On the statistical physics modeling of dye adsorption onto anionized nylon: Consequent new interpretations

Experimental adsorption isotherm of two basic dyes: Basic Blue 3 and Basic Red 24 from aqueous solution onto modified nylon 6,6 were analyzed by using a double layer adsorption model with two energy levels. Such model is based on statistical physics treatment. The parameters involved in the analytical expression of this model such as the fraction or the number of adsorbed dye molecule(s) per site, n, the receptor sites density, N_M, and the energetic parameters, c₁ and c₂, were determined by fitting the experimental adsorption isotherms at four temperatures between 293 and 353 K with different degrees of grafting between 20 and 80%. The evolution of these parameters versus temperature and the grafting percent allows us to interpret and better understand this adsorption process at molecular level. Two different behaviors of the two dye molecules were highlighted according to their localized and non localized charges. The configurational entropy at various temperatures has also been studied. This parameter allowed to deduce some results related to the evolution of the disorder at the adsorption surface. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of temperature on the removal of lead(II) by adsorption on China clay and wollastonite

The removal of Pb(II) from aqueous solution by adsorption on china clay and wollastonite is an attractive process. The amount of Pb(II) removed by adsorption is highly dependent on the temperature of the adsorbate solution and favours low temperature. The equilibrium times were noted, i.e. 90 min for china clay and 120 min for wollastonite. The various rate parameters of the adsorption process have been determined at different temperatures. The activation energies were determined and found to be ?5.345 kJ mol^?1 and ?8.730 kJ mol^?1 for Pb(II)-china clay and Pb(II)-wollastonite systems, respectively. The adsorption isotherm was measured experimentally at various temperatures. The negative values of enthalpy change (ΔH = ?77.95 kJ mol^?1 and ?16.40 kJ mol^?1 for china clay and wollastonite, respectively) indicate the exothermic nature of the adsorption processes for both systems. The isosteric heats of the adsorption process have been determined at various surface coverages of the adsorbents used. The various thermodynamic parameters have been calculated to elucidate the mechanism involved in the adsorption process.     

Determination of porosity in pillared clays by N2 adsorption isotherms

N₂ adsorption isotherms of various pillared montmorillonites (PILCs) were analyzed for evaluation of their porosities. The quantitative data of the total and micropore volumes were calculated using the B.J.H. method and the t-plot, respectively. The volume of mesopores is the difference between the total volume and the micropore volume. The linear branch above the P/P ₀ of 0.5 should be used for the calculations of the micropore volume and external surface area.The evaluation of the specific surface area (SA) of the PILCs and influences of the porosity on the calculations were discussed in detail. An upper limit of the monolayer capacity of a porous solid is proposed, based on the adsorption on a nonporous solid. Due to the space restriction in the fine slit-like pores of the PILCs, the specific surface areas calculated with the B.E.T. equation using the adsorption data in a relative pressure region ranging from 0.01 to 0.1 are more accurate.The mean micropore widths of the PILCs, derived from the data of the multi-point B.E.T. SA and micropore volume consist reasonably with the pore widths obtained by XRD diffraction.The step-like curves of the t-plot in low-pressure region and of the logarithmic plot reveal presence of pores of various sizes in the pillared clays. The micropore size distribution can be derived by a new method using the N₂ adsorption data.     

凹凸棒石对废水中Ni~(2+)吸附性能的研究

采用靖远凹凸棒石对废水中Ni2+离子的吸附性能进行了研究。确定了Ni2+离子的吸附平衡时间、最大吸附量对应的pH、最大吸附率对应的吸附剂用量,最大吸附量对应的Ni2+的初始浓度及吸附速率方程。实验结果显示,Ni2+离子浓度在100 mg/L下,吸附平衡时间为90 min,pH值在5~6时,凹凸棒石用量为0.8 g时吸附率达到最大值16.54 mg/g,速率方程为V=0.200 1C。     

Study on the adsorption of hemoglobin onto bentonite clay surfaces

The adsorption behavior of a hemoglobin (Hb) solution onto bentonite powder was studied from its alkaline solution (pH 12.6) and at room temperature. Different types of adsorption isotherms are discussed and various adsorption parameters, such as the adsorption coefficient, rate constants for adsorption and desorption, diffusion constant, penetration rate constant, were evaluated. The effects of pH and temperature of the adsorption medium on the extent of adsorption and the influence of solvents were studied, and the effect of salt concentrations on the rate of adsorption were also observed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1607–1618, 2002     

氯丙酸改性壳聚糖对Hg~(2+)的吸附性能研究

研究了改性壳聚糖对重金属Hg2+的吸附特性,包括吸附动力学和吸附等温式,且研究了pH、反应时间对其吸附性能的影响.结果表明:羧乙基壳聚糖对Hg2+的吸附在不同温度下符合Freundlich和Langmuir吸附等温式,吸附过程动力学适合二级反应.当pH为4～6,吸附时间为180 min时,羧乙基壳聚糖对Hg2+有较高吸附效果.     

