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1.
Dipti Prakasini Das Kulamani Parida Bhudev Ranjan De 《Journal of molecular catalysis. A, Chemical》2005,240(1-2):1-6
The photodegradation of phenol was studied in the aqueous solutions over titania pillared zirconium phosphate and titanium phosphate under solar radiation and compared with that of the UV-radiation (6 W low pressure Hg vapor lamp). This reaction was studied by varying different parameters such as catalyst dose, initial phenol concentration, pH of solution and irradiation time. The degradation rate of phenol was favourable under neutral pH condition. The degradation process approximately obeyed first-order kinetics with apparent rate of degradation constant increasing with decreasing the initial phenol concentration. 相似文献
2.
The effect of initial panipenem (CAS No. 87726-17-8) concentration on its degradation in an aqueous solution was investigated. The degradation of panipenem followed pseudo-first-order kinetics at all the pH values tested. However, in an acidic solution, the degradation rate increased with the initial panipenem concentration. On the other hand, in an alkaline solution, the degradation rate was not affected by its initial concentration. In an acidic solution, the plots of the first-order rate constants versus initial panipenem concentrations showed a linear relationship. Theoretically, the first-order rate constant is independent of the initial concentration, and therefore, the results suggested unusualness. We investigated the results obtained under acidic conditions in detail to find a very complex reaction mechanism: panipenem and its degradation products are factors causing the unusual increase in the degradation rate. Moreover, it was shown that the dissociation of the carboxyl group played an important role in the degradation of panipenem. 相似文献
3.
Liquid-phase degradation of chlorobenzene (CB), induced by contact glow discharge electrolysis under various reaction conditions,
such as, the initial solution pH, current intensity, volume of solution and iron salts was investigated. Experimental results
indicated that, in the absence of catalysts, the depletion of CB followed first-order kinetics, where the observed value of
the first-order rate constant ‘k’ is directly proportional to the applied current intensity and inversely proportional to the solution volume. Initial solution
pH had little effect on the value of k. HPLC and IC analyses showed that the major intermediate products were chlorophenols, phenol, organic acids and chloride
ions. During the treatment, a lot of hydrogen peroxide was formed. Role of Fenton’s reaction was examined. A reaction pathway
is proposed based on the degradation kinetics and the distribution of intermediate products. 相似文献
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5.
E. S. Bobkova E. S. Ivanova R. A. Nevedomyi A. V. Sungurova 《High Energy Chemistry》2014,48(5):346-349
The influence of discharge parameters and phenol concentration on the kinetics of phenol degradation in an aqueous solution by the action of direct-current discharge with an electrolyte cathode has been studied. The degradation rate constants of phenol as a function of its initial concentration at different discharge parameters and volumes of the treated solution have been obtained. The energy efficiency of the degradation process has been determined, and the dependences of the rate constants on the concentration, the discharge current, and the volume of the solution have been explained. 相似文献
6.
苯酚在含氯体系中的电化学氧化 总被引:2,自引:0,他引:2
以Ru-Ir/Ti三元电极作阳极电解处理苯酚废水,研究废水中Cl-初始浓度对处理效果的影响.结果表明,在一定的电解时间内,苯酚的电化学氧化符合一级动力学方程;废水中Cl-的初始浓度越大,苯酚完全被氧化所需的时间也越短,即其表观速率常数越大.苯酚在Cl-体系中降解的中间产物主要有4-氯苯酚,1-氯苯酚,2,4-二氯苯酚,2,6二氯苯酚,2,4,6-三氯苯酚及各种短链脂肪酸和氯代醇等;最终产物是CO2、CHCl2和CHCl3.电解中间体的生成和降解速率随废水中Cl-初始浓度的增加而增大.据此,导出苯酚在含Cl-体系中电化学氧化的反应途径. 相似文献
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8.
