ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n-HEXANE ON ACTIVATED CARBONS BY TPD TECHNIQUE

In this paper, six kinds of activated carbons such as Ag+-activated carbon, Cu2+-activated carbon, Fe3+- activated carbon, activated carbon, Ba2+- activated carbon and Ca2+-activated carbon were prepared. The model for estimating activated energy of desorption was established. Temperature-programmed desorption (TPD) experiments were conducted to measure the TPD curves of n-hexanol and then estimate the activation energy for desorption of n-hexanol on the activated carbons. Results showed that the activation energy for the desorption of n-hexanol on the Ag+- activated carbon, the Cu2+- activated carbon and the Fe3+- activated carbon were higher than those of n-hexanol on the activated carbon, the Ca2+- activated carbon and the Ba2+- activated carbon.     

ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n—HEXANE ON ACTIVATED CARBONS BY PTD TECHNIQUE

In this paper,six kinds of activated carbons such as Ag^+-activated carbon,Cu^2+activated carbon,Fe^3+-activated carbon,activated carbon,Ba^2+-activated carbon and Ca^2+activated carbon were prepared.The model for estimating activated energy of desorption was established.Temperature-programmed desorption(TPD)experiments were conducted to measure the TPD curves of n-hexanol and then estimate the activation energy for desorption of n-hexanol on the activated carbons.Results showed that the activation energy for the desorption of n-hexanol on the Ag^+-activated carbon,the Cu^2+-activated carbon and the Fe^3+-activated carbon were higher than those of n-hexanol on the activated carbon,the Ca^2+-activated carbon and the Ba^2+-activated carbon.     

ACTIVATION ENERGY OF DESORPTION OF DIBENZOFURAN ON ACTIVATED CARBONS

Three kinds of commercial activated carbons, such as Norit RBI, Monolith and Chemviron activated carbons, were used as adsorbents for adsorption of dibenzofiuran. The average pore size and specific surface area of these activated carbons were measured Temperature Programmed Desorption (‘TPD) experiments were conducted to measure the TPD curves of dibenzofuran on the activated carbons, and then the activation energy for desorption of dibenzofuran on the activated carbons was estimated. The results showed that the Chemviron and the Norit RB1 activated carbon maintained higher specific surface area and larger micropore pore volume in comparison with the Monolith activated carbon, and the activation energy for the desorption of dibencofuran on these two activated carbons was higher than that on the Monolith activated carbon. The smaller the pore of the activated carbon was, the higher the activated energy of dibenzofiuran desorption was.     

ACTIVATION ENERGY OF DESORPTION OF DIBENZOFURAN ON ACTIVATED CARBONS

1. INTRODUCTION With the development of municipalization in China, more and more cities are challenged by the problem of how to dispose of the dramatically increased municipal waste. Generally, most of municipal solid waste is landfilled or dumped openly in the suburbs. It causes not only land waste, but also serious environment pollution. In order to solve efficiently the environment pollution caused by municipal solid waste, incineration technique was introduced in some big cities such…     

活性炭吸附及离子交换富集分离-分光光度法测定水中痕量银

建立了用活性炭对水中痕量银进行预富集的新方法。结果表明,pH=1.0时,活性炭能对水中被抗坏血酸还原后的痕量银进行吸附富集,而Cu(Ⅱ)、Fe(Ⅲ)、Co(Ⅱ)、Ni(Ⅱ)、Pb(Ⅱ)、Zn(Ⅱ)、Mn(Ⅱ)、Al(Ⅲ)、Bi(Ⅲ)和Sb(Ⅲ)等常见阳离子不被吸附,用K2S2O8将吸附在活性炭上的单质银氧化解脱后,用Mg(NO3)2辅助置换洗脱,可用分光光度法测定。该法在8～50μg/L银(Ⅰ)范围内加标回收率为93.2～97.1%。同时还研究了活性炭对银的吸附行为,提出了活性炭表面上被氧化的Ag(Ⅰ)和Mg(Ⅱ)有离子交换作用。应用该法测定自来水中痕量银,结果令人满意。     

Ag+及其配合物在活性炭上吸附行为研究

研究了配位体和氧化改性对活性炭吸附Ag^ 及其配合物的影响以及银在活性炭表面的分布特征。结果表明：(1)活性炭对Ag^ 的吸附非常快,且不受离子强度的影响．但当Ag^ 形成[Ag(NH3)2]^ 和[Ag(S2O3)2]^3-后在活性炭上吸附性能下降,氨水浓度增加对[Ag(NH3)2]^ 的吸附没有影响,而还原性的Na2S2O3浓度增加使[Ag(S2O3)2]^3-的吸附下降。(2)银主要分布在活性炭的外表面,Ag^ 浓度和吸附时间不同将导致银颗粒的分布及粒径也不同,合理控制Ag^ 浓度和吸附时间,就可以在活性炭表面负载纳米金属银．(3)活性炭氧化改性不利于Ag^ 和[Ag(S2O3)2]^3-的吸附,却有利于[Ag(NH3)2]^ 的吸附。     

