木质素磺酸钠在TiO2/水界面的吸附特性

木质素磺酸钠在固体表面的吸附特性决定了其应用性能,利用红外和紫外分光光度仪,采用剩余质量分数法研究了温度、pH值、无机盐和氢键破坏剂脲对木质素磺酸钠在TiO₂/水界面吸附动力学和等温吸附性能的影响,初步探讨了其在固液界面的吸附作用机理。结果表明,该吸附为单层多点式吸附,随着温度升高和pH值减小,木质素磺酸钠在TiO₂/水界面的吸附速率常数和饱和吸附量均增大,而离子强度的增大和脲的加入却使吸附速率常数减小;木质素磺酸钠在TiO₂/水界面的吸附驱动力为静电、疏水和氢键作用,疏水作用力可显著增加其吸附量。     

油茶果壳活性炭对铜离子的动态吸附

利用油茶果壳活性炭填料柱对水中铜离子进行动态吸附。探讨了pH值、初始质量浓度、床层高度等因素对穿透曲线的影响。结果表明,油茶果壳活性炭能有效去除水中的铜离子,随着床层高度的增高、pH的增大和初始浓度的减小,油茶果壳活性炭填料柱对水中铜离子的吸附穿透曲线位点向右移。通过数学模型得到的速率常数、相关系数、平衡吸附量和动力学参数,能较好地描述油茶果壳活性炭填料柱吸附铜离子的吸附动力学。     

油茶果壳活性炭对铜离子的吸附性能

利用油茶壳活性炭吸附铜离子,探讨了时间、pH值、Cu(Ⅱ)初始质量浓度等因素对油茶壳活性炭吸附性能的影响;并分析了其吸附等温曲线和动力学方程。结果表明,油茶壳活性炭对铜离子吸附量可达到63.6 mg/g。油茶壳活性炭对铜离子的去除率随吸附时间的增加而增大,5 h后达到平衡;随着pH值的升高,油茶壳活性炭吸附铜离子的吸附量不断下降。油茶壳活性炭对铜离子的吸附等温数据符合Langmuir方程,吸附动力学过程可用准二级动力学模型进行模拟,相关系数为0.997 5。     

聚丙烯酸钠在中空纤维超滤膜表面的吸附研究

以KCl溶液为背景电解质液,测得聚砜中空纤维超滤膜等电点的pH值为2.9±0.1.当聚丙烯酸钠溶液pH值在等电点附近时,溶质在膜表面吸附量显著增大,导致膜通量迅速下降.研究了不同温度下膜表面吸附量随时间的变化,结果表明:吸附反应可用拟二级速率方程来描述,温度为293～308 K时,速率常数在0.359～0.604 m2·g-1·min-1内递增.考察不同pH值和离子强度对吸附过程的影响可得:当pH值为2.6～9时,平衡吸附量由0.218下降至0.012 g·m-2;当离子强度为0.0～0.1 mol·L-1时,平衡吸附量由0.218降低至0.154 g·m-2.进一步研究了平衡浓度对吸附量的影响,结果表明当聚丙烯酸钠浓度为0.05～5.0 g·L-1及pH≤4时,Langmuir吸附等温线对实验数据能较好地拟合,方程参数qm和b值的大小随膜表面吸附量的增大而增大.     

纳米MnO2离子筛的锂吸附性能

通过控制水热合成反应条件制备了不同晶相的一维纳米MnO₂，进一步用浸渍法制备了Li-Mn-O三元氧化物前驱体，并经酸处理后得到对锂离子具有特殊选择性的离子筛。用XRD、TEM、吸附等温线及反应动力学等手段对产物的晶相结构和锂吸附性能进行了研究。实验结果表明，反应物浓度对MnO₂不同晶面的生长速率有不同的影响；从TEM图像中可以清楚地看到，水热合成法制备出了尺寸为φ5nm×400nm的一维MnO₂纳米线；在pH＝9.19时每克离子筛的单分子层锂离子饱和吸附量Q_m为2.43mmol·g^-1；吸附速率常数为2.17×10^-6 s^-1；吸附量随溶液pH值的增加而增加，当pH=12.5时，相应的吸附量为3.47mmol·g^-1。     