Rongliang Qiu Lin Song Yueqi Mo Dongdong Zhang Eric Brewer 《Reaction Kinetics and Catalysis Letters》2008,94(1):183-189
To investigate the influencing factors and the kinetics of photocatalytic degradation of phenol, experiments were carried
out using conjugated polymer poly(fluorene-co-thiophene) (PFT) sensitized TiO2 and ZnO under LED (light-emitting diode) lights of the wavelength of 450–475 nm. Influencing factors, such as initial phenol
concentration, photocatalyst dosage and pH value on the photocatalytic degradation of phenol were studied in detail. The reaction
kinetics was found to follow pseudo first-order law. 相似文献
9.
离子液体内耦合液膜迁移苯酚的研究 总被引:1,自引:0,他引:1
本文以N-甲基咪唑为原料,采用微波合成法,制备了疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF6),并将其作为液膜,对苯酚的内耦合液膜迁移进行了研究,考察了温度、搅拌速度、料液相酸度、初始浓度及解析相NaOH浓度等因素对苯酚迁移的影响,得出了最佳迁移条件:温度300 K,搅拌速度350 r/min,料液相pH为3.65,解析相NaOH浓度为0.8 mol/L.在最佳液膜条件下,对于10 mg/L苯酚溶液,迁移110 min,迁移率可以达到97.3%,膜相中有少量苯酚滞留.离子液体可循环使用. 相似文献
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11.
J. M. Doña C. Garriga J. Araña J. Pérez G. Colon M. Macías J. A. Navio 《Research on Chemical Intermediates》2007,33(3-5):351-358
Heterogeneous photocatalytic degradation of many organic pollutants, such as phenol and phenol derivatives, may be optimised if the catalyst surface saturation and the appearance and accumulation of non-photocatalytically degradable intermediates is avoided. It has been shown that under certain concentration threshold the highest degradation efficiencies are achieved. Over these concentrations, degradation rates become constant owing to the limited catalyst surface. By the dosage of the contaminant, currently in an aqueous solution, the process may be optimised, thus avoiding the formation of inert intermediates which may be more toxic than the parental compound. The effect of dosage on the photocatalytic degradation of phenol and phenol derivatives, such as salicylic acid and 4-aminophenol has been studied. Comparatively notably higher efficiencies have been obtained compared to those of the high initial single dose experiments (non-dosage), for which high initial concentrations of the organics resulted in the catalysts poisoning. Degussa P-25 and its combination with 13% (w/w) activated carbon, namely AC?TiO2, have been used as catalysts. Almost complete degradations are achieved at low dosage rates (1–2 pmm/min). At higher dosage rates, different processes such as catalyst poisoning predominate, resulting in lower degradation efficiencies. 相似文献
12.
Keggin型铜取代磷钨杂多阴离子可见光催化降解罗丹明B 总被引:3,自引:2,他引:1
以Keggin型铜取代杂多阴离子PW11O39Cu(Ⅱ)(H2O)5-[PW11Cu]为可见光催化剂,有机染料罗丹明B(RhB)为模型污染物,研究了在可见光照射下PW11Cu对RhB的可见光催化降解作用,提出了PW11Cu可见光催化作用的反应机理,同时考察了RhB初始浓度、PW11Cu初始浓度和溶液pH值对RhB光催化降解速率的影响。 实验结果表明,含有15.6 μmol/L PW11Cu+10 μmol/L RhB的水溶液在可见光照射下反应80 min,RhB的降解率达100%,总有机碳去除率约33%。 RhB的可见光催化降解服从准一级动力学方程,在RhB初始浓度为20、30和40 μmol/L的情况下,其表观一级速率常数分别为3.1×10-2、2.0×10-2和1.5×10-2 min-1。 相似文献
13.