改性蜂窝状活性炭吸附二氧化碳和氮气的热力学

蜂窝状活性炭具有较高的比表面积、多孔道、压降低、吸脱附速率快、不易堵塞等优点,因此被认为是捕集烟道气中CO₂重要吸附材料。选用蜂窝状煤基和椰壳两种活性炭吸附剂,采用磁悬浮热天平分别测定了CO₂和N₂的吸附等温线。采用1 mol·L^-1 K₂CO₃对蜂窝状活性炭材料进行浸渍改性,提高在低二氧化碳分压下的CO₂吸附性能。采用Langmuir、multi-site Langmuir和Virial 3种模型对吸附平衡数据进行拟合,得出热力学参数,为后续吸附工艺优化设计提供基础数据。结果表明在实验范围内3种模型均能对实验测量的等温线进行较好的拟合,Langmuir模型总体拟合效果最好。     

对辊处理对凹凸棒黏土理化性能和吸附性能的影响

将凹凸棒黏土分别经1～5次对辊处理后,通过红外光谱、扫描电镜、比表面积和ζ电位的测定,考察了对辊次数对凹凸棒黏土微结构和理化性能的影响。在此基础上,考察了对辊处理凹凸棒黏土对双氯芬酸钠的吸附性能。结果表明,经过2次对辊处理后,凹凸棒黏土聚集体已经基本解离,比表面积增加趋势变缓,在蒸馏水中的ζ电位最小。对辊处理5次时,比表面积最大,但对双氯芬酸钠吸附容量却最小。结果表明,凹凸棒黏土的吸附性能不仅与比表面积有关,还与凹凸棒黏土的表面电荷及所吸附物质的极性有关。     

负载型离子液体吸附分离CO2的研究现状及展望

人口增长与全球工业化的加速发展促使化石能源需求量逐年递增,由此导致大气中二氧化碳（CO₂）含量快速上升并引发了全球系列气候问题,“碳达峰·碳中和”背景下的CO₂减排刻不容缓。传统工业捕集CO₂方法由于能耗高、选择性较差、溶剂损耗大等问题限制了其大规模推广应用,离子液体因其极低挥发性、强的气体亲和性、可调的结构性质等特点在CO₂捕集分离领域逐渐显示出独特优势,但离子液体特别是功能化后通常黏度较高或室温呈固态,导致气液传质效果差或无法直接应用于吸收分离过程。负载型离子液体兼具离子液体和多孔材料的共同优势,不仅能提升选择性分离效果,有效避免离子液体直接吸收造成的高黏度,还可拓展离子液体应用范围,具有广阔的发展前景。重点总结了近些年物理和化学负载型离子液体在CO₂吸附分离方面的研究现状和进展,并对负载型离子液体捕集分离CO₂研究的发展趋势进行了展望。     

负载型离子液体吸附分离CO2的研究现状及展望

人口增长与全球工业化的加速发展促使化石能源需求量逐年递增,由此导致大气中二氧化碳（CO₂）含量快速上升并引发了全球系列气候问题,“碳达峰·碳中和”背景下的CO₂减排刻不容缓。传统工业捕集CO₂方法由于能耗高、选择性较差、溶剂损耗大等问题限制了其大规模推广应用,离子液体因其极低挥发性、强的气体亲和性、可调的结构性质等特点在CO₂捕集分离领域逐渐显示出独特优势,但离子液体特别是功能化后通常黏度较高或室温呈固态,导致气液传质效果差或无法直接应用于吸收分离过程。负载型离子液体兼具离子液体和多孔材料的共同优势,不仅能提升选择性分离效果,有效避免离子液体直接吸收造成的高黏度,还可拓展离子液体应用范围,具有广阔的发展前景。重点总结了近些年物理和化学负载型离子液体在CO₂吸附分离方面的研究现状和进展,并对负载型离子液体捕集分离CO₂研究的发展趋势进行了展望。     

