Monte Carlo模拟对称型三嵌段共聚高分子的吸附

The adsorption behavior of symmetric triblock copolymers, Am/2BnAm/2, from a nonselective solvent at solid-liquid interface has been studied by Monte Carlo simulations on a simple lattice model. Either segment A or segment B is attractive, while the other is non-attractive to the surface. Influences of the adsorption energy,bulk concentration, chain composition and chain length on the microstructure of adsorbed layers are presented.The results show that the total surface coverage and the adsorption amount increases monotonically as the bulk concentration increases. The larger the adsorption energy and the higher the fraction of adsorbing segments, the higher the total surface coverage is exhibited. The product of surface coverage and the proportion of non-attractive segments are nearly independent of the chain length, and the logarithm of the adsorption amount is a linear function of the reciprocal of the reduced temperature. When the adsorption energy is larger, the adsorption amount exhibits a maximum as the fraction of adsorbing segment increases. The adsorption isotherms of copolymers with different length of non-attractive segments can be mapped onto a single curve under given adsorption energy. The adsorption layer thickness decreases as the adsorption energy and the fraction of adsorbing segments increases, but it increhses as the length of non-attractive segments increases. The tails mainly govern the adsorption layer thickness.     

固定床柱动态吸附法脱除人参醇提物中铅离子(英文)

The removal of lead from ginseng ethanol extracts by a fixed-bed column filled with an adsorbent bearing amine and carboxyl groups was investigated. The Pb2+ content was determined by inductively coupled plasma mass spectrometry. When the flowrate increased from 0.12 to 0.34 ml·min-1 , the column exhibited a marked increase in percentage of lead removal from 54.9% to 92.3%. Further increase in the flowrate did not bring evident changes to the lead removal, whereas an increase in the temperature could reinforce adsorption further, suggesting that the adsorption process was controlled by external film diffusion below the flowrate of 0.34 ml·min-1 , and by the intraparticle pore diffusion of lead ions when the flowrate exceeded it. A low remaining lead amount in extracts such as 0.11 mg·kg-1 (extracts powder) was achieved. The adsorbents also adsorbed effective constituents to some extent. But 88% of constituents adsorbed were taken off using a 70% ethanol aqueous solution.     

Removal of Cd（II） by Nanometer AIO（OH） Loaded on Fiberglass with Activated Carbon Fiber Felt as Carrier

A new nanometer material, nanometer AlO（OH） loaded on the fiberglass with activated carbon fibers felt（ACF） as the carrier, was prepared by hydrolytic reaction for the removal of Cd（II） from aqueous solution using column adsorption experiment. As was confirmed by XRD determination, the hydrolysis production loaded on fiberglass was similar to the orthorhombic phase AlO（OH）. SEM images showed that AlO（OH） particles were in the form of small aggregated clusters. The Thomas model was applied for estimating the kinetic parameters and the saturated adsorption ability of Cd（II） adsorption on the new adsorbent. The results showed that the maximum adsorption capacity of Cd（II） was 128.50 mg·g^-1 and 117.86 mg·g^-1 for the adsorbent mass of 0.3289 g and the adsorbent mass of 0.2867 g, respectively. The elution experiment result indicated that the adsorbed Cd ions was easily desorbed from the material with 0.1 mol·L^-1 HCl solution. Adsorption-desorption cycles showed the feasibility of repealed uses of the composited material. The adsorption capacities were influenced by pH and the initial Cd（II） concentration. The amount adsorbed was greatest at pH 6.5 and the initial Cd（II） concentration of 0.07 mg·L^-1, respectively. Nanometer AlO（OH） played a major role in the adsorption process, whereas the fiberglass and ACF were assistants in the process of removing Cd（II）. In addition, the adsorption capacities for Cd（II） were obviously reduced from 128.50 mg·L^-1 to 64.28 mg·L^-1 when Pb ions were present because Pb ions took up more adsorption sites.     

