含酚废水电化学处理动力学研究

以实验研究为基础,探讨了含酚废水电化学处理的动力学规律,分析了曝气量、电解电压和支持电解质浓度对反应速率的影响。研究表明：污染物的电解氧化反应过程符合表观一级反应动力学规律,电解电压对电化学处理反应速率影响较大,而曝气量和支持电解质浓度对反应速率影响相对很小。     

硼掺杂金刚石膜电极电氧化降解对氯苯酚废水

采用循环伏安法研究了中性介质中对氯苯酚在硼掺杂金刚石(BDD)膜电极上的电氧化行为。提出了一种以BDD膜电极为阳极的电化学氧化降解对氯苯酚废水的新工艺,考察了阳极电流密度、对氯苯酚初始浓度、电解液初始pH、支持电解质浓度等工艺因素对电氧化降解效果的影响。结果表明:在阳极极化电位为1.4～1.6V(vs.SCE)时,对氯苯酚在BDD膜电极表面发生直接电氧化反应,生成易吸附的中间产物,导致电极活性降低;在阳极极化电位高于2.0V(vs.SCE)时,BDD膜电极能够良好地电氧化降解对氯苯酚溶液,该过程是通过直接电氧化过程与间接电氧化过程联合作用实现的。通过考察若干工艺因素对对氯苯酚电氧化降解效果的影响发现,较为理想的工艺参数组合为,阳极电流密度60mA·cm-2、支持电解质浓度10g·L-1、对氯苯酚初始浓度10mmol·L-1、电解液初始pH7。在该工艺条件下,COD去除率达到96.1%,平均电流效率为50.2%。高效液相色谱证实了BDD膜电极能有效地电氧化降解对氯苯酚。     

电化学氧化降解磺胺嘧啶模拟废水的工艺优化

在无隔膜电解槽中,以NaCl为电解质,利用形稳阳极(DSA)产生的羟基自由基(·OH)和原位电生成的活性氯氧化降解磺胺嘧啶(Sulfadiazine,SD)模拟废水。通过高效液相色谱分析SD及其产物含量变化,水杨酸捕集羟基自由基法测定·OH的浓度,探讨工艺参数对·OH、氯离子、余氯、总氯和总有机碳(TOC)去除率的影响。结果表明,反应10 min后SD去除率达100%,反应4 h后溶液TOC明显下降;反应4 h后,pH=3、4、8、8.5、10和12的反应体系中TOC去除率分别为29%、46%、55%、61%、52%和47%,峰值出现在pH=8.5时;提高电流密度、电解质NaCl浓度及降低SD初始质量浓度可增大TOC去除率。该实验最优工艺条件为:pH=8.5,外加NaCl 0.025 mol/L,电流密度20 mA/cm2,初始质量浓度100 mg/L SD,经4 h的电化学氧化降解,TOC去除率达到66%。     

原位红外光谱法研究碱性溶液中对氯苯酚电还原反应

采用循环伏安和原位红外光谱技术,研究了对氯苯酚（4-CP）在碱性体系中的电化学还原反应。对氯苯酚在Ag电极、Pt电极和GC电极上的循环伏安行为表明,Ag电极对4-CP有较好的电还原活性,能在较正的电位下还原4-CP。通过原位红外光谱技术对4-CP在Ag电极上的电还原机理的初步探讨,结果表明4-CP首先在电极表面形成自由基负离子,随着电位的进一步负移,生成苯酚负离子,从而实现4-CP电化学脱氯降解的目标。     

支持电解质对酸性大红染料废水电解的影响

通过静态试验对比研究了模拟酸性大红3R染料废水在NaCl和Na2SO4体系中的电化学氧化过程,考察了电流密度、电解质浓度和初始pH对色度去除效果的影响,比较了两种电解质对染料废水的处理效果。结果表明,在不同支持电解质体系中,电流密度、电解质浓度和初始pH对染料废水脱色作用的影响具有基本相同的规律;在不同支持电解质体系中,染料废水降解效果差别很大,以NaCl为支持电解质时的脱色率明显高于以Na2SO4作为支持电解质。     

电化学氧化处理对苯二酚废水的试验研究

选用石墨为阳极,不锈钢为阴极构成二维电极降解对苯二酚模拟废水.利用正交试验考察了各种条件对苯二酚去除效果的影响,并分析了对苯二酚的降解过程.当电解质的浓度为0.04mol·L~(-1)、电压为8V、pH为8.5时,对苯二酚去除效果最好,可达到90.44%.电压对有机物去除影响显著,在中性以及弱酸弱碱条件下有机物去除比较稳定,电解质对有机物去除影响较小.对苯二酚在电化学催化系统中的降解过程很好地符合了1级反应模型;在最佳试验条件下,去除对苯二酚的速率常数k_1为0.017 9 min~(-1).     

