笼形聚偕胺肟树脂的研究─—卤素及其化合物在树脂上的吸附

考查了碱处理笼形聚偕胺肟树脂（BCAO）和乙酸、硝酸或盐酸处理的笼形聚偕胺肟树脂（HOAC／ACAO、HNO。／ACAO、HCI／ACAO）对卤化物、卤酸盐和卤素的吸附行为。发现BCAO和HOAC／ACAO不吸附卤化物和卤酸盐；HNO3/ACAO和HCl/ACAO对两类化合物则表现出不同的吸附能力。BCAO和ACAO均吸附溴和碘，并符合Freundlich和Langmuir等温吸附方程。研究了溴在BCAO上的吸附动力学，讨论了吸附机理。     

Improvement of water vapor adsorption ability of natural mesoporous material by impregnating with chloride salts for development of a new desiccant filter

The aim of this study is the development of a new adsorbent for the desiccant material which can be regenerated by the domestic exhaust heat by using natural mesoporous material, Wakkanai siliceous shale. To improve this shale’s performance to adsorb/desorb the water vapor, lithium chloride, calcium chloride or sodium chloride was supported into the mesopores by impregnating with each chloride solution. Especially sodium chloride was effective to increase the water vapor adsorption amount 5–7 times of that of natural shale in the relative humidity range from 50 to 70%. Moreover, the appropriate impregnating concentrations were determined as 5wt% from the relationship between the maximum water vapor adsorption amount and the mesopore volume. Based on these results, a new desiccant filter has been developed by impregnated original paper with lithium chloride and sodium chloride. This paper contained shale powder in the synthetic fibers. The dehumidification performance of this filter was evaluated under the simulated summer condition in Tokyo. From the cyclic adsorption/regeneration test, this shale and chlorides filter could adsorb and desorb 60 g/h water vapor repeatedly at the regeneration temperature of 40°C. On the other hand, a silica gel filter and a zeolite filter adsorbed and desorbed only 10 g/h and 25 g/h, respectively. These results suggested that the shale impregnated with the chlorides has the best dehumidification ability as a new desiccant material. Further, the desiccant filter made from the shale will achieve the effective use of the low temperature exhaust heat.     

N-去甲万古霉素的亲和吸附

通过交联聚丙烯酸甲酯与乙醇胺反应,形成聚(N-羟乙基丙烯酰胺)树脂,在酸催化作用下与环氧氯丙烷反应,形成含有α-羟基氯乙基的树脂.含α-羟基氯乙基的树脂与D-丙氨酸、L-丙氨酸或甘氨酸反应,分别得到含有这3种氨基酸的吸附剂.这3种吸附剂吸附N-去甲万古霉素的结果表明,含D-丙氨酸的吸附剂的吸附量最大,含甘氨酸的吸附剂的吸附量次之,而含L-丙氨酸的吸附剂不吸附N-去万古霉素.说明前两种吸附剂对N-去甲万古霉素存在亲和吸附作用.含D-丙氨酸吸附剂的最佳吸附pH值为5.8,当吸附液中的盐(NaCl)浓度增加时,吸附量降低.用0.4mol/LNa₂CO₃/CH₃CN(摩尔比7∶3,pH=9.5)作为洗脱剂可完全脱附被吸附的N-去甲万古霉素.     

Adsorption of CO2 on nitrogen-enriched activated carbon and zeolite 13X

Adsorption may be a potentially attractive alternative to capturing CO₂ from stationary sources in the context of Carbon Capture and Sequestration (CCS) technologies. Activated carbon and zeolites are state-of-art adsorbents which may be used for CO₂ adsorption, however physisorption alone tends to be insignificant at high temperatures. In the present work, commercial adsorbents have been impregnated with monoethanolamine (MEA) and triethanolamine (TEA) in order to investigate the effect of the modified surface chemistry on CO₂ adsorption, especially above room temperature. Adsorption isotherms for CO₂, N₂ and CH₄ were measured in a gravimetrically system in the pressure range of UHV to 10 bar, at 298 and 348 K for activated carbon and zeolite 13X supports. The adsorbed concentration of CO₂ was significantly higher than those of CH₄ and N₂ for both adsorbents in the whole pressure range studied, zeolite 13X showing a remarkable affinity for CO₂ at very low pressures. However, at 348 K, the adsorbed concentration of CO₂ decreases significantly. The supports impregnated with concentrated amine solutions and dried in air suffered a detrimental effect on the textural properties, although CO₂ uptake became much less susceptible to temperature increase. Impregnations carried out with dilute solution followed by drying in inert atmosphere yielded materials with very similar textural characteristics as compared to the parent support. CO₂ isotherms in such materials showed a significant change with similar capacities at 348 K as compared to the original support at 298 K in the case of activated carbons. The impregnated zeolite showed a decrease in adsorbed phase concentration in low pressures for a given temperature, but the adsorbed amount also seemed to be less affected by temperature. These results are promising and indicate that CO₂ adsorption may be enhanced despite high process temperatures (e.g. 348 K), if convenient impregnation and drying methods are applied.     

