添加Na4P2O7对CaO催化剂上甲烷氧化偶联反应的影响

用Na_4P_2O_7做为Na+添加剂制备Na_4P_2O_7/CaO催化剂。在5.5×10~(_2)的Na_4P_2O_7/CaO上及760℃,w/F=0.0.9g·s·mL~(-1)条件下可以获得23.4×10~(-2)的CH_4转化率和66.8×10~(-2)的C_2烃选择率。催化剂表面Na~+的富集有利于表面活性中心的形成。催化剂表面存在CO_2的碳酸化与脱碳酸化平衡。表面Na~+的流失会引起催化剂活性的下降。     

4,4-二甲基二氧六环-1,3裂解用P2O5/SiO2催化剂的活性相研究

本文对4,4-二甲基二氧六环-1,3裂解制异戊二烯的P_2O_5/SiO_2催化剂,用XRD,IR,DTA-DTG及NH_3吸附等方法,研究了其活性相的形成条件、结晶度以及它们对裂解反应的影响。结果证明配酸比为0.6的P_2O_5/SiO_2中的晶相Si_3(PO_4)_4是活性相,P_2O_5/SiO_2在>700℃,10小时的条件下,能充分形成这种结构,热稳定性良好。水分子使P_2O_5/SiO_2表面产生的B酸点和L酸点,在反应中发挥协同作用。     

甲硫醇离子选择性电极的研制及其在甲胺磷残留量测定中的应用

本文以甲硫醇银及硫化银为电活性材料制得对甲硫醇离子有选择性响应的固态膜离子选择性电极。在pH为9.3的0.035mol/L Na_2B_4O_7-0.1mol/L NaOH-0.1mol/L Na_2SO_3介质中,电极的线性响应范围为5×10~(-6)～1×10~(-2)mol/L,响应斜率为58mV/pX。蔬菜中甲胺磷的残留量可以用乙酸乙酯或甲醇水溶液提取后,利用其在碱性条件下水解生成甲硫醇离子的特性用本电极测定,检测限2μg/g,设备简单,操作方便。     

H_8[P_2Mo_(17)Co(OH_2)O_(61)]和H_8[P_2Mo_(17)Ni(OH_2)O_(61)]的抑酶活性研究

合成了2种过渡金属取代的多酸H_8[P_2Mo_(17)Co(OH_2)O_(61)]和H_8[P_2Mo_(17)Ni(OH_2)O_(61)],并对其抑酶活性进行了研究.结果表明,这2种化合物对酪氨酸酶均有有效的抑制效果.抑制机理表明2种化合物均是可逆竞争型抑制剂.H_8[P_2Mo_(17)Co(OH_2)O_(61)]和H_8[P_2Mo_(17)Ni(OH_2)O_(61)]的半抑制率IC_(50)值分别为(0.434 0±0.000 4)和(0.466 5±0.012 0)mmol/L,抑制常数K_Ⅰ分别为0.216 7和0.220 4mmol/L.该研究能够扩大多金属氧酸盐的应用范围.     

花岗岩风化壳稀土存在形态分析方法研究

研究了一个测定花岗岩风化壳中REE存在形态的方法。以0.2 mol/L MgCl_2,2.5 mol/LHCl,0.5 mol/L NaOH及含15%H_2O_2的2.5 mol/L HCl连续提取风化壳试样中的稀土。经X射线衍射、红外光谱及剖面试样测试,论证了每一提取态的内涵,提出了花岗岩风化壳中非原生矿物相稀土存在活性态、铁铝共沉淀态和有机结合态的新认识。     

新型抗癌药物长春地辛的电化学研究

以纳米金(AuNPs)/聚乙烯吡咯烷酮(PVP)为修饰剂,制备了一种新型修饰电极AuNPs/PVP/Au/CME,运用循环伏安法,详细探究了长春地辛(Vindesine,VDS)的电化学行为,研究了最佳测定条件。结果表明,修饰电极在pH=7.19的Na_2B_4O_7-KH_2PO_4底液中进行循环伏安扫描时,在0.39V处产生一个灵敏的还原峰P_1和一个不太灵敏的氧化峰P_2。用差分脉冲伏安法研究了修饰电极对VDS的电化学响应,结果表明响应电流与VDS浓度在1.0×10~(-8)~1.0×10~(-4) mol/L范围内呈良好的线性关系,相关系数R~2=0.9972,检出限为3.2×10~(-9) mol/L。AuNPs/PVP/Au/CME修饰电极对长春地辛的电化学检测具有高的灵敏度和好的选择性。     