沸石和活性炭为载体的Fe3+和Cu2+型催化剂催化氧化苯酚的比较

以沸石和活性炭为载体，制备了Fe3 和Cu2 型沸石和活性炭催化荆，研究了非均相Fe和Cu催化剂催化氧化高浓度含酚废水．在Fenton反应机理的基础上，探讨了Cu2 的均相和非均相催化氧化机理，以人造沸石和活性炭为栽体制备了相应的4种非均相催化剂，进行了均相、非均相Fe和Cu催化剂催化氧化高浓度含酚废水的对比试验，分析了这两种载体的比表面积、孔径分布和中孔孔容，比较了4种非均相催化剂对苯酚降解率的影响．结果发现Cu2 不仅能大大提高反应速率，而且其均相、非均相反应体系的苯酚降解率均可达到约97％．     

超声场下苯酚吸附相平衡和均相催化剂氧化降解实验研究

测定了常规条件和超声场条件下苯酚在活性炭上的吸附等温线,并研究了超声再生活性炭和均相催化剂氧化降解苯酚实验.研究结果表明,超声场作用下苯酚在活性炭上的吸附等温线降低,平衡吸附量减少,被脱附下来的苯酚及时被Cu2 和Fe3 型催化剂氧化降解,吸附剂得到更彻底再生,避免了二次污染,而且再生后的活性炭均具有较高的二次吸附能力,对于处理低浓度含酚废水具有实际意义.     

含铜MFI分子筛的H2-TPT和O2-TPD研究

 采用H2－TPR和O2－TPD手段考察了不同金属离子交换的ZSM－5分子筛催化剂上的氢还原性能和氧脱附性能．发现Cu－ZSM－5催化剂的储氧能力及氧脱附性能优于Co－ZSM－5和Fe－ZSM－5催化剂;储氧能力强、低温下氧脱附性能好的催化剂,对NO分解反应的催化活性就高．铜离子是反应的活性中心．添加Ag和Ce可使Cu－ZSM－5催化剂上氧的脱附温度大大降低．Cu－ZSM－5／堇青石整体式催化剂上Cu的存在形式与单纯的Cu－ZSM－5有差异,整体式催化剂上的一价铜数量少,但较稳定．     

Tl2Ba2Ca2Cu3O10的化学键性质和同质异能位移研究

Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can-1CunO2n+4. The direct information on the Cu ion site at the atomic level is important for elucidating the superconductivity mechanism. The local bond properties of Tl2Ba2Ca2Cu3O10 were studied using the average band-gap model. The calculated results show that the covalency of Cu(1)-O bond is 0.561, and the average covalency of Cu(2)-O is 0.296. M(o)ssbauer isomer shifts of 57Fe in Tl2Ba2Ca2Cu3O10 were calculated using the chemical surrounding factor, defined by covalency and electronic polarizability. It is verified that for lower doping, Fe substitute the Cu at the Cu (1) site in forms of Fe3+ and Fe4+; for higher doping, Fe3+ and Fe4+ ion occupies Cu(1) and Cu(2) site respectively.The studies show that the determination of the correspondence between spectrum components and actual copper sites occupied by M(o)ssbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.     

Effect of activated carbon support on CS_2 removal over coupling catalysts

Supported coupling catalysts for CS2 removal were prepared with different activated carbons originated from wood,coconut shell and coal as supports,and their catalytic activities for CS2 removal were tested at ambient temperature.The textural and surface properties of the activated carbons were characterized by nitrogen adsorption,temperature-programmed desorption(TPD)and Boehm titration.The activated carbon support with meso-and macropores,and oxygen-functional groups performs higher CS2 removal ability at ambient temperature.The effects of flow rate,CS2 inlet concentration,temperature and relative humidity on CS2 removal were also investigated.High efficient removal is obtained at temperature of 50-C,space velocity of 2000 h-1,inlet CS2 concentration of 500 mgS/m3 and relative humidity of 20%with the breakthrough sulfur capacity up to 4.3 gS/gCat and working sulfur capacity up to 7 gS/gCat.     