基于沸石ZSM-5的CH4/N2/CO2二元体系吸附平衡

采用Rubotherm磁悬浮天平测量CH₄、N₂和CO₂在沸石ZSM-5上的单组分吸附平衡等温线,温度273～353 K,压力0～500 kPa。采用Sips模型、Toth模型和MSL模型对单组分吸附平衡实验数据进行拟合,拟合结果良好,非线性回归得到相应的模型参数。测量双组分CO₂/N₂、CO₂/CH₄和CH₄/N₂在沸石ZSM-5上的竞争吸附平衡等温线,实验温度为293 K,实验压力为0～500 kPa。采用基于Sips模型的理想吸附溶液理论和双组分MSL模型预测双组分气体在沸石ZSM-5上的竞争吸附平衡等温线,并与实验结果进行比较,预测结果良好。比较CO₂/N₂、CO₂/CH₄以及CH₄/N₂体系在沸石ZSM-5上的竞争吸附选择性系数,探究沸石ZSM-5吸附分离烟道气（CO₂/N₂体系）、垃圾填埋气（CO₂/CH₄体系）或煤层气（CH₄/N₂体系）的可行性,为将来进行工艺设计提供基础数据。     

Dynamics adsorption of the enhanced CH4 recovery by CO2 injection

The dynamic adsorption isotherms of CO₂-EGR were measured by using an Intelligent Gravimetric Analysis system. In the initial CO₂ injecting stage, all the injected CO₂ enters into the adsorbent and the mole fraction of CH₄ in the gas phase () is maintained at 1.0. The CH₄ recovery factor () increases. The duration of this stage (t_CD) depends on the selectivity of CO₂ over CH₄ (). An adsorbent with large has long t_CD. In the second stage, the injected CO₂ competes with CH₄ for adsorption. The cumulative of the second stage is much larger than that of the initial stage. However, decreases sharply. in the whole CO₂ injection is always larger than that before CO₂ injection, suggesting that CH₄ desorption results from the displacement of CO₂ rather than from pressure depletion.     

Adsorbents for adsorption separation of CO2 and CH4: A literature review

Natural gas consisting mainly of methane is becoming increasingly prominent as a clean energy source. However, the major impurity, carbon dioxide, can adversely affect the performance of natural gas. Therefore, separating CO₂ from CH₄ is necessary to decrease the erosion of pipelines and increase the calorific value. This paper aimed at reviewing the performances, mechanisms, and novel developments of common adsorbents to adsorb pure CH₄, pure CO₂, and their mixtures. Several studies suggest that zeolites exhibit better separating performance than metal organic frameworks (MOFs) except the modified amine-MIL group. Activated carbons may not be suitable adsorbents due to low selectivity between CO₂ and CH₄. The modified amine-MIL group are the best type of adsorbent to separate CO₂ from CH₄ and its best operating conditions are at low pressure (<2 bar), low feed composition of CO₂, and near room temperature using pressure swing adsorption (PSA) method.     

吸附剂特性对CO2/CH4吸附分离的影响分析

用于CO2/CH4二元混合体系吸附分离的吸附剂种类较多,效果参差不齐,而吸附剂的各种特性是影响分离效果的主要原因。本文从吸附剂特性出发,总结了孔结构、可交换阳离子、表面化学以及吸附剂湿度4个因素对吸附分离效果的影响,并解释了造成各种影响的原因。得出结论：中孔有利于该二元体系的分离和胺基嫁接;在吸附剂骨架之外引入合适的可交换阳离子可促进吸附剂与CO2四极矩之间吸引力,提升分离效果;吸附剂的表面羟基也是影响胺基嫁接的重要因素;水分既有利于该体系的吸附分离,又可以促进胺基吸附剂再生。     

Removal of Basic Red 46 dye from aqueous solution by adsorption and photocatalysis: equilibrium,isotherms, kinetics,and thermodynamic studies

ABSTRACT

In this study, the main objective is the elimination of Basic Red 46 dye by coupling two processes, adsorption on activated clay followed by photocatalysis over ZnO as photocatalyst. The adsorption was investigated under different conditions of pH, adsorbent dose, dye concentrations, and temperature. The best adsorption yield occurs at neutral pH ~ 7 within 60 min with an uptake percentage of 97% for a concentration of 25 mg/L and a dose of 0.5 g/L. The results at equilibrium were successfully described by the Langmuir model with an adsorption capacity of 175 mg/g. To investigate the mechanism of dye adsorption characteristic, the adsorption constants were determined using pseudo first order, pseudo second-order and intraparticle diffusion model. It was found that the Basic Red 46 dye adsorption is well described by the pseudo second-order kinetic. The second part of this work was dedicated to the photodegradation onto ZnO under solar irradiation of the residual BR 46 concentration, remained after adsorption. For the remaining concentrations, the removal yields reach 100% under.     

