Adsorption isotherms of squash (Cucurbita moschata) seed oil on activated carbon

With vegetal carbon as adsorbent (5% w/w), the effects of temperature (30°C and 50°C), concentration of H₂O (0% and 25%) and adsorption time (0 hr, 1 hr, 2 hr, 3 hr) on the chemical characteristics of unrefinedCucurbita moschata seed oil were studied in a batch adsorption system by using a “split-plot” experimental design. With the exception of the iodine value, the chemical properties of the oil (saponification and peroxide value, carotenoid, and free fatty acids concentration) were affected significantly by interactions among the adsorption time, temperature and concentration of H₂O in the adsorption system. The results suggest that the physicochemical characteristics of the oil, and therefore its functional properties, may be modified and controlled by the conditions utilized during the adsorption process.     

Prediction of binary component isotherms for adsorption on heterogeneous surfaces

The adsorption of three basic dyes onto peat has been studied as single and bisolute equilibrium isotherms. The Freundlich equilibrium isotherm, suitable for heterogeneous adsorption systems has been selected to describe the single component data. Furthermore, the extended Freundlich formula for binary systems has been used to describe binary system equilibrium. A very good agreement is obtained between experiment and theory. The dyes under investigation are: Basic Blue 3, Basic Red 22 and Basic Yellow 21 in their single phases and binary solutions, respectively, all onto peat.     

Calculation of single adsorption isotherms from gravimetrically measured binary gas mixture adsorption isotherms on activated carbon at high pressures

A method is developed for the calculation of single-component adsorption isotherms from gravimetrically measured binary gas mixture adsorption isotherms at high pressures, at two temperatures and for different mole fractions of the gas phase. The adsorption of nitrogen/methane on active carbon Norit R1 is taken as an experimental example.     

CO/N2/CO2在MOF-74(Ni)上吸附相平衡和选择性

主要研究了MOF-74(Ni)材料对CO/N₂/CO₂的吸附分离性能。应用水热法合成制备MOF-74(Ni),分别采用全自动表面积吸附仪、P-XRD、扫描电子显微镜对材料的孔隙结构和晶体形貌进行了表征,应用静态吸附法测定了CO、N₂和CO₂在MOF-74(Ni)上的吸附等温线,应用DSLF方程模拟了3种气体MOF-74(Ni)上的吸附等温线,依据IAST理论模型计算了MOF-74(Ni)对CO/N₂二元混合物和CO/CO₂二元混合物的吸附选择性。研究结果表明:在0.1 MPa和常温条件下,MOF-74(Ni)材料对CO吸附容量高达6.15 mmol·g^-1,而相同条件下N₂的吸附量只有0.86 mmol·g^-1。MOF-74(Ni)在低压下(0～40 kPa)对CO的吸附量明显高于其对CO₂的吸附量。应用IAST模型估算MOF-74(Ni)对二元混合物吸附选择性的结果表明:MOF-74(Ni)对CO/N₂混合物的吸附选择性在1000以上;MOF-74(Ni)对CO/CO₂的吸附选择性在4～9范围,在所研究的二元气体混合物吸附体系中,MOF-74(Ni)都能优先吸附CO。     

Adsorption from binary and ternary mixtures on activated carbons containing different amounts of chemically bonded oxygen

The adsorption process from the gas and liquid phase on activated carbons was investigated. Unmodified and chemically modified activated carbon Norit RKD-3 with different contents of chemisorbed oxygen were used. The surfaces were characterized by their content of surface functional groups, and the pore structure was characterized on the basis of adsorption-desorption isotherms of benzene vapor. Surface excess isotherms from binary and ternary mixtures of dioxane, n-heptane, and benzene were also determined. The influence of the chemical composition of the carbon surface on the adsorption from the gaseous and liquid phase is discussed.     

Adsorption of flavour esters on granular activated carbon

This article reports on the liquid phase adsorption of flavour esters onto granular activated carbon. Ethyl propionate, ethyl butyrate, and ethyl isovalerate were used as adsorbates, and Filtrasorb 400 activated carbon was chosen as the adsorbent. Sips, Toth, Unilan, and Dubinin‐Radushkevich isotherm equations which are generally used for heterogeneous adsorbents were used to fit the data. Although satisfactory in fitting the data, inconsistency in parameter values indicated these models to be inadequate. On the other hand the Dubinin‐Radushkevich model gave more consistent and meaningful parameter values and adsorption capacities. By employing the Dubinin‐Radushkevich equation, the limiting volume of the adsorbed space, which equals the accessible micropore volume, was determined, and found to correlate with the value from carbon dioxide adsorption.     