Study of activated carbon supported iron catalysts for the Fischer-Tropsch synthesis

Summary Characterization (BET and TPD) and reaction studies were conducted with activated carbon supported iron catalysts (Fe/AC) used for the Fischer-Tropsch synthesis (FTS). The TPD study showed that there existed interactions between metals and the AC surface. Greater association of Cu and K promoters with the AC surface resulted in stronger promoter to surface interaction, which enhanced the H₂ desorption ability of the Cu and K promoted Fe/AC catalyst prepared under vacuum impregnation (VI). Catalytic behavior of a Fe/AC catalyst (VI-15 Fe/2 Cu/2 K/81 AC, in parts per weight) was studied in a 1-liter slurry phase continuous stirred tank reactor. The catalyst presented moderate syngas conversion (44.3-60.6%) and high gaseous selectivity (CH₄, 12.8-15.1% and C₂-C₄, 42.4-46.1%) under 304^oC, 3.0 MPa, 1.1 L(STP)/g-cat/h, and H₂/CO = 2.0 during 166 h of testing. Detectable hydrocarbons up to C₁₈ were formed on the Fe/AC catalyst.     

Utilization of Thermal Analysis to Establish the Optimal Conditions for Regeneration of Activated Carbons

Thermoanalytical methods (TG, DTG and DTA) were used to determine the temperature interval (140–350°C) in which p-nitroaniline undergoes thermal desorption from the surface of activated carbons obtained from the shells of oxidized plum stones and impregnated with aqueous solutions of Cu, Fe and Ti salts, which simulate the processes of activated carbon regeneration. It was established that the impregnation of the activated carbons facilitated the regeneration processes in the sense that they can occur at lower temperatures: 135–320 (Cu), 150–340 (Ti) and 130–320°C (Fe). The utilized activated carbons were preliminarily characterized by BET surface area, DSC and scanning electron microscopic methods. This revised version was published online in July 2006 with corrections to the Cover Date.     

铊(I)离子选择电极动力学分析法测定超痕量铁

Fe(II) induces the reaction between Tl3+ and H2O2. The rate of reaction is linearly proportional to the concentration of Fe2+ in the range 2.5 ?10-9-2.5 ?10-8 mol dm-3 (20? and 5 ?10-9-5 ?10-8 mol dm-3 (15?. The standard deviation is less than 0.071 ?10-8. A 1000-fold excess of Zn2+, Cd2+, Mg2+, Ni2+, Pb2+, Ba2+, Ca2+, Li+, Na+, Ag+, NO3-, SO42-, AcO-, HPO42-, 500-fold excess of Al3+, Fe3+, Co2+, Hg2+ and 100-fold excess of Ti4+, Cr3+, Cu2+, Br-, Cl- can be tolerated, but reducing agents such as (NH2)2SO4, NH2OH.HCl interfered. This kinetic method was applied to determine Fe(II) in standard zinc sample and fountain water, with satisfactory results.     

The growth of silver on an ordered alumina surface

The growth of Ag on an ordered Al2O3 surface was studied by low energy ion scattering spectroscopy (LEIS), scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption (TPD). Three-dimensional (3D) growth of Ag clusters was observed with STM and LEIS, with the cluster size increasing with Ag coverage. The XPS core level binding energies and the Auger parameters indicate a weak interaction between the Ag clusters and the Al2O3 support. Final state effects are determined to be the primary contribution to the Ag core level binding energy shift. Nonzero order kinetics was observed for Ag desorption in TPD with the Ag sublimation energy decreasing with decreasing cluster size.     

1-Phenyl-1-propyne on Cu(111): TOFMS TPD, XPS, UPS, and 2PPE Studies

The bonding properties of 1-phenyl-1-propyne (PP, C6H5CCCH3) on Cu(111) at 100 K have been studied using temperature-programmed desorption (TPD), and X-ray, ultraviolet, and two-photon photoemission spectroscopies (XPS, UPS, and 2PPE). In TPD, there is no evidence for dissociation. Multilayer desorption occurs at 187 K, and monolayer desorption occurs at 320 (83.5 kJ/mol) and 390 K (102.4 kJ/mol), with the latter dominating. Based on the calibrated C(1s) XPS, the saturation monolayer coverage is one PP per four surface Cu atoms. The broad and asymmetric C(1s) intensity profile of the monolayer can be resolved into three symmetric components, with peaks at 283.6, 284.5, and 285.2 eV and intensities of 2:6:1, respectively. These are attributed, respectively, to acetylenic carbons bound to Cu, phenyl, and methyl carbons. The monolayer valence band ultraviolet photoemission spectrum profile contains four resonances attributable to PP perturbed by interactions with the Cu(111) substrate. With the exception of the highest occupied molecular orbital (HOMO) that is shifted by 0.4 eV, these are uniformly shifted by 1 eV further from the Fermi level for the multilayer. Calculated electron density plots of the occupied orbitals coupled with UPS profiles suggest a spectator role for the phenyl group and bonding to Cu via the acetylenic carbons. The adsorption of 1.0 monolayer (ML) of PP on Cu(111) lowers the work function by 0.85 eV. Using 2PPE, two unoccupied orbitals were identified at 1.0 (U1*-LUMO) and 0.6 eV (U2*-image state) below the vacuum level. A chemisorption model consistent with these spectroscopic results and the major chemisorption peak in TPD involve di-sigma-bonding of the acetylenic carbons to a pair of second-nearest neighbor surface Cu atoms (cross-bridge).     

