MOF-Fe吸附Se(Ⅳ)的特性与机制研究

水热法合成了MOF-Fe样品,研究了不同pH条件下MOF-Fe对亚硒酸根(Se(Ⅳ))的等温吸附和动力学吸附特性;基于吸附前后样品悬浮液的pH和Zeta电位、粉末样品的衰减漫反射红外光谱(ATR-IR)和X-射线光电子能谱(XPS),分析了MOF-Fe对Se(Ⅳ)的吸附机制.当吸附体系的初始pH分别为3.0、4.0和5.0时,样品对Se(Ⅳ)的Langmuir最大吸附容量(Qm)分别为0.690、0.534和0.538 mmol·g-1,3种pH条件下的吸附亲和力(b)表现为pH 3.0pH 4.0pH 5.0.3种pH条件下,样品对Se(Ⅳ)的吸附都在20 min内趋于饱和,二级动力学方程对吸附动力学数据的拟合度(R2)均大于0.999,MOF-Fe吸附Se(Ⅳ)的内扩散过程可用Weber-Morris方程描述.当吸附体系初始pH为3.0时,MOF-Fe与Se(Ⅳ)之间的吸附作用机制主要为:配位不饱和Fe与H_2SeO_3之间的配位作用、脱羟基后的活性Fe与[O_2SeOH]~-的键合作用及单齿羧羰基氧与Se(Ⅳ)之间的氢键作用.当吸附体系初始pH为5.0时,MOF-Fe与Se(Ⅳ)之间的吸附作用机制主要为:Fe—OH与[O_2SeOH]~-的阴离子交换作用,[SeO_3]~(2-)破坏了桥式羧羟基Fe—O键并与Fe—OH发生阴离子交换作用形成双齿吸附态Se(Ⅳ)以及单齿羧羰基氧与Se(Ⅳ)之间的氢键作用.     

Ignition advancement study for optimized characteristics of a raw biogas operated spark ignition engine

In the current investigation, raw biogas obtained from rural sectors was used as the alternative to gasoline fuel in the spark ignition (SI) engine. The performance and efficiency are mainly dependent on the combustion phasing for which “ignition timing” is an effective tool in a SI engine. Hence, the objective of the present work is to understand the effect of “variable ignition timing” for a biogas-fueled SI engine. For this purpose, a single cylinder, 4-stroke, SI engine of rated power 4.5 kW was operated with raw biogas at a compression ratio (CR) of 10. By maintaining a speed of 1650 rpm, the engine was operated in wide open (WOT) and part throttle (PT) mode with an equivalence ratio of 0.81 and 0.83, respectively. It was observed that the biogas fueled SI engine was found to be operative only within the ignition advance (IA) range of 33–47° CA bTDC both in WOT and PT conditions. The results showed optimal brake power (BP), brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) are achieved at 45° CA bTDC. The average peak cylinder pressure, neat heat release rate (NHRR) and mean gas temperature (MGT) are also observed to be maximum while CO and HC emission at this point of IA were found to be minimum. Due to controlled and complete combustion, CO₂ and NO_x concentration in the exhaust emission were found to be higher at this point of ignition timing.     

pH对亚硝化、厌氧氨氧化反应及联合工艺氮素转化的影响

利用具有pH调节功能的序批式反应器,分别接种好氧生物膜和厌氧颗粒污泥,研究了不同pH对自养生物脱氮工艺氮素转化的影响。结果表明:当pH为8.18时,亚硝氮累积速率较高,为0.79 kg/(m3·d)。当pH为7.85时,厌氧氨氧化菌脱氮效能达到最大,为1.52 kg/(m3·d)。联合工艺进水pH为7.7±0.1时,优先控制好氧段pH为7.5左右,厌氧段pH为7.6,氮去除速率高达0.98 kg/(m3·d)。     

水污染源在线设备比对监测问题与解决方案——以长沙市在线监测系统为例

总结了长沙市7年来水污染源在线监测系统开展比对监测工作的情况,对氨氮、p H、重金属比对监测存在的问题进行了剖析,分析了在线监测仪器比对不合格的原因以及目前在线监测仪器部分项目缺乏误差标准等亟待解决的问题,研究出各因子误差的合理区间,提出了切实可行的解决方案:氨氮应该按照检测浓度高低确定误差范围;p H质控样不应使用相对误差,建议采用±0.3 p H的绝对误差;重金属实际水样浓度小于一定量时,用接近水样浓度的低浓度质控样替代。     