Peanut Shell Activated Carbon： Characterization,Surface Modification and Adsorption of Pb^2＋ from Aqueous Solution

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell （PAC） was used for the removal of Pb^2＋ from aqueous solution. The impacts of the Pb25 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared （FTIR） spectroscopy, X-ray photoelectron spectroscopy （XPS）, Boehm titration. The textural properties （surface area, total pore volume） were evaluated from the nitrogen adsorption isotherm at 77 K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon （GAC） showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% （by mass）] modified PAC has larger adsorption capacity of Pb^2＋ from aqueous solution （as much as 35.5 mg·g^-1）. The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.     

Adsorption equilibria of paeoniflorin and albiflorin on cyano-silica column from supercritical carbon dioxide/ethanol

Adsorption equilibria of paeoniflorin and albiflorin on a cyano-silica column(CN column) from the solution of supercritical carbon dioxide(scCO_2) modified with ethanol were studied. The adsorption capacity at 308.15 K,313.15 K, 318.15 K and 323.15 K under pressures corresponding to carbon dioxide/ethanol densities from0.347 g·cm~(-3) to 0.662 g·cm~(-3) were determined using the elution by characteristic point method(ECP). The effects of temperature and pressure on the solute loading were investigated. The results showed that the lower the temperature, the higher the adsorption capacity. With the decrease of density of scCO2, the adsorption capacity strengthens. The maximum adsorption capacity of paeoniflorin(albiflorin) on the CN column was15.24 mg·ml~(-1)(31.14 mg·ml~(-1)) in the range of 0–1.84 mg·ml~(-1)(0–1.67 mg·ml~(-1)) of paeoniflorin(albiflorin)standard solution. The adsorption capacity of albiflorin was twice as much as that of paeoniflorin under the same conditions. Adsorption data of paeoniflorin and albiflorin could be well described by the Langmuir model and Freundlich model. Compared with the two model fitting results, the adsorption of paeoniflorin and albiflorin belonged to the monolayer adsorption under conditions of 308.15–323.15 K and 10–17 MPa.     

Removal of Phosphate from Aqueous Solution with Modified Bentonite

Bentonite combined with sawdust and other metallic compounds was used to remove phosphate from aqueous solutions in this study. The adsorption characteristics of phosphate on the modified bentonite were investigated, including the effects of temperature, adsorbent dosage, initial concentration of phosphate and pH on removal of phosphate by conducting a series of batch adsorption experiments. The results showed that 98% removal rate of phosphate was obtained since sawdust and bentonite used in this investigation were abundantly and locally available. It is concluded that modified bentonite is a relatively efficient, low cost and easily available adsorbent for the removal of phosphate from aqueous solutions.     

活性白土对模拟油脂中β-胡萝卜素和叶绿素的吸附动力学研究

The textural properties of acid-activated bentonite (AAB), which were prepared using four different concentrations of sulfuric acid, were analyzed by adsorption-desorption isotherm of nitrogen using an automated specific surface area and porosity analyzer. The total pore volume, specific surface area and average pore diameter of these four kinds of AAB show a regular changing trend, increasing first and then decreasing, the optimum of which can be achieved at a sulfuric acid concentration of 25% (sample A25). The kinetic analysis of the adsorption ofβ-carotene and chlorophyll in model oil solutions, namely, xylene and edible oil solution, has been investigated by using AAB. Experimental results indicated that the adsorption data fit the pseudo-second-order model well. The whole adsorption process of the two pigments on AAB was divided basically into two parts the initial adsorption of pigments was rapid in the first 10 min, followed by a slower adsorption process till equilibrium was attained at 60 min. In addition, the amount and rate of adsorption on A25 increase synchronously with the initial pigment concen-tration and temperature. The results showed that the adsorption kinetics behavior of AAB with respect to the pig- ments is not influence by the xylene and edible oil solution.     

