T酸废母液蒸氨预处理的动力学研究

为了有效降低经络合萃取处理后的T酸废母液中氨氮和总氮的浓度,为后续生物处理创造条件,对T酸母液进行Fenton氧化和蒸氨预处理,讨论了Fenton氧化、pH值、气液比、温度和反应时间对氨氮和总氮去除效果的影响.结果表明,Fenton氧化降低了T酸废母液的氨氮浓度,有利于氨氮和总氮的去除,去除率增幅明显.蒸氨过程中,氨氮和总氮的去除率随着pH值、温度和气液比的增大而升高,在pH值为11,气液比为3000,温度为95℃的条件下反应120min,氨氮去除率大于99%,总氮去除率大于97%.蒸氨预处理的氨氮去除动力学方程符合一级反应动力学,反应速率常数为k=0.00883min-1.反应的阿伦尼乌斯方程为:ln(k)=-1.97161-1016.5026/RT,R2=0.9959,反应活化能为8451.20J/mol,指前因子为0.139min-1.蒸氨是处理高氨氮T酸废母液有效手段,有工业应用价值.     

化铣废液中铝离子快速结晶去除的工艺研究

采用L1(64)5正交试验法,优化化铣废液中铝离子快速结晶去除的工艺。结果表明:稀释倍数和晶种添加量是显著性影响因素;最优工艺组合为:化铣废液稀释1.2倍至铝离子浓度为41.43 g/L;添加与溶液中铝离子比例成0.3:1的氢氧化铝晶种;温度控制在35℃;机械搅拌转速100 r/min;搅拌时间为1 h/d。反应48 h后,化铣废液中铝离子浓度从41.43 g/L降至30.10 g/L,铝离子去除效率为27.35%,化铣废液达到再生回用要求。     

Accident risk of foreign drivers in various road environments

INTRODUCTION: This paper reports on the accident risk of foreign and native drivers in various road environments in Greece. In particular, the analysis aims to determine the combined effect of driver nationality, area type (inside/outside urban area), junction (yes/no), and lighting conditions (day/night) on accident fault risk. METHODS: Data from the national accident database of Greece are used in a hierarchical log-linear analysis. The induced exposure technique is applied due to the lack of exposure data. Estimated and observed odds ratios are then examined for the quantification of the various effects in terms of relative risk. RESULTS: The initial examination of a saturated model leads to the rejection of all three- and higher-order effects within variables, without providing an adequate fit to the data. On the contrary, a non-saturated second-order model presents a very satisfactory overall fit. The examination of single and combined effects indicates that the most significant effect on accident risk rises from the presence of foreign drivers at junctions. CONCLUSIONS: Results confirm that foreign drivers in Greece are at increased risk. However, immigrant permanent residents appear to have a lower risk compared to tourists, regardless of the road environment.     

Seed selections for crystallization of calcium phosphate for phosphorus recovery

Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.     

镁盐改性生物质炭的合成及其在废水氮磷资源化中的应用研究

通过直接沉淀-热改性法将纳米氢氧化镁晶体(Mg(OH)_2)负载在生物质炭(BC)上,系统研究了该改性材料(Mg(OH)_2-BC)对模拟废水中氮、磷的固定特性,并探讨了投加量、反应溶液pH、接触时间对吸附过程的影响.结果表明,Mg(OH)_2-BC在投加量为0.3 g·L~(-1),反应溶液初始pH为7,反应时间≥40 min时对氮、磷的固定效果最佳,最大吸附量分别达到58.8、130.0 mg·g~(-1).Mg(OH)_2-BC对氮、磷的吸附过程均符合准二级动力学模型,吸附过程受化学吸附机理的控制.通过SEM、XRD、FTIR等对反应产物进行表征分析,结果表明,Mg(OH)_2-BC对氮、磷的固定机制主要为鸟粪石结晶沉淀,也即化学沉淀.     

