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51.
Co3O4具有优良的活化过硫酸盐的性能而受到人们的重视,但Co3O4粉体易团聚、使用过程中难以分离、易流失和重复利用率差等问题严重制约了其实际应用.通过水热法制备碳化三聚氰胺泡沫负载Co3O4非均相催化剂.采用X-射线衍射仪(XRD)和扫描电子显微镜(SEM)对催化剂的结构和表面形貌进行分析.研究不同因素对催化剂活化过硫酸氢钾(PMS)降解罗丹明B(RhB)的性能.其最优催化工艺参数:催化剂投加量为35 mg·L-1、PMS质量浓度为50 mg·L-1和pH为7、RhB初始质量浓度为10 mg·L-1,30 min反应后对RhB降解率为98%.结果表明,增大碳化泡沫负载Co3O4非均相催化剂投加量和PMS质量浓度能明显提高对RhB的降解率;而增加RhB初始质量浓度和提高pH值会明显抑制RhB的降解率.催化反应过程符合准一级动力学方程.温度对RhB降... 相似文献
52.
楼静 《中国环境管理干部学院学报》2004,14(3):38-39
利用由O2和Fenton试剂组成的类Fenton系统处理对氨基苯磺酸废水,取得了很好的降解效果.当FeSO4(10g/L)投加量为1.2mL、H2O2(3%)投加量为3mL时,COD去除率可达到70%. 相似文献
53.
以金霉素为降解对象,采用沉淀法制备α-FeOOH光催化剂,进一步将其用共价结合法负载在陶瓷膜上,用SEM、XRD、EDS、UV-Vis和FTIR对α-FeOOH和光催化陶瓷膜进行表征.结果表明催化剂α-FeOOH呈针状或纺锤长片状,长宽分别为500~550nm、25~50nm,经α-FeOOH改性的陶瓷膜孔隙率由14.83%变为8.11%.研究光芬顿陶瓷膜耦合体系对金霉素的降解效率和动力学行为,确定了光芬顿陶瓷膜耦合体系的最优降解条件为金霉素初始浓度50mg/L,H2O2投加浓度10mmol/L,UV强度为3796.6μW/cm2.进一步利用UV-Vis光谱分析了两种体系对金霉素的降解机理,光催化剂体系下,H2O2的浓度基本保持不变,而光芬顿陶瓷膜耦合体系下H2O2的浓度先升后降,同时后者在同一时间点对TOC和NH4+-N去除率更高,表明光芬顿陶瓷膜耦合体系氧化能力更强,对金霉素的降解更为彻底. 相似文献
54.
Siedlecka EM Stepnowski P 《Environmental science and pollution research international》2009,16(4):453-458
Background, aim, and scope Ionic liquids are regarded as essentially “green” chemicals because of their insignificant vapor pressure and, hence, are
a good alternative to the emissions of toxic conventional volatile solvents. Not only because of their attractive industrial
applications, but also due to their very high stability, ionic liquids could soon become persistent contaminants of technological
wastewaters and, moreover, break through into natural waters following classical treatment systems. The removal of harmful
organic pollutants has forced the development of new methodologies known as advanced oxidation processes (AOPs). Among them,
the Fenton and Fenton-like reactions are usually modified by the use of a higher hydrogen peroxide concentration and through
different catalysts. The aim of this study was to assess the effect of hydrogen peroxide concentration on degradation rates
in a Fenton-like system of alkylimidazolium ionic liquids with alkyl chains of varying length and 3-methyl-N-butylpyridinium chloride.
Materials and methods The ionic liquids were oxidized in dilute aqueous solution in the presence of two different concentrations of hydrogen peroxide.
All reactions were performed in the dark to prevent photoreduction of Fe(III). The concentrations of ionic liquids during
the process were monitored with high-performance liquid chromatography. Preliminary degradation pathways were studied with
the aid of 1H NMR.
Results Degradation of ionic liquids in this system was quite effective. Increasing the H2O2 concentration from 100 to 400 mM improved ionic liquid degradation from 57–84% to 87–100% after 60 min reaction time. Resistance
to degradation was weaker, the shorter the alkyl chain.
Discussion The compound omimCl was more resistant to oxidation then other compounds, which suggests that the oxidation rates of imidazolium
ionic liquids by OH· are structure-dependent and are correlated with the n-alkyl chain length substituted at the N-1-position. The level of degradation was dependent on the type of head group. Replacing
the imidazolium head group with pyridinium increased resistance to degradation. Nonetheless, lengthening the alkyl chain from
four to eight carbons lowered the rate of ionic liquid degradation to a greater extent than changing the head group from imidazolium
to pyridinium. 1H-NMR spectra show, in the first stage of degradation, that it is likely that radical attack is nonspecific,
with any one of the carbon atoms in the ring and the n-alkyl chain being susceptible to attack.
Conclusions The proposed method has proven to be an efficient and reliable method for the degradation of imidazolium ionic liquids by
a Fenton-like reagent deteriorated with lengthening n-alkyl substituents and by replacing the imidazolium head group with pyridinium. The enhanced resistance of 1-butyl-3-methylpyridinium
chloride when the resistance of imidazolium ionic liquids decreases with increasing H2O2 concentration is probably indicative of a change in the degradation mechanism in a vigorous Fenton-like system. H-NMR spectra
showed, in the first stage of degradation, that radical attack is nonspecific, with any one of the carbon atoms in the ring
and the n-alkyl chain being susceptible to attack.
