Fe-AC微电解活化过硫酸盐降解直接耐酸大红4BS

为快速脱色降解偶氮类染料,同时解决零价铁活化效率低、易被氧化的问题,以直接耐酸大红4BS(大红4BS)为模拟废水污染物,通过Fe-AC/PDS(铁碳微电解活化过硫酸钠)反应体系对大红4BS进行脱色降解。对影响大红4BS降解的几种因素如Fe:AC(铁碳质量比)、PDS浓度、初始pH等进行探究。结果表明,大红4BS脱色率在Fe:AC=3:1时高达94.7%。增大PDS浓度能明显促进反应进行,但超过5 mmol·L~(-1)时,对体系影响不大。初始溶液pH对Fe-AC/PDS体系降解大红4BS作用显著,在酸性和中性(pH=3.02、4.67、7.32)时,大红4BS的脱色率分别高达98.8%、96.2%、94.7%,但在碱性(pH=9.38、10.78)条件下,其脱色率只有24.5%、18.7%。无机盐阴离子对Fe-AC/PDS体系降解大红4BS有抑制作用,而阳离子对其产生促进作用。自由基俘获实验表明Fe-AC/PDS体系降解大红4BS并不仅仅只是自由基的氧化反应,还存在其他复杂反应,继而对Fe-AC/PDS体系降解大红4BS的机理进行探讨。     

铁电极活化过硫酸盐对金橙G的降解

研究了铁电极活化过硫酸盐(EC/PDS)产生的具有强氧化性的硫酸根自由基(SO_4~-·)对溶液中金橙G(orange G,OG)的氧化降解行为。重点考察了电流强度、PDS投加量、金橙G初始浓度、溶液初始pH值以及共存阴离子对金橙G降解速率的影响。实验结果表明:相比单独絮凝(EC)和投加过硫酸盐(PDS),EC/PDS体系能够有效地去除金橙G;金橙G的去除效率随着电流强度的增大而增大,随着PDS投加量的增大而增大,随着金橙G初始浓度增大而减小;较低的溶液pH值更利于OG的降解。水中共存阴离子对金橙G的降解存在着不同程度的抑制作用:PO_4~(3-)CO_3~(2-)Cl~-。此外,通过加入不同的淬灭剂(甲醇和叔丁醇),确定了体系中主要存在的自由基。     

低频超声协同Fe-Ni-Mn/Al_2O_3催化降解酸性绿B的研究

采用低频超声与Fe-Ni-Mn/Al2O3催化剂协同降解偶氮染料酸性绿B模拟废水,考察染料初始浓度和pH值、催化剂、饱和气体及H2O2等因素对酸性绿B降解效果的影响,结果表明:催化剂Fe-Ni-Mn/Al2O3与低频超声存在协同效应,催化剂的最佳投加量为6 g/L;酸性条件有利于染料的超声降解,当pH=3.8时,可取得最佳的降解效果;酸性绿B降解率随初始浓度的增大而降低,其优化初始浓度为100 mg/L,此外,在反应体系中鼓入饱和气体也可促进酸性B的降解,且影响顺序为混合气体(air+Ar)>氧气>氩气;在反应过程中投加H2O2有利于染料降解率的提高.在优化实验条件下降解150 min,酸性绿B色度去除率达到91.4%.     

Fenton氧化活性深蓝染料B-2GLN的动力学

为了考查H2O2/Fe2+的摩尔比和H2O2的初始剂量、pH值以及活性深蓝染料B-2GLN(RDB B-2GLN)的初始浓度对活性深蓝染料B-2GLN降解过程的影响,采用在线分光光度法对活性深蓝染料B-2GLN的Fenton氧化过程进行了研究,探讨了其动力学过程,并利用气相色谱-质谱联用分析降解中间产物。结果显示,采用Fenton氧化降解水溶液中活性深蓝染料B-2GLN,在H2O2的剂量为2.635 mmol/L,pH值为2.7,H2O2/Fe2+的摩尔比为37.80和活性深蓝染料B-2GLN的初始浓度16 mg/L的条件下,得到300 s后活性深蓝染料B-2GLN的最大色度去除率为85.04%。水溶液中活性深蓝染料B-2GLN与·OH的反应速率常数为2.62×1011L/(mol·s)。活性深蓝B-2GLN染料的分子结构被Fenton试剂分解而未被完全矿化,同时对活性深蓝染料降解产物进行了分析。在线分光光度法是研究染料色度去除率的一种精确、快速与可行的方法。     

