吸附等温方程参数估算方法的分析

采用定容容量法,在温度6~60℃、平衡压力达106Pa的条件下,测得N2和O2在5A分子筛上系统的吸附相平衡数据。通过Langmuir和Toth等温方程关联这些相平衡数据,结果表明:线性化拟合的方法不可靠,其中用1/q~1/P形式线性化Langmuir方程,会得到误差很大的结果;用非线性法在各温度下单独拟合的等温方程和实验结果吻合很好,但是参数不符合其物理意义,进一步处理则误差较大。应当用非线性最小二乘法将所有温度下的相平衡数据一起拟合吸附等温方程。Langmuir和Toth方程都能用于描述体系的平衡吸附量随温度和压力的变化关系,而Toth方程的误差更小。     

十四烷基芳基磺酸盐在大庆油砂上的吸附性能

利用静态吸附实验研究了实验室自制的三种高纯度十四烷基芳基磺酸盐在大庆油砂上的吸附规律,并考察了吸附时间,吸附温度及磺酸盐、NaCl、NaOH、正丁醇的浓度对吸附量的影响.结果表明:吸附量随着磺酸盐浓度的增大逐渐增加后趋于平稳,随着吸附温度和正丁醇体积浓度的降低、NaCl 和NaOH浓度的增加而增大; 磺酸盐活性剂的三种同分异构体中,随两部分碳链长度趋于均等,吸附量下降,且受助剂的影响变小.吸附热力学研究表明,十四烷基芳基磺酸盐在油砂上的吸附等温线服从Langmuir 等温方程,并且计算得到的各参数均能很好地反映磺酸盐在油砂上的吸附特征.吸附动力学研究表明,Elovich 方程能够更好地描述吸附量随时间的变化情况.     

磁性多壁碳纳米管吸附水中双氯芬酸的热力学与动力学

研究了磁化多壁碳纳米管(MWCNTs)对于水中非甾体抗炎药双氯芬酸的吸附过程.结果表明,双氯芬酸的吸附量随磁性MWCNTs投加量的增加而增大,而且吸附剂量增加到一定阶段后,双氯芬酸的吸附量达到平衡.在磁性MWCNTs的量为0.7g·L-1时,水溶液中双氯芬酸被磁性MWCNTs吸附的量达到最大,为33.37mg·g-1,对应的双氯芬酸去除率为98.1%.双氯芬酸的去除率随溶液pH的增加先增大后下降,随温度的升高而下降.用准一级、准二级模型进行了动力学分析.回归结果表明,准二级模型更准确地反映了吸附动力学.通过实验确定了Langmuir和Freundlich等温线的线性相关系数与标准偏差,结果揭示出Langmuir等温线与实验数据有很好的拟合度.对热力学参数的计算表明,ΔG00,意味着磁性MWCNTs对双氯芬酸的吸附是自发的;ΔH00,指明吸附是一个放热的物理吸附过程,温度低对吸附有利;ΔS00,代表该吸附是熵增过程.     

血竭总黄酮在大孔树脂上的吸附行为研究

以静态和动态两种方式研究了D101大孔树脂对血竭总黄酮的吸附情况,对静态吸附曲线和动态穿透曲线进行了数学拟合,并计算了静态吸附的热力学参数,结果表明:(1)D101树脂对血竭总黄酮的吸附等温线能用Langmuir方程和Freundlich方程较好的拟合,外加KCi或NaCl能提高D101树脂对血竭总黄酮的吸附容量;(2...     

