填充吸附微萃取-高效液相色谱法检测水中3种肼类

建立了基于填充吸附微萃取-液相色谱法检测水中肼、甲肼和偏二甲肼的方法。对影响方法效果的重要参数（如填充吸附微萃取的萃取材料、萃取循环次数和萃取速度、洗脱溶剂和洗脱体积、样品pH等）均进行了测试和优化。明确最优条件为先将样品pH调节为3.5，用HLB作为萃取材料，以15 μL/s的速度进行15次重复萃取，用100 μL含0.2%乙酸的乙腈进行洗脱。3种目标物在3 min内分离良好，并在10~500 μg/L范围内线性良好，相关系数范围为0.997 8~0.999 1，检出限范围为2.0~5.0 μg/L。在10、50、100 μg/L 3个浓度水平加标实验中，3种肼类的平均回收率为76.7%~96.5%，日内相对标准偏差为5.6%~9.1%，日间相对标准偏差为8.5%~16.7%。该方法能够满足水体中3种肼类物质的快速测定要求。     

Enhancement of extracellular Cr(VI) reduction for anammox recovery using hydrazine: performance,pathways, and mechanism

● N₂H₄ addition enhanced and recovered anammox performance under Cr(VI) stress. ● N₂H₄ accelerated electron transfer of Cr(VI) reduction for detoxification. ● N₂H₄ enhanced anammox metabolism for activity recovery from Cr(VI) inhibition. ● Extracellular Cr(VI) reduction to less toxic Cr(III) was the dominant mechanism. The hexavalent chromium (Cr(VI)) would frequently impose inhibition to anaerobic ammonium oxidation (anammox) process, hindering the efficiency of nitrogen removal in wastewater treatment. Hydrazine (N₂H₄), which is an intermediate product of anammox, participates in intracellular metabolism and extracellular Cr(VI) reduction. However, the roles of N₂H₄-induced intracellular metabolism and extracellular reduction in nitrogen removal under Cr(VI) stress remain unclear. The addition of 3.67 mg/L of N₂H₄ increased the anammox activity by 17%. As an intermediate, N₂H₄ enhanced anammox metabolism by increasing the heme c content and electron transfer system activity. As a reductant, N₂H₄ accelerated the reduction of c-Cyts-mediated extracellular Cr(VI) to the less toxic Cr(III). Extracellular Cr(III) accounts for 74% of the total Cr in a Cr(VI)-stressed anammox consortia. These findings highlight that N₂H₄-induced extracellular Cr(VI) reduction is the dominant mechanism for the survival of anammox consortia. We also found that N₂H₄ increased the production of extracellular polymeric substances to sequester excessive Cr(VI) and produced Cr(III). Taken together, the study findings suggest a potential strategy for enhancing nitrogen removal from ammonium-rich wastewater contaminated with Cr(VI).     

分光光度法测定水中水合肼方法检出限的优化

用对二甲氨基苯甲醛分光光度法测定水中水合肼,将显色剂用量由5.0 m L降至3.0 m L,比色皿厚度由30 mm增至50 mm,水样酸度由1 mol/L降至0.5 mol/L,同时增加低浓度校准曲线,实现对其方法检出限的优化。结果表明,优化后方法检出限由0.007 8 mg/L降至0.001 0 mg/L,精密度及加标回收率均符合规范要求,能够保证低浓度水样的准确测定。     

流动注射化学发光测定大气环境中的肼

在 0 .0 5 mol/ L的碱性条件下 ,NBS(N-溴代丁二酰亚胺 )在荧光素的增敏作用下氧化硫酸肼 ,产生化学发光。基于此 ,本文详细研究了其反应的特性和影响因素 ,在优化的实验条件下硫酸肼的测定范围为 0～ 1.0× 10 - 5g/ ml,检出限为 3.0× 10 - 8g/ ml,对 5 .0× 10 - 8g/ ml硫酸肼进行 11次平行测定 ,其 RSD为 2 .7%。本法用于大气环境中肼的分析 ,并与常规的方法进行对照 ,结果令人满意     

环境水样中痕量肼的分析方法研究

报道一种微量测定环境水样中痕量肼的新方法。该方法基于在氢氧化钠碱性介质中高锰酸钾直接氧化肼的化学发光现象,建立了微量肼的流动注射化学发光分析方法。该方法线性范围为1.0×10-9~8.0×10-5g/ml,检出限3.6×10-10g/ml,对1.0×10-8g/ml的肼连续11次测定的相对标准偏差为2.1%,该方法已成功用于环境水样中痕量肼的测定。     

空气中微量肼的离子色谱法测定

以稀硫酸为吸收液,铂工作电极为安培检测器,用离子色谱法测定空气中的微量肼。经试验,选择了较适宜的淋洗液浓度、流量,吸收液的酸度,安培检测器的最佳施加电位及抗干扰实验。方法的相对标准偏差小于10％,取样鞋为60升时,最低检出浓度为0.001mg/m~3。     

肼类燃料与环境污染

本文比较了作为火箭推进剂的腓、甲基肼和偏二甲肼三种类燃料的毒性，论述了三种肼类燃料对环境的影响：与大气环境中的水、二氧化碳、氧气、氮氧化物、臭氧和紫外光相互作用及降解规律，在水体中与水作中的氧气、光金属高于及微生物的相互作用及降解规律，在土壤环境中，与土壤组份的相互作用机理及降解产物。肼类燃料在环境中的自然降解非常复杂，有些降解产物甚至比肼类燃料本身的毒性更大，因此对环境的污染并不是随着肼类燃料的消失而消失，且存在二次污染。     

Performance and microbial response during the fast reactivation of Anammox system by hydrodynamic stress control

Anaerobic ammonium oxidation （Anammox） has become a promising method for biological nitrogen removal. However, this biotechnology application is always limited due to the low growth rate and biomass yield of Anammox bacteria. This study investigated the process of fast reactivation of an Anammox consortium idled for 2 years uia hydrodynamic stress control. The results showed that the Anammox system was efficiently and quickly reactivated by shortening of the hydraulic retention time （I-IRT） of the reactor from 12 to 6 hr within 68 days of operation. Moreover, at a 4-hr HRT with an influent total nitrogen loading rate of 1.2 kg N/（m3.day）, the reactor maintained high biological performance with an ammonium removal loading rate of 0.52 kg N/（m3.day） and a nitrite removal rate of 0.59 kg N/（m3.day）. In the reactivated Anammox reaction, the stoichiometric coefficients of NH4-N to NOE-N and NH4-N to NO4-N were 1：1.04± 0.08 and 1：0.31 ± 0.03, respectively. The specific Anammox activity and hydrazine oxidoreductase activity, both of which represent the degree of Anammox bacteria present, increased as the hydrodynamic stress increased and were maximally （125.38 ± 3.01 mg N/（g VSS.day） and 339.42 ± 6.83 μmol/（min.g VSS）, respectively） at 4-hr HRT. Microbial response analysis showed that the dominant microbial community was obviously shifted and the dominance of Anammox bacteria was enhanced durinR the hydrodynamic selection.