土壤腐殖质各组分红外光谱研究

土壤腐殖质是土壤中所特有的一类特殊的高分子化合物,具有重要的肥力和环境调节功能。其中胡敏素的提取和纯化很困难,从而限制了对其性质和结构的研究。为揭示胡敏素的结构性质,本研究按Pallo分组,将胡敏酸(HA)分为焦磷酸钠提取的胡敏酸(HAP)、氢氧化钠提取的胡敏酸(HAS);富里酸(FA)分为焦磷酸钠提取的富里酸(FAP)和氢氧化钠提取的富里酸(FAS);胡敏素(HM)分为铁结合胡敏素(HMi)、粘粒结合胡敏素(HMc)和不溶性胡敏素(HMr)三个组分,采用红外光谱法对黑土、草甸土以及黑土底土加入大量玉米秸秆培养后腐殖质各组分的结构特征进行研究。腐殖质各组分按Pallo法分组。结果表明:铁结合胡敏素(HMi)、粘粒结合胡敏素(HMc)与胡敏酸(HA)、富里酸(FA)具有相似的光谱特征,但存在明显差异。黑土、草甸土中HMi和HMc的脂族性强于HA和FA;HMi与HMc相比,HMi具有较高的脂族性。黑土中氢氧化钠提取的胡敏酸(HAS)的脂族性强于焦磷酸钠提取的胡敏酸(HAP);NaOH提取的富里酸(FAS)的脂族性强于Na4P2O7提取的富里酸(FAP)。草甸土中HAP的脂族结构较多,而HAS脂族结构相对较少。在培养土中,新形成的FA脂族性强于HA、HMi和HMc组分。新形成的HMc脂族性强于HMi和HMc的脂族性强于HAP,而弱于HAS。     

离子色谱法测定柠檬酸、柠檬酸钠中的F~-、Cl~-、SO_4~(2-)、C_2O_4~(2-)等

利用离子色谱仪,对柠檬酸、柠檬酸钠中的痕量F~-、Cl~-、SO_4~(2-)、C_2O_4~(2-)等进行测定,采用DIONEX ION PAC ASll-HC分离柱,以电导检测器检测,对淋洗分离条件进行了试验。选择NaOH作淋洗液,0.025～0.050mol/L NaOH做梯度淋洗,可使F~-、Cl~-、SO_4~(2-)、C_2O_4~(2-)等很好地分离,其中Cl~-在0.01～200mg/L,F~-在0.05～200mg/L,SO_4~(2-)在0.05～200mg/L,C~2O_4~(2-)在0.1～200mg/L范围内,浓度和响应值有良好的线性关系,检出限分别为F~-0.01mg/L、Cl~-0.01mg/L、SO_4~(2-)0.03mg/L、C_2O_4~(2-)0.03mg/L,回收率为90％～110％。该方法无需前处理,无基体干扰,可用于柠檬酸、柠檬酸钠中F~-、Cl~-、SO_4~(2-)、C_2O_4~(2-)的测定。     

吸附溶出催化伏安法测定人参中的锗

本文提出了利用吸附溶出催化伏安法测定人参中锗的方法。最佳体系为:2.5×10~(-2)mol/LH_2O_2、2.0×10~(-2)mol/L邻苯二酚、2.0×10~(-3)mol/L H_2SO_4。线性范围为2.0×10~(-9)～2.0×10~(-7)mol/L。当富集时间为4 min时,最低检测浓度为4.0×10~(-10)mol/L。此法己成功地应用于测定人参中的锗。     

ZrO2负载碳纳米管吸附去除水中氟的研究

以ZrO2负载多壁碳纳米管(ZrO2-MWCT)为吸附剂,系统研究了其对水中F-的吸附、脱附性能。结果表明,F-在ZrO2-MWCT吸附剂上的吸附等温线可以用Freundlich方程模拟,吸附动力学符合拟二级动力学方程,吸附速率随着F-初始浓度的提高而减低。当pH为4~5时,F-在ZrO2-MWCT吸附剂上的吸附量最大。水中阴离子的存在降低ZrO2-MWCT对F-的吸附量,不同阴离子对F-影响的大小顺序为:CO32->SO42->Cl->NO3-。吸附饱和的ZrO2-MWCT可用0.1mol/L的NaOH脱附再生,经4次再生后,其吸附量仍为14.55mg/g。     

