Catalytic oxidation of phenol in wastewater-A new application of the amorphous Fe78Si9B13 alloy

The amorphous Fe78Si9B13 alloy was used as a heterogeneous Fenton catalyst in the process of phenol degradation.The influences of main operating parameters such as reaction temperature,catalyst amount,hydrogen peroxide dosage and initial pH of solution on phenol degradation rate were investigated.The maximum mineralization of phenol was achieved at 60°C,6 g/L Fe78Si9B13, 0.31 mol/L hydrogen peroxide,with an initial pH of 2.5.More than 99%of phenol was completely removed under the optimum conditions within 10 min for a solution containing 1000 mg/L of phenol.Batch experiments for solutions containing phenol con- centrations ranging from 50 to 2000 mg/L were investigated under the above conditions and the same excellent degradation rate was obtained.The Fe78Si9B13 showed better catalytic activity than iron powder and Fe 2+ .Addition of n-butannol(hydroxyl radical scavenger)decreased the degradation rate of phenol,which demonstrates that hydroxyl radicals were mainly responsible for the removal of phenol.We demonstrated that phenol may be degraded by hydroxyl radicals decomposed by hydrogen peroxide on the surface of Fe78Si9B13 and illustrated the reaction mechanism for this process.This amorphous alloy exhibited high stability in recycling experiments and showed excellent reuse performance even after continuous operations of 8 cycles.     

Degradation of the antibiotic sulfamonomethoxine sodium in aqueous solution by photo-Fenton oxidation

In this study, photo-Fenton oxidation was applied to degradation of sulfamonomethoxine sodium (SMMS) in aqueous solution. The operation parameters of pH, temperature, and concentrations of H2O2, Fe2+ and SMMS were investigated. The optimum conditions for the photo-Fenton process were determined as follows: [SMMS]=4.53 mg/L, pH 4.0, [H2O2]=0.49 mmol/L, [Fe2+]= 19.51 μmol/L and T=25°C. Under these conditions 98.5% of the SMMS degraded. The kinetics were also studied, and degradation of SMMS by the photo-Fenton process could be described by first-order kinetics. The apparent activation energy was calculated as 23.95 kJ/mol. Mineralization of the process was investigated by measuring the chemical oxygen demand (COD), and the COD decreased by 99% after 120 min. This process could be used as a pretreatment method for wastewater containing sulfamonomethoxine sodium.     

Energy consumption of electrooxidation systems with boron-doped diamond electrodes in the pulse current mode

A pulse current technique was conducted in a boron-doped diamond (BDD) anode system for electrochemical wastewater treatment. Due to the strong generation and weak absorption of hydroxyl radicals on the diamond surface, the BDD electrode possesses a powerful capability of electrochemical oxidation of organic compounds, especially in the pulse current mode. The influences of pulse current parameters such as current density, pulse duty cycle, and frequency were investigated in terms of chemical oxygen demand (COD) removal, average current efficiency, and specific energy consumption. The results demonstrated that the relatively high COD removal and low specific energy consumption were obtained simultaneously only if the current density or pulse duty cycle was adjusted to a reasonable value. Increasing the frequency slightly enhanced the COD removal and average current efficiency. A pulse-BDD anode system showed a stronger energy saving ability than a constant-BDD anode system when the electrochemical oxidation of phenol of the two systems was compared. The results prove that the pulse current technique is more cost-effective and more suitable for a BDD anode system for real wastewater treatment. A kinetic analysis was presented to explain the above results.     

Different Performances of H2O2 to Oxidise Aldicarb and Hexazinone in the Advanced Oxidation Process of Ozone/Hydrogen Peroxide

The degradations of hexazinone and aldicarb by direct ozonation combined an advanced oxidation process（ AOP） of O3/H2O2 were investigated in this study focusing on the oxidation mechanism by identifying the hydrogen peroxide consumption during the oxidation process of the two chemicals. The results showed that H2O2 could enhance the removal rate of the triazine herbicide hexazinone,and it was consumed along with the variation of removal rate in the light of different pH levels. The addition of H2O2 contributed little to the removal of the thiocarbamate herbicide aldicarb and H2O2 content kept constantly throughout the degradation process. Tert-butyl alcohol（ TBA） effectively scavenged the ·OH radical for hexazinone,but had no effect on the removal rate of aldicarb. Aldicarb removal was mainly attributed to direct ozonation molecule in both O3（ 97.00%） and O3/H2O2（ 96.76%）systems. Moreover,sole O3 could hardly oxidize hexazinone whereas·OH radicals contribute respective 74.70% and 97.50% of removal in O3 system and O3/H2O2 AOP. All of these findings suggest that the mechanism of ·OH radical generation and the chain reaction in O3/H2O2 AOP should be further discussed.     