Can chiral single walled carbon nanotubes be used as enantiospecific adsorbents?

Single-walled carbon nanotubes can exist in chiral forms and can adsorb a range of molecules. We use atomistic simulations to consider whether enantiopure carbon nanotubes might be effective enantiospecific adsorbents for chiral molecules. We examine the adsorption of both enantiomers of trans-1,2-dimethylcyclopropane and trans-1,2-dimethylcyclohexane in a range of chiral nanotubes. Our simulations indicate that these molecules are strongly adsorbed in nanotubes, that is, they have large heats of adsorption, but the energy differences between adsorbed enantiomers are negligible. We argue that this result is generic for chiral organic molecules adsorbed in carbon nanotubes, suggesting that these materials will not be effective enantiospecific adsorbents.     

Determination of Arsenic by Electrothermal Atomic Absorption Spectrometry Using Arsine Preconcentration on Palladium-Containing Adsorbents

A procedure was developed for the preconcentration of arsine on palladium-containing adsorbents followed by the determination of arsenic by electrothermal atomic absorption spectrometry. Aqueous suspensions of the adsorbent were placed in a graphite furnace at the determination step. The selection of the adsorbent was substantiated; adsorption properties of palladium-containing adsorbents were studied to validate their modifying properties. The absolute and concentration limits of detection for arsenic were 28 pg and 12 ng/L, respectively (sample volume of 100 mL).     

Adsorption of gases on layered silicates at high pressures

Equilibrium adsorption of nitrogen, carbon dioxide, and argon was examined on the sodium and pyridinium forms of montmorillonite and on the hydrogen form of bentonite. The measurements were carried out at 303, 343, 373, and 400 K over pressure ranges of 0.1–90 MPa (Ar and N₂) and 0.1–6 MPa (CO₂). The amount of nitrogen vapor adsorbed was determined at 77 K and pressures from 0 to 0.1 MPa. The porous structure parameters of the studied samples were determined using adsorption isotherms of nitrogen, argon, and carbon dioxide vapors. At elevated temperatures and pressures >10 MPa, Ar and N₂ adsorption processes on the Na-form of montmorillonite and Ar adsorption on bentonite are activated, since the amounts of the gases adsorbed and adsorption volumes increase with temperature. No activated adsorption is observed for carbon dioxide adsorption on these adsorbents. A comparison of the excess adsorption isotherms of gases on the Py-form of montmorillonite and H-form of bentonite shows that adsorption in micropores predominates for the Py-form of montmorillonite, whereas for the Na-form of bentonite and H-form of bentonite adsorption occurs mainly in meso- and macropores.     

Sequential spectrophotometric determination of inorganic arsenic species by hydride generation from selective medium reactions and colour bleaching of permanganate

A simple spectrophotometric method is presented for the sequential determination of inorganic arsenic (As) species in one sample. It is based on the sequential arsine generation from As(III) and As(V) using selective medium reactions, collection of the arsine generated in an absorbing solution containing permanganate and ethanol at 5 °C and subsequent reduction of permanganate by arsine. The decrease in permanganate absorbance at 524.2 nm is monitored for As determination. The acetic acid/sodium acetate and HCl mediums were used for selective arsine generation from As(III) and remaining As(V) in one solution, respectively. The effect of interferences and their possible mechanisms were discussed. Interferences from transition metal ions were removed by using a Chelex 100 resin. Under optimized conditions, the established method is applicable to the determination of 3-30 μg of each arsenic species. Good recoveries (96-102%) of spiked artificial sea water, tap water and standard mixtures of As(III) and As(V) were also found. The method is simple, accurate, precise and environmental friendly.     

