Assessment of sampling designs to measure riverine fluxes from the Pearl River Delta, China to the South China Sea

The Pearl River Delta (PRD), located in South China and adjacent to the South China Sea, is comprised of a complicated hydrological system; therefore, it was a great challenge to sample adequately to measure fluxes of organic and inorganic materials to the coastal ocean. In this study, several sampling designs, including five-point (the number of sampling points along the river cross-section and three samples collected at the upper, middle, and bottom parts at each vertical line), three-point (at the middle and two other profiles), one-point (at the middle profile), and single-point (upper, middle, or bottom sub-sampling point at the middle profile) methods, were assessed using total organic carbon (TOC) and suspended particulate matter (SPM) as the measurables. Statistical analysis showed that the three- and five-point designs were consistent with one another for TOC measurements (p > 0.05). The three- and one-point sampling methods also yielded similar TOC results (95% of the differences within 10%). Single-point sampling yielded considerably larger errors than the three- and one-point designs, relative to the results from the five-point design, but sampling at the middle sub-point from the middle profile of a river achieved a relatively smaller error than sampling at the upper or bottom sub-point. Comparison of the sampling frequencies of 12 times a year, four times a year, and twice a year indicated that the frequency of twice a year was sufficient to acquire representative TOC data, but larger sample size and higher sampling frequency were deemed necessary to characterize SPM.     

Methane–benzene binary mixture destruction in a reverse flow catalytic reactor

An experimental study of methane–benzene binary mixture purification in a bench-scale reverse flow reactor is carried out. Results for catalytic oxidation of the two hydrocarbons with remarkably discrepant chemical properties show that autothermal catalytic combustion of very lean combustible concentration can be achieved with periodic feed reversal. Benzene is well removed, but methane conversion is relatively low and mainly determined by the thermal level of the reactor. If methane is added as auxiliary fuel to maintain autothermal operation when the volatile organic compound (VOC) concentration in the contaminated air is too low, an excess amount is needed. The influences of gas superficial velocity, cycle period, and methane-to-benzene ratio are discussed. A mathematical model is developed and solved using a FORTRAN code, with good correspondence being observed between the two approaches. Results of experimental and numerical study indicate that, during catalytic oxidation of lean VOCs in reverse flow reactor, the mutual inhibition effect between different kinds of hydrocarbon can be neglected.     

底灰动态吸附焦化和造纸废水研究

分析了底灰的化学组成、矿物组成和比表面积等基本理化性质;采用动态吸附柱法研究了底灰处理焦化和造纸废水的性能,探讨了进水流量和吸附柱高度对吸附效果的影响.结果表明,底灰不仅有吸附作用,还具有一定的混凝作用;颗粒态有机碳(POC)较易被混凝除去,焦化废水中POC占总有机碳(TOC)的17%,而造纸废水中POC仅占TOC的2.3%,因此底厌对焦化废水COD的去除效果比造纸废水好;底灰对焦化废水色度的去除率要高于COD;接近吸附饱和时,底灰对造纸废水OM275的去除率仍有约27%,说明造纸废水中苯环类物质相比于其他有机物较易被去除.     

尼克酰胺与核黄素提高红串红球菌USTB-03对4,6-二甲基二苯并噻吩脱硫活性研究

主要考察了尼克酰胺和核黄素提高红串红球菌USTB-03对4,6-二甲基二苯并噻吩(4,6-DMDBT)脱硫活性的效应。研究结果表明,在培养基中添加初始浓度为10 mmol/L的尼克酰胺,脱硫比活性由原来302.4 mmol 4,6-DMDBT/(kg细胞干重·h)增加到476.4 mmol 4,6-DMDBT/(kg细胞干重·h),提高了57.5%。添加初始浓度为25μmol/L的核黄素,脱硫比活性增加到了465.8 mmol 4,6-DMDBT/(kg细胞干重·h),提高了54%。无论是采用微量的尼克酰胺或核黄素都可以大幅度提高红串红球菌USTB-03对4,6-DMDBT的脱硫活性,在此研究领域尚未发现有研究报道。尼克酰胺和核黄素分别是NAD和FMN的主要成分,可以促进脱硫关键辅酶FMNH_2的生物合成,因此,大幅度提高了红串红球菌USTB-03对4,6-DMDBT的脱硫活性。     

尿素/三乙醇胺吸收烟气NOx的实验研究

以尿素作为吸收液,与NO_x反应生成N₂和CO₂,脱除烟气中的氮氧化物。以一套双级串连的填料塔为主体反应器,分别对气速、液气比、反应物浓度、添加剂浓度和反应温度等参数对尿素溶液吸收NO_x反应的影响进行了实验研究,获得了优化实验工况,研究结果显示,在气速为0.1 m/s、液气比为16 L/m³、三乙醇胺为0.01%(质量比)、尿素浓度为13%（质量比）工况下, 反应温度为30~70℃,脱硝总效率可达50％以上,且随着NO_x体积分数增加而提高。     

纳米Au/TiO2复合物光催化降解亚甲基蓝

以纳米金棒为掺杂物,采用溶胶-凝胶法制备了纳米Au/TiO2复合材料,在紫外光下对亚甲基蓝溶液进行光催化降解。结果表明,在紫外光下,Au/TiO2复合物对亚甲基蓝的脱色率最高可达99.6%,是纯TiO2的1.3倍。这主要归结于掺杂纳米尺寸的Au可增加TiO2对光的吸收以及减少电子-空穴对的复合,由此提高其光催化能力。     

Halogenated polycyclic aromatic hydrocarbons in the environment

Halogenated polycyclic aromatic hydrocarbons (HPAHs) have been reported to occur in air, sediment, fly ash, and biota samples. This review summarized current existing data on the environmental occurrence, behavior, physicochemical properties, emission sources, and toxic equivalents of HPAHs. Firstly, the physicochemical properties of HPAHs were summarized. Then, an overview of environmental occurrence of HPAHs in ambient matrices including biological samples was reviewed. Meanwhile, the emission sources and possible formation mechanisms of HPAHs were discussed. Apart from that, the aryl hydrocarbon receptor (AhR)-mediated activities were summarized, which indicated that the position and number of halogen atoms on the parent PAHs molecule were important determinant factors affecting the AhR-mediated activity of individual HPAHs congeners. Finally, some research recommendations on HPAHs were given.