焙烧温度对加氢脱氮催化剂性能的影响

A series of Mo/Ni-based hydrotreating catalysts calcined at different temperatures was prepared by impregnation method,and characterized by means of N₂ adsorption-desorption,NH₃-TPD and TPR techniques.The HDN performance of the catalysts was investigated in a microreactor.The results indicated that with the increase of calcination temperatures,the specific surface area of the catalysts was decreased,the average pore size was gradually increased,and the pore volume change was very small.The acid amount on the surface of the catalysts showed a tendency to ascend firstly, and then to descend with the increase of calcination temperatures, and the acid amount reached the maximum at 500 ℃. The activity of the hydrotreating catalysts was enhanced firstly and then reduced with the increase of calicination temperature,and the optimal calcination temperature was 500 ℃.On the whole,the activity of the catalysts could be improved prepared under suitable calcination temperature,and be suppressed obtained under high calcination temperature.     

Adsorption equilibrium of citric acid from supercritical carbon dioxide/ethanol on cyano column

Supercritical adsorption equilibrium has a significant role in defining supercritical adsorption behavior. In this paper, the adsorption equilibrium of citric acid from supercritical CO2/ethanol on a cyano column was systemat-ical y investigated with the elution by characteristic point method. Equilibrium loading was obtained at 313.15 K and 321.15 K with supercritical CO2/ethanol densities varying from 0.7068 g·cm?3 to 0.8019 g·cm?3. The exper-imental results showed that the adsorption capacity of citric acid decreased with increasing temperature and in-creasing density of the supercritical CO2/ethanol mobile phase. The adsorption equilibrium data were fitted wel by the Quadratic Hill isotherm model and the isotherms showed anti-Langmuir behavior. The monolayer satura-tion adsorption capacity of citric acid is in the range of 44.54 mg·cm?3 to 64.66 mg·cm?3 with an average value of 56.86 mg·cm?3.     

Kinetic and thermodynamic studies of acid scarlet 3R adsorption onto low-cost adsorbent developed from sludge and straw简

A low-cost adsorbent was prepared from sludge and straw by pyrolysis in a dried state with the surface area of the adsorbent of 829.49 ma. g-l, micropore volume of 0.176 cm2·g-1 and average pore radius of 5.0 nm. The kinetic, equilibrium isotherm and thermodynamic characteristics of trisodium 1-（1-naphthylazo）-2-hydroxynaphthalene- 4＇,6,8-trisulphonate （acid scarlet 3R） onto the adsorbent from sludge and straw were investigated. The results indicated that the pseudo second order adsorption was the predominant adsorption mechanism of acid scarlet 3R. Thus, the adsorption phenomenon was suggested as a chemical process. The adsorption data were fitted better with Langmuir model than Freundlich model, indicating that the adsorption of acid scarlet 3R belonged to the monolayer adsorption and mainly occurred in micropores.     

改性膨润土对废水中Cd(II)的吸附特征及吸附动力学研究

为探讨改性膨润土对Cd(II)的吸附特征及吸附动力学机制,通过吸附实验探讨了pH值、初始浓度和吸附时间对改性膨润土吸附Cd(II)的影响。结果表明,盐酸改性膨润土对Cd(II)的去除率表现为随溶液pH值升高而升高,而氢氧化钠改性膨润土、膨润土与十二烷基磺酸钠改性膨润土的去除率分别在pH=6和7时达到最大值。膨润土及改性膨润土对Cd(II)的去除率随初始浓度的增加而降低,吸附量随平衡浓度增加而增大,并趋向平稳,吸附符合Langmuir方程,吸附为单分子层吸附。膨润土及改性膨润土的吸附反应在240 min内基本达到平衡,吸附动力学分析表明吸附过程更符合准二级动力学模型,吸附过程以化学吸附为主,膨润土及改性膨润土的吸附速率大小依次为K2HCl-B＞K2NaOH-B＞K2B＞K2SDS-B,液膜扩散与颗粒内扩散过程均为控速步骤。该研究可为改性膨润土处理含镉废水和修复镉污染土壤提供参考。     

A novel lanthanum-modified bentonite,Phoslock, for phosphate removal from wastewaters

