臭氧氧化技术在有色金属湿法冶金中的应用研究进展

臭氧是一种氧化性极强、多功能化的绿色氧化剂。本文综述了臭氧氧化技术在有色金属湿法冶金领域的研究进展和应用现状,重点介绍了在贵金属、重金属、稀有金属及轻金属等有色金属湿法冶金领域的应用研究。详细探讨了臭氧的强氧化性对低品位金属矿和难冶金属矿浸出、溶液中低价态金属离子氧化沉淀、溶液净化除杂等方面的作用机理,并对目前面临的问题进行简要叙述,对其在有色金属湿法冶金领域的应用前景进行了展望。     

The effects of ozone,ultrasound and coating with shellac and lysozyme–chitosan on fresh egg during storage at ambient temperature – part 1: interior quality changes

The objective of this research was to investigate and compare the effect of different treatments including gaseous ozone (6-ppm/4-min), ultrasound (450 W/4 min) and coating of shellac, lysozyme–chitosan (L-C) on fresh eggs internal quality during storage for six weeks at ambient temperature. The internal quality attributes such as weight loss (WL), albumen viscosity, Haugh unit (HU), yolk index, total soluble solids, albumen and yolk's pH were monitored. Control groups had the worst HU (50.04), WL (8.35%), albumen pH (9.27) and viscosity (7.72 mPa·s) values after storage. The best interior qualities were obtained by shellac coating [HU (72.37), WL (1.37) and viscosity (30.10 mPa·s)] and sonication (albumen pH: 8.22). Thus, the shellac-coated eggs maintained all the internal quality parameters at the highest values, while the ozone and ultrasound only helped to keep the internal quality and enhance the shelf life of eggs.     

煤粉锅炉污染物限值排放综合控制系统研究

燃煤锅炉产生的SO2、NOx是大气污染物的重要组成部分,随着环境形势的日益严峻,国家环保政策对电站锅炉和中小型工业锅炉的污染物排放标准提出了更高要求。煤粉工业锅炉烟气净化系统采用手动调节方式控制,系统惯性大,已不能满足最新环保排放标准。针对这些问题,基于可编程控制器(PLC)和以太网通讯架构,结合神东矿区某煤粉锅炉站限值排放改造工程,设计了集成化的污染物排放控制系统。在分析各系统工艺流程的基础上,分别提出了脱硫、脱硝系统的优化控制策略。脱硫系统基于站内原有NGD系统进行改造,增加了脱硫剂储运设备,在灰钙循环和增湿活化控制的基础上设计了自动脱硫剂补充和调节逻辑。脱硝系统增设了臭氧制备和输送装置,采用SNCR-臭氧协同方式,并设计了串级启动和自动投送控制逻辑。控制系统采取分布式硬件架构部署,采用西门子SIMATIC系列PLC作为主控制器,基于优化的控制逻辑,分别组态脱硫子系统、SNCR子系统及臭氧子系统。通过以太网络构建通讯子网,共享各子系统内部数据,以保证设备之间的安全联锁,以及脱硫、脱硝系统对锅炉负荷情况的跟踪响应,试验结果表明,控制系统能够在起炉后10 min内将SO2浓度控制在100 mg/m^3以内,在锅炉变负荷工况条件下可维持SO2浓度低于设定限值。多台锅炉连续运行时,各炉脱硫剂缓冲仓平均用料周期约为80 min,平均补充周期约为4.5 min,平均等待时间约为7 min,控制逻辑能够保证脱硫剂连续不间断供给。起炉后控制系统依次投入SNCR及臭氧系统,自动调节尿素溶液和臭氧的投加量,能够在20 min内将NOx浓度控制在100 mg/m^3以内。与改造前相比,锅炉站长周期运行时SO2、NOx排放浓度均显著下降,由100~200 mg/m^3降低至50~100 mg/m^3;根据运行期间80 h数据,SO2排放浓度平均值由163.55 mg/m^3降低至72.54 mg/m^3,NOx排放浓度平均值由160.85 mg/m^3降至71.06 mg/m^3,均满足国家与地方的环保排放标准。污染物排放波动性较改造前亦有所降低,SO2浓度标准差由21.04降至18.14,NOx浓度标准差由25.09降至15.84。     

Low concentration short time ozonation of rapeseed seeds reduces the stability of the oil and content of some antioxidant components

Ozonation is an innovative way to preserve high quality of seed during storage and it is an alternative to harmful organophosphorus agents. Disclosure of changes in the rapeseed oil under the influence of oxidative action of ozone on the seeds was the aim of the work and is presented for the first time. Two ozone concentrations and different length of ozonation were applied. The changes in tocopherols, phenolics, flavonoids contents, antiradical activity and oxidative stability were examined. The average vitamin E concentration was 33 mg per 100 g of oil before and 31.7 after ozonation of seeds. The average content of phenolic compounds was 14.3 mg of sinapic acid g⁻¹ and 16.9 after the ozone treatment. Changes in the flavonoids content and antioxidant activity were observed too. Ozonation caused a decrease in the vitamin E concentration which resulted also in reducing the quenching of free radicals and reduction of oil induction time.     