Total-factor water efficiency of regions in China

Water is a limited and unevenly distributed resource in China, with the per capita amount of water resource there only about one-fourth of the world's average. However, water is an essential resource for people's lives and economic development. Over the past two decades China has seen the fruit of its rapid economic growth; nevertheless, a severe water shortage is behind this prosperous scenario and is becoming worse. Efficient water supply is certainly essential for the sustainable development of human beings. This paper analyzes water efficiency by incorporating water as an input as well as using conventional inputs such as labor employment and capital stock. An index of a water adjustment target ratio (WATR) is established from the production frontier constructed by data envelopment analysis (DEA) including water as an input. The water efficiency of regions is obtained from a total-factor framework with both residential and productive water use. A U-shape relation is discovered between the total-factor water efficiency and per capita real income among areas in China. The central area has the worst water efficiency ranking and the total adjustment amount of water used there is around three-fourths of China's total. More efficient production processes and advanced technologies need to be adopted in the central area to improve its water efficiency, especially for its productive use of water.     

WATER QUALITY DURING STORM EVENTS FROM TWO CONSTRUCTED WETLANDS RECEWING MINE DRAINAGE1

ABSTRACT: Flow rates, pH, iron concentration, and manganese concentration were measured during several storm events at two constructed wetlands receiving mine water. During a substantial rain event, flow rates at both the wetland outlets surpassed flow rates at the wetland inlets, reflecting incident rainfall and differences in wetland area at the two sites. A significant positive correlation existed between local rainfall and outflow rates at the larger wetland, but not between rainfall and inflow rates. During storm events, outlet pH, relative to inlet pH, was slightly elevated at the larger wetland, and depressed at the smaller wetland. However, over the course of one year, rainfall was uncorrelated to outlet pH in the larger wetland. A substantial rain event at the smaller wetland resulted in a temporary elevation in outlet iron concentrations, with treatment efficiency reduced to near zero. However, in the larger wetland, outlet iron concentrations were not significantly affected by storm events. Although rainfall and outlet iron concentration were not significant correlates at the larger wetland, flow rate was positively correlated to outlet iron concentration. A normal manganese treatment efficiency of 50 percent at the smaller wetland was reduced to zero during a heavy rain.     

采场调压数学模型在煤矿火区治理中的应用

采场调压可改变采场内气体流动的状况,抑制采空区自然发火。笔者采用Ｗａｒｄ 非线性运动方程,建立采场调压数学模型,利用有限元法对其进行求解。通过对小恒山煤矿东正巷出口的调压进行计算机模拟,从而掌握火区内部参数的变化趋势,及时预测调压潜力及效果,指导调压措施的进一步实施。     

树皮填料补充碳源人工湿地脱氮初步试验研究

人工湿地可应用于城市污水厂出水深度处理和农业污染治理,但反硝化碳源不足问题制约了其脱氮能力.本试验利用树皮作为垂直流人工湿地强化反硝化脱氮填料,分析了水力负荷、硝酸盐负荷以及pH对人工湿地脱氮效果的影响.结果表明,人工湿地可以达到预期的反硝化水平,反硝化速率随水力负荷、硝酸盐负荷的增加而增大,去除率随两者的增加而减小,...     

小麦秸杆对水中Pb（2＋）和Cd（2＋）的吸附特性

以农业废弃物小麦秸杆为吸附材料,探讨了小麦秸杆对Pb2＋、Cd2＋的吸附特性,重点研究了吸附时间、离子浓度、溶液pH值等对小麦秸杆吸附Pb2＋、Cd2＋的影响.结果表明,溶液pH值对吸附的影响大,在pH 2.0～6.0范围内,吸附量随溶液初始pH值的升高而升高.小麦秸杆吸附Pb2＋、Cd2＋的速度快,吸附动力学过程可以...     

潜流人工湿地中氮磷污染物净化的分层效应研究

选定芦苇、小叶章为湿地植物,土壤、炉渣为基质,构建3个小型潜流人工湿地系统,通过间歇运行方式,考察了模拟系统上层、下层中N、P和pH值等指标的变化.结果表明,当水力停留时间为10 d时,小叶章和芦苇湿地上层总氮的去除负荷分别为0.771 g·(m2·d)-1和1.481 g·(m2·d)-1,分别是下层的1.15倍和1...