活性炭对废水中对氯硝基苯的吸附特性研究

研究了活性炭加入量、吸附温度、吸附时间、pH值不同时活性炭对模拟废水中对氯硝基苯的吸附特性。结果表明:活性炭对对氯硝基苯废水中的对氯硝基苯的去除率随活性炭加入量的增加而增大,在200m L浓度为100mg/L对氯硝基苯废水中最佳活性炭加入量为0.2g,去除率达96.68%,动态吸附平衡时间为22min;随温度的升高活性炭对对氯硝基苯废水中的对氯硝基苯的去除率也增大,最佳吸附温度为35℃;100mg/L对氯硝基苯废水的最佳吸附pH值为7。活性炭对对氯硝基苯的吸附符合BET等温吸附方程式,在20℃条件下,吸附等温线方程为:qe=500ce/(cs-ce)(1+14ce/cs),线性相关系数R~2=0.998 6,估算出所用活性炭比表面积为428m~2/g。     

碱性紫在活性炭上的吸附等温线

采用静态法测定了活性炭对碱性紫的平衡吸附量。研究了吸附时间、溶液的pH值等条件对吸附量的影响。结果表明。吸附平衡需要一定的时问．吸附等温线是S型曲发，符合BET多层吸附规律。pH值对平衡吸附量有一定的影响，在酸性条件下平衡吸附量较小且变化不大．当溶液为中性时，平衡吸附量略有增大。且饱和吸附量可达到237．13mg/g．表明活性炭对碱性紫有较大的吸附量，可用于碱性紫印染度水的脱色处理。     

氯苯酚在活性炭纤维上吸附平衡的研究

研究了水溶液中氯苯酚在活性炭纤维上的吸附平衡,实验探讨了反应温度、溶液pH值对活性炭纤维吸附平衡的影响。实验结果表明,平衡吸附量随着温度降低而升高;当pH值<7时,平衡吸附量几乎不随溶液的pH值而变化,而当pH值>7时,氯苯酚在活性炭纤维上的平衡吸附量随着pH值的增加而减小,pH值愈大,平衡吸附量减小的愈快。分别采用Langmuir模型和Freundlich模型描述吸附平衡等温线,在实验范围内Langmuir模型与实验数据吻合较好。     

活性炭电极对不同阳离子电吸附行为的研究

自制活性炭电极,并用于不同含量的KCl、CdCl_2、CuCl_2和FeCl_3溶液电吸附行为研究.结果表明,多价离子吸附速率和吸附容量大,但脱附率低;单价离子吸附速率和吸附容量小,但脱附率高;同价态离子,离子半径越小的离子越容易被吸附.各离子在活性炭电极上的电吸附,均符合2级动力学方程,速率常数K与电压U关系符合指数函数,在相同电压下,吸附速率常数K(Fe~(3+))>K(Cu~(2+))>K(Cd~(2+))>K(K~+);吸附等温线均符合Langmuir等温式,活性炭电极的最大吸附量q_m与操作电压U线性相关,在相同电压下,活性炭电极的最大吸附容量q_m(Fe~(3+))>q_m(Cu~(2+))>q_m(Cd~(2+))>q_m(K~+).循环伏安和交流阻抗进一步验证了电吸附试验结果.     

超细涤纶微胶囊分散染料染色动力学及热力学参数

将偶氮、蒽醌、杂环三种不同结构类型的微胶囊分散染料对涤纶超细织物进行无助剂高温高压染色,结合IOB值(无机/有机平衡值),考察了扩散系数Dt、半染时间t1/2、比速率常数k’及吸附等温线类型等染色动力学和热力学参数。结果表明:与织物IOB值相近或较大的微胶囊分散染料具有较高的Dt值;随Dt值增大,平衡吸附量C∞增大,k’值增大,但t1/2值减小;不同结构类型的微胶囊分散染料在涤纶超细织物上的吸附呈现Lang-muir型和混合型吸附类型。     

Adsorption of Imazamox herbicide onto Filtrasorb 400 activated carbon

Imazamox is an imidazolinone herbicide, a new class of pesticides, which can exist as cationic, anionic or neutral species in water. The adsorption isotherms of Imazamox onto Filtrasorb 400 (F400) activated carbon were determined varying the pH and the ionic strength of the aqueous medium. The results show that ionic strength has no significant effect on Imazamox uptake, contrary to pH, and that F400 has a high affinity for Imazamox. Moreover, it is found that Imazamox adsorbs onto F400 as its neutral form. The best fit of the experimental points is obtained with the Langmuir–Freundlich model, consistent with surface site heterogeneity. Finally, calculating Langmuir–Freundlich isotherms for various constant pH values, it is shown that the two plateaus observed in the experimental isotherms obtained at free pH are due to the variation of the pH along the isotherms.     