Simultaneous Removal of Polymers with Different Ionic Character from Their Mixed Solutions Using Herb-Based Biochars and Activated Carbons

Nettle and the sage herbs were used to obtain carbonaceous adsorbents. For the biochar preparation the precursors were dried and subjected to conventional pyrolysis. Activated carbons were obtained during precursor impregnation with phosphoric(V) acid and multistep pyrolysis. The textural parameters and acidic-basic properties of the obtained adsorbents were studied. The activated carbons prepared from the above herbs were characterized by the largely developed specific surface area. The obtained carbonaceous adsorbents were used for polymer removal from aqueous solution. Poly(acrylic acid) (PAA) and polyethylenimine (PEI) were chosen, due to their frequent presence in wastewater resulting from their extensive usage in many industrial fields. The influence of polymers on the electrokinetic properties of activated carbon were considered. PAA adsorption caused a decrease in the zeta potential and the surface charge density, whereas PEI increased these values. The activated carbons and biochars were used as polymer adsorbents from their single and binary solutions. Both polymers showed the greatest adsorption at pH 3. Poly (acrylic acid) had no significant effect on the polyethylenimine adsorbed amount, whereas PEI presence decreased the amount of PAA adsorption. Both polymers could be successfully desorbed from the activated carbons and biochar surfaces. The presented studies are innovatory and greatly required for the development of new environment protection procedures.     

Adsorption of ionic surfactants on polar surfaces with a low content of chemically adsorbed alkyl chains

Colloidal silica and titanium dioxide were surface-modified by chemisorption of octadecyl dimethylmethoxy silane. The surface density of these alkyl silane groups was adjusted to less than 7% of the available surface hydroxyls, leaving the adsorbents hydrophilic and electrically charged in aqueous solution.Ionic surfactants (tetradecylpyridinium chloride and sodium lauryl sulfate) are adsorbed onto the surface-modified silica and titanium dioxide from aqueous solution, even in the case where the surface of the adsorbents exhibits the same sign of electrical charge as the surfactant ionic head groups. According to the adsorption model of Gu the chemiadsorbed alkyl chains are supposed to serve as anchors for small surface aggregates of the ionic surfactants.     

Creation of active sites by impregnation of carbon fibers: application to the fixation of hydrogen sulfide

Activated carbon fibers, which exhibit high specific area and numerous active surface sites, constitute very powerful adsorbents and are widely used in filtration to eliminate pollutants from liquid or gaseous effluents. The fibers studied in this work are devoted to the filtration of gaseous effluent containing very small amounts (few vpm) of hydrogen sulfide. Preliminary experiments evidenced that these fibers weakly adsorb hydrogen sulfide. To improve their fixation capacity toward H(2)S the activated fibers are impregnated in an aqueous solution of potassium hydroxide. The impregnation treatment usually takes place before activation but in this work it occurs at room temperature after activation of the fibers. A further thermal treatment is performed to increase the efficiency of the system. The overall treatment leads to the creation of basic sites showing a great activity for H(2)S gas in the presence of water vapor. The mechanism has been established by a series of characterizations before, during, and after the different operation units. The KOH deposited after impregnation is carbonated into KHCO(3) at room temperature and then decomposed into K(2)CO(3) during the thermal treatment. K(2)CO(3) and H(2)S dissolve in a liquid aqueous solution formed on the fiber surface. Then carbonate ions and H(2)S molecules react together almost completely to yield HS(-) species. As a consequence the sorption capacities of hydrogen sulfide on the impregnated fibers are much higher, even for small hydrogen sulfide volume fractions.     

Selective determination of trace arsenic and antimony species in natural waters by gas chromatography with a photoionization detector

Traces amounts of arsenic and antimony in water samples were determined by gas chromatography with a photoionization detector after liquidnitrogen cold trapping of their hydrides. The sample solution was treated with sodium hydroborate (NaBH₄) under weak-acid conditions for arsenic(III) and antimony(III) determination, and under strong-acid conditions for arsenic(III+V) and antimony(III+V) determination. Large amounts of carbon dioxide (CO₂) and water vapor obscured determination of arsine and stibine. Better separation from interference could be achieved by removing CO₂ and water vapor in two tubes containing sodium hydroxide pellets and calcium chloride, respectively. The detection limits of this method were 1.8 ng dm^?3 for arsenic and 9.4 ng dm^?3 for antimony in the case of 100-cm³ sample volumes. Therefore, it is suitable for determination of trace arsenic and antimony in natural waters.     

