超声波降解水中的氯苯

考察了用超声波降解水中氯苯的可行性、动力学、产物和TOC变化。在20kHz和40w的超声波作用下，氯苯的一级降解常数为0．05／min。随着所加超声功率的增高，氯苯降解常数呈线性增加。30min内超声脱氯效率达到66％,TOC去除达到43％。     

纳米铁协同超声降解氯苯的研究

报道了纳米铁协同超声波降解一氯代苯 (CB)的研究。探讨了有效声强、pH、CB初始浓度对降解效果的影响。比较了纳米铁协同超声波和单纯超声波对CB的降解效果和降解速率 ,反应 2 0min时 ,纳米铁协同超声波的降解率达到95 % ,而单纯超声波的降解率仅为 1 0 8%。上述两者都符合准一级反应动力学 ,超声波降解CB的准一级速率动力学常数k=6× 1 0 -3 min-1 ,而协同作用降解CB的准一级动力学常数k =1 6 3× 1 0 -1 min-1 ,提高了 2 7倍。     

超声波/零价铁降解对氯苯胺性能及机理研究

在超声波/零价铁体系中考察了溶液初始pH值、浓度对对氯苯胺降解的影响.在pH值为3～11范围内最佳条件为pH=9;初始浓度为0.1、0.2和0.4 mmol/L时的降解率(180 min)分别为83.2%、63.5%和36.1%.对氯苯胺在单纯铁粉、单纯超声波和超声波/零价铁3种体系中降解符合拟一级反应动力学规律,速率常数分别为6.83×10-4、3.95×10-3和1.01×10-2 min-1,增强因子为218%,表明铁粉与超声波对对氯苯胺降解有明显的协同效应.在体系中加入自由基捕捉剂正丁醇能抑制对氯苯胺的降解,证实对氯苯胺降解主要是依靠羟基自由基的氧化作用.     

US-UV-Fenton降解硝基苯

采用超声波(US)、紫外光(UV)和Fenton联合降解硝基苯,初步探讨了其作用规律。研究结果表明,UV可以促进双氧水转化自由基的效率,而US同时具有强化传质作用和超声氧化作用,两者均能够强化Fenton氧化硝基苯的降解过程。正交实验结果表明,H2O2初始浓度是硝基苯降解和矿化的最显著影响因素,反应时间和超声功率是矿化的显著影响因素。最佳反应条件为:H2O2500 mg/L、Fe2+10 mg/L、反应时间60 min、超声波功率100 W,此时,硝基苯完全降解,TOC去除率达到73.0%。Fenton、UV/Fenton和US/UV/Fenton降解硝基苯过程均符合伪一级反应动力学模式,反应速率常数分别为3.37×10-2、3.81×10-2和5.10×10-2min-1。     

含氯苯废水的超声降解研究

以氯苯模拟废水为考察对象,研究其浓度、pH、超声时间等因素对氯苯超声降解效率的影响。实验结果表明：超声反应时间小于5min,氯苯降解率很低;5－20min,氯苯降解率成线性增大;超过20min后,氯苯降解率增大缓慢。pH值的增大,氯苯降解率略有减小。水浴温度提高,氯苯降解率增大。反应时间小于15min,初始浓度低的溶液,降解率增加较快,反应时间大于15min,初始浓度高的溶液,降解率增加较快。     

低强度超声波预处理对污泥自热式高温好氧消化的影响

以0.3 W·cm-2的低强度超声波对调配好的污泥进行5、10和20 min的辐照,再经过12 d的自热式高温好氧消化(ATAD)。结果表明,适当的低强度超声预处理能够有效地加快稳定化进程,其中超声波辐照10 min后的实验组效果最好,在第8.5天时,温度升高至58.3℃,VSS去除率达到42.1%,比未经超声预处理的实验组提前2 d达到稳定状态。在消化过程中脱氢酶的活性与VSS去除率有着很好的相关性(R20.86),它能有效地表征VSS的高温好氧降解规律及有机物去除程度。稳定后的污泥上清液中TP浓度降至初始浓度的40%以下,TOC浓度升高至初始浓度的3~4倍。然它们的浓度仍很高,仍会给后续处理增加一定的负担。     