NaClO氧化去除高盐废水中氨氮的影响因素及其动力学研究

采用NaClO氧化降解高盐废水中的氨氮,对其影响因素及动力学进行研究。结果表明:NaClO对氨氮的氧化降解过程符合伪一级反应动力学模型,影响其降解效果的因素有NaClO的投加量、氨氮的初始浓度、盐分、温度等。当NaClO投加量为0.6%时,反应速率常数高达0.015 75 min~(-1)。氨氮初始浓度越大,氧化反应效果越差,且初始质量浓度不超过45 mg/L时,随着初始浓度的增加,其对氧化反应速率常数的影响增大。低浓度盐分对氨氮氧化基本无影响,但超过2.0%时,随着盐分的增加,其对氨氮氧化效果的抑制作用增强,反应速率常数明显降低。提高反应温度,有利于氨氮的氧化降解,当温度从10℃增加至35℃的过程中,反应速率常数从0.001 88 min~(-1)增加至0.010 43 min~(-1)。     

阳极电化学氧化降解水体中酚的研究

研究了不同种类支持电解质阳极氧化降解水体中的苯酚时,电解质种类与浓度、电流密度、苯酚初始浓度等对苯酚去除率、槽电压和COD去除率的影响。结果表明:支持电解质对COD的去除率影响较大。苯酚的去除率和去除速率顺序为碱(NaOH)>盐(Na2SO4)>酸(H2SO4),COD的去除率和去除速率顺序为酸(H2SO4)>盐(Na2SO4)>>碱(NaOH)。碱性条件有利于苯酚的电化学转化,酸性条件有利于苯酚的彻底氧化处理。在一定的条件下,使用各类电解质,苯酚的最大去除率均能接近100%。当支持电解质H2SO4的浓度为0.1mol/L、苯酚初始浓度为200mg/L、电流密度为0.03A/cm2、温度为25℃、阳极氧化进行550min时,COD的去除率达70%。     

碳基含铁催化剂催化过氧化氢氧化去除对氯苯酚的试验研究

为了考察自研发的一种低成本、制作简便的碳基含铁新型催化剂(简称HACO-P型)的催化氧化性能,以对氯苯酚(4-CP)为对象,研究其催化H2O2降解水中4-CP的效果及影响因素.对HACO-P进行形貌表征,结果表明其表面多孔、具有巨大比表面积.单独考察了HACO-P对4-CP的吸附性能并进行了等温线拟合,发现其最大吸附容...     

Sb-SnO2/Ti电极对对硝基苯酚电催化氧化影响因素和机理研究

以自制掺锑二氧化锡涂层电极为阳极,钛板为阴极,进行了对硝基苯酚溶液的电催化氧化降解试验.系统研究了pH、溶液温度、对硝基苯酚初始浓度、电解质浓度、电流密度等因素对电催化氧化降解效果的影响,并对氧化降解历程进行了讨论.结果表明,pH为3、温度为30℃、电流密度为20mA·cm-2,Na2SO4电解质浓度为0.2 mol·L-1时,对硝基苯酚去除率和TOC的去除率都较高;对硝基苯酚的电催化氧化反应属于电化学燃烧过程.     

Electrooxidation of dyestuffs in waste waters

An electrochemical oxidation cell is used to reduce the concentrations of organic dyes and chemical oxygen demand in an aqueous effluent. The importance of the presence of an electrolyte is recorded and the effects of changing both electrolyte concentration and initial dye concentration are reported. The rate of the electrooxidation process is shown to be a pseudo-first-order kinetic process with the rate constant being affected by both the electrolyte concentration and the dye concentration. The use of different electrolytes is reported.     

罗丹明B的声化学反应速率研究

选择了水溶液中的罗丹明B的声化学反应为研究体系,探讨了超声频率为19.6 kHz时,罗丹明B声化学反应的速率规律。结果表明,在实验条件下,罗丹明B的声化学反应符合一级反应的动力学规律,反应速率常数随着超声功率的增加而增加,随着操作温度、罗丹明B的初始浓度和pH值的增加而减小,当罗丹明B的初始浓度为0.01 mmol/L,操作温度为35℃,超声功率为230 W,pH值从1.9变化到11.7时,其声化学反应速率常数从0.21 min-1变化到4.39×10-2min-1;曝气也能影响罗丹明B的声化学反应速率常数。     

Electrochemical degradation of aqueous phenols using graphite electrode in a divided electrolytic cell

Untreated industrial effluents invariably contain large amounts of heavy metals and organics. This paper reports the electrochemical oxidation of synthetic water containing 200 ppm of phenol. Studies have been carried out in a compartmentalized cell using platinum (cathode) and graphite (anode). Electrolysis has been done for 40 h at constant applied potential of 5 V in different electrolytes, such as, NaCl (aq), NaOH (aq) and a mixture containing both NaCl (aq) and NaOH (aq) as the anolyte and acid as the catholyte. Phenol concentration decreased from the initial value of 200 to about 10 ppm.; the corresponding COD values, respectively, are ∼400 to ∼100 ppm. The reaction goes through chloro-compounds as intermediates before being mineralized. The carbon anode seems to be passivated with a thin layer of poly-phenol. A concomitant amount of hydrogen is generated during the electrolytic degradation of phenol.     