多壁碳纳米管对稀土元素的吸附性能

研究了改性多壁碳纳米管(MWCNTs)对稀土元素的吸附。 采用硝酸、次氯酸钠、过氧化氢、高锰酸钾4种方法对MWCNTs进行改性,考察了改性MWCNTs对稀土元素的吸附能力。 采用紫外-可见分光光度法测定稀土元素的浓度,比较了未处理和不同方法处理的MWCNTs对稀土元素的吸附能力。实验结果表明,NaClO改性的MWCNTs对稀土元素的吸附能力最强。以稀土元素钐(Sm)、钆(Gd)、镱(Yb)为代表,研究了NaClO改性MWCNTs对稀土元素的吸附性能。 考察了溶液pH值、离子强度、吸附剂用量、温度等因素对吸附性能的影响。当溶液pH值在2~7范围内,NaClO改性的MWCNTs对Sm、Gd、Yb的吸附随pH值增大而增强。 当离子强度和MWCNTs的用量增大时,对稀土元素的吸附能力降低。3种元素在NaClO改性的MWCNTs上的吸附均为放热过程,其反应焓变ΔH分别为：-6.44、-5.63和8.31 kJ/mol。吸附等温线符合Langmuir和Freundlich等温吸附方程。     

沥青基球形活性炭对葡萄糖分子的吸附行为研究

考察了沥青基球形活性炭(PSAC)对葡萄糖分子的吸附行为,以探讨其治疗糖尿病的可能性.在不同吸附时间、不同活性炭用量及不同浓度等条件下,测定沥青基球形活性炭对葡萄糖分子的吸附量,根据Langmuir和Freundlich等温线方程对吸附等温线数据进行拟合,检验实验数据与方程的吻合度,确定方程参数.同时,研究了葡萄糖和α-淀粉酶在沥青基球形活性炭上的竞争吸附行为.结果表明,所选用沥青基球形活性炭对葡萄糖分子的吸附在5h内达到吸附平衡;葡萄糖的初始浓度为3g/时,平衡吸附量为71mg/g;平衡吸附量受葡萄糖分子空间构象的影响,且随葡萄糖浓度的升高而增加,吸附等温线数据与Langmuir方程吻合,说明该吸附为单分子层吸附.在葡萄糖分子和α-淀粉酶的共存环境下,沥青基球形活性炭对葡萄糖有较好的吸附选择性.     

不同基团修饰的吸附树脂对芳香两性化合物的吸附等温线研究

研究了带有不同功能基团的超高交联吸附树脂NG-10和NJ-99对水溶液中芳香两性化合物氨基苯甲酸的静态吸附性能,并与不带功能基团的吸附树脂CHA-111和XAD-4进行了比较.研究结果表明,树脂NJ-99对水溶液中氨基苯甲酸的吸附能力高于其他树脂.邻氨基苯甲酸在4种树脂上的吸附量均大于对氨基苯甲酸,主要原因是其溶解度小.吸附等温线采用经验的Freundlich方程和理论的Langmuir吸附方程来拟合,在实验所研究的浓度范围内,方程的拟合相关性均很好.     

Adsorption of Au ( Ⅲ ) and Pd ( Ⅱ ) in Solution of 2,2'-Diaminodiethylamine Modified Multiwalled Carbon Nanotubes

以二乙烯三胺( DETA)为改性剂,对多壁碳纳米管(MWCNTs)进行共价键修饰,合成了一种对Au(Ⅲ)和pd(Ⅱ)有选择性的吸附剂MWCNTs-DETA,并对Au(Ⅲ)和Pd(Ⅱ)的吸附参数进行了研究和优化.结果表明,最佳洗脱剂浓度为1.0 mol/L硫脲-1.0 mol/L盐酸,Au(Ⅲ)和Pd(Ⅱ)的洗脱率分别为94.48％和89.06％,最佳条件下Au(Ⅲ)和Pd(Ⅱ)的饱和吸附容量分别为50.45和25.68 mg/g.在对吸附等温线的考察中,Au(Ⅲ)拟合Langmuir等温线较好,而Pd(Ⅱ)则拟合Freundlich等温线较好.吸附动力学均拟合二级模型较好.     

