有/无隔膜体系电化学法降解甲基橙对比试验

在自制的电化学反应器中设置隔膜系统,对比了有/无隔膜体系对甲基橙的降解效果。在甲基橙溶液初始浓度为100 mg/L,pH值为7,电解质投加量为0. 02 mol/L,电极板间距为4cm,曝气速度为2 L/min,电解时间为60 min时,通过试验和数据计算建立了两种体系的能耗数学模型,并对比了能耗差异。结果表明,隔膜体系电化学法对甲基橙的平均脱色率为94. 91%,COD平均去除率为73. 08%,节能效果明显,更适用于对染料废水的处理。     

隔膜体系阴阳极共同作用电化学法降解水中的甲基橙

本文针对隔膜体系阴阳极共同作用电化学法处理甲基橙废水,在自制的电化学反应器中设置隔膜系统,确定了隔膜体系阴阳极共同作用电化学法处理甲基橙废水的最佳反应条件:进水甲基橙浓度100mg/L,电解质投加量0.02mol/L,电解电压20V,电极板间距4cm,曝气速率2.0L/min,此时阴、阳极室中甲基橙脱色率最高达到90.87%和99.45%。通过数据分析得出阴、阳极室脱色率与能耗的关系式,并对甲基橙降解机理进行了分析。     

低温等离子体技术降解甲基橙染料废水

利用低温等离子体技术对甲基橙溶液进行降解,采用自制线筒式介质阻挡放电反应器,研究了放电电压、放电频率、溶液初始p H值对甲基橙降解性能的影响。结果表明,对甲基橙的去除率随放电电压的升高和溶液初始p H值的减小而增大。当甲基橙溶液初始浓度为50 mg/L、放电电压为17 k V、频率为275 Hz、p H值为2.95时,降解处理20 min后,对甲基橙的去除率可以达到86%。介质阻挡放电等离子体破坏甲基橙分子中的发色基团,将结构复杂的大分子有机物降解为小分子有机物等。     

Cu_2O/石墨烯复合光催化处理甲基橙废水的效能分析

分别制作了氧化亚铜催化剂、石墨烯催化剂、氧化亚铜/石墨烯复合催化剂(Cu_2O/石墨烯)用于处理甲基橙废水,并采用X射线衍射(XRD)、扫描电子显微镜(SEM)和能谱(EDS)等技术对Cu_2O/石墨烯复合催化剂的物相和形貌进行表征。结果表明,Cu_2O/石墨烯复合催化剂中Cu_2O属于立方晶型,且呈粒子状较均匀地分散在薄层石墨烯表面。3种催化剂在可见光、pH值为中性、常温条件下,对甲基橙废水中COD和色度均有较高的去除率,其中Cu_2O/石墨烯复合催化剂对甲基橙废水的降解效果最好,当甲基橙废水中COD为335~1452mg/L时,在最佳投加量为0.6g/L的条件下,对COD的去除率可达到96.7%~97.4%,且催化效果受甲基橙废水浓度的影响较小,甲基橙废水降解的较佳pH值范围为7.2~7.8。     

溶液pH对Fe-Mn催化氧化甲基橙去除效果的影响研究

研究了Fe-Mn掺杂催化剂在溶液不同p H值条件下催化氧化及吸附对甲基橙降解情况的影响。结果表明,在碱性、中性和弱酸性条件下,催化氧化对甲基橙的去除效果比单独臭氧氧化有一定提高,但催化剂对甲基橙基本没有吸附作用;在强酸性条件下(p H=3),催化剂对甲基橙具有较好的吸附作用,同时催化氧化效果明显,在反应进行20 min时甲基橙的去除率能够达到88.15%,与臭氧单独氧化相比去除率提高了24%。反应中均伴随有Fe、Mn离子的溶出,但对催化氧化无明显的影响。     

银掺杂多孔氧化钛光催化甲基橙降解反应条件的探究

利用溶胶-凝胶法结合光还原法制备Ag掺杂多孔TiO_2光催化剂,以甲基橙的降解效果为评价标准,考查了光照降解时间、光催化剂用量、甲基橙溶液初始浓度、溶液pH值对光催化剂催化降解甲基橙的影响。结果表明,本方法制备的光催化剂无论是在紫外光还是可见光下均具有优良的光催化性能:在浓度为10 mg/L的甲基橙溶液中,4 g/L光催化剂,紫外光照射80 min,甲基橙可实现100%完全降解;相同催化条件下,可见光照100 min,甲基橙完全降解;当反应溶液pH=2时,紫外光和可见光都可在20 min内实现甲基橙的完全降解。     

