Performance Evaluation of Modified Black Clay as a Heterogeneous Fenton Catalyst on Decolorization of Azure B Dye: Kinetic Study and Cost Evaluation

Black clay(BC) was used as a catalyst for the decolorization of Azure B dye by Fenton process. BC was modified by acid, alkali, distilled water, and calcination to check their changes in characterization and efficiency on decolorization of Azure B. Among three modified catalysts, maximum decolorization was obtained by acid-modified BC(AMBC) catalyst due to the highest removal of impurities, comparatively. The characterization of AMBC was done by Fourier-transform infrared spectroscopy and X-ray diffraction spectroscopy which show the presence of metal ion. The BET surface area, pore volume, pore size, and density of AMBC were calculated to be 79.402 m~2/g, 0.0608 m~3/g, 0.00306 nm, and 16 g/cm~3, respectively. The highest decolorization of 97.59% was achieved only in 10 min using AMBC at optimized calcination of 100 °C and 3 h of aging. AMBC was considered as the main catalyst for optimizing the different process parameters. Optimized conditions were obtained: pH 2, 0.2 mL of H_2O_2, catalyst dose 0.3 g, room temperature(30 °C), and stirring speed 400 r/min. The catalyst has showed excellent stability and reusability. It could remove more than 85% of color even after four cycles of run and less than negligible leaching of iron. AMBC has good recycling ability among other modified catalysts. To check the selectivity of catalyst, different dyes such as Congo red and mixed dye(mixture of Azure B and Congo red) decolorization were studied. In the present work, kinetic study was also carried out and a three-stage decolorization process was found.     

Investigating the potential of using acoustic frequency on the degradation of linear alkylbenzen sulfonates from aqueous solution

The effectiveness of using acoustical (sonochemical) reactor for degradation of linear alkylbenzen sulfonate (LAS) from aqueous solution was investigated. LASs are anionic surfactants,found in relatively high amounts in domestic and industrial wastewaters. In this study,experiments on LAS solution were performed using methylene blue active substances (MBAS) method. The effectiveness of acoustical processor reactor for LAS degradation is evaluated with emphasis on the effect of treatment time and initial LAS concentration. Experiments were performed at initial concentrations of 0.2,0.5,0.8 and 1.0 mg/L,acoustic fre-quency of 130 kHz,applied power of 500 W and temperature of 18 °C～20 °C. At the conditions involved,LAS degradation was found to increase with increasing sonochemical time. In addition,as the concentration increased,the LAS degradation rate de-creased in the acoustical processor reactor.     

In-situ production of ozone and ultraviolet light using a barrier discharge reactor for wastewater treatment

A dielectric barrier discharge （DBD） reactor consisting of water-filled dielectric tube electrodes was used for the treatment ofwastewater. The inner dielectric tube, which acted as the discharging electrode, was filled with an aqueous electrolyte solution. The outer dielectric tube, which served as the other electrode, was in contact with the wastewater, which was grounded. The present reactor system was energy-efficient for the production of ozone, not only because the perfect contact between the aqueous electrode and the dielectric surface minimized the loss of the electrical energy, but also because the DBD reactor was cooled by the wastewater. In addition, the ultraviolet （UV） light produced in the DBD reactor was able to assist in the wastewater treatment since the quartz tube used as the dielectric material was UV-transparent. The performance of the present DBD system was evaluated using a synthetic wastewater formed from distilled water and an azo dye, amaranth. The experimental parameters were the concentration of the electrolyte in the aqueous electrode, the discharge power, the initial pH of the wastewater and the concentration of hydrogen peroxide added to the wastewater. The wastewater treatment system was found to be effective for achieving decomposition of the dye.     