Kinetic behaviour of adsorption of gelatin at solid–liquid interface

The kinetics of adsorption of gelatin from its aqueous solution on to silica has been studied at room temperature. The adsorption isotherms were found to be of the Langmuir type. From the adsorption isotherms, the adsorption coefficient, surface coverage and rate constants for adsorption and desorption were evaluated. The rate of adsorption was found to be maximum at the isoelectric point of gelatin and decreased with increase in pH of the adsorption medium. The increased ionic strength of the medium also caused an increase in the rate and amount of adsorption.     

Relation between the adsorbed quantity and the immersion enthalpy in catechol aqueous solutions on activated carbons

An activated carbon, Carbochem(TM)-PS230, was modified by chemical and thermal treatment in flow of H(2), in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pK(a). The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g(-1) for catechol aqueous solutions in a range of 20 at 1500 mg·L(-1).     

Adsorption of dissolved organics from industrial effluents on to activated carbon

Industrial effluents usually include multicomponent organic solutes. The optimum pH for adsorption of a specific industrial effluent on activated carbon should be determined experimentally because, in general, more than one mechanism is involved. A series of experiments was conducted to establish the influence of the initial hydrogen ion concentration on carbon adsorption of organic solutes. For these studies, powdered activated carbon was used, and the water systems studied included both single component pure organic compounds as well as multicomponent organic wastes. Results indicate that the pH effect upon the effectiveness of carbon adsorption mainly depends upon the nature of the adsorbed substance. In general, the degree of ionisation is the controlling factor for adsorption of ionic organic solutes on activated carbon. Adsorption reaches a maximum at the point of least ionisation of the adsorbate. As the organic compounds become more complex (i.e. longer hydrocarbon chains, higher molecular weights, increased branching), the electrical adsorption forces between activated carbon and ionic organic solutes will govern. Anionic surfactants meet with decreased electronegative repulsive forces at low pH levels, which increase the effectiveness of carbon adsorption. However, the adsorption of a cationic surfactant is increased by an increase in the electronegative carbon surface at high pH levels. When ionic organic solutes become much more complex, like a polymer, the effects of both ionisation and electrical adsorption forces become less important. Instead, the adsorption rate will be controlled by the extent of hydrolysis caused by the pH adjustment. For non-ionic organic solutes, chemical reaction(s) between the adsorbate and the added chemical (acid or base) for pH adjustment is an important controlling factor. Again, hydrolysis is responsible for the breakdown of larger size molecules to smaller sizes. Then an increase in adsorption rate with decreasing molecular weight of adsorbate is expected.     

Removal of amino acids from water by adsorption on polystyrene resins

The adsorption of eight amino acids, L ‐asparagine, D,L ‐threonine, L ‐lysine, L ‐leucine D,L ‐methionine, L ‐tyrosine, L ‐phenylalanine and D,L ‐tryptophan, on the non‐polar macroporous adsorbents Amberlite XAD‐2 and XAD‐4 (polystyrene–divinylbenzene copolymers) was studied. Equilibrium adsorption experiments were conducted to estimate the types of isotherm and their parameters. The effect the chemical composition and structure of the amino acids on the efficiency of adsorption was evaluated. The influence of pH and ionic strength was also studied. The data of adsorption isotherms of the examined amino acids seemed generally to approach the Freundlich isotherm model. Tryptophan isotherm adsorption data could match in some cases the Langmuir model. The majority of the adsorption isotherms were almost linear. In terms of adsorbed amino acid on both resin surfaces, the amino acids can be ranked thus: D,L ‐tryptophan > L ‐phenylalanine > D,L ‐methionine, L ‐tyrosine > L ‐leucine > L ‐lysine > D,L ‐threonine > L ‐asparagine. In low pH solution, adsorption was generally higher than that at intermediate and high pH values. Generally, as the ionic strength increases, the adsorption of the amino acids increases. © 2001 Society of Chemical Industry     