臭氧高级氧化法降解生化尾水中喹啉

采用O_3、O_3/UV、O_3/H_2O_23种工艺对喹啉的去除、矿化效果,生化性提高及降解规律等方面进行了对比分析,结果表明,单独H_2O_2、单独UV不能有效地降解喹啉;单独O_3、O_3/H_2O_2对喹啉有一定的去除效果,但两者差别不大;反应时间为6 min时,喹啉去除率分别为78.7%和79%,反应30 min时,喹啉的矿化率为33.4%和38.2%;O_3/UV工艺明显优于前2种,在6 min内,喹啉基本降解完全,30 min矿化率超过90%;3种工艺的降解过程都很好地满足伪一级动力学规律,O_3/UV的表观反应速率常数(0.7204 min~(-1))大于单独O_3(0.2832 min~(-1))和O_3/H_2O_2(0.29 min~(-1))工艺的表观反应速率常数;采用O_3/UV工艺处理实际工业园区生化尾水,6 min内喹啉降解完全,30 min时,COD去除率为88%,TOC的去除率达到89%,UV254的去除率为96%,出水指标达到《城镇污水处理厂污染物综合排放标准》一级A标准。     

UV及UV/US降解对二氯苯水溶液的研究

使用紫外光(UV)和超声波(US)降解水溶液中的对二氯苯(p-DCB)。考察了p-DCB初始浓度,初始pH、腐殖酸和H2O2的存在对p-DCB光解的影响。结果表明,较低的初始浓度或弱酸性pH有利于p-DCB降解。溶液中存在20 mg/L的腐殖酸可使p-DCB的反应速率常数提高32.6%。加入氧化剂H2O2可以显著提高p-DCB的降解率,在[p-DCB]0=0.1 mmol/L,[H2O2]0=0.1 mmol/L,pH0=5.8,反应180 min条件下,p-DCB的降解率为95.5%。超声波对p-DCB的降解速率(14.6×10-3/min)大约是紫外光(4.3×10-3/min)的3.4倍,紫外光-超声波耦合时的降解速率(20.6×10-3/min)大于两者单独降解速率的加合。在各种实验条件下,p-DCB的降解均遵循表观一级动力学。     

介质阻挡放电氧化降解木质素磺酸钠的动力学研究

为了有效地处理难生物降解的造纸废水,采用气相介质阻挡放电产生氧化性物质,对木质素磺酸钠进行了氧化降解研究。在不同操作条件下,对其降解动力学及矿化程度进行了研究。结果表明,介质阻挡放电能有效地降解木质素磺酸钠,其氧化降解反应遵循准一级动力学反应。当峰值电压为20 kV,被水蒸气饱和的空气为气源,流量为7 L/min时,氧化处理60 min后,木质素磺酸钠降解率达到70％。其速率常数K随峰值电压、气源、气体流量和木质素磺酸钠的初始浓度的变化而不同。气体流量越大,木质素磺酸钠的初始浓度越低,速率常数K越大,降解效果越好。随着处理时间的增加,氧化性物质能将部分木质素磺酸钠矿化使溶液TOC降低,当被水蒸气饱和的空气作为气源时,氧化处理120min,21.38%的TOC被去除。     

活性炭纤维上4-氯酚及焦化废水尾水的O3催化氧化降解实验研究

选择YT-1000型活性炭纤维(ACF)作为催化剂,考察ACF与O3协同作用催化降解水溶液中4-氯酚的最佳反应条件,并将该条件应用于焦化废水生物处理尾水中难降解有机污染物的催化氧化.ACF表面具有丰富的微孔结构,对4-氯酚有良好的吸附作用,在动力学上提高了其与O3反应的起始浓度,并且在ACF表面含氧、含氮等基团的催化作用下发生氧化反应,1 L浓度为100 mg/L的4-氯酚水样中投加2 g ACF反应6 min时,吸附作用对TOC的去除率为43.4%.而ACF协同O3作用时的TOC去除率提高到72.5%,协同增效作用为67.1%;在选定的反应条件下,ACF协同O3降解焦化废水生物处理尾水,60 min时的TOC与色度的去除率分别达到56.8%和96.3%.上述研究过程证明了吸附作用与催化作用的协同能有效降解生物过程不能降解的焦化废水中惰性有机污染物.     