Piyabutr Sunsap Dong-Joo Kim Tawatchai Charinpanitkul Kyo-Seon Kim 《Research on Chemical Intermediates》2008,34(4):319-329
TiO2 nanoparticles were produced in the diffusion flame reactor, and the size and anatase/rutile content of TiO2 were examined by a Particle Size Analyzer and X-ray diffraction, respectively. Increase in fuel/O2 ratio, initial concentration of TiCl4 or total gas flow rate causes the larger particle size and the higher rutile composition. The photocatalytic activities of
TiO2 powders were tested on the decompositions of phenol and toluene in the aqueous solution under UV irradiation. The degradation
rate increases as the TiO2 particle size decreases and as the initial concentration of phenol or toluene increases. The photodegradation rate of phenol
by TiO2 particles is higher than that of toluene at the same process conditions. The computational method was used to simulate the
gas temperature, velocity and species mass fractions inside the diffusion flame reactor during synthesis of TiO2 nanoparticles. The measured and simulated temperature results were compared on several positions above the burner and both
of them show good agreements. The typical contours of TiCl4, TiO2 mass fractions and gas velocities in flame reactor were presented. 相似文献
14.
A simple, inexpensive, and reproducible procedure is described for large-scale synthesis of highly stable nanocrystalline ZnS powders. Cysteine-capped ZnS nanocrystals (NCs) were produced by a colloidal aqueous synthesis, employing a ligand-competition mechanism in which sulfide was introduced into a preformed zinc-cysteine solution. The synthesis procedure resulted in highly concentrated ZnS NC solutions ( approximately 100 mM) which could be ethanol-precipitated, redissolved, and dried to produce fine powders stable for more than 30 months at 4 degrees C. The NC powders were readily dissolved in aqueous solvents to concentrations as high as 300 mM. ZnS NCs could be prepared without cysteine capping, but only at extremely dilute concentrations ( approximately 0.2 mM ZnSO(4)) as per Sooklal et al. J. Phys. Chem. 100, 4551 (1996). The 30-month-old ZnS NC powders retained their original optical and photocatalytic properties and could be handled much like routine shelf chemicals, unaffected by ambient air or moderate moisture and temperature. UV/vis absorption spectroscopy showed band gap energies (E(g)) ranging from 4.82 eV (257 nm lambda(max)) to 4.47 eV (277 nm lambda(max)) for ZnS samples prepared with 0.25-2.0 initial sulfide ratios (as compared to zinc). Samples stored at 4 degrees C for 30 months showed equivalent band gap energies and spectral profiles. The average NC particle size was estimated to be 6.08+/-0.76 nm by high-resolution transmission electron microscopy. Selected-area electron diffraction and X-ray diffraction analyses concurred in suggesting a hexagonal crystal structure, with diffractions near d=3.1, 1.9, and 1.6 ?. The average NC composition of size-fractionated samples was estimated to be Cys(1)Zn(7)S(6). p-Nitrophenol, a model organic, was photocatalytically degraded using 30-month-old ZnS NC powders dissolved in an aqueous buffer. Rates of degradation (first-order rate constant k=0.261 min(-1); t(1/2)=2.66 min) were comparable to those of experiments using freshly prepared ZnS NCs (first-order rate constant k=0.247 min(-1); t(1/2)=2.80 min), further demonstrating the long-term stability of thus-produced NC powders. Copyright 2000 Academic Press. 相似文献
15.
JIN Xiaoyuan LI Aiming CHEN Jinlong ZHANG Quanxing State Key Laboratory of Pollution Control Resources Reuse School of the Environment Nanjing University Nanjing China 《Chinese Journal of Reactive Polymers》2002,(2)
1. INTRODUCTION Nitrophenols are versatile raw materials in chemical industry and used in a great diversity of applications such as herbicides, insecticides and bactericides. Due to their extreme toxicity and adverse effect upon human and biota at very l… 相似文献
16.
采用自制的Bi2O3及氮掺杂Bi2O3(N-Bi2O3)光催化剂,以卤钨灯为光源,在可见光下对2,4-二氯酚进行光催化降解.结果表明,N-Bi2O3较Bi2O3具有更高的可见光催化活性.当N-Bi2O3光催化剂投加量为2.0 g/L、2,4-二氯酚初始浓度为20 mg/L和pH =7时,光催化反应320 min,2,4-二氯酚的降解率最高可达到91.5%.2,4-二氯酚的光催化反应初活性与其浓度之间的关系符合Langmuir-Hinshelwood动力学速率模型.对降解过程中总有机碳及Cl-测试结果表明,N-Bi2O3光催化剂能较好地完成对2,4-二氯酚的深度矿化及脱氯. 相似文献
17.