Regressor selection for ozone prediction

Being able to predict high concentrations of tropospheric ozone is important because of its negative impact on human health. In this paper eight regressor-selection methods are utilised in a case study for ozone prediction in the city of Nova Gorica, Slovenia. The comparison of the selected methods proved to be useful for building models that successfully predict the ozone concentrations for the treated case. Different regressors are selected for different models, with different methods based on the validation procedure’s cost functions. Namely, for the model to predict the maximum daily ozone concentration, ten regressors are selected; for the average concentration of ozone between 8.00 and 20.00 h, fifteen regressors are selected; and for the average daily concentration, ten regressors are selected. The result of the study is a regressor selection that is specific for a particular geographical location. Moreover, the study reveals that regressor selection, as well as the obtained models, differ depending on the kind of averaging interval of the ozone concentration.     

Investigation on concentration characteristics of ozone micro-bubbles fixed in ice and ozone gas released from ice

Ice formed from water in which ozone gas is dissolved is promising for the cold storage of foods because of the ozone's sterilization and deodorization capabilities. However, effective dissolution of ozone gas in water and taking ozone gas into ice are not easy. Furthermore, the decomposition rate of the ozone itself is usually very fast, regardless of its phase. Thus, to effectively take ozone gas into ice, the authors have developed ice containing ozone micro-bubbles. In this paper, ice containing ozone micro-bubbles formed by adding surfactant was kept for a desired time at a desired constant temperature without melting of the ice. The concentration of ozone micro-bubbles fixed in ice and the ozone gas concentration released from ice by melting were measured to investigate the ozone decomposition rate due to fixation in ice and the characteristics of the released concentration. Furthermore, the influences of surfactant on both concentrations were examined.     

Indoor boundary layer chemistry modeling

Ozone (O₃) chemistry is thought to dominate the oxidation of indoor surfaces. We consider the hypothesis that reactions taking place within indoor boundary layers result in greater than anticipated hydroxyl radical (OH) deposition rates. We develop models that account for boundary layer mass‐transfer phenomena, O₃‐terpene chemistry and OH formation, removal, and deposition; we solve these analytically and by applying numerical methods. For an O₃‐limonene system, we find that OH flux to a surface with an O₃ reaction probability of 10^?8 is 4.3 × 10^?5 molec/(cm² s) which is about 10 times greater than predicted by a traditional boundary layer theory. At very low air exchange rates the OH surface flux can be as much as 10% of that for O₃. This effect becomes less pronounced for more O₃‐reactive surfaces. Turbulence intensity does not strongly influence the OH concentration gradient except for surfaces with an O₃ reaction probability >10^?4. Although the O₃ flux dominates OH flux under most conditions, OH flux can be responsible for as much as 10% of total oxidant uptake to otherwise low‐reactivity surfaces. Further, OH chemistry differs from that for ozone; therefore, its deposition is important in understanding the chemical evolution of some indoor surfaces and surface films.     

Oxidative enzymes and functional quality of minimally processed grape berries sanitised with ozonated water

Thompson Seedless (TS) and Black (BS) grapes sanitised with 2, 4, 6, 8 mg L^?1 O₃ or NaOCl (100 mg L^?1) were stored 21 days at 5 °C. Ozonated water stimulated the respiration rate, especially after 5 days of storage, and increased superoxide dismutase and catalase activity compared to NaOCl‐sanitised grapes. Total polyphenol content (TPC) was 23–50% higher in TS and 18.5–28% higher in BS samples sanitised with ozonated water. Twofold higher total antioxidant capacity (TAC) was registered in TS at all of the evaluated O₃ doses while the doses of 6 and 8 mg L^?1 increased TAC by 19–30% in BS. The use of ozonated water as a sanitising method, especially at 6 and 8 mg L^?1 doses, improved the functional quality and maintained low microbial counts on fresh‐cut grapes being a good alternative for the industry.     

Effects of ozone treatment on pesticide residues in food: a review

In agriculture, pesticide residues have always posed a major safety hazard to human health. With the development of agricultural production and improvements in science and technology, additional methods for degradation of pesticide residues have emerged. Amongst them, ozone treatment recently became a popular method owing to its outstanding technical advantages. This review is an in-depth analysis of the mechanisms by which ozone treatment degrades pesticide residues. The main mechanism involves direct oxidation by oxygen atoms, and indirect oxidation driven by hydroxyl radicals. The effects of ozone treatment on pesticide residues in food with respect to the ozone concentration, duration of ozone treatment, type of food, variety of pesticides, level of pesticide residues and environmental factors have been discussed. Furthermore, the impact of ozone treatment on the quality of food is highlighted. Low levels of ozone result in minor changes to the visual and sensory characteristics of food. In addition, this article discusses several restrictions surrounding the current application of ozone treatment for the degradation of pesticide residues. More specifically, the most crucial issue is the potential toxicity of ozonation byproducts generated by the process, which is also the current focus of research on ozone treatment for the degradation of pesticide residues. After weighing the advantages and disadvantages of ozone treatment, it is recommended as a method of degrading pesticide residues.     

臭氧联合高级氧化方法处理有机废水的技术进展

臭氧因其强氧化能力而在废水处理中得到广泛的应用,但单独采用臭氧氧化技术处理废水存在处理费用高、利用率低和矿化程度低等问题。高级氧化方法与臭氧联用,可大大促进臭氧分解,提高有机物的去除率。因此臭氧与紫外线、过氧化氢、超声波、及催化剂等多种高级氧化方法用于有机废水处理已经成为目前研究的热点,并取得了显著的进步。