Heterogeneous UV／Fenton catalytic degradation of wastewater containing phenol with Fe－Cu－Mn－Y catalyst

The heterogeneous UV/Fenton process with the appropriate amount of Fe-Mn-Cu-Y as catalyst was developed and various operation conditions for the degradation of phenol were evaluated. The results indicated that by using the heterogeneous UV/Fenton process, the CODer removal rate reached almost 100% for wastewater containing phenol. Compared with the homogeneous process, the developed catalyst could be used at wider pH range in the UV/Fenton process. Comparison of various heterogeneous process showed that heterogeneous UV/Fenton process was best. The heterogeneous UV/Fenton process with Fe-Mn-Cu-Y catalyst is highly efficient in degrading various organic pollutants.     

Dechlorination of 2,4-dichlorophenol by nickel nanoparticles under the acidic conditions

Metal nanoparticles are effective for remediation of contamination with a range of compounds including chlorinated organics.However,the sorption process of the passivation oxide layers on the metal nanoparticle surfaces may result in incomplete degradation of contaminants.This phenomenon can be prevented by an acidic washing procedure or reaction in an acidic medium.In this paper,nickel nanoparticles manufactured via the carbonyl powder process were analyzed using scanning electron microscopy,transmission electron microscopy,X-ray diffraction and energy-dispersive X-ray spectroscopy.The sorption and degradation of 2,4-dichlorophenol (2,4-DCP) by nickel nanoparticles under acidic conditions was then investigated.Transmission electron microscopy and XRD results showed that the nickel nanoparticles range in size from 10 to 20 nm,and a thin passivation layer of NiO is present on the surface.This oxide layer can be removed by pretreatment washing with acidic solutions.It was indicated that dechlorination was the key reaction pathway for degradation of 2,4-DCP by nickel nanoparticles under acidic conditions.The main degradation products were 4-Chlorophenol,2-Chlorophenol,and Phenol,and among these,Phenol was dominant.The acidic medium promoted degradation by providing an appropriate pH,and H+ may be involved in the reaction.Dechlorination of 2,4-DCP by nickel nanoparticles under the acidic condition follows the second order kinetic model,and the rate constants at 298,306,316 K are 0.02,0.2 and 0.3 (g L h)-1,respectively.     

Performance of Sequencing Biofilm Batch Reactor（SBBR） under Micro-aerobic Condition for Aniline-Contaminated Wastewater Treatment

The performance of sequencing biofilm batch reactor（ SBBR） under micro-aerobic condition for aniline-contaminated wastewater treatment was investigated in this study. Dissolved oxygen（ DO） and aniline concentrations were selected as the operating variables to analyze,model,and optimize the process. In order to analyze the process,5 dependent parameters,chemical oxygen demand（ COD）,aniline,ammonium,total nitrogen（ TN）,and total phosphorous（ TP） removal as the process responses were studied. From the results, increase in DO concentration could promote the removal of COD,aniline,ammonium,and TN,while increase in aniline concentration has a slightly negative impact on the removal of pollutants. The optimum DO concentration was found to be 0. 4-0. 5 mg /L. The removal efficiencies for COD,aniline,ammonium,and TN at the optimum point（ DO concentration0. 5 mg /L,aniline concentration 11 mg /L） were 95. 84%,100%,75. 72%,and 45. 39%,respectively. The oxidative deamination was the main degradation method for aniline under micro-aerobic condition. Simultaneously nitrification-denitrification（ SND）process performed under micro-aerobic condition and about 20%-40% nitrogen was removed by SND.     

Effects of Influencing Factors on Fenton Oxidation of Antibiotic Pharmaceutical Wastewater by a Statistical Design Approach

A series of batch-scale experiments were completed to investigate the effects of operational parameters on chemical oxygen demand (COD) removal by Fenton reagent for antibiotic pharmaceutical wastewater (APW). The significance of five operational factors including the mass ratio of H2O2/COD (g/g), the mole ratio of H2O2/Fe2+ (mol/mol), initial pH, oxidation temperature T, and reaction time t were evaluated statistically by Box-Behnken design (BBD). It was found that the five parameters were all significant to the COD removal efficiency by t-test, as well as the interactions between mass ratio/reaction time and oxidation temperature/reaction. The optimal COD removal efficiency (89.50%) was achieved when the mass ratio of H2O2/COD and the mole ratio of H2O2/Fe2+ were 3.00 and 5.00 respectively, with pH value of 3.68 at 298K for 72min reaction. A quadratic regression model with 0.9907 regression coefficient (R2) was developed which had good agreement to the experimental data.     

Visible light-induced degradation of organic pollutants using Fe（ll） supported on silica gel as an effective catalyst

Silica gel-supported Fe（ll） （SiOFe） was prepared and used for heterogeneous degradation of sulforhodamine B （SRB） and 2,4-dichlorophenol （DCP） under visible irradiation （λ 〉 420 nm） as an effective catalyst. UV-visible spectra, and infrared Spectrophotometry （IR）, fluorescence, total organic carbon （TOC） and electron spin resonance （ESR） measurements were employed to analyze the photoreaction products. The results showed that SRB could be efficiently degraded by SiOFe/H2O2 system under visible irradiation with 100% decolorization and 72.3% TOC removal after 180 min illumination. The results of ESR and fluorescence measurements indicated that the oxidative process was predominated mainly by the hydroxyl radical （.OH） generated in the system.     