电化学/过硫酸盐耦合体系降解水中有机药物卡马西平

采用电化学/过硫酸盐耦合体系(E-PS过程)降解水中的有机药物卡马西平(CBZ)。实验采用了分批模式进行,研究了温度、过硫酸钠浓度、初始pH值、电压等因素对E-PS过程降解CBZ的影响。反应100min后,单独过硫酸钠、电解和E-PS过程对卡马西平的降解率分别为25.5%、59.3%、78.1%,TOC去除率分别为8.25%、23.48%、26.68%。升高温度可以有效提高CBZ的降解率。反应100min后,在288K,CBZ降解率为60.2%;在298K,CBZ降解率达到78.1%;而在308K,CBZ降解率为90.1%。CBZ的降解率随着过硫酸盐浓度的增加而提高。当过硫酸盐浓度为40g/L时,反应100min,CBZ降解率达94.7%。初始pH值对CBZ降解率的影响为pH 3.0pH 5.0pH 7.0;电压对CBZ降解率的影响为6V5V4V。     

电解氧化处理垃圾渗滤液研究

采用电解氧化法对垃圾渗滤液进行深度处理的研究结果表明,电解氧化过程中,NH3－N优先于COD被氧化去除;SPR三元电极的处理效果优于DSA二元电极和石墨电极;酸性条件比碱性条件更有利于电解氧化作用对COD及NH3－N的去除;Cl^-浓度高时,有利于COD及NH3－N被氧化去除。试验得到的适宜电解氧化条件是：pH值为4、Cl^-浓度为5000mg/L、电流密度为10A/dm^2、SPR三元电极为阳极、电解时间为4h。当COD及NH3－N浓度分别为693mg/L和263mg/L时,COD去除率为90．6％,NH3－N的去除率为100％。     

电化学除磷过程的条件优化与机理研究

为优化电化学除磷过程的条件并探究反应机理,通过模拟实际污水研究了初始pH值、初始磷浓度C_0及曝气强度j对电化学除磷过程的影响,同时对不同条件下电化学除磷过程进行了动力学分析。结果表明:随着初始pH值的增加,TP去除率先增加后减小;随着电解时间的增加,溶液pH值增大。当C_0为5 mg/L、电解时间为60 min、初始p H值为6～8时,TP去除率达到84. 5%以上;且当初始pH值为7时,TP去除率达到最高值,为87. 69%。C_0越高,TP去除率越低,但除磷的能耗也越低。当C_0为9 mg/L时,电解60 min后,TP去除率为72. 79%,去除单位质量磷的能耗仅为0. 059 kW·h/g,比C_0为5 mg/L时节约能耗0. 025 kW·h/g。当j为0. 14～0. 28 L/min时,电解60 min后,TP去除率达到86. 0%以上,比j为零时至少提高了43. 6%。动力学拟合结果表明,电化学除磷过程中存在着化学配位反应和吸附反应。当pH值为3～5时,除磷过程以化学配位反应为主,当pH值为7～11时,除磷过程则以吸附反应为主;且pH值增加不会减弱除磷过程中的吸附反应。当C_0为8～9 mg/L时,化学配位作用的除磷效果达到极限水平。曝气一方面有利于Fe~(2+)氧化为Fe~(3+),促进化学配位反应,另一方面可以缓解电极钝化,提高除磷效率。     

铁炭微电解工艺对高硝态氮制药废水的脱氮效能

以高硝态氮、难降解的有机制药废水为处理对象,探讨了铁炭微电解工艺对其脱氮效能及影响因素.结果表明:填料粒径、pH值、铁炭比、气水比、停留时间等因素均对铁炭微电解系统的脱氮效能有显著影响;在铁屑和活性炭粒径均为35目、pH值为3、Fe/C值为3:1(体积比)、气水比为5:1、停留时间为1.5 h的最佳条件下,当进水TN、NH4+-N和NO3--N的平均浓度分别为823、30和793 mg/L,BOD5/COD值为0.1时,铁炭微电解系统对TN、NH4+-N和NO3--N的平均去除率分别可达到51.5%、70%和50.94%.     