Phoslock^®, a lanthanum-modified bentonite, has been investigated for phosphate uptake from synthetic and real wastewaters in laboratory and field. In laboratory tests, equilibrium and kinetics were studied at various temperatures, ionic strength, and pHs. The investigation indicated that phosphate adsorption occurs through a chemisorption process. The activation energy of the adsorption process was calculated based on pseudo-second order rate constant. The maximum adsorption capacity of Phoslock was unaffected at pH 5–7, but decreased at higher pHs. The monovalent phosphate anion, H₂PO₄⁻, had the greatest affinity for the adsorbent surface. Furthermore, it was also shown that the activation energy was lower at a higher solution pH attributed to the loss of adsorption sites at the higher pHs while it remained unaffected by the ionic strength of the solution. A field test also demonstrated that the Phoslock works well for phosphate uptake in polluted waters.     

水稻秸秆/膨润土基高吸水树脂的制备及其对Cu2+的吸附

以丙烯酸、丙烯酰胺为单体,水稻秸秆为有机材料,膨润土为无机材料,过二硫酸钾为引发剂,N-羟甲基丙烯酰胺为交联剂,采用水溶液聚合法制备了水稻秸秆/膨润土基高吸水树脂,并对其结构进行了表征。研究了溶液pH值、溶液初始浓度、树脂用量、吸附时间和温度对吸附Cu^2+的影响。结果表明:树脂对Cu^2+的吸附符合Langmuir等温模型,伪二阶动力学模型更能描述树脂对Cu^2+的吸附行为;吸附主要为单分子层吸附,吸附速率取决于表面的空吸附位点;温度越高越有利于反应的进行,且吸附过程中存在化学反应。     

氨氮废水的吸附处理

探讨了经镁离子改性并煅烧的膨润土对氨氮废水的吸附特性，考察了pH、反应温度、反应时间、改性膨润土的用量等因素对改性膨润土吸附性能的影响。结果表明：经镁离子改性的膨润土对氮有较好的吸附性能。且当膨润土中镁离子质量分数为2．0％、经300℃煅烧2h时，在pH=6、镁离子改性的膨润土的用量为10g／L、吸附时间为30min的条件下，对质量浓度为100mg／L的氨氮废水的去除率可达到91％，处理后的废水氨氮质量浓度小于15mg／L，达到了国家一级排放标准。     

膨润土的改性及其对水体中Zn2+的净化作用

用十六烷基三甲基氯化铵对钠基膨润土进行了改性,研究了土样用量、吸附时间、溶液pH值对Zn2 吸附的影响,对比研究了无机膨润土和有机改性膨润土吸附Zn2 的结果.结果表明:无机膨润土和有机改性膨润土均能较好地吸附Zn2 ,且有机改性膨润土吸附的能力更强;溶液pH值对无机膨润土和有机改性膨润土吸附Zn2 的影响不同.     

Cadmium adsorption on modified chitosan‐coated bentonite: batch experimental studies

BACKGROUND: Several researchers have investigated the use of chitosan as an adsorbent for removal of heavy metals from aqueous streams. Chitosan flake or powder swells and crumbles making it unsuitable for use in an adsorption column. Chitosan also has a tendency to agglomerate or form a gel in aqueous media. The adsorption capacity can be enhanced by spreading chitosan on physical supports that can increase the accessibility of the metal binding sites. Although several attempts have been made to enhance the adsorption capacity of chitosan, using various chemicals, the sorption capacity for metal ions decreased after cross‐linking of chitosan. RESULTS: Bentonite was coated with chitosan (Chi) and its derivative, 3,4‐dimethoxy‐benzaldehyde (Chi/DMB). The product was then used as adsorbent for the removal of Cd²⁺ from aqueous solutions. The presence of imine groups resulting from chemical modification was confirmed using IR, DRS and SEM. The adsorption followed the Langmuir isotherm and could be described by pseudo‐second order kinetics. CONCLUSION: Chi/DMB coated on bentonite increased the accessibility of metal binding sites. The Chi/DMB/bentonite showed no significant pH dependence in the pH range 2–9, but bentonite coated with chitosan revealed very intensive pH dependence, which had a considerable effect on cadmium removal. As expected adsorption of Cd²⁺ by Chi/bentonite and Chi/DMB/bentonite is dependent on contact time and adsorbent dose. In addition, an EDTA solution is suitable for desorption of cadmium ions, and the reusability of Chi/DMB/bentonite is quite good. © 2012 Society of Chemical Industry     