Photocatalytic degradation kinetics of Rhodamine B catalyzed by nanosized TiO<Subscript>2</Subscript> film

A fixed bed photocatalytic reactor was designed,and dynamic fast scan of UV-Vis adsorption spectrum was adopted to study the photocatalytic degradation dynamic behavior of Rhodamine B,a kind of dye generally recognized as to be degraded difficultly ,on the surface of nanosized TiO2 thin film,The results indicate that the photocatalytic degradation process of Rhodamine B does not comply with the first-order reaction kinetic process ,As a result,a kinetic model of Rhodamine B photocataly tic degradation ,reaction is brough forward ,and the model is proved by the theoretical deduction and experiment.     

催化氧化法处理对氯硝基苯(PCNB)废水的研究

以活性炭为催化剂，H2O2作氧化剂催化氧化降解对氯硝基苯(PCNB)，结果表明，在H2O2／CODcr=1．2，活性炭／H2O2=0．4，pH=3．0的条件下，反应可在180min结束，PCNB的去除率高于99％，CODcr去除率可达80％，与Fenton试剂法相比较，CODcr去除率提高1．78倍，并对降解机理作了初步讨论。     

活性炭-H2O2催化氧化处理垃圾渗滤液的试验研究

处理垃圾渗滤液试验以活性炭作催化剂、H2 O2 作氧化剂。结果表明 ,在H2 O2 /COD0 =1 .5 ,活性炭 /H2 O2 =0 .6,pH值为 2的条件下反应可以在 1 80min内结束 ,其中COD及色度的去除率分别为 82 .8%和 85 .5 % ,臭味消失 ,比Fenton试剂法处理渗滤液效果要好 ,并对氧化机理进行了初步探讨     

活性氧-臭氧联用处理含酚废水

用羟基自由基活性氧与臭氧联合使用处理含酚废水,并在电磁波作用下对含酸废水进行了研究,考察了活性氧药剂投加量和反应时间对苯酚去除率和COD去除率的影响,并对这些方法的处理效果进行了比较分析。结果表明,活性氧药剂与臭氧联用,并辅以微波能场的方法处理含酸废水表现出了明显的优势,具有最好的处理效果。对于浓度为0.500g/L的含酚废水,在处理时间为5min的条件下,苯酚去除率达到98.23%,COD去除率达到68.12%。     

UV/Fenton法处理水中苯酚的研究

通过大量试验，确定了UV/Fenton法处理水中苯酚的最佳条件。pH为3.0，[H     

Kinetics of aerobically activated sludge on terylene artificial silk printing and dyeing wastewater treatment

Aerobically activated sludge processing was carried out to treat terylene artificial silk printing and dyeing wastewater (TPD wastewater) in a lab-scale experiment, focusing on the kinetics of the COD removal. The kinetics parameters determined from experiment were applied to evaluate the biological treatability of wastewater. Experiments showed that COD removal could be divided into two stages, in which the ratio BOD/COD (B/C) was the key factor for stage division. At the rapid-removal stage with B/C>0.1, COD removal could be described by a zero order reaction. At the moderate-removal stage with B/C<0.1, COD removal could be described by a first order reaction. Then Monod equation was introduced to indicate COD removal. The reaction rate constant (K) and half saturation constant (K(S)) were 0.0208-0.0642 L/(gMLSS).h and 0.44-0.59 (gCOD)/L respectively at 20 degrees C-35 degrees C. Activation energy (E(a)) was 6.05 x 10(4) J/mol. By comparison of kinetic parameters, the biological treatability of TPD wastewater was superior to that of traditional textile wastewater. But COD removal from TPD-wastewater was much more difficult than that from domestic and industrial wastewater, such as papermaking, beer, phenol wastewater, etc. The expected effluent quality strongly related to un-biodegradable COD and kinetics rather than total COD. The results provide useful basis for further scaling up and efficient operation of TPD wastewater treatment.     

A~2/O工艺抗焦化厂区废水负荷波动能力研究

为研究A2/O工艺对焦化产区废水处理效果以及该工艺抗负荷波动能力,选取贵阳某焦化厂区废水4个主要特征指标(COD、NH3-N、挥发酚、总氰化物)进行了系统的研究.结果表明:A2/O工艺对COD、NH3-N、挥发酚的去除效果良好,单一的A2/O工艺对废水中的总氰化物去除效果一般,约为10;左右,但A2/O工艺-芬顿试剂联用技术对总氰化物去除效果良好.另外,当系统中进水的COD负荷波动为100; ～ 148;时,其平均去除率在87;以上;当NH3-N负荷波动为100; ～ 152;时,其平均去除率在95;以上;当挥发酚负荷波动为100; ～ 353;时,其平均去除率在97.8;以上;当总氰化物负荷波动为100; ～ 139;时,其平均去除率在93;以上.这表明A2/O工艺具有良好的抗击负荷波动能力,适合焦化厂区废水处理.