三维电极-混凝法处理酵母生产废水的试验研究

采用三维电极-混凝法处理广东某酵母厂经厌氧、好氧、缺氧处理后的酵母生产废水，结果表明，采用石墨电极，在电压为9V、极板间距为4cm、电解时间为3h的条件下，废水经三维电极法处理后出水COD可降至400mg／L左右；继续采用混凝法对上清液进行处理，在聚合氯化铝投量为1～2g／L时，出水COD可降至300mg／L以下，色度可降至14倍，出水水质可达到《污水综合排放标准》（GB8978-1996）的二级标准。     

Bioavailability of diuron in soil containing wheat-straw-derived char

This study evaluated the bioavailability of diuron in soil as influenced by char arising from the burning of wheat straw. The wheat char was a highly effective sorbent for diuron. The presence of 1% wheat char in soil resulted in a 7-80 times higher diuron sorption. A 10-week incubation resulted in <40% of 0.5 mg/kg diuron in 0.5% char-amended soil microbially degraded, as compared to 50% in char-free soil under the same conditions. Over the experimental range of diuron application rates from 0 to 12 mg/kg and of char contents from 0% to 1.0%, a 4-week bioassay indicated that both the barnyardgrass survival rating and the fresh weight of aboveground biomass decreased with increasing diuron application at given char contents but increased with increasing char content at potentially damaging diuron application rates. Residual analyses of bioassayed soils showed that the soils with char contents of 0.5% and higher and diuron application rates of 3.0 mg/kg and higher, as compared to those with no or low (0.05%) char and a diuron application rate of 1.5 mg/kg, had higher residual diuron levels but higher barnyardgrass survival ratings and fresh weights. These results suggest that enhanced sorption of diuron in soil in the presence of wheat char reduced the bioavailability of diuron, as manifested by reduced microbial degradation of diuron and its herbicidal efficacy to barnyardgrass. This study may have greater implication than for burning of wheat straw that field burning of vegetations may reduce bioavailability of pesticides.     

Electrocatalytic characterization and dye degradation of Nano-TiO2 electrode films fabricated by CVD

A 20-40 nm anatase-titania film on a titanium electrode was fabricated using chemical vapor deposition (CVD). The film was characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The CVD deposition time and number of deposition coatings were evaluated to establish the appropriate film fabrication parameters. Results indicate that two coatings at a deposition time of 6 h each produced the best nano-TiO₂ electrode films (NTEFs) with an even distribution of ca. 20 nm diameter nanoparticles in the anatase lattice. The NTEF was tested as an electrocatalytic anode to investigate the degradation efficiency in treating methyl orange dye wastewater. A high removal efficiency of methyl orange dye and total organic carbon (TOC) of 97 and 56%, respectively; was achieved using a current density of 20 mA cm^− 2 for 160 min. Cyclic voltammetry showed that the electrochemical degradation reaction rate at the NTEF surface was predominately driven by molecular diffusion. The electrocatalytic decomposition rate of organic pollutants at the NTEF is controlled by mass transport, which was associated with the nanostructure of the electrocatalytic electrode.     

十二烷基苯磺酸钠改性沸石吸附甲基橙的研究

以表面活性剂十二烷基苯磺酸钠改性天然沸石,对废水中甲基橙进行吸附,以紫外可见分光光度计分析最佳吸附条件,结果表明：在改性沸石的用量为20g/L、吸附时间为100min、温度为35℃、pH值为4.2时,十二烷基苯磺酸钠改性沸石对甲基橙溶液（10g/L）的吸附率达到了92.8%,吸附符合Langmuir等温方程。     

Photocatalytic degradation of methyl orange by TiO2-coated activated carbon and kinetic study

TiO2-coated activated carbon (AC) grain (TiO2/AC) was prepared through hydrolytic precipitation of TiO2 from Tetrabutylorthotitanate and following heat treatment. The TiO2/AC was characterized by BET, SEM, XRD and optical absorption spectroscopy. The samples were employed as catalysts for methyl orange photocatalytic oxidation degradation in aqueous suspension, used as probe reaction. The kinetics of methyl orange photodegradation was analyzed. The results indicate that BET surface area of TiO2-coated ACs decreased drastically in comparison with the original AC with increasing TiO2 coatings by more than 1 doped cycle. Nano-TiO2 particles were dispersed on the AC with the size of 20-40 nm. Crystalline TiO2 doped onto AC was from anatase to rutile with increase of heat-treatment temperature. The TiO2/AC was shown high photoactivity for the photodegradation of methyl orange (MO) dyestuff in aqueous solution under UV irradiation. The kinetics of photocatalytic MO dyestuff degradation was found to follow a pseudo-first-order rate law. It was observed that the presence of the AC enhanced the photoefficiency of the titanium dioxide catalyst. Different amount of TiO2 coatings induced different increases in the apparent first-order rate constant of the process. The kinetic behavior could be described in terms of a modified Langmuir-Hinshelwood model. The values of the adsorption equilibrium constants for the organic molecules, KC, and for the rate constants, kc, were certainly dependent on TiO2 content. At 47wt% TiO2 coatings with the highest rate constant, the KC and kc was 0.1116l mmol(-1) and 0.1872 mmol l(-1) min(-1), respectively. The mechanism of methyl orange degradation was discussed in terms of the titanium dioxide photosensitization by the AC.     

