基于高级氧化技术的污酸废水除氯性能与机制研究

氯离子(Cl-)的高效脱除是有色冶金污酸废水资源化领域的一项瓶颈难题。近年来,高级氧化技术在废水除氯方面表现出极大的应用潜力,本文围绕二氧化铅(PbO_(2))、铋酸钠(NaBiO_(3))和过硫酸氢钾(PMS)三种强氧化剂的除氯效率、机制、成本和运营管理展开了对比分析,指出PbO_(2)、NaBiO_(3)和PMS的投加量分别为理论值的4、1.5及1.5倍,反应温度分别为50、20和60℃时,剩余Cl-浓度低于200 mg/L,达到污酸回用的要求。将除氯固体产物与氯气吸收液混合反应,实现了PbO_(2)和NaBiO_(3)的再生,再生药剂5次循环试验的除氯效率高于90%。PbO_(2)、NaBiO_(3)和PMS除氯过程涉及羟基自由基(·OH)、硫酸根自由基(·SO_(4)^(-))、氯自由基(·Cl)等高活性中间物种的参与,其中直接氧化、·OH间接氧化和·SO_(4)^(-)间接氧化对PMS脱氯的贡献分别约为84%、9%和7%。综合评价实际应用价值,NaBiO_(3)因其可再生、副产物回收价值高且反应温度低,在成本和能耗方面更具优势,PMS因未引入杂质,在操作管理方面更为简单。

消除法制备低氯漂白紫胶及机理

在漂白紫胶乙醇溶液中加入乙醇钠(一种亲核试剂),选择性与紫胶分子中结合氯的碳原子反应,脱除漂白紫胶中的氯,制备了低氯漂白紫胶。研究乙醇钠加入量、反应温度和反应时间对脱氯效果的影响。结果表明:100g漂白紫胶中加入4.2g的乙醇钠,在90℃反应90min脱氯效果最佳;最佳反应条件时,产品中氯的质量分数为0.28%,远低于脱氯前的2.6%。紫外光谱分析表明,漂白紫胶最大吸收峰的波长由236nm蓝移至222nm,脱除结合氯后最大吸收峰的波长值恢复。通过亲核消除反应,乙醇钠能脱除漂白紫胶的结合氯,漂白紫胶脱氯前后的结构不同。

浅析影响烧结烟气湿法脱硫中除盐效率的因素

近年来随着我国工业的大力发展,各种污染也日渐严重。文章通过对烧结烟气湿法脱硫中除盐方法的简单介绍,阐述了哪些方法能有效地除去有害物质达到安全排废。

Response surface optimization of process parameters for removal of F and Cl from zinc oxide fume by microwave roasting

Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The results show that the effects of roasting temperature and holding time on the removal rate of F and Cl are the most significant, and the effect of stirring speed is the second. The defluorination rate reaches 92.6% while the dechlorination rate reaches 90.2%, under the process conditions of roasting temperature of 700 °C, holding time of 80 min and stirring speed of 120 r/min. The results indicate that the removal of F and Cl from fuming furnace production of zinc oxide fumes using microwave roasting process is feasible and reliable.

Degradation of bond between steel bar and freeze-thaw concrete after electrochemical chloride extraction

The effect of electrochemical chloride extraction （ECE） on bond strength between steel bar and freeze-thaw concrete contaminated by chloride was experimentally investigated for beam specimens with dimensions of 100 mm × 100 mm × 400 ram. During the experiment, 3% NaC1 （vs mass of cement, mass fraction） was mixed into concrete to simulate chloride contamination, and the specimens experienced 0, 25, 50, 75 freeze-thaw cycles before ECE. In the process of ECE, different current densities and durations were adopted. It is indicated that the bond strength between reinforcement and concrete decreases with the increase of freeze-thaw cycles; the more the current and the electric quantity of ECE are, the more the loss of bond strength is; and the largest loss is up to 58.7%. So, it is important to choose proper parameters of ECE for the reinforced concrete structures contaminated by chloride and subjected to freeze-thaw cycles.

人工湿地脱除富营养化水体氮磷的研究进展

水体中氮磷营养物质不断积累,部分藻类及水生生物的过度繁殖,导致了水体的富营养化。水体富营养化防治的关键是减小水中氮、磷的含量。人工湿地是一项新型的废水处理技术,近年来在脱除富营养化水体氮磷中获得广泛研究和应用。本文在简述脱氮除磷机理的基础上,较系统地阐述了影响人工湿地脱除氮磷的因素及工艺的在改善水体富营养化的研究进展,以便在构建人工湿地中对各项因素综合考虑及兼顾利用,提高人工湿地修复富营养化水体的综合效能。

Removal of Trace Olefins from Aromatics by Catalytic Alkylation Using 1-Alkyl-3-methylimidazolium Bromochloroaluminate Catalyst

Removal of trace olefins from aromatic liquids had been investigated in the presence of various ionic liquids like 1-ethyl-3-methylimidazoliurn bromochloroaluminate （EMIMBr-AlCl3）, 1-butyl-3-methylimidazolium bromochloroaluminate （BMIMBr-AlCl3）, l-hexyl-3-methylimidazolium bromochloroaluminate （HMIMBr-AlCl3）, and 1-octyl-3-methylimidazolium bromochloroaluminate （OMIMBr-A1C13）. It was found that the longer the alkyl chain of ionic liquid cations was, the higher the olefins conversion would be. OMIMBr-AlCl3 （with 0.67 molar fraction of AlCl3） had an obvious performance on olefins removal. The influences of various reaction parameters such as the dosage of catalyst, the reaction temperature, and the reaction time on the reaction catalyzed by OMIMBr-AlCl3 were investigated. Under optimum reaction conditions, a higher than 99% conversion of olefins was achieved. The preliminary results revealed that the process could save time, consume less energy, separate products easier, and cause less pollution to the environment.

Catalytic Decomposition of Chlorophenols Using Fiber-supported Cobalt Phthalocyanine

A novel heterogeneous catalyst, viscose fiber- supported cobalt phthalocyanine （Co - TDTAPc - F）, was prepared by immobilizing cobalt tetra（2.4 - dichloro- 1,3, 5 -triazine）aminophtbalocyanine （Co- TDTAPc） on viscose fibers covalcntly. The oxidative removal of chlorophenols such as 2 - chlorophenoi, 4 - chlorophenol, 2, 4 - dichlorophenol, and 2, 4, 6 - trichlorophenol was investigated in the catalytic oxidative system of Co - TDTAPc- F/H2O2. Furthermore, more than 98% of these chloropbenols were decomposed in 4 h. Phenol, oxalic acid, maleic acid, and succinic acid, etc., were detected by high performance liquid chromatography （HPLC） and gas chromatography-mass spectrophotometer （GC - MS）, and these short-chain organic acids could be further oxidized easily. The results indicated that the catalytic oxidation in the Co- TDTAPc - F/H2O2 system leaded to a deeper oxidation. In addition, a degradation pathway for chlorophenols was proposed on the basis of detection of intermediate compounds.