钢渣及电石渣与废弃混凝土固化储存CO_2基本参数研究

对钢渣、电石渣、废弃混凝土等固体废弃物碳酸化固化储存温室气体二氧化碳(CO2)进行研究。实验从固体废弃物颗粒粒径、水分添加量等因素,考察碳酸化固化储存二氧化碳(CO2)的效果,并利用XRD、FTIR和SEM对反应机理进行分析。结果表明,固体废弃物颗粒粒径越小,二氧化碳(CO2)固化效率越高。水分添加量过低或过高均不利于碳酸化反应的进行,适宜的水分添加量为4kg/kg。XRD和FTIR分析表明,固体废弃物中的大量的CH、硅酸三钙(C3S)和氧化钙(CaO)转化为碳酸钙(CaCO3),以达到固化储存二氧化碳(CO2)的效果。SEM实验结果表明,经碳酸化处理后固体废弃物颗粒表面生成颗粒状的晶体物质。电石渣,钢渣及废弃混凝土对二氧化碳(CO2)固化效率分别为81%,76%和49%;每千克电石渣,钢渣及废弃混凝土分别可以固化二氧化碳(CO2)气体0.094kg,0.088kg及0.057kg。     

Comparison of parameters calculated from the BET and Freundlich isotherms obtained by nitrogen adsorption on activated carbons: A new method for calculating the specific surface area

The empirical linear relationship between the BET surface area S_BET and the Freundlich constant K_F, calculated from nitrogen adsorption isotherms of activated carbons, S_BET = a₀K_F is mathematically demonstrated. This correlation exists in the relative pressure domain in which the BET equation is valid, whatever the value of c for the BET equation and for values of the Freundlich exponent, , between 0 and 0.2. This study allows to determine the correlation factor a₀ = 1/a with . From this result, a new expression, depending of and K_F, can be deduced for calculating the specific surface area.     

CO2和N2吸附的研究札记

Experiments were made for the adsorption of CO2 and N2 on typical adsorbents to investigate the effects of porous structure and surface affinity of adsorbents as well as those of adsorption temperature and pressure that might cause the variation of adsorption mechanism. It is shown that polar surface tends to enlarge the adsorption difference between CO2 and N2, and the difference is more sensitive to temperature than the adsorbents with non-polar surface. The adsorbents with non-polar surface are not much sensitive to the effect of water vapor, though the water vapor interferes the separation remarkably. The separation coefficient linearly increases with the micropore volume per unit surface area of activated carbons, but no rule is shown on mesoporous silicon materials. The function of adsorption mechanism on the separation is not as much as expected.     

低渗透油藏CO_2驱油机理及应用现状研究

当今社会快速发展,能源问题日益严峻。由于低渗透油藏低孔、低渗、自然能量不足等特点,采用常规方法已经不能有效采出原油,CO_2驱是三次采油方法中提高低渗透油藏采收率的一种方法。综述了CO_2驱油的机理、CO_2驱油效果的影响因素以及近些年来国内外CO_2驱油的应用现状,指出CO_2驱在我国低渗透油藏的可行性和巨大潜力。     

Numerical analysis of CO2 concentration and recovery from flue gas by a novel vacuum swing adsorption cycle

The objective of this work is to study the feasibility of carbon dioxide concentration and recovery from flue gases using a novel VSA cycle without rinse step with the aid of mathematical modeling. A theoretical model based on conservation equations (following the one proposed by Da Silva and Rodrigues (2001)) is used for an initial evaluation of the process performance. Activated carbon is the adsorbent considered, simulating adsorption equilibrium and kinetics with the equations proposed by Kikkinides, Yang, and Cho (1993). According to the simulated results, it is possible to recover carbon dioxide with high purity (>93%) from a mixture with 13% carbon dioxide at 40 °C, with higher recovery (>90%) and a lower power consumption (<0.12 kWh/kgCO₂) than other processes with rinse step reaching the same purity. Although these results are theoretical, they show the potential advantages of this process for CO₂ capture.