低频超声协同Fe-Ni-Mn/Al2O3催化降解酸性绿B的研究

采用低频超声与Fe-Ni-Mn/Al₂O₃催化剂协同降解偶氮染料酸性绿B模拟废水,考察染料初始浓度和pH值、催化剂、饱和气体及H₂O₂等因素对酸性绿B降解效果的影响, 结果表明：催化剂Fe-Ni-Mn/Al₂O₃与低频超声存在协同效应,催化剂的最佳投加量为6 g/L;酸性条件有利于染料的超声降解,当pH=3.8时, 可取得最佳的降解效果; 酸性绿B降解率随初始浓度的增大而降低,其优化初始浓度为100 mg/L,此外,在反应体系中鼓入饱和气体也可促进酸性B的降解,且影响顺序为混合气体(air+Ar)＞氧气＞氩气;在反应过程中投加H₂O₂有利于染料降解率的提高。在优化实验条件下降解150 min,酸性绿B色度去除率达到91.4%。     

CuO活化过硫酸盐对孔雀石绿的降解

为研究CuO在活化过一硫酸氢盐(PMS)与过二硫酸盐(PS)降解染料时的差异,通过单因素控制实验,探究PMS/PS浓度、CuO投加量、初始pH和氯离子对CuO/PMS和CuO/PS体系降解孔雀石绿染料(MG)的影响。结果表明:常温常压下,在MG初始浓度为10μmol·L~(-1),PMS浓度为250μmol·L~(-1),CuO投加量为200 mg·L~(-1)的条件下,60 min后CuO/PMS体系对MG的降解率为86.73%;当MG初始浓度为10μmol·L~(-1),PS浓度为200μmol·L~(-1),CuO投加量为200 mg·L~(-1)时,60 min后CuO/PS体系对MG的降解率为79.07%,过量的CuO和过低的pH均会降低体系的氧化能力。当MG初始浓度为10μmol·L~(-1),氧化剂浓度为200μmol·L~(-1),CuO投加量为200 mg·L~(-1)时,CuO/PMS体系与CuO/PS体系对MG降解率分别为80.35%和79.07%,降解效果大致相当。在地下水/工业废水中氯离子普遍存在情况下,CuO/PS体系由于不产生硫酸根自由基,则避免了氯代副产物的生成,因而相对硫酸根自由基氧化体系具有一定优势。动力学分析显示,两种体系中MG的降解均遵循一级反应动力学模型。     

低温等离子体联合光催化技术降解甲苯的实验研究

采用低温等离子体联合光催化技术降解甲苯,从电压、电源频率、甲苯气体流量、初始浓度和Mn2+掺杂量等方面考察其对甲苯降解率的影响,并对比γ-Al2O3、TiO2/γ-Al2O3和Mn1.0/TiO2/γ-Al2O3(Mn2+摩尔分数为1.0%)3种填料的甲苯降解能量利用效果.结果表明,在相同电压和频率条件下,3种填料的甲...     

Fe(0)-EDTA-空气体系降解活性黑染料废水

利用Fe(0)-EDTA-空气(ZEA)体系处理活性黑模拟染料废水。考察了活性黑初始浓度、反应温度、EDTA浓度和溶液酸度对降解效果的影响,用紫外可见吸收光谱检测了染料的降解过程。结果表明,Fe(0)-EDTA混合物在室温常压下,能够活化空气中的氧分子,进而使染料快速降解,升高温度和增加溶液酸度均能提高降解率。在pH为5.35,活性黑初始浓度为25 mg/L,EDTA浓度为0.1 mmol/L,Fe粉用量0.20 g,温度25℃时,脱色率达到95.60%,符合1级反应动力学。     