二乙烯三胺改性多壁碳纳米管对溶液中Au(Ⅲ)和Pd(Ⅱ)的吸附

以二乙烯三胺(DETA)为改性剂, 对多壁碳纳米管(MWCNTs) 进行共价键修饰,合成了一种对Au(Ⅲ)和Pd(Ⅱ)有选择性的吸附剂MWCNTs-DETA, 并对Au(Ⅲ)和Pd(Ⅱ)的吸附参数进行了研究和优化. 结果表明, 最佳洗脱剂浓度为1.0 mol/L 硫脲-1.0 mol/L 盐酸, Au(Ⅲ)和Pd(Ⅱ)的洗脱率分别为94.48%和89.06%, 最佳条件下Au(Ⅲ)和Pd(Ⅱ)的饱和吸附容量分别为50.45和25.68 mg/g. 在对吸附等温线的考察中, Au(Ⅲ)拟合Langmuir等温线较好, 而Pd(Ⅱ)则拟合Freundlich等温线较好. 吸附动力学均拟合二级模型较好.     

胶原在聚乳酸旋涂膜表面的吸附研究

采用石英晶体微天平(QCM)、原子力显微镜(AFM)研究了胶原在聚乳酸旋涂膜表面的吸附,考察了溶液浓度(0～9.25μg/mL)和温度(10～50℃)对胶原吸附的影响.实验结果表明,随着胶原浓度的增加,胶原在聚乳酸表面的吸附量和吸附初速率都相应增加.采用Langmuir模型和Freundlich模型拟合实验数据得到吸附等温线方程,分别为q=11690.99c1+0.99c和q=610c3.179.实验结果显示,Langmuir模型拟合效果要好于Freundlich模型.采用Lagergren拟一阶吸附速率方程和Lagergren拟二阶速率方程拟合不同浓度下的吸附动力学数据.在低浓度下Lagergren拟一阶速率方程拟合效果比较好,在高浓度下Lagergren拟二阶速率方程拟合效果比较好,说明在低浓度时扩散过程是胶原吸附的控速步骤,高浓度时胶原和聚乳酸表面的相互作用是吸附的控速步骤.原子力显微镜显示,吸附在聚乳酸表面的胶原形成网状结构.胶原的吸附受温度影响显著,说明胶原是一种对温度非常敏感的物质.实验结果表明随着温度的升高,在10～40℃范围内胶原的吸附量逐渐降低,在40～45℃范围内锐减,40℃是本实验条件下胶原的变性温度.     

A Comparison between Different Agro-wastes and Carbon Nanotubes for Removal of Sarafloxacin from Wastewater: Kinetics and Equilibrium Studies

In the current study, eco-structured and efficient removal of the veterinary fluoroquinolone antibiotic sarafloxacin (SARA) from wastewater has been explored. The adsorptive power of four agro-wastes (AWs) derived from pistachio nutshells (PNS) and Aloe vera leaves (AV) as well as the multi-walled carbon nanotubes (MWCNTs) has been assessed. Adsorbent derived from raw pistachio nutshells (RPNS) was the most efficient among the four tested AWs (%removal ‘%R’ = 82.39%), while MWCNTs showed the best adsorptive power amongst the five adsorbents (%R = 96.20%). Plackett-Burman design (PBD) was used to optimize the adsorption process. Two responses (‘%R’ and adsorption capacity ‘q_e’) were optimized as a function of four variables (pH, adsorbent dose ‘AD’ (dose of RPNS and MWCNTs), adsorbate concentration [SARA] and contact time ‘CT’). The effect of pH was similar for both RPNS and MWCNTs. Morphological and textural characterization of the tested adsorbents was carried out using FT-IR spectroscopy, SEM and BET analyses. Conversion of waste-derived materials into carbonaceous material was investigated by Raman spectroscopy. Equilibrium studies showed that Freundlich isotherm is the most suitable isotherm to describe the adsorption of SARA onto RPNS. Kinetics’ investigation shows that the adsorption of SARA onto RPNS follows a pseudo-second order (PSO) model.     

