亚铁羟基络合物还原转化水溶性偶氮染料

偶氮染料是印染工艺中应用最广泛的一类染料,目前染料废水脱色是污水处理难题。亚铁混凝处理染料废水过程中可能存在亚铁的还原作用,本实验制备了比溶解态亚铁更具还原反应活性的亚铁羟基络合物(ferrous hydroxycomplex,FHC),以5种不同类型的水溶性偶氮染料为目标污染物,研究FHC还原水溶性偶氮染料的脱色性能。实验结果表明,FHC对活性艳红X-3B、酸性大红GR和阳离子红X-GRL有较好的还原脱色效果,仅投加含铁89.6 mg/L的FHC,染料脱色率达到90%以上,继续增大FHC投加量可以完全脱色;中性枣红GRL的FHC还原脱色效果较差,需加入313.6 mg/L的FHC才能达到90%以上脱色率;134.4 mg/L的FHC能够将直接耐酸大红4BS完全脱色,但其脱色主要以混凝沉淀为主;溶液pH对FHC的还原性能产生重要影响,FHC还原染料脱色的适宜的pH值范围为4～10。该研究为亲水性染料脱色提供了一种新的技术,也为FHC运用于印染废水脱色提供了理论基础。     

醌介体催化强化酸性红B生物脱色

考察了5种结构相似的醌介体(AQS、2,7-AQDS、AQDS、1,5-AQDS和α-AQS)对酸性红B生物脱色的催化强化作用。结果表明,反应进行至5 h,在0～0.24 mmol/L AQS的浓度范围内,最高脱色率达89%(0.24 mmol/L),相对于空白组(28%)提高约3.2倍,且零级反应速率常数K与介体浓度呈正相关线性关系,K=56.571CAQS+22.616(R2=0.9012);最适实验条件为AQS浓度0.24 mmol/L,0.25%NaCl,温度35℃,pH 7;在此实验条件下,5种醌介体相对于空白组脱色效率分别提高了1.14～1.53倍,体系氧化还原电位降低了38～87 mV。本研究为解决偶氮染料生物脱色技术存在的降解速率低的问题提供了新的思路。     

Phanerochaete chrysosporium吸附载体的选择及染料降解研究

研究了游离细胞与载体吸附培养、不同载体材料对Phanerochaete chrysosporium进行连续染料脱色及产酶能力的影响。结果表明,P.chrysosporium可在载体上良好生长,甚至生长到载体内部。木屑、玉米芯、花生壳3种载体材料中,以木屑载体吸附培养物的持续脱色和产酶效果最佳,该培养物经三轮连续脱色后对染料RB5仍能达到最高95%的脱色率,并产生596 U/L锰依赖过氧化物酶（MnP）和1 326 U/L木质素过氧化物酶（LiP）,对染料的持续脱色和产酶能力明显优于游离细胞培养物。     

隔膜槽中ACF电极成对电解脱色活性艳蓝KN-R

同时以活性炭纤维(ACF)为阳极和阴极,在隔膜电解槽中研究了不同电流密度下蒽醌染料活性艳蓝KN-R的电化学脱色.考察了ACF阳极和ACF阴极各自对染料的脱色性能.结果表明,当电流密度为1.0～1.5 mA/cm2时,电解槽中发生阳极电氧化和阴极电还原同时进行的成对电解脱色.在ACF电极上,活性艳蓝KN-R的电氧化脱色比电还原脱色容易进行,1.0 mA/cm2时,阴阳两极室脱色率分别为69%和93%,而1.5 mA/cm2时,阳极室脱色率保持在93%,阴极室脱色率达到79%.     

Phanerochaete chrysosporium吸附载体的选择及染料降解研究

研究了游离细胞与载体吸附培养、不同载体材料对Phanerochaete chrysosporium进行连续染料脱色及产酶能力的影响。结果表明，P. chrysosporium可在载体上良好生长，甚至生长到载体内部。木屑、玉米芯、花生壳3种载体材料中，以木屑载体吸附培养物的持续脱色和产酶效果最佳，该培养物经三轮连续脱色后对染料RB5仍能达到最高95%的脱色率，并产生596 U/L锰依赖过氧化物酶（MnP）和1 326 U/L木质素过氧化物酶（LiP），对染料的持续脱色和产酶能力明显优于游离细胞培养物。     