Adsorption of cadmium on acid-modified Transcarpathian clinoptilolite

The adsorption properties of acid-modified Ukrainian Transcarpathian clinoptilolite towards aqueous cadmium(II) solutions under dynamic conditions have been investigated. It has been demonstrated that the adsorption capacity of the H-form of clinoptilolite depends on the nature and concentration of acid as well as the duration of contact of clinoptilolite with acid in the process of modification. The most effective adsorption of cadmium(II) was demonstrated by clinoptilolite pre-treated with 1 M of HCl during 24 h. It has been determined that the optimum for concentration of cadmium(II) is the H-form of clinoptilolite obtained without considerable dealumination. Under optimum conditions (diameter of zeolite grains equal to ca. 0.20–0.30 mm; flow rate of cadmium(II) solution of 500 ng/ml concentration through adsorbent equal to 3 ml/min; pH=5.6) the dynamic absorption capacity is 7.41 mg of cadmium per 1 g of acid-modified clinoptilolite. The conditions of desorption of cadmium from acid-modified clinoptilolite have been investigated. The solutions of potassium salts are the best desorbent of the ones that have been approved. The extraction of cadmium in these solutions reaches 88–92%.     

Adsorption states of carbon monoxide on oxygenated Cu(110) faces

Oxygen preadsorption on Cu(110) surfaces strongly reduces the CO desorption peak at 220 K, typical for clean Cu(110) and induces the development of less tightly bound states, which probably correspond to sites on Cu(111) micro-facets, formed in the course of oxygen stimulated surface reconstruction. A smaller part of the CO molecules ( 20%) seems to interact with adsorbed oxygen to give adsorbed CO ₂ ^– which can be stabilized in the presence of CO₂ by formation of van der Waals complexes, e.g. [CO₂ · CO ₂ ^– ]. At increasing temperature this complex decomposes or disproportionates to give desorbing CO and adsorbed CO ₃ ^– . The interpretation is tentative, but some evidence is given to it by TDS from Cu(111), by XPS, STM and SIMS studies and by theoretical calculations.     

CO高温变换催化剂浸渍条件研究

采用γ-Al₂O₃作载体,Ni^2＋、Cu^2＋和Mn^2＋水溶液为浸渍液,进行制备无铬CO高温变换催化剂浸渍条件的研究。由实验数据回归出Ni^2＋、Cu^2＋和Mn^2＋活性组分在载体上的浸渍动力学方程,得到Ni^2＋、Cu^2＋和Mn^2＋组分在载体上浸渍的速率常数为：k_Ni2＋= 0.000 2,k_Cu2＋=0.000 2,k_Mn2＋=0.001 6。Freundlich等温吸附表达式为：lnC_Ni2＋=－0.000 2 t＋4.447 4,lnC_Cu2＋=－0.000 2 t＋4.590 9和lnC_Mn2＋=－0.001 6 t＋3.589 5。考察了催化剂中活性组分含量与共浸渍组分浓度的关系,并得出从浸前液浓度来预测和控制催化剂成品中Ni^2＋、Cu^2＋和Mn^2＋活性组分含量的经验式。     

The adsorption of sulphate, hydrogenchromate and dihydrogenphosphate anions on surfactant-modified clinoptilolite

The adsorption of sulphate, hydrogenchromate and dihydrogenphosphate anions on surfactant-modified clinoptilolite (SMC) was investigated. The SMCs were prepared by the adsorption of cis-1-aminoctadecen-9 (oleylamine) on both modified and unmodified natural clinoptilolite tuff. The properties of the modified clinoptilolite samples, such as cation type, structure of the zeolite framework and ECEC value, determined the mechanism of oleylamine adsorption, and consequently anion adsorption on the external clinoptilolite surface. According to the strength of the anion adsorption, two groups of SMCs could be distinguished: strong and weak anion adsorbents. Strong anion adsorbents were obtained by oleylamine adsorption on H⁺-clinoptilolites by protonation of the –NH₂ groups. This mechanism of oleylamine adsorption resulted in the surface precipitation mechanism of anion adsorption being the dominant mechanism. The oleylamine derivatives of Ca- and Na-clinoptilolite were weak anion adsorbents. Oleylamine is adsorbed on Ca- and Na-clinoptilolite by hydrogen bonding, thus yielding insufficient adsorption sites for anions. Hydrogenchromate and dihydrogenphosphate anions were nevertheless adsorbed on these SMCs by interaction with oleylamine. The experiments of anion adsorption on various oleylamine loaded SMCs confirmed the existence of two types of anion adsorption sites and showed that excess oleylamine did not significantly influence the anion adsorption in the investigated concentration range. The kinetic results showed that SO₄²⁻ and H₂PO₄⁻ adsorptions were slow processes while HCrO₄⁻ adsorption was completed in a few minutes.     

