2-chlorophenol oxidation kinetic by photo-ssisted Fenton process

IntroductionTheo chlorophenolisaverytoxicandpoorlybiodegradablepollutant,whichisusedasanintermediateinthemanufactureofhigherchlorophenolandphenolresinsandforextractingsulphurandnitrogencompoundsfromcoals.Itisalsousedinorganicsynthesis(dyesandpesticide) .Oxidationofo chlorophenolwastewaterincatalyticwetairoxidationisofpracticalinterestsinceawastewatercontainingo chlorophenolover 2 0 0ppmmaynotbetreatedeffectivelybydirectbiologicalmethods.Advancedoxidationprocesses(AOPs)havebeensuccessfullyuse…     

NDA-100大孔树脂对水溶液中水杨酸的吸附行为研究

通过静态吸附试验，研究了NDA－100大孔树脂对水溶液中水杨酸的吸附动力学及热力学特性，结果表明吸附符合一级动力吸附方程，颗粒内扩散过程是影响吸附速率的主要控制步骤，吸附符合Langmuir和Freundlich等温吸附方程，吸附为放热的物理吸附过程。     

The study for polyaromatic hydrocarbons decay on Chinese coal soot particles in atmosphere

A study for the photochemical behavior of some polyaromatic hydrocarbons (PAH), for example B(a )P, B( k )F and fluoranthene in coal smoke particles was performed by using indoor Teflon smog chamber.Experiments suggest that the photochemical reaction of PAH is first order reaction and kinetic rates of some PAH were obtained. It was shown that the reaction rate constant is proportional to light intensity and water vapor concentration. Temperature and PAH loading also have influence on PAH decay rate. A model for PAH loss has been set up on the basis of the results of our experiments and the simulating results of this model suggest that coal particle PAH half lives are of the order of a period of days in winter and a few hours in summer. Other factors which may have effect on the photochemical reaction of PAH have also been discussed.     

2-Chlorophenol oxidation kinetic by photo-assisted Fenton process

Experimental data are presented to test and validate a kinetic model for the oxidation of 2-chlorophenol wastewater by photo-assisted Fenton process. The data showed that this process had produced good effects under acidic conductions. Up to 90% 2-chlorophenol was removed after 90-minute reaction time with H2O2 of 25% CODCr. in, while in UV/H2O2 system ordy 16.8% 2-chlorophenol was removed after one hour treatment. The optimal pH in this reaction occurred between pH 3.0 and pH 4.0. The reaction kinetics for photo-assisted Fenton process experimented in this research was investigated. Kinetic models were proposed for the treatment of 2-chlorophenol wastewater. The reaction was found to follow the 2nd order. The equations of reaction kinetics are as follows:-d[RH]/dt=KRH[RH][H2O2]0exp(-KH2o2t);-d[CODCr]/dt=KCODCr[CODCr][H2O2]0exp(-K′t).The prediction of the models was found to be in a good agreement with experimental results, thus confimfing the proposed reaction mechanism.     

Kinetic-spectrophotometric determination of free cyanide by stopped-flow reversed flow injection analysis

A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.     

再燃脱硝的动力学模拟和组分影响分析

采用Gear算法模拟了再燃脱硝再燃区中化学反应过程，反应的热力学和动力学参数采用GRI3．0,模拟结果和实验结果作比较，说明该模拟可以用于预测再燃脱硝的基本过程。在模拟的基础上讨论了不同再燃燃料及其中的不同组分如HCN、NH3、H2和CO等对脱硝效果的影响。     

Denitrification potential enhancement by addition of external carbon sources in a pre-denitrification process

The aim of this study is to investigate the denitrification potential enhancement by addition of external carbon sources and to estimate the denitrification potential for the predenitrification system using nitrate utilization rate （NUR） batch tests. It is shown that the denitrification potential can be substantially increased with the addition of three external carbon sources, i.e. methanol, ethanol, and acetate, and the denitrification rates of ethanol, acetate, and methanol reached up to 9.6, 12, and 3.2 mgN/（g VSS.h）, respectively, while that of starch wastewater was only 0.74 mgN/（g VSS,h）. By comparison, ethanol was found to be the best external carbon source. NUR batch tests with starch wastewater and waste ethanol were carried out. The denitfification potential increased from 5.6 to 16.5 mg NO3-N/L owing to waste ethanol addition. By means of NUR tests, the wastewater characteristics and kinetic parameters can be estimated, which are used to determine the denitrification potential of wastewater, to calculate the denitrification potential of the plant and to predict the nitrate effluent quality, as well as provide information for developing carbon dosage control strategy.     

Dissipation of chlorpyrifos in pakchoi-vegetated soil in a greenhouse

The dissipation of chlorpyrifos in pakchoi-vegetated soil was investigated in the summer and autumn in a greenhouse and field, respectively. The dissipation of chlorpyrifos in pakchoi-grown soil was comparatively described by fitting the residue data to seven models （lst-order, 1.5th-order, 2nd-order, RF lst-order, RF 1.5th-order, RF 2nd-order, and bi-exponential or two-compartment models）. Statistical analysis was performed using the SPSS 11.5 statistical package. The bi-exponential model was selected as the optimal model according to the coefficient of determination r^2. The dissipation half-lives （DT50） of chlorpyrifos in pakchoi-vegetated soil at the recommended dose in the summer and autumn, calculated by the bi-exponential model, were 0.6 and 1.2 d in a greenhouse, 0.4 and 1.0 d in a field, respectively; the corresponding values at double dose were 1.2 and 2.1 d in a greenhouse, 0.5 and 1.3 d in a field, respectively. The kinetic data indicate the dissipation of chlorpyrifos in pakchoi-grown soil in a greenhouse is slower than that in a field, and dissipates slower in the autumn than in the summer.     

气动絮凝动力学机理探讨及试验分析

对气动絮凝动力学机理进行进一步探讨,并在设定的絮凝条件下,进行试验室小试,分析气动絮凝对浊度、COD等污染指标的去除效果和提高溶解氧的意义,并简单比较了其气动絮凝与机械絮凝的差异。通过机理探讨和试验效果分析,展望气动絮凝方式进行污水强化一级处理的研究方向。     

氯化钠抑制下乙酸厌氧降解的动力学模型

作者利用五个实验室规模的完全混合反应器进行较长时间的半连续培养,研究在氯化钠抑制下乙酸盐的厌氧降解。结果表明,在不同条件下运行的反应器内,存在优势菌群的显著差异,因此在不同条件下运行的反应器对抑制有不同的响应。作者引入抑制因子的概念,建立了在氯化钠抑制下乙酸厌氧降解的动力学模型。同时指出反应器运行条件与菌群组成的联系以及菌群组成的差别对反应器运行状况的影响,在废水生物处理的动力学模型研究中应给予足够的重视。