活性黑KN-B染料模拟废水电化学脱色

为进一步明确活性染料在可溶性阳极电化学体系中的脱色机理，以铝为牺牲阳极，不锈钢为阴极，在恒电流操作模式下，针对活性黑KN-B模拟废水，考察了电流密度、初始pH值、电解质种类及浓度、温度、染料浓度因素对染料脱色过程的影响。结果表明：(1)电流密度、电解液初始pH值、氯化钠电解质浓度、温度、染料浓度对染料溶液脱色效率影响显著，在一定实验条件下，染料溶液脱色率可达到88%；(2) 在不同pH的范围内，活性黑KN-B表现的脱色机理不同，pH 4～9为混凝与阴极还原脱色共同作用；pH＜4和＞9则表现为阴极还原脱色为主； (3) 氯化钠的加入在增强染料脱色的同时，也有助于芳环类物质的后续混凝去除。     

理化环境条件对青霉菌和细菌吸附脱色染料的影响

在筛选到的染料吸附脱色真菌和细菌的基础上 ,测定了温度和pH值对青霉G 1吸附和与细菌共培养脱色降解染料的影响。结果表明 ,16— 36℃下青霉G 1对艳紫KN B(C .I.Re .Vi.2 2 )和黄M 3RE(C .I.Re .Ye .14 5 )的吸附去除能力受温度影响不大 ,吸附 5h去除率在 97.1%— 98.7% ,而染料的脱色时间受温度影响较大 ,2 8— 36℃下脱色速度快 .青霉G 1对pH 3— 11染料水中染料的吸附去除率高 ,达 94 .9%— 97.8% ,对pH 13的吸附去除率低 ,仅为 5 5 .4 %和 5 6 .2 % ,从pH 5—13染料水中吸附染料的菌丝在与细菌共培养 5— 2 6h即完成了对染料的脱色 ,脱色速度较快     

沼泽红假单胞菌W12对活性黑5的厌氧脱色和降解作用

从处理印染废水的厌氧移动床生物膜反应器（moving bed biofilm reactor, MBBR）中分离到一株具有高效脱色活性的沼泽红假单胞菌W12。经实验确定W12对活性黑5（reactive black 5，RB5）脱色的适宜条件为：pH＜10；有光照；谷氨酸盐或乳酸盐作为碳源，当乳酸钠为碳源时浓度应＞500 mg/L；盐度不超过5％；RB5浓度不大于700 mg/L。紫外可见光谱扫描结果表明，RB5的脱色和降解过程生成芳香胺类化合物，这些中间产物可进一步降解。此外发现，RB5诱导生成的胞外代谢物能提高W12的脱色活性。     

膨胀珍珠岩负载TiO2光催化脱色性能的研究

以钛酸四丁酯为原料,膨胀珍珠岩为载体,用溶胶-凝胶法制备可漂浮于水面的负载型TiO2.利用该负载型TiO2对罗丹明B(RB)进行光催化脱色实验,结果表明,浸渍3次的负载型TiO2光催化活性最高,催化剂最佳用量为500mg/100mL RB,经5 h光照,对100mL浓度为1 mg/L和2.5 mg/L RB脱色率分别为76.67%和47.27%;该催化剂使用寿命长,25h后催化剂脱色性能没有减弱,可重复使用;经8 h光照,染料废水脱色效果好.     

理化环境条件对青霉菌和细菌吸附脱色染料的影响

在筛选到的染料吸附脱色真菌和细菌的基础上，测定了温度和pH值对青霉G-1吸附和与细菌共培养脱色降解染料的影响。结果表明，16—36℃下青霉G-1对艳紫KN-B(C．I．Re．Vi．22)和黄M--3RE(C．I．Re．Ye．145)的吸附去除能力受温度影响不大，吸附5h去除率在97．1％--98．7％，而染料的脱色时间受温度影响较大，28—36℃下脱色速度快．青霉D1对pH3-11染料水中染料的吸附去除率高，达94．9％--97．8％，对pH13的吸附去除率低，仅为55．4％和56．2％，从pH5—13染料水中吸附染料的菌丝在与细菌共培养5—26h即完成了对染料的脱色，脱色速度较快。     

Decolorization of direct dyes by salt fractionated turnip proteins enhanced in the presence of hydrogen peroxide and redox mediators

