Electrochemical degradation of p-nitrophenol with different processes

The electrochemical degradation of p-nitrophenol (PNP) under di erent conditions was investigated. The electrochemical behavior of PNP and its reduction product p-aminophenol (PAP) on stainless steel cathode and Ti/Pt anode through cyclic voltammetry were observed. Electrochemical degradation process was performed in an undivided cell and 92% PNP was removed corresponding to a 22% total organic carbon removal. A divided cell was also used and it was found that PNP degradation was mainly attributed to cathodic reduction, while anodic oxidation was responsible for PNP removal due to the reaction with hydroxyl radicals and surface oxide generated on the anode. The sequential electrolytic processes, reduction-oxidation and oxidation-reduction, were compared in the divided cell. In the case of reduction-oxidation process, the total organic carbon removal reached 40%, but PNP removal was the same with the undivided cell. A black deposit was found in the e uent and identified by Fourier transform infrared spectroscopy as a polymer of PAP produced by the 1,4-addition reaction of quinoneimine. Intermediates left in the solution such as hydroquinone, p-benzoquinone and PAP were determined by high performance liquid chromatography. Whereas, the oxidation-reduction process proved unsatisfying.     

样品中总α/β放射性的测量

以某一比对样品中总α/β放射性的测量过程为例,叙述了样品预处理、上机测量及参数确定的方法,并结合实践,对工作中需要注意的问题进行了探讨。     

HTPB药柱老化对SRM内弹道性能的影响及偏差分析

为了定性和定量的描述药柱燃面、密度、燃速等因素对固体火箭发动机（SRM）内弹道性能的影响,在HTPB复合固体推进剂老化研究和SRM内弹道性能预估研究的基础上,分析了HTPB推进剂因贮存老化引起的SRM内弹道性能偏差,建立了性能偏差计算模型。结果表明,老化引起的药柱燃面、密度、燃速变化以及侵蚀燃烧引起的喷喉烧蚀是SRM贮存过程中影响内弹道性能偏差的直接因素,老化引起它们微小的波动都会引起发动机内弹道性能较大的偏离。在发动机寿命预估和进行可靠性分析时必须考虑老化对内弹道性能的影响。     

有机垃圾单级高固体厌氧消化的中试实验

在中温(37℃)条件下,应用连续式单级高固体厌氧消化技术对有机垃圾进行了实验室规模的处理研究.结果表明:①根据产气量及pH值变化在时间上可划分为酸化阶段、恢复阶段、稳定阶段及过饱和阶段.②经过酸化的过程后,pH值最低达到5.6左右;在恢复阶段反应器内pH值随TS浓度的增加而稳定在6.8～7.8之间,产气量及甲烷气体浓度均增加;③稳定阶段有机垃圾消化反应总体运行状况良好,第125d出现最大日产气量.为91.86 L·d-1,此时消化液TS浓度为14.78%,甲烷气体的浓度50%一55%左右,HRT为20d,生物降解率为65.28%.④超负荷阶段,TS浓度达到17.71%,氨氮浓度为3770 mg·L-1,抑制了产甲烷杆菌的代谢,发酵液的PH值持续下降到5.8左右,生物降解率也下降到48.25%.     

原子荧光法测定水中总汞的测量不确定度分析

以测定水中汞含量为例,对其在分析过程中产生的不确定度进行识别和计算,对原子荧光法测量水中总汞的不确定度加以分析评定。     

接种比例对餐厨垃圾高固体浓度厌氧发酵的影响

文章在12%～18%高固体浓度和中温（35±1）℃条件下,开展了不同接种比例对餐厨垃圾厌氧发酵过程影响的研究。考察了沼气产率、发酵液特性和TS、VS去除率等随接种比例变化的关系。结果表明,接种比例不低于50%的沼气日产率、累积沼气产率和平均甲烷含量显著高于接种量低于25%的发酵过程,并且pH值相较于低于25%的发酵体系能够稳定在6.8～7.2之间。提高接种比例能够降低发酵液中TN、TP和CODcr的浓度。餐厨垃圾与接种污泥TS比为1∶1时,甲烷含量和TS、VS去除率达到最大值,分别为64%、43.6%和52.8%。此时,累积沼气产率为228.6 ml/gVS。     

冶金钢铁行业废水中CODcr与TOC相关性研究

CODcr和TOC均是表征水体有机污染程度的指标,对于一般有机废水,理论上两者线性相关。采用线性回归法对冶金钢铁行业废水中TOC和CODcr两项指标的监测数据进行统计分析,建立CODcr对TOC的转换方程,并用相关系数法进行显著性检验。结果表明冶金钢铁行业废水中CODcr值和TOC值的线性关系显著,建立的一元线性回归方程的准确度可以满足水质监测的需要,在一定条件下可以使用TOC监测值间接换算CODcr值。     

测定废水中总铬前处理方法的改进探究

采用COD消解器加热氧化法代替锥形瓶加热氧化法或密塞高压蒸汽法测定总铬,结果表明:此方法缩短了分析时间,操作简便,分析结果准确度高.     

热解吸气相色谱双通道检测空气中TVOC

探讨了通过气相色谱仪双通道检测室内空气中总挥发性有机化合物的可行性.建立了前、后双通道的苯、甲苯、乙酸丁酯、乙苯、苯乙烯、对(间)二甲苯、邻二甲苯、正十一烷等9种典型有机污染物的外标曲线,各组分相关系数R2为0.9995～1,并通过各自的标准曲线来计算其标样考核结果,对比标样真实浓度值,验证前、后双通道的准确性以及相互...