纳米γ-Al_2O_3吸附Ge(Ⅳ)的机理及性能

研究了纳米γ-Al2O3吸附剂对Ge(Ⅳ)的吸附行为,考察了吸附平衡时间、温度和溶液的pH值等因素对吸附过程的影响.结果表明,纳米Al2O3对Ge(Ⅳ)的吸附在2min时基本达到平衡,在pH=4～11范围内,Ge(Ⅳ)可以被纳米Al2O3定量富集,吸附率大于95%;吸附于纳米Al2O3上的Ge(Ⅳ)可以用0.3mol/LK3PO4和1mol/LH2SO4混合溶液洗脱,5min后基本达到解析平衡,解析率能达到97%;该吸附过程符合准二级反应动力学模型,计算了不同温度下的吸附速率常数,并求得纳米Al2O3对Ge(Ⅳ)的吸附活化能(Ea)为11.63kJ/mol;该体系的吸附过程符合Freundlich等温式,由D-R等温式求得常温下纳米Al2O3对Ge(Ⅳ)的平均吸附能为10.87kJ/mol.Ge(Ⅳ)吸附反应的ΔG0为负值,焓变ΔH0为正值,说明该吸附过程是自发的吸热反应.     

气相色谱法研究有机物在河流沉积物上的吸附

本文提出用有机物在沉积物上的色谱比保留体积值估算沉积物有机碳吸附系数，为此，以河流沉积物作气相色谱固定相，用测定气相色谱固定液相对极性和有机物比保留体积的方法，测定了沉积物相对极性和有机物在其上比保留体积，研究了Ｖｇ与Ｋｏｃ的相关性，结果表明，萘的线性关系式为ｌｏｇＫ＝０．１８＋３．１１（ｒ＝０．９８３１，ｎ＝５）。硝基苯的关系为ｌｏｇＫ＝０．２４ｌｏｇＶｇ＋２．５９（ｒ＝０．９５４４，ｎ＝５）．     

Effects of acid rain on soil humic compounds

The modifications induced by acid rain on the solubility, molecular configuration and molecular weight distribution of humic (HA) and fulvic (FA) acids were studied. A natural soil was subjected to simulated acid rain until a soil pH of 4 was obtained; HA and FA acids were then extracted and characterised. The results obtained were compared both with those of natural soil and with those of a soil subjected to acid rain. Elute analysis indicates the continuous release of soluble organic compounds as a consequence of acid rain simulation, although no relationship was found with the process of soil acidification. The yields of HA and FA show that HA values are the same while FA amount is higher in the natural soil; in acid soils their water solubility increases. The molecular weight distribution shows that HA consist of a mixture of compounds of different molecular weights; they are molecules for the most part larger than 100 kDa and their distribution is not changed by soil acidification. FA can be considered to form a much more homogeneous system; in natural soil, the molecules are larger than 50 kDa, while in acidified soil they are for the most part smaller than 3 kDa.     

Entrapment of Humic Acid in a Sol-Gel Matrix—A New Tool for Sorption Studies

Humic substances are natural complexed mixtures of organic compounds originated from the decomposition of plant and animal residues. These compounds are ubiquitous in soils, sediments, surface waters and groundwaters. They contain both hydrophobic and hydrophilic moieties, able to interact with hydrophobic organic contaminants and with heavy metals. These sorption interactions play a crucial role in contaminants fate and transport and their understanding and quantification are essential for modeling and predictions. However, sorption analyses frequently suffer from experimental problems. A novel idea presented in this study is to use sol-gel as an inert matrix to immobilize (entrap) specific, well defined, humic molecules which then be used in sorption studies. We developed a successful procedure for the immobilization of humic acid (HA) in a sol-gel matrix. After gelation and drying, the doped gel was crushed and washed several times, yielding a very stable product. It was then used in a series of batch experiments, studying the sorption of several polycyclic aromatic hydrocarbons (PAHs) with Aldrich HA. The sorption coefficients (K _oc) obtained with the immobilized HA were highly correlated with the values expected based on the hydrophobicity of the contaminants. We concluded that the entrapped HA retained its original properties and that it was accessible to the external contaminants through the pore network.     