Decolorization Kinetics of Sludge Protein Solution by ~（60）Coγ-Ray Irradiation/H_2O_2 Oxidation

In order to carry out decolorization, sludge protein solution, a dark brown close to black solution from activated sludge, was subjected to ⁶⁰Co γ-ray irradiation in the presence of hydrogen peroxide. UV/Vis spectrophotometric method was used to investigate the effect of H2O2 on the coloration apparent kinetics and rate constants of sludge protein solution under γ-ray irradiation. In addition, the effects of irradiation dose, initial sludge protein solution concentration, and pH value on the decolorization efficiency of sludge protein solution were studied. Results showed that the decolorization apparent kinetics of sludge protein solution was a first-order reaction. The solution decolorization percentage increased with the increase of irradiation dose or the decrease of initial sludge protein solution concentration. The examination results of pH value showed that the sludge protein solution could be more efficiently decolorized in alkaline media than in acid media. Moreover, sensory evaluation and foamability analysis indicated that irradiated samples under H2O2 oxidation showed better sensory score and foamability.     

Science Letters:Anodic oxidation of salicylic acid at Ta/BDD electrode

Boron-doped diamond (BDD) film electrodes using Ta as substrates were employed for anodic oxidation of salicylic acid (SA). The effects of operational variables including initial concentration,current density,temperature and pH were examined. The results showed that BDD films deposited on the Ta substrates had high electrocatalytic activity for SA degradation. There was little effect of pH on SA degradation. The current efficiency (CE) was found to be dependent mainly on the initial SA concentration,current density and temperature. Chemical oxygen demand (COD) was reduced from 830 mg/L to 42 mg/L under a current density of 200 A/m2 at 30 °C.     

用改进的序批式生物膜反应器技术处理废水

This paper describes the removel of COD and nitrogen from wastewater with modified sequencing batch biofilm reactor,The strategy of simultaneous feeding and draining was explored.The results show that introduction of a new batch of wastewater and withdrawal of the purifeid water can be conducted simultaneously with the maximum volumetric exchange rate of about 70%,Application of this feeding and draining mode leads to the reduction of the cycle time,the increase of the utilization of the reactor volume and the simplification of the reactor structure.The treatment of a synthetic wastewater containing COD and nitrogen was investigated.The operation mode of F(D)-O(i.e.,simultaneous feeding and draining followed by the aerobic condition)was adopted.It was found that COD was degraded very fast in the initial reaction period of time,then reduced slowly and the ammonia nitrogen and nitrate nitrogen concentrations decreased and increased with time respectively,while the nitrite nitrogen level increased first and then reduced.The relationship between the COD or ammonia nitrogen loading and its removal rate was examined,and the removal of COD,ammonia nitrogen and total nitrogen could exceed 95%,90%and 80% respectively,The fact that nitrogen could e removed more completely under constant aeration(aerobic condition)of the SBBR operation mode is very interesting and could be explained in several respects.     

Characterization of Aquabacterium parvum sp. Strain B6 during Nitrate-Dependent Fe(Ⅱ) Oxidation Batch Cultivation with Various Impact Factors

In order to assess the capacity of Aquabacterium parvum sp. strain B6 for nitrate-dependent Fe(Ⅱ) oxidation,batch cultivation was conducted, and its ability to oxidize Fe(Ⅱ) coupled to nitrate reduction in the presence of diverse organic substrates was studied. Meanwhile, the nitrate-removal rate of B6 with various impact factors was further optimized by the response surface methodology(RSM). The results show that strain B6 is capable of utilizing different organic compounds as substrates for nitrate reduction. Compared with yeast extract, B6 showed a greater potential of chemical oxygen demand(COD)degradation and cell proliferation with acetate and glucose mediums, respectively, while citrate was not beneficial for this process due to its low consumption rate. RSM analysis demonstrated that the maximum nitrate-reduction rate of 30.64% could be achieved with an initial pH of 7.4,incubation temperature of 25.0 °C, and carbon source concentration of 266.10 mg/L.     

Experimental and model comparisons of H2O2 assisted UV photodegradation of Microcystin-LR in simulated drinking water

The degradation of Microcystin-LR （MC-LR） in water by hydrogen peroxide assisted ultraviolet （UV/H2O2） process was investigated in this paper. The UV/H2O2 process appeared to be effective in removal of the MC-LR. MC-LR decomposition was primarily ascribed to production of strong and nonselective oxidant-hydroxyl radicals within the system. The intensity of UV radiation, initial concentration of MC-LR, MC-LR purity, dosages of H2O2, the initial solution pH, and anions present in water, to some extent, influenced the degradation rate of MC-LR. A modified pseudo-first-order kinetic model was developed to predict the removal efficiency under different experimental conditions.     