Fe2O3有机物光催化降解有机染料的研究进展

探讨了Fe2O3/H2O2体系在可见光下降解有机染料的研究进展,采用Fe2O3/H2O2体系,对大红4BS、甲基橙等染料进行了光氧化降解实验,得出Fe2O3/H2O2/太阳光体系和Fe2O3/H2O2/UV体系在不同pH值条件下的光降解效率。     

A field study to assess the degradation and transport of diuron and its metabolites in a calcareous soil

An experimental plot has been established on a calcareous soil in southern England to investigate the fate and transport of diuron (N'-[3,4-dichlorophenyl]-N,N-dimethylurea), a commonly used phenylurea herbicide. An agricultural grade of diuron was applied to the soil surface at a rate of 6.7 kg/ha along with a potassium bromide conservative tracer applied at 200 kg/ha, in early January, 2001. Hand augured samples were taken at regular intervals over the next 50 days, with samples collected down to 54 cm. Porewaters were extracted from the soil cores by using high speed centrifugation and the supernatant fluids were retained for analysis by HPLC, for diuron and three of its metabolites, N'-[3,4-dichlorophenyl]-N,N-methylurea (DCPMU), N'-3,4-dichlorophenylurea (DCPU) and 3,4-dichloroaniline (DCA). The centrifuged soil was retained and then extracted with methanol prior to HPLC analysis for the same suite of phenylureas. A mass balance approach showed large variations in diuron distribution, but on average accounted for 104% of the diuron applied. Concentrations of diuron and its metabolites were roughly five times higher in the soil than in the soil porewaters. After 50 days, metabolites comprised 10% of the total diuron present in the porewater and 20% of the total diuron sorbed to the soil matrix. After 36 days, a large pulse of diuron and DCPMU appeared in the porewaters and soil matrix at a depth of 54 cm, travelling an average of 0.15 cm/day faster than Br. A preferential route for diuron transport is suggested. There is evidence to suggest that degradation occurs at depth as well as at the soil surface. Metabolites generally appear to move more slowly than the parent compound. All metabolites were encountered, but interpreting transport and degradation processes simultaneously proved beyond the scope of the study. Diuron was detected once in a shallow (5 m) observation well, situated on the experimental plot. High concentrations of diuron and metabolites were still present in the soil and soil solutions after 50 days and remain as a source of potential groundwater contamination.     

锌铝电极电絮凝法处理高氟饮用水的研究

在双铝极板电絮凝法的基础上引入锌电极,考察锌铝电极电絮凝法对高氟饮用水的除氟效果.静态试验结果表明,采用锌铝电极可以有效降低水中的氟离子浓度,对CODMn和浊度的去除效果优于双铝电极;当原水的氟离子浓度为6 mg/L时,最佳处理条件:锌、铝极板比为1:3、电解电压为18 V、反应pH值为6、反应时间为25～30 min.动态试验结果表明,当进水流量和氟离子浓度分别高达42 mL/min、8 ms/L时,调节进水pH值为6可使其出水中的氟离子浓度达标.     

高岭土负载氧化锌／氧化钛制备光催化功能材料的研究

以硫酸钛、硫酸锌、高岭土、尿素、无水乙醇等为原料,水热法制备了氧化锌／氧化钛复合纳米粉体以及高岭土负载纳米氧化锌／氧化钛复合粉体;利用X-射线衍射（XRD）对所得粉体进行了表征,研究了不同粉体对甲基橙溶液的光催化降解效果,制备出了光催化性能良好的高岭土负载纳米氧化锌／氧化钛复合粉体。     

阴阳两极联合降解对硝基苯酚的研究

以铁掺杂PbO2／Ti为阳极、气体扩散电极为阴极，构建了新型电催化反应体系，研究了阴阳两极联合降解水中对硝基苯酚的效果，考察了电流密度、初始浓度、pH值、曝气量对去除效果的影响，初步探讨了反应动力学和氧化机理。结果表明，在阳极电流密度为24mA／cm^2、曝气量为20mL／s的条件下，处理浓度为100mg／L的对硝基苯酚废水，电解55min后去除率达100％；对硝基苯酚的降解符合表观一级反应动力学。该体系能耗低、效率高，且对pH的适用范围广，有较好的应用前景。