Recommendations and perspectives Since ionic liquids are now one of the most promising alternative chemicals of the future, the degradation and waste management
studies should be integrated into a general development research of these chemicals. In the case of imidazolium and pyridinium
ionic liquids that are known to be resistant to bio- or thermal degradation, studies in the field of AOPs should assist the
future structural design as well as tailor the technological process of these chemicals 相似文献
55.
56.
研究了微波辐射下Cr(VI)-H2O2催化降解甲基橙溶液的行为,探索了微波功率、微波辐射时间、pH值、H2O2浓度、Cr(VI)等对甲基橙溶液脱色率和COD去除率的影响。研究结果表明,Cr(VI)-H2O2能形成类Fenton体系;微波辐射可提高H2O2产生羟基自由基(·OH)的效率。1000 mg/L的甲基橙溶液,在Cr(VI)浓度为10.0 mmol/L、pH值为2.5、H2O2浓度为20.0 mmol/L、微波功率为700W下加热2 min,甲基橙溶液的脱色率为99.2%,COD去除率为82.8%。 相似文献
57.
58.
在石英砂充填的二维砂箱中开展表面活性剂(Tween 80)冲洗四氯乙烯(PCE)的修复实验,基于图像分析技术监测不同污染源区结构条件下NAPL相的去除过程.由于实验条件限制,实验中缺乏溶解相浓度数据.为此进一步基于UTCHEM数值模拟方法来理解NAPL相和溶解态之间的质量传输过程,并探讨表面活性剂浓度、注入速率等因素对修复效率的影响.综合砂箱实验和数值模拟结果表明:介质均质和非均质条件下会形成不同类型DNAPL污染源区结构,表现为离散状PCE与池状PCE体积比(GTP)差异.由于离散状污染物与表面活性剂的接触面积更大,更易被优先去除;初始GTP值越高,污染物的修复速率和修复效率也越高.增大表面活性剂浓度或提高表面活性剂的注入速率,虽然能提高DNAPL的修复速率,但会明显降低表面活性剂的修复效率,实验过程中修复效率降幅可达93%.线性驱动溶解模型可以有效地模拟表面活性剂修复DNAPLs过程,基于数值模拟方法选择合适的表面活性剂配比可有效的节省实际污染场址修复经费和时间成本. 相似文献
59.
森林保险支付意愿及影响因素分析——基于异质性营林主体视角 总被引:1,自引:0,他引:1
基于期望效用函数理论分析了异质性营林主体的森林保险支付意愿及差异,并以传统小林农和新型林业经营主体为研究对象,以福建省382户传统小林农和88户新型林业经营主体的调研数据为基础,综合运用条件估值法、卡方检验及Cox比例风险模型,对异质性营林主体的森林保险支付意愿与差异及支付意愿影响因素进行对比与分析。研究表明:传统小林农和新型林业经营主体的森林保险意愿支付水平存在显著差异,在1000~2500元/亩保障水平下,传统小林农的意愿支付水平分别为1.911元/亩、2.941元/亩、3.532元/亩及3.979元/亩,新型林业经营主体为1.632元/亩、3.971元/亩、5.809元/亩及6.864元/亩;两类营林主体的支付意愿均随保额的提高而提高,但新型林业经营主体的提升幅度远高于小林农。异质性营林主体的森林保险支付意愿影响因素也存在明显差别,这与其在森林保险认知特征、林业生产经营特征、林业灾损特征、森林保险产品评价特征等方面存在显著差异有关。此外,林地面积对两类营林主体支付意愿均具有显著影响,规模化、集约化的林业生产经营可促进林业经营主体的森林保险愿意支付水平。 相似文献
60.
本研究于2017年4月在江苏省常州市环境监测中心使用一套基于湿化学法的仪器对大气中的HONO进行了实时在线观测,HONO浓度范围在0.2~13.9μg·m~(-3)之间,平均值为(2.9±2.3)μg·m~(-3);同时,对O_3、 HCHO、 VOCs、光解频率以及气象参数进行了同步监测.利用MCM箱体模式模拟得到白天·OH浓度最大值范围在1.0×10~6~1.4×10~7个·cm~(-3)之间.同时结合观测结果与模式模拟结果计算了HONO、 O_3、 HCHO和H_2O_2的光解以及烯烃臭氧化反应对·OH的生成速率,定量表征大气氧化性,揭示了这5种来源对大气氧化能力的影响:整体上O_3光解(46.4%)HONO光解(41.1%)烯烃臭氧化反应(10.9%)HCHO光解(1.5%)H_2O_2光解(0.1%);清晨时HONO光解对·OH生成起主要作用,之后随着O_3浓度的增加,O_3光解对·OH的贡献占主导地位;在17:00之后,由于太阳光解频率显著降低,烯烃臭氧化反应对·OH生成有主要贡献;甲醛与过氧化氢的光解对·OH的贡献可忽略. 相似文献