纳米二氧化钛光催化性能研究

Nano-TiO2 powders with pure anatase sturcture were prepared by the method of precipitation-solution-gelation,using H2TiO3,hydrogen peroxide and ammonia as reactants.Active red X-3B dye solution was selected as a model pollutant for the photocatalysis degradation experiments,The effects of grain sizes,dosage and microostructure of nano-TiO2 on itsphotocatalysis properties were studied.The results show that photo-activity of the nano-TiO2 is enhanced with the grain sizes reducing or dosages increasing of nano-TiO2,Howerver,excess increase in nano-TiO2 concentration is not advantageous to the enhancement of the photo-activity.Anatase TiO2 demonstrated a higher photo-activity than rutile TiO2,The dye solution hardly degraded without nano-TiO2 powders being added into it or under sunlight irradiation.     

固定化细胞滤床和生物膜滤床净化二甲苯的比较

The Bacillus firmus was immobilized into Ca-alginate beads according to the different initial biomass concentration, calcification time and activation time.Three types of immobilized Bacillus firmus beads were packed respectively in trickling biofilter to purify xylene contained waste gases,and the performance of immobilized-cell biofilter was compared with traditional biofilm attached biofilter packed with two types of ceramic pellets.The results showed that three types of immobilized beads had different capabilities for removing xylene and life-spans.Higher initial biomass in immobilized beads resulted in better performance but shorter life-span.Activation process can remarkably enhance the activity of bacteria,and the removal efficiency of xylene can substantially be improved.Calcification time had influence on life-span of immobilized beads.Without acclimation,the cell-entrapped biofilter can obtain the maximum elimination capacity of 92.4 g/(m~3·h).However,compared with biofilm attached biofilter,it has a poorer intrinsic drawback in volatile organic compounds (VOCs) removal due to the existence of excess mass transfer resistance.     

TiO2光催化氧化降解偶氮染料

研究了催化剂、光源、溶液初始浓度、溶液初始pH值等因素对甲基橙光催化氧化降解反应的影响．实验结果表明,最佳实验条件为：以灼烧的TiO2为催化剂,催化剂的投加量为0,8g·L^-1,采用浸波式紫外灯作光源,甲基橙初始浓度为20mg·L^-1,溶液初始pH=3．该实验条件下,甲基橙一小时脱色率可达81．3％．该研究可为偶氮染料降解提供新的思路．     

Fenton氧化法处理五种偶氮染料的研究

偶氮染料废水是一种有机物含量高、成分复杂、色度高、可生化性差的难降解废水,其处理方法已引起广泛关注。用Fenton氧化法研究了五种偶氮染料(橙黄Ⅱ、橙黄Ⅳ、铬黑T、皂黄和酸性铬兰K)的降解脱色情况。研究结果表明,这几种偶氮染料均有显著的降解。当偶氮染料浓度为200ppm、H2O2(30%)的用量为0.2ml、Fe SO4·7H2O用量为83.4mg,反应1小时后,橙黄Ⅱ和铬黑T在p H=10时的脱色降解率高达94.55%和88.19%;橙黄Ⅳ和酸性铬兰K在p H=12时降解脱色率是最高的,达到了98.74%和96.97%;而皂黄则在p H=2时的降解脱色率最好,高达97.36%,是一个降解高浓度染料废水的有效方法。根据偶氮染料降解后的UV-Vis图谱,简单探讨了氧化过程中可能的反应机理。     