The present paper demonstrates the effect of salt fractionated turnip (Brassica rapa) proteins on the decolorization of direct dyes, used in textile industry, in the presence of various redox mediators. The rate and extent of decolorization of dyes was significantly enhanced by the presence of different types of redox mediators. Six out of 10 investigated compounds have shown their potential in enhancing the decolorization of direct dyes. The performance was evaluated at different concentrations of mediator and enzyme. The efficiency of each natural mediator depends on the type of dye treated. The decolorization of all tested direct dyes was maximum in the presence of 0.6mM redox mediator at pH 5.5 and 30 degrees C. Complex mixtures of dyes were also maximally decolorized in the presence of 0.6mM redox mediator (1-hydroxybenzotriazole/violuric acid). In order to examine the operational stability of the enzyme preparation, the enzyme was exploited for the decolorization of mixtures of dyes for different times in a stirred batch process. There was no further change in decolorization of an individual dye or their mixtures after 60 min; the enzyme caused more than 80% decolorization of all dyes in the presence of 1-hydroxybenzotriazole/violuric acid. However, there was no desirable increase in dye decolorization of the mixtures on overnight stay. Total organic carbon analysis of treated dyes or their mixtures showed that these results were quite comparable to the loss of color from solutions. However, the treatment of such polluted water in the presence of redox mediators caused the formation of insoluble precipitate, which could be removed by the process of centrifugation. The results suggested that catalyzed oxidative coupling reactions might be important for natural transformation pathways for dyes and indicate their potential use as an efficient means for removal of dyes color from waters and wastewaters.     

Kinetics of chemical decolorization of the azo dye C.I. Reactive Orange 96 by sulfide

The mechanism of decolorization of azo dyes based on the extracellular chemical reduction with sulfide (H2S, HS-, S2-) was postulated for sulfate reducing environments. To design technical decolorization processes of textile wastewater treatment with sulfide produced by sulfate reducing bacteria (SRB), kinetics is of great significance. Batch experiments were made in order to investigate the kinetics of abiotic decolorization of the reactive mono-azo dye C.I. Reactive Orange 96 (RO 96) with sulfide, with varying pH. The decolorization of RO 96 by sulfide under the exclusion of O2 corresponded to first-order kinetics with respect to both dye and sulfide concentration. The decolorization of RO 96 with sulfide at neutral pH (7.1) was advantageous compared with that at pH for 4.1, 6.3, and 6.5. This is attributed to an increase in the fraction of HS- of total sulfide species at neutral pH. The rate constants k for the decolorization at 37 degrees C were obtained as 0.01 for pH = 4.1, 0.06 for pH = 6.3, 0.08 for pH = 6.5, and 0.09 for pH = 7.1 in mM(-1) min(-1). The high rate constants for sulfide at pH 6.5-7.1 support that the decolorization through SRB (i.e. by bio-sulfide) can be effective in anaerobic bacterial systems with sulfate.     

Biological decolorization of reactive anthraquinone and phthalocyanine dyes under various oxidation-reduction conditions.

The decolorization of two anthraquinone dyes (Reactive Blue 4 [RB4] and Reactive Blue 19 [RB19]) and two phthalocyanine dyes (Reactive Blue 7 [RB7] and Reactive Blue 21 [RB21]) was investigated at an initial dye concentration of 300 mg/L using an unacclimated, enrichment culture. The culture was fed a mixture of organic compounds and maintained initially under aerobic conditions, and then progressively developed anoxic/ anaerobic conditions. Biotransformation-related decolorization of the dyes did not take place under aerobic conditions, but use of the feed organic mixture and biomass production by the enrichment culture were not affected. Complete ammonia removal occurred in the control and all dye-amended cultures. The development and extent of nitrification were much lower in the latter cultures, in which ammonia removal via air stripping was the dominant mechanism. Prolonged incubation of the culture under anoxic/anaerobic conditions with multiple carbon source additions resulted in a high decolorization extent of anthraquinone dyes (over 84%) and only partial decolorization of phthalocyanine dyes (49 to 66%). Development of significant methanogenic activity took place in the control and, to a lesser extent, in the two phthalocyanine dye-amended cultures, but the anthraquinone dyes severely inhibited the development of methanogenic activity. The RB4 and RB19 decolorization was attributed to nonreversible, microbially mediated dye transformation(s), demonstrated by the accumulation of decolorization products with absorbance maxima in the 420- to 460-nm region. The decolorization of RB4 and RB19 followed Michaelis-Menten kinetics. At an initial dye concentration of 300 mg/L, the observed maximum decolorization rate per unit biomass was 9.1 and 37.5 mg dye/mg volatile suspended solids x day for the RB4 and RB19, respectively. Thus, partial decolorization of reactive phthalocyanine dyes and extensive biological decolorization of reactive anthraquinone dyes is feasible only under anoxic/anaerobic conditions.     