Determination of inorganic arsenic and organic arsenic compounds in marine organisms by hydride generation/cold trap/gas chromatography— mass spectrometry

The behavior of arsenite, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, dimethyl-R-arsine oxides, and trimethyl-R-arsonium compounds (R = carboxymethyl, 2-carboxyethyl, 2-hydroxyethyl) toward sodium borohydride and hot aqueous sodium hydroxide was investigated. The arsines obtained by sodium borohydride reduction of the undigested and digested solutions were collected in a liquid-nitrogen cooled trap, separated with a gas chromatograph, and detected with a mass spectrometer in the selected-ion-monitoring mode. The investigated arsenic compounds were stable in hot 2 mol dm^?3 sodium hydroxide except arsenobetaine [trimethyl(carboxymethyl)arsonium zwitterion] that was converted to trimethylarsine oxide, and dimethyl(ribosyl)arsine oxides that were decomposed to dimethylarsinic acid. Hydride generation before and after digestion of extracts from marine organisms allowed inorganic arsenic, methylated arsenic, arsenobetaine, and ribosyl arsenic compounds to be identified and quantified. This method was applied to extracts from shellfish, fish, crustaceans, and seaweeds.     

无氧下低浓度硫化氢在浸渍活性炭上的吸附研究

为了考察常温、无氧下浸渍Na2CO3改性、原料气相对湿度对活性炭吸附硫化氢的促进作用，用动态吸附法分别测试了不同湿度下原活性炭和浸渍活性炭对低浓度硫化氢的吸附，同时考察了温度对该吸附过程的影响。结果表明，吸附平衡数据均符合Freundlich吸附等温方程。与原活性炭相比，浸渍活性炭的孔容和比表面积略有降低，但对硫化氢的吸附能力却显著提高，说明硫化氢与浸渍剂在活性炭表面上发生了化学反应。相对湿度增加，活性炭和浸渍活性炭对H2S的吸附能力均显著增强。温度升高，平衡吸附量均略有下降。     

Principles of methane adsorption and natural gas storage

The adsorption amount of methane on 16 different kinds of materials at 3.5 MPa and 298 K holds a linear relation with the specific surface area. The linear relationship implies that gases are adsorbed monolayerly on the surface of adsorbents at above-critical temperatures. Determination of surface area and calculation of storage capacity of a material are explicitly discussed. It is indicated that methane storage is different from natural gas storage and the difference affects the development of storage material. Natural gas is a mixture and all components other than methane cannot be desorbed when the tank pressure released to atmospheric at ambient temperature, therefore, a storage mechanism other than adsorption might be more suitable.     

改性碳纳米管常温下吸附分离低浓度CO2

采用浸渍法将四乙烯五胺(TEPA)和三乙烯四胺(TETA)负载至碳纳米管(CNTs)上,得到一种固态胺吸附剂CNTs-TEPA和CNTs-TETA,用以吸附低浓度下的CO2.利用扫描电镜(SEM)、透射电镜(TEM)、傅里叶红外(FTIR)光谱、N2物理吸附脱附、元素分析和热重分析(TGA)等方法表征样品.结果表明:CNTs-TEPA和CNTs-TETA形态并未发生变化,仍保留CNTs规整有序的孔道结构,但样品的比表面积和孔容都显著减小.在常温条件下,CNTs-TEPA和CNTs-TETA的CO2吸附量与CNTs相比有显著提高,同时,在胺浸渍质量相同的情况下,改性后的CNTs-TEPA效果优于CNTs-TETA.温度从20℃升至30℃,CNTs-TEPA和CNTs-TETA的CO2吸附量分别从126.7、101.2mg·g-1升至139.3、110.4mg·g-1.CNTs的吸附量随着温度的增加变化不明显.最后,采用Suyadal和Yasyerli两种模型对CO2的动态吸附穿透曲线进行拟合,结果说明Yasyerli模型对CNTs、CNTs-TEPA和CNTs-TETA的CO2吸附过程的拟合程度更高.     