Sorption of strontium ions from aqueous solutions by oxidized multiwall carbon nanotubes

Multiwall carbon nanotubes (MWCNTs) oxidized by nitric acid solution were used to investigate the adsorption behavior of strontium from aqueous solutions similar to the nuclear waste media. The physical properties of both as produced and oxidized MWCNTs were studied by Boehm’s titration method and nitrogen adsorption/desorption. The results showed that the surface properties of MWCNTs such as specific surface area, functional groups and the total number of acid sites were improved after oxidation. Furthermore, the effect of solution conditions such as initial concentration of strontium(II), pH, ionic strength, MWCNT concentration and contact time were studied at room temperature. The results of this study showed that the adsorption of strontium(II) was significantly influenced by the pH value and the solution ionic strength. According to the Langmuir model, the maximum adsorption capacities of strontium(II) onto the as produced and oxidized MWCNTs were obtained as 1.62 and 6.62 mg g^?1, respectively. The contact time to reach equilibrium was 100 min. The good adsorption of strontium(II) on oxidized MWCNTs at the lower ionic strength, the relatively high pH and the short equilibrium time indicate that the oxidized MWCNTs have great potential applications in the field of the environmental protection.     

Kinetics and thermodynamic study of aniline adsorption by multi-walled carbon nanotubes from aqueous solution

Multi-walled carbon nanotubes (MWCNTs) were used in the adsorptive removal of aniline, an organic pollutant, from an aqueous solution. It was found that carbon nanotubes with a higher specific surface area adsorbed and removed more aniline from an aqueous solution. The adsorption was dependent on factors, such as MWCNTs dosage, contact time, aniline concentration, solution pH and temperature. The adsorption study was analyzed kinetically, and the results revealed that the adsorption followed pseudo-second order kinetics with good correlation coefficients. In addition, it was found that the adsorption of aniline occurred in two consecutive steps, including the slow intra-particle diffusion of aniline molecules through the nanotubes. Various thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), were calculated. The results indicated that the spontaneity of the adsorption, exothermic nature of the adsorption and the decrease in the randomness reported as ΔG°, ΔH° and ΔS°, respectively, were all negative.     

Adsorptive Stripping Voltammetric Detection of Tea Polyphenols at Multiwalled Carbon Nanotubes‐Chitosan Composite Electrode

This study reports the catalytic oxidation and detection of tea polyphenols (TPs) at glassy‐carbon electrode modified with multiwalled carbon nanotubes‐chitosan (MWCNTs‐CS) film. The adsorption of TPs at the surface of the MWCNTs through π–π conjugation prevents the aggregation of nanotubes and induces a stable MWCNTs suspension in water over 30 days. Based on the adsorptive accumulation of polyphenols at MWCNTs, TPs is sensitively and selectively detected by adsorptive stripping voltammetry. The accumulation conditions and pH effect on the adsorptive stripping detection were examined. The linear range was found to be 100 to 1000 mg L^?1 with a detection limit of 10 mg L^?1 (S/N=3) for 2.5 min accumulation. Additionally, the MWCNTs‐CS electrode is easily renewed by applying positive potential to remove the adsorbed TPs. This method was successfully applied to determine TPs in commercially available teas with satisfied result compared with that of conventional spectrometric analysis.     

多壁碳纳米管对甘草中3种有效成分的选择性吸附

考察了多壁碳纳米管(MWNTs)对3种甘草有效成分异甘草苷、甘草苷和甘草酸的吸附性能。 分别用紫外分光光度法和HPLC法测定了吸附前后溶液中异甘草苷、甘草苷、甘草酸的含量,考察了静态吸附实验时间、料液起始浓度、溶液体积和pH值对各成分吸附的影响。 结果显示,MWNTs对甘草中3种主要有效成分的吸附量明显不同,对异甘草苷的吸附远大于甘草苷和甘草酸,并且不存在竞争吸附,具有明显的选择性吸附特点。     

Carbon nanotubes modified with 5,7-dinitro-8-quinolinol as potentially applicable tool for efficient removal of industrial wastewater pollutants