CO与CO2甲烷化反应研究进展

介绍了甲烷化反应的催化剂,尤其是Ni基催化剂的研究进展,综述了助剂、载体以及制备方法对甲烷化催化剂催化性能的影响,不同催化剂上CO和CO2甲烷化反应过程的机理。     

Determination of Site Specific Adsorption Energies of CO on Copper

The binding energies of (isolated) CO molecules adsorbed at several atomic sites (terrace, step, kink) on a number of differently oriented copper surfaces have been measured by thermal desorption spectroscopy (TDS). In addition to the three low-indexed Cu surfaces several regular stepped and kinked single crystal surfaces have been employed. Using LEED measurements together with available data in the literature allowed identification of the various different CO adlayers and to assign the different TDS binding energies to the different adsorbate sites. For the close-packed surfaces binding energies between 47 kJ/mol (Cu(111)) and 51 kJ/mol (Cu(100)) were observed, which increased to 58 kJ/mol for CO molecules bound to step edges. Unexpectedly, for kink sites the same binding energy (to within 1 kJ/mol) as for step edges was observed. Moreover, a very similar binding energy of 58 kJ/mol was also measured for random defect sites on sputtered and on poly-crystalline substrates.     

CO等气体在苯酚中的溶解度的测定及关联

建立了一套用于测定高中压下气体在黏度大、易结晶高黏度溶剂中溶解度的汽液平衡测定装置,该装置采用整体温浴、流动的方法很好地解决了溶剂苯酚易结晶而带来操作困难的问题,利用该套高中压汽液平衡测定装置,在不同温度和压力下,测定了CO₂、CO、N₂、O₂气体在纯苯酚中的溶解度数据.采用RK方程的维里展开式和正规溶液理论推算得到的气体溶解度与温度和压力的函数关系式,并对相同温度和压力下CO等气体在纯苯酚中的溶解度进行了三参数关联,得出了溶解度的计算模型.最后,用这一模型关联计算CO₂、N₂、O₂和CO在纯苯酚中的溶解度,结果表明,计算值和实验值误差较小,因此,该计算模型可以用于对相同温度下加压气体在纯苯酚中溶解度的关联和内插计算.     

高比表面积活性炭吸附存储天然气性能研究

天然气中少量乙烷和丙烷的存在会直接影响活性炭对天然气的吸附存储容量。为此,体积法测定了高比表面积活性炭对甲烷、乙烷和丙烷的吸附等温线,吸附温度分别为283,293,303和313K;采用Langmuir-Freundlich(LF)方程拟合吸附等温线,得到各气体的方程参数,进而采用LRC关联式预测多组分吸附平衡数据,并计算活性炭对模拟天然气的存储能力。结果表明:活性炭对3种气体的吸附等温线都属于I型等温线,采用L-F方程可以很好地描述各气体的吸附等温线;高比表面积活性炭对模拟天然气的存储量随吸附温度的升高而显著降低,在吸附存储压力为3.5 MPa,吸附温度从283 K上升到313 K,相应的存储量(体积比)由139降低为103;与纯甲烷的吸附存储相比,模拟天然气的吸附储量(体积比)提高约20。     