催化臭氧氧化染料溶液的研究

采用催化臭氧化技术降解染料废水,以甲基紫溶液为目标污染物,研究了过渡型金属离子的类型,Fe2+的浓度,溶液初始pH值,染料浓度和正丁醇等因素对其降解率的影响。实验结果表明:臭氧氧化甲基紫溶液的过程中,加入一定浓度的过渡型金属离子对甲基紫的去除具有促进作用;当臭氧浓度为16 mg/L,一定浓度范围内,Fe2+催化臭氧化的效果随着浓度的增加而增加,但Fe2+浓度为13 mg/L时,甲基紫的降解率下降;在酸性范围时,pH值增大其降解率会减小;染料浓度增加,甲基紫的降解率减小,但是其绝对降解值会增加;正丁醇的加入抑制氧化反应的进行,甲基紫的降解率下降,说明催化臭氧化过程中有羟基自由基产生。染料降解过程符合一级反应动力学规律。     

双频超声辐射协同H_2O_2降解偶氮染料废水的研究

采用双频超声协同H2O2降解酸性绿20染料废水,考察超声功率密度、染料初始浓度和pH、饱和气体及H2O2投加量等因素对酸性绿20降解效果的影响,结果表明,在给定实验条件下,双频降解效果优于单频超声波,且降解率随超声功率密度的增大而增大。酸性条件有利于酸性绿20的降解,当染料废水初始pH=4可取得最佳的降解效果;酸性绿20的降解效率随染料初始浓度的增大而降低,其优化初始浓度为40 mg/L。在反应体系中通入空气并投加H2O2,可取得最佳的降解效果。在优化实验条件下,采用双频超声协同H2O2降解5 h,酸性绿20的色度和TOC去除率分别为94.6%和36.3%;分析降解前后的紫外-可见光谱图可知,酸性绿20并非完全被降解为CO2和H2O,而是生成一些小分子有机中间体。     

Sorption and desorption of Cu and Cd by macroalgae and microalgae

The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment.     

Kinetic and structural relationships of transition monomeric and oligomeric carboxyl- and choline-esterases

The kinetic and structural relationships of eight electrophoretically pure mammalian serum and liver serine carboxylesterases (CE) and cholinesterases (ChE) have been studied. Eight CE's and ChE's, which were fully resolved but only partially purified, provided additional information. Five of the electrophoretically pure esterases were monomeric, and of these, four belonged to a new and widely distributed class. These four monomeric esterases hydrolyzed choline esters, but at widely differing rates. Thus two were termed monomeric butyrylcholinesterases, mBuChE I and II, and two were monomeric CE's (mCE). The rabbit liver mCE was not a subunit of the oligomeric CE (oCE), although the oCE also hydrolyzed choline esters at a very low rate. The complex kinetics of the mCE's, mBuChE's, oCE's, and of the oligomeric BuChE's of horse and human serum could be interpreted according to a single reaction scheme involving an allosteric site and the equation derived from it. Thus activation and inhibition at high substrate concentrations, together with sigmoidal activity versus substrate concentration plots, all of which characterize the reactions of these esterases, could be interpreted by a single scheme and equation. Structural and kinetic comparisons showed a progressive transition of properties from the oCE's through the mCE's to the oBuChE's. One of the purified mCE's was from horse serum, and it exhibited physical and kinetic properties unlike those of the liver mCE's or oCE's.     

Persistence and dissipation kinetics of trifloxystrobin and tebuconazole in onion and soil

The persistence and dissipation kinetics of trifloxystrobin and tebuconazole on onion were studied after application of their combination formulation at a standard and double dose of 75 + 150 and 150 + 300 g a.i. ha^?1. The fungicides were extracted with acetone, cleaned-up using activated charcoal (trifloxystrobin) and neutral alumina (tebuconazole). Analysis was carried out by gas chromatograph (GC) and confirmed by gas chromatograph mass spectrometry (GC-MS). The recovery was above 80% and limit of quantification (LOQ) 0.05 mg kg^?1 for both fungicides. Initial residue deposits of trifloxystrobin were 0.68 and 1.01 mg kg^?1 and tebuconazole 0.673 and 1.95 mg kg^?1 from standard and double dose treatments, respectively. Dissipation of the fungicides followed first-order kinetics and the half life of degradation was 6–6.6 days. Matured onion bulb (and field soil) harvested after 30 days was free from fungicide residues. These findings suggest recommended safe pre-harvest interval (PHI) of 14 and 25 days for spring onion consumption after treatment of Nativo 75 WG at the standard and double doses, respectively. Matured onion bulbs at harvest were free from fungicide residues.     