Parental decisions regarding termination of pregnancy following prenatal detection of sex chromosome abnormality

In the period of a retrospective study (1979–1984 inclusive) forty cases of sex chromosome aneuploidy were identified at amniocentesis in Oxford, England and in Kuopio, Finland; 25 of these pregnancies were subsequently terminated. A decision to continue was made more often for XYY and XXX karyotypes, by older mothers and older fathers, by couples with more previous children, and by couples living in England. A decision to terminate was made more often for XXY and non-mosaic 45,X karyotypes, by younger mothers and younger fathers, by couples with few previous children, in all cases with abnormal ultrasound findings, when post-amniocentesis counselling was given by an obstetrician, and by couples living in Finland. Previous miscarriages, or terminations of pregnancy, previous problems with infertility, marital status, or the type of counselling given before amniocentesis, appeared not to influence a couples' decision. Religious and ethical ideas were not studied systematically at the time and cannot be reported on.     

硫化镍异相结晶法处理含镍废水

针对含络合剂的重金属废水,以含镍废水为例,探索了以气体硫化氢为结晶药剂的硫化镍异相结晶技术。废水以薄层液膜方式铺展于结晶载体表面,硫化氢气体穿过气液界面进入液相,硫离子与金属离子在载体表面异相结晶析出,重金属得以去除。以含酒石酸的模拟化学镀镍废水为对象,静态实验与动态实验均表明该技术具有可行性,硫化镍沉淀在结晶载体表面异相结晶析出,且附着稳定;络合剂对反应影响小;进水流速为4 mL/min,硫化钠流速为0.65 g/min,氮气流速为0.16 L/min时,出水镍浓度为49～53 mg/L,单位面积滤布表面结晶平均去除镍量为0.98 g/(m2.h)。     

碳酸钙诱导结晶动力学影响因素研究

碳酸钙诱导结晶速率受到水中多种因素的影响,采用pH-stat法对pH值、过饱和度、钙和镁离子活度和金属离子（铁、锰）等因素对碳酸钙诱导结晶速率的影响进行研究.结果表明,当pH值在8.0~10.0之间,过饱和度在1.4~4.03之间时,碳酸钙诱导结晶速率随着pH值的增大或者过饱和度的增大而增大,当钙离子和镁离子活度在0~1.18之间时,碳酸钙的结晶速率随着镁离子的增多而降低.碳酸钙结晶速率介于1.0×10^-10m/s~5.0×10^-10m/s.铁离子和锰离子的存在会促进碳酸钙的诱导结晶过程,且铁离子和锰离子同时存在时碳酸钙结晶速率高于其单独存在时碳酸钙的结晶速率.通过深入研究不同因素对碳酸钙诱导结晶动力学的影响,为碳酸钙结晶造粒工艺提供数据支持.     

Recovery of Cu(Ⅱ) from aqueous solution by induced crystallization in a long-term operation

The feasibility of copper recovery by induced crystallization in a long period(174 days) was investigated in a seeded fluidized bed reactor(FBR). The process was divided into 3 periods according to different influent conditions, and the period III was separated into III-a and IIIb due to the adjustment of the molar ratio of CO_3~(2-)concentration to copper concentration([CT]/[Cu~(2+)]). The removal efficiency could exceed 95% and the average effluent copper concentration decreased to 3.0 mg/L. The mean particle size of seed grains with copper crystals coating on, raised to 0.36 mm from initial 0.18 mm. During period III-a, the supersaturation exceeded 2.88 × 104, the removal efficiency decreased to 60%–80% and the particle size dropped to 0.30 mm, due to the generation of fines by homogeneous crystallization and seeds breaking. And the morphology of the crystals on the seed grains changed from rod-like to spherical which lead to the particle size decreasing. In period III-b,the supersaturation was modified by adjusting the molar ratio of [CT]/[Cu2+] to 1.2 from 2.The efficiency was back to 95% and the mean particle size grew to 0.36 mm at the end of IIIb, the crystals coating on the seeds turned back to rod-like products of good stability. This study illustrated that the copper salt crystal could keep on growing on the seed grains for over 150 days, the feasibility and controllability of copper recovery by induced crystallization process in FBR were satisfactory, even under the dramatic changes in influent conditions.     

超临界流体的应用及发展趋势

介绍了超临界流体的定义、性质和特征，及超临界流体技术在萃取、重结晶、色谱和化学反应等不同方面的应用，并对其发展前景进行了展望。