亚甲蓝的声化学反应速率研究

选择了水溶液中亚甲蓝的声化学反应为研究体系,探讨了超声频率为19．6kHz时,亚甲蓝声化学反应的速率规律。实验结果表明,在实验条件下,亚甲蓝的声化学反应符合一级反应的动力学规律。亚甲蓝声化学反应速率常数随着超声功率的增加而增加,随着操作温度、亚甲蓝的初始浓度的增加而减小,催化剂Fe^2＋能增加亚甲蓝的声化学反应速率常数。pH值和曝气也能影响其声化学反应速率常数。     

对苯二甲酸-丁二醇催化单酯化反应动力学(英文)

The chemical kinetics of the monoesterification between terephthalic acid (TPA) and 1,4-butanediol (BDO) catalyzed by a metallo-organic compound was studied using the initial rate method. The experiments were carried out in the temperature range of 463-483 K, and butylhydroxyoxo-stannane (BuSnOOH) and tetrabutyl titanate [Ti(OBu)4] were used as catalyst respectively. The initial rates of the reaction catalyzed by BuSnOOH or Ti(OBu)4 were measured at a series of initial concentrations of BDO (or TPA) with the concentration of TPA (or BDO) kept constant. The reaction orders of reagents were determined by the initial rate method. The results indicate that the reaction order for TPA is related with the species of catalyst and it is 2 and 0.7 for BuSnOOH and Ti(OBu)4 respectively. However, the order for BDO is the same 0.9 for the two catalysts. Furthermore, the effects of temperature and catalyst concentration are investigated, and the activation energies and the reaction rate constants for the two catalysts were deter-mined.     

Degradation of Caffeine by Advanced Oxidative Processes: O3 and O3/UV

The degradation of caffeine by ozone was investigated in this article. In the laboratory experimental scale, the effect of pH, caffeine initial concentration, power UV light and reaction time were studied by experimental design. The use of response surface methodology (RSM) allowed to adjust the optimal regions of the parameters leading to the response factor (% mineralization). In addition, a single polynomial expression for modeling the reaction was obtained. Results clearly demonstrated that caffeine is quickly degraded, but not mineralized as quickly. The results indicated that the caffeine mineralization rate increased with pH and reaction time. Power UV light showed little effect on mineralization efficiency.     

星型高苯乙烯橡胶聚合及机理探讨

用阴离子聚合的方法合成了星型结构的高苯乙烯橡胶,对高苯乙烯橡胶的聚合反应动力学过程进行了研究,求得不同聚合温度、不同引发剂浓度下假一级表观增长反应速度常数kp"。并根据不同温度下的kp",求取了高苯乙烯橡胶聚合表观增长活化能Ep’=56.7 kJ/mol,高苯乙烯橡胶聚合反应动力学方程表明,聚合反应速率与单体浓度一次方、引发剂浓度1/2次方成正比关系。     

Indirect Electrochemical Oxidation of Phenol in the Presence of Chloride for Wastewater Treatment

Electrochemical oxidation of phenol using a Ti/TiO₂‐RuO₂‐IrO₂ anode in the presence of chloride as the supporting electrolyte was investigated. The experiments were performed in an undivided batch reactor. Preliminary investigations showed that only a small fraction of phenol was oxidized by direct electrolysis, while complete degradation of phenol was achieved by indirect electrochemical oxidation using chloride as a supporting electrolyte. The effect of operating parameters such as initial pH, supporting electrolyte concentration, phenol concentration, and charge input was studied using Box‐Behnken second order composite experimental design. The effect of current density on COD removal was studied separately. TOC removal and AOX formation were studied for selected conditions. It was found that the formation of chlorinated organic compounds was pronounced at the beginning of electrolysis, but it was reduced to lower levels by extended electrolysis.     

Kinetic study of chitosan degradation by an electrochemical process

The kinetics of chitosan degradation by an electrochemical process was studied in this work. The order of degradation reaction was determined according to the dependence of degradation rate constant on initial chitosan concentration. For electrochemical degradation of chitosan, the apparent rate constant varied inversely with initial chitosan concentration, suggesting that the degradation reaction was zeroth-order in chitosan concentration. The influence of experimental conditions on the degradation rate constant was also investigated in detail. The degradation rate constant increased with current density, acetic acid concentration, and temperature. The influence of temperature on the degradation rate was modeled using the Arrhenius equation and the activation energy was determined to be 14.16 kJ/mol under the experimental conditions examined. The variation of sodium acetate concentrations had a negligible influence on degradation rate of chitosan.