微波辐射紫茎泽兰制备优质活性炭的研究

以紫茎泽兰为原料,碳酸钾为活化剂,采用超声波浸渍,微波辐射法制备活性炭.研究了浸渍方式与时间、微波功率、微波辐射时间、剂料比对活性炭吸附性能和得率的影响.得到了本实验条件下的优化工艺条件:超声波浸渍20min、120℃脱水2h,微波功率700W、微波辐射时间12min、剂料比1.25∶1.优化工艺条件下制备的活性炭碘吸附值为1470.27mg/g,亚甲基蓝吸附值为300mL/g,得率为16.35%.浸渍时间极大的缩短,微波辐射时间只有传统法活化时间的1/15左右,活性炭的吸附指标超过了国标GB/T 13803.1-1999和GB/T 13803.2-1999一级品的标准,其中碘吸附值是国家一级标准的1.47倍,亚甲基蓝吸附值是国家一级标准的2.73倍.同时,测定了该活性炭氮吸附,其BET比表面积为1540.97m2/g,总孔容为0.7393mL/g,并通过DFT表征了活性炭的孔径分布,结果表明该活性炭为微孔型活性炭.     

常见金属离子对漆酶酶活的影响

检测了14种不同的金属离子对两种漆酶(laccaseA和laccaseB,简称LacA和LacB)活性的影响.结果表明:Al3+,Fe3+,Ag+,Hg2+对两种漆酶的活性都有抑制作用,其中Fe3+,Ag+的抑制作用最强,酶活完全损失;Mg2+,Cu2+对两种漆酶的活性有激活作用.     

Neutral bidentate organophosphorus compounds as novel ionophores for potentiometric membrane sensors for barium(II)

Bis(diarylphosphine oxide) naphthalene compounds are used as novel ionophores in plasticized poly(vinyl chloride) matrix membrane sensors for barium ions. The most favorable sensor was 1,2-bis(diethylphenylphosphine oxide)naphthalene containing potassium tetrakis(4-chlorophenyl)borate as lipophilic salt and o-nitrophenyloctyl ether as plasticizer for ion-selective electrode membrane construction. The electrode showed excellent properties. It gave a linear response with a Nernstian slope of 30 mV per decade within the concentration range 10(-1)-10(-5) mol L(-1) BaCl2. The electrode exhibits a high selectivity towards Ba2+ with respect to Li+, Na+, K+, Rb+, Cs+, NH4+, Ag+, Mg2+, Ca2+, Sr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Al3+, La3+, and Ce3+ ions. The electrode response was stable over a wide pH range (3-11). The lifetime of the electrode was about 2 months. It was successfully applied to the determination of Ba2+ contents in some rocks.     

Predicting adsorption isotherms of low-volatile compounds by temperature programmed desorption: iodine on carbon

Equilibrium adsorption isotherms for low-volatile compounds are extremely difficult to measure. A simple technique using temperature programmed desorption (TPD) is proposed. It is demonstrated that the two parameters needed for constructing the Langmuir isotherm can be derived with data from the TPD technique alone. Thus, the Langmuir isotherms of iodine on AX-21 super-activated carbon were obtained with this technique. A series of TPD experiments for samples with different initial loadings of iodine were carried out by varying the heating rates which resulted in different peak desorption temperatures. The peak desorption temperature decreased as the initial loading was increased because of the re-adsorption effect. The Langmuir constant was derived from kinetic theory with the activation energy for desorption obtained from the experiment. The activation energy for desorption was 12.3 kcal/mol. The Langmuir constants determined by this technique were in comparable order of magnitude to the reported values for iodine on activated carbon. The saturation capacity of AX-21 for iodine could also be determined from the TPD data obtained from samples with different initial loadings. The estimated saturation capacity from the TPD experiment was 2.96 g I(2)/g AX-21, which was close to the experimentally measured saturation capacity of 3.25 g I(2)/g AX-21 for the same system.