电化学转盘/电凝聚法处理模拟活性染料废水的研究

采用一种新的电化学方法--电化学转盘/电凝聚法来处理模拟活性翠蓝KN-G废水,考察了电压、转速、pH、反应时间对色度、TOC去除率的影响,并确定了最佳反应条件.在最佳反应条件(电压12 V,转速70 r/min,pH为4～5,反应时间为60 min)下,色度和TOC去除率可分别达到95.3%和73.5%.并初步探讨了活性翠蓝KN-G的降解机理.     

直接红染料的臭氧脱色与中间产物研究

以直接红B模拟染料废水为研究对象,考察了臭氧化过程中染料溶液的吸光度和TOC的变化,同时利用离子色谱仪和GC/MS对染料的降解过程进行了分析,最后用发光细菌法检测了染料溶液急性毒性的变化。结果表明,臭氧对染料的降解符合一级反应动力学,20 min时对染料的脱色率达到99.2%;反应40 min后TOC减少32.55%,染料分子有97.8%的S被氧化为SO^2-₄,偶氮键被臭氧化为N₂,分子中的仲胺基小部分转化成游离NH⁺₄和NO^-₃;在臭氧化过程前期新生成的醛类和酰胺类物质使溶液急性毒性迅速上升,25 min后溶液毒性开始逐渐下降。     

Multivariate analysis of photo-Fenton degradation of the herbicides tebuthiuron, diuron and 2,4-D

The degradation of herbicides in aqueous solution by photo-Fenton process using ferrioxalate complex (FeOx) as source of Fe2+ was evaluated under blacklight irradiation. The commercial products of the herbicides tebuthiuron, diuron and 2,4-D were used. The multivariate analysis, more precisely, the response surface methodology was applied to evaluate the role of FeOx and hydrogen peroxide concentrations as variables in the degradation process, and in particular, to define the concentration ranges that result in the most efficient degradation of the herbicides. The degradation process was evaluated by the determination of the remaining total organic carbon content (TOC), by monitoring the decrease of the concentrations of the original compounds using HPLC and by the chloride ion release in the case of diuron and 2,4-D. Under optimized conditions, 20 min were sufficient to mineralize 93% of TOC from 2,4-D and 90% of diuron, including oxalate. Complete dechlorination of these compounds was achieved after 10 min reaction. It was found that the most recalcitrant herbicide is tebuthiuron, while diuron shows the highest degradability. However, under optimized conditions the initial concentration of tebuthiuron was reduced to less than 15%, while diuron and 2,4-D were reduced to around 2% after only 1 min reaction. Furthermore, it was observed that the ferrioxalate complex plays a more important role than H2O2 in the photodegradation of these herbicides in the ranges of concentrations investigated.     

Degradation of nitrogen-heterocyclic compounds by anodic oxidation and electro-Fenton methods.

This study describes the degradation of nitrogen-heterocyclic compounds (NHCs) by anodic oxidation and electro-Fenton. Using indole as a model nitrogen-heterocyclic compound, the removal of indole reached 68% and 97% by anodic oxidation and electro-Fenton, respectively, while the decay of TOC was 15% and 38% correspondingly. By the analysis of ultraviolet-visible spectra and liquid chromatography/mass spectrum, the degradation mechanism of indole by electro-Fenton was proposed as hydroxyl oxidation and anodic oxidation. The degradation of other NHCs including quinoline, isoquinoline and pyridine by anodic oxidation and electro-Fenton revealed the same sequence: quinoline approximately equal isoquinoline > indole > pyridine. A significant correlation between ln k (natural logarithm of rate constants) and E(LUMO) (the energy of the lowest unoccupied molecular orbit) was obtained by quantitative structure-activity relationship analysis. Degradation of coking plant wastewater showed the removal of COD and TOC were 42% and 22% respectively after 180 min treatment by electro-Fenton.     