四乙烯五胺接枝膨润土对酸性大红GR的吸附性能

在膨润土（Bent）表面接枝四乙烯五胺（TEPA）制备四乙烯五胺改性膨润土（TEPA/Bent）,利用FTIR（红外光谱仪）、XRD（X射线衍射仪）、EA（元素分析）、SEM（扫描电镜）和EDS（能谱仪）对其进行表征分析,并考察对水体中阴离子染料酸性大红GR的吸附性能。结果表明：TEPA成功接枝于膨润土表面,提高了膨润土对酸性大红GR的吸附量;pH对TEPA/Bent表面电位和吸附量影响较大;随着初始pH的增大,TEPA/Bent的zeta电位由正变为负,对酸性大红GR吸附量减少;在pH=3,染料初始质量浓度为100mg/L条件下,TEPA/Bent对酸性大红GR的吸附量可达44.63mg/g;TEPA/Bent对酸性大红GR的吸附动力学符合准二级动力学模型;吸附等温线符合Langmuir吸附等温模型,为单分子层吸附;吸附热力学表明该吸附为自发吸热过程。吸附剂经过5次再生后,吸附量仍保持为初始80%以上。研究表明,TEPA/Bent是从水溶液中去除阴离子染料的潜在有效吸附剂。     

改性膨润土对氨氮废水吸附性能的研究

用内蒙膨润土及其碱改性膨润土进行模拟氨氮废水的脱氮实验研究。结果表明,在氨氮溶液初始浓度为300 mg/L,pH值为3.0～7.0时,相对于天然膨润土,碱改性膨润土对氨氮的吸附量有了很大提高,其吸附等温线符合Freundlich和Langmuir方程,且对氨氮的吸附动力学符合准一级和准二级吸附动力学模型,说明化学吸附和物理吸附共同起作用;在应用于畜禽废水处理中,碱改性膨润土对氨氮去除率达到91.0%。     

Kinetic and isothermal studies of lead ion adsorption onto bentonite

The use of bentonite for the removal of Pb(II) from aqueous solutions for different contact times, pH of suspension, and initial concentration of Pb and particle sizes of absorbent was investigated. Batch adsorption kinetic experiments revealed that the adsorption of Pb(II) onto bentonite involved fast and slow processes. The adsorption mechanisms in the lead/bentonite system followed pseudo-second-order kinetics with a significant contribution of film diffusion. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms and the Langmuir model represented the adsorption process better than the Freundlich model. The maximum adsorption capacity of Pb(II) onto natural bentonite was 78.82 mg g^− 1.     

CTAB改性铁柱撑膨润土对苯酚的吸附

为了研究膨润土对含酚废水的吸附性能,采用羟基铁柱撑剂对钠基膨润土进行预改性,随后用十六烷基三甲基溴化铵(CTAB)改性,制备CTAB改性铁柱撑膨润土。利用X射线衍射仪(XRD)、红外光谱仪(FTIR)和场发射扫描电镜(FESEM)对改性膨润土的结构和性能进行表征。考察了吸附剂用量、吸附时间、吸附温度、苯酚初始浓度和pH值对吸附性能的影响,研究了吸附热力学和吸附动力学规律。结果表明,CTAB进入铁柱撑膨润土的层间和表面。当吸附剂用量为3 g·L^-1、吸附时间为60 min、吸附温度为25 ℃、苯酚初始浓度为300 mg·L^-1、苯酚初始pH值为7时,改性膨润土吸附量达到29.7 mg·g^-1,吸附过程符合准二级动力学模型和Freundlich热力学模型。