活性染料废水电凝聚脱色能耗分析

文章在铝阳极和不锈钢阴极的电化学体系中,在恒电流模式下,考察了．活性生红M-3BE模拟废水脱色过程及能耗的影响因素。实验结果表明,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较大;电流密度、电解液初始pH值、氯化钠与硫酸钠电解质浓度、温度对脱色过程能耗影响显著。在一定实验条件下,染料溶液脱色率可达到98％,能耗117．75kwh／（kg dye）。在不同pH的范围内,活性红M～3BE表现的脱色机理不同,pH4～8为混凝与阴极还原脱色共同作用,pH小于4和大于9则表现为阴极还原脱色为主,且低pH下能耗较低。氯化钠既有助于提高染料废水的脱水效率,又有助于降低脱色过程中的能耗。     

几种离子对光催化降解罗丹明B的影响

采用罗丹明B作为目标降解物,考察了几种离子对光催化降解罗丹明B脱色率的影响.结果显示,低浓度的Ca2＋和Al3＋对罗丹明B的脱色率影响不明显,但是当它们的浓度增加到一定值后,则脱色率明显下降;当Fe3＋的浓度为0.2 ～0.5 mmol·L-1时,其对光催化降解罗丹明B有一定的促进作用,继续增加Fe3＋的浓度,反而起到明显的抑制作用;Cu2＋对光催化降解罗丹明B具有显著的抑制作用;Na＋、Cl-、NO3-、SO42-对光催化降解的影响均不明显,有些离子的影响机制有待进一步研究.     

光催化降解甲基橙过程的评价方法研究

以300W汞灯为光源,纳米TiO2为光催化剂,甲基橙为目标降解物,以分光光度法测定其脱色率,以重铬酸钾法测定其COD降解率,研究了在不同溶液pH值、甲基橙初始浓度及TiO2投加量等条件下的甲基橙光催化降解效率．结果表明,甲基橙溶液脱色率和COD降解率并不一致,脱色比COD降解更容易发生;将脱色率、COD降解率等指标的变化综合考虑,才能更全面准确地判断光催化反应的效率．     

铁改性蒙脱石/UV-Fenton系统对橙黄G的氧化脱色性能研究

基于当前各种偶氮染料废水的生物难降解问题,以廉价的粘土矿物蒙脱石（Mt）作为一种分散相,成功制备了聚羟基铁阳离子插层改性蒙脱石（简称Fe-Mt）。采用批处理吸附与脱色实验方法,研究Fe-Mt的催化光-Fenton氧化OG脱色性能,并着重考查了初始p H值对光-Fenton氧化偶氮染料橙黄G（OG）脱色的效应。此外,考查铁改性蒙脱石的工艺稳定性。获得的结果表明：在较强的酸性介质条件下（p H=2~3）,Fe-Mt催化的紫外光光-Fenton氧化OG脱色效果最佳,比如在某优化工艺条件下,60 min内浓度为50 mg/L的OG经光-Fenton氧化的脱色率几乎达到100%。铁改性蒙脱石/光-Fenton系统氧化性能很好及工艺稳定,因而在染料处理方面具有广泛的应用前景。     

辣根过氧化物酶催化H2O2氧化橙黄Ⅱ的降解研究

研究了pH值、温度、反应时间、过氧化氢用量、染料初始浓度等对辣根过氧化物酶（HRP）催化过氧化氢氧化降解橙黄Ⅱ染料溶液的影响.结果表明在pH值为2、温度为43℃、反应时间为12 min、H2 O2用量为2.0 mmol·L-1、染料初始浓度0.8 mmol·L-1时橙黄Ⅱ的降解最为理想,脱色率可达到83.7％.     

基于Powell算法的改进微粒群算法

提出一种与Powell算法相结合的新型改进微粒群算法——Powell-PSO.改进算法将粒子的搜索过程分为两阶段,第一阶段,将标准微粒群算法的速度公式加以改进进行搜索;第二阶段,将第一阶段的最后一代粒子作为Powell算法的初始点,让Powell算法与PSO算法交替进行.这样既克服了微粒群算法陷入局优的缺点,也大大提高了算法的求解精度,同时提高了收敛速度并保持了微粒的多样性.仿真结果表明：与标准微粒群算法相比,Powell-PSO具有较高求解精度和较强寻优能力,并且不论是对单峰还是多峰函数都能取得较好的优化效果.