电化学一氧化碳传感器电解质研究进展

本文对国内外电化学CO传感器的基本情况进行了简介,重点对电化学CO传感器电解质的研究和应用情况做了概述,并对未来的发展做了展望。     

Adsorption isotherms of sesame oil in a concentrated miscella system

The adsorption of peroxides, unsaturated carbonyls, free fatty acids and carotenoids from unrefined sesame oil on vegetable carbon (5%, w/w) in a miscella system was studied. Three different solvent conditions (hexane/ethanol, 100:0, 95:5 and 75:25, vol/vol), combined in a factorial design with five levels of solvent (0, 10, 20, 30 and 40%, w/w), were used to develop the miscella. Equilibrium adsorption was not achieved during the 100 min of adsorption, mainly because the oil components were involved in oxidation reactions during the adsorption process. However, for a given solvent concentration, adsorption of the oil components showed a significant linear regression on their respective initial concentration in the miscella (C_i). Peroxides and carbonyls showed, at all solvent levels investigated, an affinity for the carbon more independent of their C_i than free fatty acids and carotenoids. In general, at the same C_i, a higher adsorption was achieved as solvent concentration increased. The results indicated that free fatty acid adsorption may depend on competitive adsorption based on molecule hydrophobicity. However, in spite of the higher hydrophobicity of carotenoids, compared with free fatty acids, they might not be competing for the same adsorbing sites. Ethanol showed a prooxidant effect that increased peroxide production during adsorption but did not affect the reaction involved in carbonyl production.     

Effect of hydrogen reduction temperature on the surface chemistry of pure and promoted magnetite

The first and repeated isotherms were measured in hydrogen reduced magnetites, using nitrogen, carbon monoxide and carbon dioxide as adsorbates. Based on a modification of the method developed by Emmett and Brunauer (P.H. Emmett and S. Brunauer, J. Am. Chem. Sot., 59 (1937) 310–315), we were able to estimate the fraction of the total surface area covered by iron, alkali and oxygen sites. In pure magnetite, as the reduction temperature increases, iron covers a higher percentage of the total surface area at the expense of oxide containing sites. By contrast, in promoted magnetites, the fraction of the surface covered by iron remains constant with reduction temperature. There is, however, an increase in the alkali surface area fraction at the expense of the oxygen-containing sites. Volumetric measurements suggest that in pure magnetite the adsorption of carbon monoxide is linear and that one of every two adsorbed carbon monoxide molecules remains chemisorbed on the iron.The latter indicates that a “bridge” type of adsorption predominates over chemisorption. Alkali promotion seemsto inhibit the development of the linearly adsorbed carbon monoxide molecule, and enhances the amount of carbon monoxide chemisorbed. This effect increases with increasing reduction temperature and promoter addition.     

改性沸石对废水中Cu2+、Cr3+的去除作用研究

用Na OH碱熔-水热法处理得到的改性斜发沸石作为吸附交换剂,对模拟废水中以Cu2+、Cr3+为代表的重金属离子进行吸附处理。研究了不同吸附时间、投加量以及初始浓度条件下,改性斜发沸石对Cu2+、Cr3+的去除效果。实验结果表明:改性沸石与水样中Cu2+、Cr3+的质量比分别为18.75∶1、13.33∶1时,对Cu2+、Cr3+的去除率分别达88.0%、87.4%,且为快速吸附平衡过程。此外,用Na Cl溶液和Na Cl溶液加氨水对吸附Cu2+饱和的改性沸石进行再生实验,再生率较高,改性斜发沸石可以多次重复利用。     

电催化还原二氧化碳制一氧化碳催化剂研究进展

电催化还原CO₂作为缓解能源危机和全球变暖的有效途径已成为催化领域的研究热点。然而,不同反应途径的氧化还原电位较为接近,使产物的选择性成为电催化还原CO₂所需解决的主要问题。迄今为止,在水性电解质中可实现CO₂选择性地转化为一氧化碳（CO）和甲酸（HCOOH）。本文简述了电催化还原CO₂制CO的机理,包括CO₂吸附过程、二电子转移过程和CO脱附过程。从贵金属的晶面设计、形貌调控和表面功能化对反应活性和产物选择性的影响,铁卟啉、钴酞菁和镍三嗪在还原CO₂为CO反应中的电子转移途径,非金属碳基材料中杂原子和碳基质间的耦合效应等方面,重点介绍了近年来贵金属催化剂、过渡金属络合物催化剂和非金属碳基材料催化剂的研究进展,总结了各类催化剂的优缺点。指出在三类电催化还原CO₂制CO的催化剂中,非金属碳材料具有较高的CO法拉第效率,尤其是非金属碳材料成本较低、制备简单、结构易调控,在电催化还原中具有潜在的应用优势,是有望实现商业化应用的新型催化剂的候选材料之一。