The environmental pollution due to the industrial wastewater of four different areas in the Gulf of Suez, Red Sea, Egypt, was studied. Adsorption capacities toward the concerned heavy metal ions Cu(II), Zn(II), Fe(II), and Pb(II) by multiwalled carbon nanotubes (MWCNTs) and modified-MWCNTs with 5,7-dinitro-8-quinolinol were investigated. MWCNTs as well as the modified-MWCNTs were characterized using Fourier transform infrared (FTIR), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). Adsorption of the studied divalent metal ions was measured by atomic absorption spectrometry (AAS). The effects of solution conditions such as pH, shaking time, metal ion concentration, ionic strength and adsorbent dosage on the adsorption process were also examined. The obtained results showed that removals of the heavy metal ions under consideration by MWCNTs are obviously dependent on the experimental conditions. The maximum adsorption capacities as calculated applying Langmuir equation to single ion adsorption isotherms were found to be 142.8 mg/g for Cu(II), 250 mg/g for Zn(II), 111.1 mg/g for Fe(II), and 200 mg/g for Pb(II) using MWCNTs; meanwhile, the modified-MWCNTs exhibited higher values of the respective maximum adsorption capacities as 333.3 mg/g for Cu(II), 500 mg/g for Zn(II), 200 mg/g for Fe(II), and 333.3 mg/g for Pb(II). Kinetic studies were also performed and the experimental data followed a pseudo-second order model of the adsorption process. The obtained results suggest that the tested adsorption systems of MWCNTs and modified-MWCNTs have suitable affinity toward the metal ion under consideration. Both systems could act as potentially applicable tool in environmental protection.     

Multi-Walled Carbon Nanotubes and Powder-Activated Carbon Adsorbents for the Removal of Nitrofurazone from Aqueous Solution

Multi-walled carbon nanotubes (MWCNTs) and powder-activated carbon (PAC) were used as adsorbents for adsorption of nitrofurazone, a veterinary medicine, from aqueous solutions. The adsorbents were characterized using FTIR transform infrared spectroscopy, N₂ adsorption/desorption isotherms, and scanning electron microscopy. The effects of initial pH, contact time, and temperature on adsorption capacity of the adsorbents were investigated. For MWCNT and PAC, the result showed that when the pH value was ranged from 2.0 to 10.0, the dosage of adsorbent was 0.02 g, and adsorptive time is 4 hours, the removal efficiencies for nitrofurazone were 96.8% and 94.7%, and the corresponding maximum capacities at 283 K were close to 50.8 mgg^?1 and 59.9 mgg^?1, respectively. For nitrofurazone, the pseudo-second-order kinetic model provided the best fit to the experimental data. The Boyd model indicated the mechanism for adsorption processes was mainly external mass transfer, while the effect of particle internal diffusion was relatively weak. Liu model could best fit to the experimental data of isothermal adsorption. The data of adsorption thermodynamics showed that the adsorption process was spontaneous.     

聚合物假冠醚研究(VI) 以苯环为端基的[2,2,2]开链穴醚及其酚醛型聚合物的合成与吸附性能

以2-苯氧乙醇为起始原料,合成了以苯环为端基的[2,2,2]开链穴醚(三足体)及其酚醛型聚合物,测定了其对金属离子的吸附性能。结果表明,开链穴醚及其聚合物对Fe3+具有良好的选择吸附性能,吸附容量达1.74mmol/g(20℃)。同时测试了反应物的摩尔比、反应温度、Fe3+离子浓度和吸附时间对聚合物吸附Fe3+的影响。     

载铜球形活性炭的制备及其吸附脱硫性能的研究

以122型弱酸性酚醛系阳离子交换树脂为炭前驱体,经过Cu²⁺交换、炭化和CO₂活化等过程制备得到负载金属铜的球形活性炭,对其进行了SEM、XRD、AAS和BET表征,采用动态吸附实验研究了其对模拟汽油中噻吩类硫化物的吸附性能,并且考察了甲苯和环己烯对其吸附性能的影响,对吸附脱硫机理进行了初步研究。结果表明,载铜球形活性炭上Cu以单质形态存在,并主要与硫原子产生配位作用,提高了对噻吩类硫化物的吸附性能,对噻吩(T)、3-甲基噻吩(MT)、2,5-二甲基噻吩(DMT)和苯并噻吩(BT)的饱和硫容依次为0.938、1.230、1.581和3.744 mg/g,吸附选择性依次为T < MT < DMT < BT。模拟汽油中加入甲苯和环己烯后,饱和硫容分别下降了77%和56%,这是甲苯和环己烯通过π电子与Cu发生作用,从而与硫化物产生竞争吸附导致的。