Fundamentals of electrosorption on activated carbon for wastewater treatment of industrial effluents

The potential of electroadsorption/desorption on activated carbon for waste water treatment of industrial effluents is studied. Adsorption isotherms of hydrophobic differently charged model substances on activated carbon were measured in order to obtain specific information about the influence of the charge (+1,–1 and 0) on the adsorbability of comparable, aromatic species and the influence of the bed potential on the adsorption equilibria. In all these cases the adsorption equilibria show a dependence on applied potential in electrolyte of approximately 1m ionic strength. With electrosorption from aqueous solution, a fivefold enhancement of the concentration in one potential controlled adsorption/desorption cycle is achievable. The use of the solvent methanol instead of water for desorption allows for a concentration enhancement by a factor of hundred in the desorptive step. The adsorption capacity of the activated carbon changes only slightly with cycle number. Two cell designs for the performance of potential controlled adsorption/desorption cycles on the large scale are discussed.     

活性碳纤维对水中喹啉的吸附性能

采用活性碳纤维（activated carbon fiber,ACF）静态吸附模拟废水中的喹啉,考察了吸附时间、喹啉初始浓度、温度、pH值、有机物等对吸附速率与吸附行为的影响。结果表明,ACF对喹啉的吸附速率快,30 min内基本达到平衡,初始浓度较高时,最终吸附容量较大,达210 mg/g,低温和pH值小于7时,吸附效果较好,苯酚与喹啉产生竞争吸附,配水中的吸附行为能较好的符合Langmuir等温方程,吸附动力学符合准二级动力学模型,热力学参数ΔH0、ΔG0为负值,表明该吸附是一个自发的放热过程。本研究为环境功能材料ACF应用于工业化生产提供了理论依据,有必要在此基础上进行动态吸附实验以及实际焦化废水的吸附处理实验,同时ACF成本高及脱附再生等方面问题还有待进一步深入研究。     

Analysis of statistical thermodynamic model for binary protein adsorption equilibria on cation exchange adsorbent

A study of nonlinear competitive adsorption equilibria of proteins is of fundamental importance in understanding the behavior of preparative chromatographic separation. This work describes the nonlinear binary protein adsorption equilibria on ion exchangers by the statistical thermodynamic (ST) model. The single-component and binary protein adsorption isotherms of bovine hemoglobin (Hb) and bovine serum albumin (BSA) on SP Sepharose FF were determined by batch adsorption experiments in 0.05 mol/L sodium acetate buffer at three pH values (4.5, 5.0 and 5.5) and three NaCl concentrations (0.05, 0.10 and 0.15 mol/L) at pH 5.0. The ST model was found to depict the effects of pH and ionic strength on the single-component equilibria well, with model parameters depending on the pH and ionic strength. Moreover, the ST model gave acceptable fitting to the binary adsorption data with the fitted single-component model parameters, leading to the estimation of the binary ST model parameter. The effects of pH and ionic strength on the model parameters are reasonably interpreted by the electrostatic and thermodynamic theories. Results demonstrate the availability of the ST model for describing nonlinear competitive protein adsorption equilibria in the presence of two proteins.     

Adsorption of peptides produced by cyanobacterium Microcystis aeruginosa onto granular activated carbon

The aim of this study was to investigate adsorption of peptides included in the cellular matter of cyanobacterium Microcystis aeruginosa, as they are difficult to remove during the coagulation/flocculation processes. In order to elucidate the effect of solution properties on peptide uptake, there were carried out equilibrium and kinetic experiments at different pH values and ionic strengths, using 2 types of activated carbon with different textural and charge characteristics – Picabiol 12×40 and Filtrasorb TL830.The results showed that the peptide adsorption on both carbons increases with decreasing pH value. The highest adsorption capacity was reached at pH 5 for Picabiol 12×40 due to a high portion of mesopores in its structure and the electrostatic attraction between functionalities of the carbon and the peptides. It was demonstrated that increasing ionic strength can enhance adsorption of the peptides by screening the repulsive forces, or by strengthening the attractive ones in the adsorption system, all of that depending on the type of carbon used and pH applied. Among peptides, those with low molecular weight of 1.0–4.5 kDa were adsorbed preferentially. Formation of H-bonds and electrostatic interactions were confirmed to play an essential role during the adsorption of peptides onto activated carbon.