Gang Xu Tingting Bu Minghong Wu Jisan Zheng Ning Liu Liang Wang 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):759-764
The degradation characteristics of clopyralid irradiated by electron beam (EB) was studied in aqueous solutions. The effects of factors, such as initial clopyralid concentrations, addition of radicals scavenger, initial solution pH and addition of H2O2, were investigated on clopyralid degradation efficiency and mechanism. It was found that the EB-radiolysis was an effective way to degrade clopyralid and its degradation rate decreased with the increasing of substrate concentration. In the investigated initial concentrations range of 100?C400 mg L?1, the radiolytic degradation of clopyralid followed a pseudo-first kinetic order. The results from addition of radicals scavenger indicated that both ?OH and e aq ? played significant roles in the degradation of clopyralid. Furthermore, the alkaline condition and addition of H2O2 (<10 mM) in the solution also slightly enhanced the efficiency of clopyralid degradation. The ion chromatography analysis showed that some organic acids (formic acid, acetic acid and oxalic acid) were formed, while the completely dechlorination of the substrate was achieved and organic nitrogen was recovered in the form of ammonium and nitrate ions during the irradiation process. 相似文献
18.
The degradation of 4-chlorophenol (4-CP) by using gamma rays generated by a 60Co source in the presence of O3 was investigated. The radiolysis of 4-CP and the kinetics of 4-CP mineralization were analyzed based on the determination
of total organic carbon (TOC). The influence of initial 4-CP concentration and the free radicals scavengers (such as NaHCO3 and t-butanol) on the 4-CP degradation was also studied. The results showed that when the radiation rate was 336 Gy·min−1, 4-chlorophenol at concentration of 10 mg·L−1 could be completely degraded at the radiation dose of 2 kGy. The degradation of 4-chlorophenol could be described by a first-order
reaction model, the rate constant of 4-CP degradation by combined ozonation and radiation was 0.1016 min−1, which was 2.4 times higher than the sum of radiation (0.0294 min−1) and ozonation (0.0137 min−1). It revealed that the combination of radiation and ozonation resulted in synergistic effect, which can remarkably increase
the degradation efficiency of 4-CP. 相似文献
19.
采用硝酸氧化联合高温处理法对活性炭(AC)进行表面改性(样品记为ACNH),并将其用于活化过硫酸盐(PS)降解苯酚.通过氮气等温吸附、元素分析、X射线光电子能谱和扫描电子显微镜等手段对改性前后活性炭的表面性质进行了表征分析.考察了活性炭投加量、PS/苯酚摩尔比、苯酚初始浓度和初始p H等条件对苯酚降解率的影响.结果表明,改性后活性炭活化PS能力显著提高,在ACNH/PS体系中苯酚的降解速率是AC0/PS体系中的5倍;ACNH的pH值适用范围宽;活性炭表面醌基、吡喃酮结构和碳原子平面层上的离域π电子(Cπ)在活化PS过程中起主要作用,而羧基起抑制作用. 相似文献
20.
L. R. Grabowski E. M. van Veldhuizen A. J. M. Pemen W. R. Rutgers 《Plasma Chemistry and Plasma Processing》2006,26(1):3-17
A small batch reactor is developed to study the removal of phenol from a thin layer of water by creating pulsed corona discharges
above the water. Pulses of up to 40 kV are applied with a duration of ~50 ns and an energy of ~60 mJ. In this CAW (Corona
Above Water) reactor an ozone yield of upto 90 g/kWh is obtained in ambient air. The phenol degradation is 48 g/kWh, using
a 1 mM initial concentration in demineralized water. The degradation yield increases to almost 100 g/kWh by adding to the
water either H2O2 or Fe2SO4 or NaOH. The first two additions are considered to increase to amount of OH radicals. In the case of NaOH addition it is
observed that much more ozone dissolves in the water. The addition of the OH scavenger t-butanol shows that in most cases
the main oxidation route of phenol in the CAW reactor is direct ozone attack. 相似文献