Fate and transformation of naphthylaminesulfonic azo dye Reactive Black 5 during wastewater treatment process

Certain aromatic amines generated by the decolorization of some azo dyes are not removed substantially by conventional anaerobic–aerobic biotreatment. These aromatic amines are potentially toxic and often released in the wastewater of industrial plants. In this study, the fate and transformation of the naphthylaminesulfonic azo dye Reactive Black 5 (RB5) during different phases of a sequencing batch reactor were investigated. The major products of RB5 decolorization during the anaerobic phase include 2-[(4-aminophenyl)sulfonyl]ethyl hydrogen sulfate (APSEHS) and 1-2-7-triamino-8-hydroxy-3-6-naphthalinedisulfate (TAHNDS). During the aerobic phase, APSEHS was hydrolyzed and produced 4-aminobenzenesulfonic acid, which was further degraded via dearomatization. TAHNDS was transformed rapidly via auto-oxidation into TAHNDS_DP-1 and TAHNDS_DP-2, which were not further removed by the activated sludge during the entire 30-day aerobic phase. In contrast, different behaviors of TAHNDS were observed during the anoxic phase. The transformation of TAHNDS was initiated either by deamination or desulfonation reaction. TAHNDS was then converted into 3,5-diamino-4-hydroxynaphthalene-2-sulfonic acid, which was subsequently removed via ring cleavage reaction under aerobic condition. In conclusion, complete degradation of TAHNDS by activated sludge occurs only during anoxic/aerobic processes instead of the conventional anaerobic/aerobic processes.     

Two stage biological treatment of a diazo reactive textile dye and the fate of the dye metabolites

A two stage anaerobic/aerobic bacterial process was used to decolorize and partially mineralize a reactive vinyl sulfone diazo dye C.I. Reactive Black 5 (RB5) in a synthetic wastewater. Since the anchor group of reactive dyes reacts during the dyeing process, the effect the degree of hydrolysis of the vinyl sulfone dye had on decolorization, mineralization and toxicity in each stage was investigated. An overall color removal of approximately 65% was found for both the fully and partially hydrolyzed dye. Partial mineralization of the fully hydrolyzed RB5 was achieved in the two stage rotating disc reactors. While the anchor group metabolite p-aminobenzene-2-hydroxyethylsulfonic acid (p-ABHES) was mineralized, an oxidized form of the center metabolite (1,2-ketimino-7-amino-8-hydroxynaphthalene-3,6-disulfonic acid) remained in the aerobic stage effluent, causing the effluent to be colored although no RB5 was present. Partially hydrolyzed dye in the influent with vinyl forms of the anchor group caused cessation of biogas production and a reduction in decolorization efficiency in the anaerobic stage. No evidence for mineralization of the partially hydrolyzed dye or its metabolites was found. A method for evaluating dye mineralization using lumped parameters is presented.     

Photocatalytic degradation of azo dyes by nitrogen-doped TiO2 nanocatalysts

This study examined the photocatalytic degradation of three azo dyes, acid orange 7 (AO7), procion red MX-5B (MX-5B) and reactive black 5 (RB5) using a new type of nitrogen-doped TiO2 nanocrystals. These newly developed doped titania nanocatalysts demonstrated high reactivity under visible light (lambda>390 nm), allowing more efficient usage of solar light. The doped titania were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Experiments were conducted to compare the photocatalytic activities of nitrogen-doped TiO2 nanocatalysts and commercially available Degussa P25 powder using both UV illumination and solar light. It is shown that nitrogen-doped TiO2 after calcination had the highest photocatalytic activity among all three catalysts tested, with 95% of AO7 decolorized in 1 h under UV illumination. The doped TiO2 also exhibited substantial photocatalytic activity under direct sunlight irradiation, with 70% of the dye color removed in 1h and complete decolorization within 3 h. Degussa P25 did not cause detectable dye decolorization under identical experimental conditions using solar light. The decrease of total organic carbon (TOC) and evolution of inorganic sulfate (SO4(2-)) ions in dye solutions were measured to monitor the dye mineralization process.     

A batch kinetic study on decolorization and inhibition of Reactive Black 5 and Direct Brown 2 in an anaerobic mixed culture

Decolorization and inhibition kinetic characteristics of two azo dyes namely Reactive Black 5 (RB 5) and Direct Brown 2 (DB 2) were investigated with partially granulated anaerobic mixed culture using glucose (3000 mg l(-1) COD) as carbon source and electron donor during batch incubation. Monod, zero-, first-, and second-order reaction kinetic models were tested in order to determine the most suitable rate model of substrate and color removal kinetic. The course of the decolorization and substrate removal process approximates to first-order kinetic model under batch conditions. Decolorization, and substrate removal were achieved effectively under test conditions but ultimate removal of azo dyes and substrate were not observed at high dye concentrations. Aromatic amine and volatile fatty acid accumulation were observed proportionally at a higher azo dye concentration. A competitive kinetic model that describes the anaerobic co-metabolism of increasing RB 5 and DB 2 dye concentrations with glucose as co-substrate has been developed based on the experimental data.