Ozonation of Cationic Red X-GRL in aqueous solution: degradation and mechanism

Ozonation of the azo dye Cationic Red X-GRL was investigated in a bubble column reactor at varying operating parameters such as oxygen flow rate, temperature, initial Cationic Red X-GRL concentration, and pH. The conversion of dye increased with the increasing of pH and oxygen flow rate. As the reaction rate constant and the volumetric mass transfer coefficient increase while the ozone equilibrium concentration decreases with the temperature, there is a minimum conversion of dye at 25 degrees C. The increasing of initial dye concentration leads to a decreasing conversion of dye while the ozonation rate increases. The formation of intermediates and the variation of pH, TOC, and nitrate ion during ozonation were investigated by the use of some analytical instruments such as GC/MS, GC, and IC. The intermediates of weak organic acids lower the pH value of the solution. The probable degradation mechanism of the Cationic Red X-GRL in aqueous solution was deliberated with the aid of Molecular Orbital calculations. The N(12)-C(13) site in Cationic Red X-GRL, instead of the N(6)-N(7) site, is found to be the principal site for ozone cycloaddition in the degradation processes. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one is converted into an amine compound, and the remaining four are transformed into two molecules of nitrogen.     

Selective extraction of trace mercury and cadmium from drinking water sources.

In this paper, a new alternative method, i.e., selective extraction by weakly basic anion exchange resin, has been developed for the removal of trace cadmium and mercury ions from drinking water sources. The mechanism of heavy metal removal is based on selective extraction as the results of LEWIS-base-acid interactions. Transfer of trace mercury species from liquid to resin phase coincides well with the performance of film diffusion. The results demonstrated that the presence of chlorine has a negligible influence on the removal of mercury. However, humic acids can strongly bind mercury by the formation of complex compounds and therefore become the obstacle in the diffusion progress. At neutral or base pH, the resin material exhibits the favorable uptake of heavy metals. In filter experiments, the studied resin material offers favorable properties in the selective extraction of trace mercury and cadmium.     

A real-time optimization method for economic and effective operation of electrostatic precipitators

ABSTRACT

Electrostatic precipitators (ESP) have been considered as the main particulate matter (PM) removal facility in the energy industry. This paper presents a real-time optimization method for a one-chamber industrial ESP in an ultra-low emission power plant with an intelligent optimization system (IOS). The IOS seeks to optimize the energy consumption of ESP subject to the outlet concentration requirement in real-time. A coordination control logic is designed to regulate the optimized operation set points with varying operation conditions. The operation optimized by the IOS is compared with the operations under PID (proportion-integral-derivative) and manual control. The results show that the IOS improves the emission compliance rate from 95% of manual control to 100% and the medium concentration is tuned to be 46.6% closer to the emission target. Furthermore, a good balance between emission and energy consumption is achieved, with 35.50% energy conservation for the same emission upper limit of 30 mg/m³. These results prove that the IOS significantly contributes to the efficient operation and economic PM removal by ESP for the energy industry.     

随身自动空气净化处理器的研究

随身自动空气净化器,采用了活性炭、光催化技术相结合的空气过滤装置.空气污染传感器与单片机组成空气质量监测电路,当空气污染超标时,产生语音提示,液晶屏显示空气质量的等级,自动(或手动)控制引风机工作,供给个人清新无污染的空气.     

Photocatalytic reactions of pyrene at TiO2/water interfaces

The photocatalytic oxidation of pyrene preadsorbed on TiO2 is examined in aqueous suspension under UV irradiation. Chemical oxygen demand measurements, UV-VIS spectrophotometer, infrared spectrometer and GC-MS analytical techniques were used to monitor the formed intermediates. During the oxidation processes, the ring-open reaction, hydroxylation and ketolysis occurred to produce some intermediate products (4-oxapyrene-5-one, 1,6- or 1,8-pyrenediones, 4,5-phenanthrenedialdehyde, cyclopenta[def]phenanthrene). Some factors affecting the photodegradation rate were also studied. The results were different from other studies: The pH of the dispersion, ratio of Py/TiO2:water had little effect on the photooxidation rate of pyrene catalyzed by TiO2, while the surface coverage, addition of Fe3+ affected it greatly.     

Removal of alachlor from water by catalyzed ozonation in the presence of Fe2+, Mn2+, and humic substances

The effects of Fe(II), Mn(III) and humic substances on the catalyzed ozonation of alachlor, an endocrine disruptor were investigated. Results revealed that small amounts of Fe(II), Mn(II), and humic substances could enhance the ozonation of alachlor, but larger amounts of them would retard the oxidation. These results were successfully identified by an electron paramagnetic resonance (EPR) spectroscopy spin-trapping method that could quantify hydroxyl radicals. The production of hydroxyl radicals was obviously increased with the increasing of Fe(II) concentration, which contributed to enhance ozonation at low concentrations. But the excess Fe(II) consumed some of the radicals when it was added at a higher concentration (1.5 mg/L). However, no obvious radicals were observed when a different amount of Mn(II) was used, and the catalytic ozonation of alachlor by Mn(II) mainly followed the mechanism of "active sites created on the surface of MnO2." The radical pathway was followed when alachlor was ozonated with different concentrations of humic substances because of its radical initiating, promoting, and inhibiting effects.     

机械镀锌工艺的清洁生产

结合机械镀锌的实际生产过程 ,讨论了机械镀锌实现清洁生产的主要途径 ,并且从工艺过程、经济效益、环境效益 3个方面对机械镀锌进行了综合评价 ,结果表明 ,机械镀锌是切实可行的清洁生产技术     

Fenton试剂-生物法联合处理有机废水研究进展

本文对Fenton试剂和生物法联合处理有机废水的工艺流程、适用废水种类、废水处理机理和衡量指标进行了综述,并对Fenton试剂和生物法相结合处理有机废水研究进行了展望。     

矿化垃圾生物反应床处理NOX废气的研究

矿化垃圾(稳定化垃圾)是一种良好的生物介质,可作为生物反应床的填料处理NOX废气.实验室研究表明,稳定化垃圾反应床可有效地处理NOX气体,其硝化能力(以N计)可达0.83 g/(kg·d)(干重).NOX去除率受停留时间的影响显著,NOX去除率随着停留时间的缩短而降低.当空床停留时间为1.5 min时,NOX气体的平均去除率为76.7%;空床停留时间为15 min时,NOX气体的平均去除率为91.0%.在NOX进气负荷低于110 mmol/(m3·h)时,NOX消除能力随进气负荷的增加而线性增加.当进气流量一定时,NOX去除能力随着进气NOX浓度的增加而线性增加.     

反硝化除磷的影响特性试验

采用SBR反应器（厌氧/缺氧/好氧工艺）,分别研究了乙酸盐及硝酸盐浓度变化对反硝化除磷的影响特性.试验结果表明,当进水COD浓度＞230 mg/L时,乙酸盐浓度的变化对释磷、除磷速率等影响并不显著.在硝酸盐浓度＜30 mg/L时,硝酸盐浓度越高,缺氧段除磷速率也就越高.在C/P＞23,C/N＞5条件下,SBR系统对磷、氮去除率在90%以上.