Two‐dimensional transport of lactate‐modified nanoscale iron particles in porous media

This study investigates the two‐dimensional transport of nanoscale iron particles (NIP) and lactate‐modified NIP (LMNIP) in homogeneous and heterogeneous porous media under typical pressurized groundwater flow conditions. A two‐dimensional bench‐scale test setup was developed and a series of experiments was conducted simulating homogeneous sand profile and two‐layer profile with two different sands. NIP and LMNIP at a concentration of 4 g/L were prepared in electrolyte simulating groundwater conditions and were injected at the inlet of the test setup under different pressure gradients (0.5. 0.8, 1, and 2 pounds per square inch). During the testing, effluent was collected and its volume and nanoiron concentrations were measured. At the end of the testing, soil cores were obtained at different distances from the inlet and were used to measure nanoiron concentrations and magnetic susceptibility values. Results showed that the transport of NIP and LMNIP was enhanced by increased pressure gradient. LMNIP transport occurred more uniformly as compared to bare NIP. The iron concentrations decreased with distance from the inlet to the outlet and increased from the top to the bottom of the test cell. The data indicate that, as the particles were transported, they underwent aggregation and sedimentation, which resulted in the observed non‐uniform spatial distribution of iron. The NIP and LMNIP transported through the high‐porosity and high‐permeability soil layer in the heterogeneous soil profile, implying that the transport occurred predominantly along the path of least resistance for the flow. Magnetic susceptibility values are found to have good correlation with the iron content in the soil and are helpful to characterize the transport of NIP and LMNIP. Overall, this study shows that the non‐uniform distribution of NIP and LMNIP occurs under two‐dimensional transport conditions and the soil heterogeneities can significantly impact the transport of NIP and LMNIP. The design of field delivery systems should consider such conditions and optimize the pressurized injection systems. © 2011 Wiley Periodicals, Inc.     

液膜分离技术处理含Cr6+废水的研究

采用液膜分离技术处理Cr^6＋质量浓度为200—1000mg／L的废水,考察了膜溶剂、载体、内水相、外水相、pH、乳水比（乳液与废水的体积比）等因素对处理效果的影响,通过正交实验得出最佳实验条件。结果表明,在膜溶剂为煤油、载体为三辛胺、内水相为氯氧化钠、氢氧化钠质量分数为2％、pn为1、乳水比为1：4的最佳条件下,Cr^6＋的去除率可达98．4％。     

内标法与外标法测定废气中挥发性有机化合物

目前采用热脱附-气相色谱-质谱法测定废气中挥发性有机化合物时多使用外标法。实验对比了内标法与外标法测定时存在的差异,发现大多数VOCs内标法的回收率均高于外标法,且内标法的相对标准偏差普遍小于外标法,内标法测定的准确度和精密度均优于外标法。内标法的标准曲线可使用更长时间,对于大量样品的测定非常有利;而外标法必须每次测定时重新绘制新曲线。故废气中VOCs测定工作推荐使用内标法定量。     

JYZ-1型烟气浊度在线监测仪介绍

介绍了JYZ-1型烟气浊度在线监测仪的测量原理、特点及其在环境监测中的应用。     

Preparation and Characterization of Xylan Derivatives and Their Blends

Although hemicellulose is found widely in nature, it is currently under-utilized as a raw material for commercial applications. It would be desirable to find new uses for hemicellulose in order to add value to this agro-based material. A common type of hemicellulose is xylan, which is found in a number of wood species and in cotton. In this work we prepared cationic and anionic xylan derivatives and characterized them by ¹³C NMR, FT-IR, size exclusion chromatography (SEC), thermal analysis, and rheology. In particular, the ¹³C NMR spectra of carboxymethyl xylan (CMX) and quaternary ammonium-adducted xylan (QAX) were fully assigned with the help of samples with different degrees of substitution. SEC indicated that the beechwood xylan showed a bimodal molecular weight distribution, but with derivatization the distribution tended to become unimodal. Thermal analysis and rheology studies did not uncover any surprises; the solution of xylan and its derivatives exhibited mostly Newtonian behavior. The blends of CMX and QAX produced a precipitate at almost all ratios, indicating the formation of a polyelectrolyte complex. When cationic and anionic xylan samples were added together to paper, the paper dry strength increased. Thus, the combination of cationic/anionic xylan may be of interest in selected applications.     

IC反应器处理MTO废水的中试研究

中试研究了内循环(IC)反应器处理甲醇制烯烃(MTO)废水的启动和运行过程,同时考察了颗粒污泥的性状及沼气产量的变化情况。试验过程运行稳定,系统抗冲击性强。以絮状污泥为接种污泥,经过131 d的启动和运行,IC反应器的COD去除负荷可达10 kg/(m~3·d)以上,COD去除率可达90%以上。IC反应器中的成熟颗粒污泥形状规则、密实、粒径大、沉降速率快。IC反应器的沼气产量符合理论预期。     

利用造纸黑液制备水煤浆添加剂

利用造纸黑液中有效成分,经过适当处理制备水煤浆添加剂,并且对添加剂的性能进行了测试。结果表明,依照该工艺生产的添加剂,性能优良,能够满足工业生产需要。