风险决策及后续跟踪等的相关规则进行了阐述.企业在应用LOPA时,应严格按照这些规则进行.     

一株中度嗜盐硫酸盐还原菌的分离及生理特性研究

本文从四川自贡盐厂卤水污泥中，分离出一株中度嗜盐硫酸盐还原菌。菌体为短杆状，０．９－１．１×２．０－２．５μｍ，革兰氏染色阴性，形成芽孢，不含脱硫孤菌素。固体培养基上无Ｆｅ２＋时，菌落为半透明状；有Ｆｅ２＋时菌落为黑色，直径为１－３ｍｍ。利用乳酸盐作为碳源，利用乙酸盐时必须添加生长因子。能在５％－２５％（Ｗ／Ｖ）Ｎａｃｌ浓度范围内生长，最适生长浓度为９％－１３％（Ｗ／Ｖ）。最适生长温度为３５℃。最适生长ｐＨ值为７．０．根据形态和生理生化特征，该菌为脱硫肠状菌属，但与该属已报导的硫酸盐还原菌在嗜盐、碳源利用、最适生长温度以及其它一些特征上均有不同，因此可能是个新种。该菌是目前已报道的嗜盐浓度最高的硫酸盐还原菌。     

响应面法分析Fenton氧化处理采油废水的过程

采用Fenton氧化对采油废水进行研究,选取双氧水与二价铁离子的摩尔比、初始pH值和反应时间为自变量,以废水的COD去除率为响应值,通过Box-Behnken设计方法进行实验设计,进行了3因素3水平共15个实验点的实验。使用响应面分析法对实验结果进行模拟及分析,建立了响应值与3个自变量的二次多项式方程模型。Fenton氧化的优化工艺条件:n(H2O2):n(Fe2+)=0.8,pH=3.0以及反应时间60 min。在该优化条件下,废水的COD去除率可达72.8%,经实验验证,实际值与模型预测值拟合性好,偏差仅为0.5%。实验结果证实了该模型分析采油废水处理运行参数的准确性。优化工艺后的处理水质COD值完全满足油田废水达标排放的要求。通过总离子色谱图和质谱检索分析原油中的成分变化情况,证实Fenton方法对原油组分的降解效果。     

聚乙烯醇/超细羽绒粒子共混膜的制备及其染料吸附动力学

为了改善并更好地研究聚乙烯醇的染料吸附性能,制备了不同超细羽绒粒子含量的聚乙烯醇/超细羽绒粒子共混膜,并将其用于对活性艳红X-3B染料的吸附。结果表明,随着超细羽绒粒子含量的增加,聚乙烯醇/超细羽绒粒子共混膜表面粗糙程度增大。当超细羽绒粒子的质量分数为27.8%时,K/S值最大,染料吸附性能最好,其吸附效果比纯聚乙烯醇膜提升约54.5%。动力学研究结果表明,伪二级动力学模型能更好地描述聚乙烯醇/超细羽绒粒子共混膜对染料的吸附。     

Uncovering the evolution of tin use in the United States and its implications

• US tin use decreases as the GDP value added by manufacturing sector increases. • Global and China’s tin use increases as the GDP added by manufacturing increases. • A sigmoid curve can fit the US tin use data well. • US tin use patterns is not due to the finite tin reserves or resources. • Policies, substitutions, etc. play key roles in the changing tin use patterns. Tin is of key importance to daily life and national security; it is considered an essential industrial metal. The United States (US) is the world’s largest economy and consumer of natural resources. Therefore, the analysis of historical tin use in the US is helpful for understanding future tin use trends in the world as a whole and in developing countries. Time series analysis, regression analysis with GDP or GDP/capita, and historical data fitted with logistic and Gompertz models are employed in this study. Historical tin use in the US shows three stages—increase-constant-decrease, as GDP per capita has increased. Tin use in the US is negatively correlated with the GDP value added by the manufacturing sector, while the use of tin worldwide and in China continues to increase along with the GDP value added by the manufacturing sector. Although a sigmoid curve can fit the US tin use data well, that use is not directly related to the limited tin reserves or resources. Rather, policies, economic restructuring, substitutions, new end-use markets, etc. have played key roles in the changing tin use patterns. This work contributes to understanding future tin use at both the global and national levels: tin use will continue to increase with GDP at the global level, but use patterns of tin at the national level can be changed through human intervention.