Sorption and desorption behavior of chloroanilines and chlorophenols on montmorillonite and kaolinite

The bioavailability of pollutants, pesticides and/or their degradation products in soil depends on the strength of their sorption by the different soil components, particularly by the clay minerals. This study reports the sorption-desorption behavior of the environmentally hazardous industrial pollutants and certain pesticides degradation products, 3-chloroaniline, 3,4-dichloroaniline, 2,4,6-trichloroaniline, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol on the reference clays kaolinite KGa-1 and Na-montmorillonite SWy-l. In batch studies, 2.0 g of clay were equilibrated with 100.0 mL solutions of each chemical at concentrations ranging from 10.0 to 200.0 mg/L. The uptake of the compounds was deduced from the results of HPLC-UV-Vis analysis. The lipophilic species were best retained by both clay materials. The most lipophilic chemical used in the study, 2,4,6-trichloroaniline, was also the most strongly retained, with sorption of up to 8 mg/g. In desorption experiments, which also relied on HPLC-UV-Vis technique, 2,4,6-trichloroaniline was the least desorbed from montmorillonite. However, on kaolinite all of the compounds under study were irreversibly retained. The experimental data have been modelled according to the Langmuir and Freundlich isotherms. A hypothesis is proposed concerning the sorption mechanism and potential applications of the findings in remediation strategies have been suggested.     

Sorption and Desorption Behavior of Chloroanilines and Chlorophenols on Montmorillonite and Kaolinite

The bioavailability of pollutants, pesticides and/or their degradation products in soil depends on the strength of their sorption by the different soil components, particularly by the clay minerals. This study reports the sorption-desorption behavior of the environmentally hazardous industrial pollutants and certain pesticides degradation products, 3-chloroaniline, 3,4-dichloroaniline, 2,4,6-trichloroaniline, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol on the reference clays kaolinite KGa-1 and Na-montmorillonite SWy-l. In batch studies, 2.0 g of clay were equilibrated with 100.0 mL solutions of each chemical at concentrations ranging from 10.0 to 200.0 mg/L. The uptake of the compounds was deduced from the results of HPLC-UV-Vis analysis. The lipophilic species were best retained by both clay materials. The most lipophilic chemical used in the study, 2,4,6-trichloroaniline, was also the most strongly retained, with sorption of up to 8 mg/g. In desorption experiments, which also relied on HPLC-UV-Vis technique, 2,4,6-trichloroaniline was the least desorbed from montmorillonite. However, on kaolinite all of the compounds under study were irreversibly retained. The experimental data have been modelled according to the Langmuir and Freundlich isotherms. A hypothesis is proposed concerning the sorption mechanism and potential applications of the findings in remediation strategies have been suggested.     

Bacterial and archaeal diversity in oil fields and reservoirs and their potential role in hydrocarbon recovery and bioprospecting

Environmental Science and Pollution Research - Hydrocarbon is a primary source of energy in the current urbanized society. Considering the increasing demand, worldwide oil productions are declining...     

畜禽养殖业污染与循环经济

解决畜禽养殖业的污染问题要以充分利用资源为根本出发点，通过对污染全过程控制及废物综合利用，达到畜禽粪便的减量化、无害化、资源化，走循环经济的发展道路。     

Sources and fate of PCDD and PCDF

PCDD and PCDF were found in urban air particulates from St. Louis and Washington, D.C., and in sediments from the Great Lakes and Siskiwit Lake, Isle Royale. The similarity between the PCDD and PCDF found in air particulates and sediment samples and the presence of PCDD and PCDF in sediment from Siskiwit Lake (a location which can receive only atmospheric inputs) suggest that these compounds are emitted to the atmosphere from combustion sources. The historical input of PCDD and PCDF to dated sediment cores shows a strong increase since 1940, and this suggests that the incineration of chlorinated organic compounds is an important source of PCDD and PCDF to the environment.     

Synthesis and characterization of m- and p-methylbenzyl-mercapturic acids derived from m- and p-xylenes

Chemical synthesis and physical properties of two mercapturic acids suggested as urinary metabolites of m- and p-xylenes ace described. These compounds may be used for the identification and quantivative determination by high-performance liquid chromatography of the corresponding mercapturic acids in urine.