真空紫外光降解五氯酚钠以及过硫酸盐对反应的促进作用

研究了真空紫外光(VUV,185 am)对于水溶液中五氯酚钠的降解,反应2 h后,初始浓度为10 mg/L的五氯酚钠的去除率达到99%以上,有机氯的脱除率达到70%以上,有效地实现了五氯酚钠的脱毒.溶液初始pH值对五氯酚钠的真空紫外光解有很大影响,pH=10.9时的降解速率常数是pH=3.1时的3倍.表观一级反应速率常数随初始浓度的增加而线性下降.在反应溶液中加入过硫酸盐,可有效提高五氯酚钠的真空紫外光降解速率和矿化速率,过硫酸盐和五氯酚钠摩尔比为24时,降解速率提高3倍,反应4 h后TOC去除率达到95%.     

Aqueous photolysis of tetracycline and toxicity of photolytic products to luminescent bacteria

The extensive utilization of antibiotics in the pharmaceutical therapies and agricultural husbandry has led to the worldwide pollution in environments. In this study the photolysis behaviors of tetracycline (TC) and toxicity of its degradation products were investigated. The results showed that TC photolysis followed first-order kinetics. The photolysis rate was found to be dependent on the initial TC concentration and increasing TC concentration from 10 to 40mgl(-1) led to the decrease of the photolysis rate constant from 0.0045min(-1) to 0.0014min(-1). TC photolysis was highly pH-dependent and strongly enhanced at high pH value. Markedly elevated TC photolysis was also observed in the presence of nitrate and dissolved organic matter. Upon irradiation for 300min, only 15% reduction of total organic carbon (TOC) occurred in spite of quick conversion of 73% of TC, suggesting that a majority of TC transformed into intermediate products without complete mineralization. The intermediate products from TC photolysis were analyzed using high-performance liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS) and the main photolysis products of TC were proposed. The toxicity of the photolysis compounds was evaluated using luminescent bacterium, and the results revealed that the toxicity increased with irradiation, indicative of a higher adversity risk of the degradation products of TC on bacteria upon photolysis.     

Photodegradation of an azo dye of the textile industry

An advanced oxidation treatment, UV/H2O2, was applied to an azo dye, Hispamin Black CA, widely used in the Peruvian textile industry. Rates of color removal and degradation of the dye have been evaluated. A strongly absorbing solution was completely decolorized after 35 min of treatment, and after 60 min an 82% reduction of the total organic carbon (TOC) was obtained. It has been found that the degradation rate increased until an optimum value, beyond which the reagent exerted an inhibitory effect. The degradation rate was also function of pH.     

Semiconductor-assisted photodegradation of lignin, dye, and kraft effluent by Ag-doped ZnO

This work reports a preliminary study of semiconductor-assisted photochemical degradation of lignin, Remazol Brilliant Blue R and Kraft E1 paper effluent by using ZnO and Ag-doped ZnO photocatalysts. The doped semiconductor was prepared in the reaction media by photoreduction of silver nitrate. With the use of 100 mg of ZnO and 15 mg of Ag-ZnO, almost total decolorization of the dye and lignin samples in reaction times lower than 60 min were observed. Extending the photochemical reaction up to 120 min, the total organic carbon content (TOC) was reduced in 90%. For the paper effluent, a fast decolorization was obtained for relatively short reaction times. However, de TOC reduction was negligible (near of 10%) up to high reaction times (300 min). By using the Ag-ZnO photocatalyst, the toxicity of lignin and Kraft E1 effluent toward E. Coli was completely removed. For the dye, the formation of transient toxic species was observed.     

Degradation of azo dye Acid Red 14 in aqueous solution by electrokinetic and electrooxidation process

A new wastewater treatment technology--electrokinetic-electrooxidation process (EK-EO process) is developed in this paper. The EK-EO process can take advantage of both electrooxidation on the anode surface and the electrokinetic process of anionic impurities under an electric field, which can enhance the TOC removal in electrolysis process. The degradation of an anionic azo dye Acid Red 14 (AR14) was experimentally investigated. It was found that under an electric field AR14 could be migrated into anode compartment and be efficiently mineralized. After 360 min electrolysis of 100 mgl(-1) AR14 solutions at 4.5 mAcm(-2), complete discoloration was observed in both cathode and anode compartment. About 60% TOC was electromigrated from cathode compartment to anode compartment, and more than 25 mgl(-1) TOC was abated in anode compartment. A possible degradation mechanism of AR14 by EK-EO process was proposed. Additionally, the effect of current density, recycling flux, and electrolyte concentration on the EK-EO degradation of AR14 was also investigated.