静态法和X射线吸收精细结构光谱技术研究腐殖酸对Eu(III)在高庙子膨润土上的吸附影响

膨润土由于其高吸附性和低渗透性而受到广泛的研究. 在本文中, 利用XRD、FTIR和酸碱滴定对我国内蒙古高庙子膨润土进行了详细的表征和分析. 用静态法研究在温度为25± 2 ℃和0.01 mol/L NaClO4溶液中, pH值、腐殖酸、接触时间和Eu(III)初始浓度对Eu(III)在钠基膨润土上的吸附影响. 研究结果表明Eu(III)的吸附受pH值影响明显. 在低pH值条件下, 腐殖酸对Eu(III)的吸附影响微弱, 而在高pH值条件下腐殖酸降低Eu(III)的吸附. X射线吸收精细结构光谱(XAFS)技术对吸附在膨润土上的Eu(III)局域微观结构研究结果表明, 在pH为4.15条件下, Eu在膨润土上与其周围的氧原子间的距离大约为2.39 Å. 本文中的研究结果对于评估其他三价镧系和锕系元素在作为填充材料的膨润土上的吸附和迁移具有重要的意义.     

Electron paramagnetic resonance (EPR) studies on stable and transient radicals in humic acids from compost, soil, peat and brown coal

Quantitative EPR method was applied to characterise four types of humic acids (HA) derived from composts, soil, peat and soft brown coal. For each sample of HA the level of native (indigenous) radicals was estimated. Interactions of the HA with various gaseous agents and organic solvents were investigated. Strong effects of gaseous ammonia and aliphatic amines on spin concentration enhancement were observed; additionally, higher values of g-value were found to be associated with the formed 'transient' radicals. Correlation of copper(II) ions uptake by different HA with effect diminishing primary spin concentration was established. It was recognised that the radical centres, which are enhanced by 'ammonia effect' are quenched in the formed HA-Cu(II) complexes. The both opposite effects are competitive from each other, where 'copper(II) quenching effect' prevails. Reaction of nitrogen dioxide with the humic acids was also examined. The presence of diketones and/or other compounds with active methylene group results in formation of the iminoxy radicals; these radicals are immobilized in the solid (macromolecular) matrix of the humic acids.     

Retention of Metamitron by Model and Natural Particulate Matter

Abstract

Adsorption isotherms of metamitron on model soil colloidal components: kaolinite, illite, montmorillonite, iron oxide and humic acid, and their binary associations were obtained using a batch equilibration procedure. Sorption parameters, K_f and n_f, were calculated by fitting the sorption data to the Freundlich equation and results obtained for binary associations were compared with those obtained for the individual model components. The sorption efficiency of the humic acids and their binary associations was measured as Koc. The adsorption behaviour of the < 2 μm fraction of two soils from Southern Spain was also studied as natural particulate matter. Montmorillonite and humic acids were found to be the most important components responsible for metamitron retention by the model adsorbents studied. On the contrary, metamitron showed little interaction with kaolinite, illite or iron oxide. These individual adsorption behaviours were reproduced in the montmorillonite-iron oxide-humic acid binary systems, but with differences suggesting changes on the surface properties upon association. Differences in Koc values of isolated humic acids and their associations indicate that the interaction transforms the humic acid surfaces and suggest different types of bonding between colloids and metamitron. The results obtained with model adsorbents and their associations were in agreement with the highest adsorption of metamitron found for the natural clay fraction of two soils which displayed the largest adsorption in that with the highest content in montmorillonite and organic carbon. The importance of organic matter and montmorillonite in metamitron adsorption by colloidal components was also shown by the decrease in K_f and the increase in Koc observed after removal of organic matter from the soil clay fraction with the highest organic carbon content.     

Preparation and characterization of humic and fulvic acid working standards—practical experience

Two fractions of both fulvic acids (FA) and humic acid (HA) were prepared by fractionation method of Pierce and Felbeck⁵ involving acid hydrolysis of soil rests. This step increases recovery of both FA and HA considerably what suggest us need for slight modification of IHSS method in some cases. The weight loss, change in organic carbon content and visible spectra are figures of merit discussed. After detailed characterization these humic substances (HS) will serve as the working standards for study of interactions between organomercurials and organic part of soil.