Adsorption of Carbon Dioxide on Activated Carbon

The adsorption of CO2 on a raw activated carbon A and three modified activated carbon samples B, C, and D at temperatures ranging from 303 to 333 K and the thermodynamics of adsorption have been investigated using a vacuum adsorption apparatus in order to obtain more information about the effect of CO2 on removal of organic sulfur-containing compounds in industrial gases. The active ingredients impregnated in the carbon samples show significant influence on the adsorption for CO2 and its volumes adsorbed on modified carbon samples B, C, and D are all larger than that on the raw carbon sample A. On the other hand, the physical parameters such as surface area, pore volume, and micropore volume of carbon samples show no influence on the adsorbed amount of CO2. The Dubinin-Radushkevich (D-R) equation was the best model for fitting the adsorption data on carbon samples A and B, while the Preundlich equation was the best fit for the adsorption on carbon samples C and D. The isosteric heats of adsorption on carbon samples A, B, C, and D derived from the adsorption isotherms using the Clapeyron equation decreased slightly increasing surface loading. The heat of adsorption lay between 10.5 and 28.4 kJ/mol, with the carbon sample D having the highest value at all surface coverages that were studied. The observed entropy change associated with the adsorption for the carbon samples A, B, and C (above the surface coverage of 7 ml/g) was lower than the theoretical value for mobile adsorption. However, it was higher than the theoretical value for mobile adsorption but lower than the theoretical value for localized adsorption for carbon sample D.     

Estimation of the energetic nonhomogeneity of the surface of oxide and carbon materials

The molecular statistical method for evaluating the distribution of active sites of various adsorbents relative to their energies has been improved. This method is used not only for the treatment of experimental data on the adsorption of hydrocarbons on various adsorbents, which is the usual procedure, but also data on the adsorption of polar water and methanol molecules on the active sites of adsorbent surfaces. Two types of active sites differing in energy have been shown to exist on the surface of graphitized carbon black, the complex shungite carbon/mineral adsorbent, and modified Silochrom. Chromatographic, calorimetric, and structural adsorption data were used to establish the relationship between the observed maxima of the energy distribution function of the adsorption sites with concrete adsorption sites or pores of the surface, on which the molecules are adsorbed. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 44, No. 5, pp. 315–320, September–October, 2008.     

Adsorption of gases on adsorbents of various nature and porous structure at high pressures

The isotherms of excess adsorption of argon, nitrogen, and carbon dioxide on adsorbents with various porous structures (active carbon AU-71, polymeric sorbent MN-200, and synthetic zeolite NaA) were measured on the precision volumetric-gravimetric device in the pressure range of 0.1—150 MPa and at temperatures 300—400 K. The results of determination of the adsorption volumes of the studied adsorbents were compared using two methods. The first method is based on the Dubinin-Radushkevich equation, whereas the second one involves a conditional division of the weight of the substance in an ampule into the adsorbed portion and the part existing in the gas phase. The behavior of the adsorbed substance is described by the equation of adsorption of complete content corresponding to the physics of the adsorption process. The relation of the parameters of the empirical Dubinin—Radushkevich equation to the energy characteristics of the system was established.     

Removal of phosphate by aluminum oxide hydroxide

The development and manufacture of an adsorbent to remove phosphate ion for the prevention of eutrophication in lakes are very important. The characteristics of phosphate adsorption onto aluminum oxide hydroxide were investigated to estimate the adsorption isotherms, the rate of adsorption, and the selectivity of adsorption. Phosphate was easily adsorbed onto aluminum oxide hydroxide, because of the hydroxyl groups. The adsorption of phosphate onto aluminum oxide hydroxide was influenced by pH in solution: the amount adsorbed was greatest at pH 4, ranging with pH from 2 to 9. The optimum pH for phosphate removal by aluminum oxide hydroxide is 4. The selectivity of phosphate adsorption onto aluminum oxide hydroxide was evaluated based on the amount of phosphate ion adsorbed onto aluminum oxide hydroxide from several anion complex solutions. It is phosphate that aluminum oxide hydroxide can selectively adsorb. The selectivity of phosphate onto aluminum oxide hydroxide was about 7000 times that of chloride. This result indicated that the hydroxyl groups on aluminum oxide hydroxide have selective adsorptivity for phosphate and could be used for the removal of phosphate from seawater.