LIQUID-PHASE ADSORPTION KINETICS OF ISOMALTOTRIOSE ON Ca^2＋ EXCHANGE RESIN

The adsorption of isomaltotriose from aqueous solution on Ca2+ resin was investigated.The adsorption isotherm and the rate curve were determined. The pseudo-first-order model,pseudo-second-order model and the intraparticle diffusion model were used to predict the rate constants of adsorption. The activation energy of adsorption has been also evaluated using the pseudo-second-order rate constants. The results showed that the adsorption of isomaltotriose onto Ca2+ resin is an exothermically activated process. The adsorption isotherm can be described by Langmuir equation. The pseudo-second-order model can fit well to the adsorption rate curve of isomaltotriose onto Ca2+ resin. It suggests that the adsorption of isomoltotriose onto Ca2+ resin involve chemical adsorption.     

Adsorption of acid dyes from aqueous solutions onto acid-activated bentonite

The adsorption of two dyes, namely, Acid Red 57 (AR57) and Acid Blue 294 (AB294), onto acid-activated bentonite in aqueous solution was studied in a batch system with respect to contact time, pH, and temperature. Acidic pH was favorable for the adsorption of these dyes. The surface characterization of acid-activated bentonite was performed using the FTIR technique. The pseudo-first-order and pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated. The dynamic data fitted the pseudo-second-order kinetic model well and also followed the intraparticle diffusion model up to 90 min, but diffusion is not the only rate controlling step. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The Freundlich model agrees very well with experimental data. The activation energies of adsorption were also evaluated for the adsorption of AR57 and AB294 onto activated bentonite.     

介孔碳CMK-3对苯酚的吸附动力学和热力学研究

研究了介孔碳CMK-3对苯酚的吸附性能, 与传统商用活性碳(CAC)进行了比较, 结果表明, CMK-3比CAC的吸附量大、吸附速率快、达到平衡时间短, 是一种较好的吸附剂. 同时探讨了介孔碳CMK-3对苯酚的吸附热力学和动力学特征. CMK-3对苯酚的吸附行为可用Langmuir和Freundlich等温式进行描述, 相关性都较好, 但更符合Freundlich经验公式. 分别采用模拟一阶反应和二阶反应模型考察了吸附动力学, 并计算了这些动力学模型的速率常数. 模拟二级反应模型和实验数据之间有较好的相关性. 分别计算了热力学参数ΔG0, ΔS0和ΔH0, 结果表明, CMK-3对苯酚的吸附过程是吸热和自发的.     

Adsorption of ethyl violet dye in aqueous solution by regenerated spent bleaching earth

The adsorption of basic dye (i.e., ethyl violet or basic violet 4) from aqueous solution onto the regenerated spent bleaching earth (RSBE) was carried out by varying the process parameters such as initial concentration, pH, and temperature. As analytical comparisons, activated bleaching earth (ABE) was also used as adsorbent for the adsorption of the basic dye at various initial concentrations. The experimental results showed that the adsorption process can be well described with the pseudo-second-order reaction model and less fitted by the intra-particle diffusion model. The kinetic parameters of both models obtained in the present work are in line with pore properties of the two adsorbents. According to the equilibrium adsorption capacity from the fitting of pseudo-second-order reaction model, it was further found that the both models of Langmuir and Freundlich appeared to fit well the isotherm data. In addition, the thermodynamic parameters were evaluated based on the pseudo-second-order rate constants, showing that the adsorption of ethyl violet onto the RSBE is endothermic in nature.     

Kinetic modeling of liquid-phase adsorption of reactive dyes on activated carbon

In this paper, adsorption equilibrium and kinetics of three reactive dyes from their single-component aqueous solutions onto activated carbon were studied in a batch reactor. Effects of the initial concentration and adsorbent particle size on adsorption rate were investigated Adsorption equilibrium data were then correlated with several well-known equilibrium isotherm models. The kinetic data were fitted using the pseudo-first-order equation, the pseudo-second-order equation, and the intraparticle diffusion model. The respective characteristic rate constants were presented. A new adsorption rate model based on the pseudo-first-order equation has been proposed to describe the experimental data over the whole adsorption process. The results show that the modified pseudo-first-order kinetic model generates the best agreement with the experimental data for the three single-component adsorption systems.     

Adsorption of Promethazine hydrochloride with KSF Montmorillonite

Adsorption of Promethazine hydrochloride (PHCl) onto KSF Montmorillonite from aqueous solution has been investigated. Experiments were conducted at various pH values, ionic backgrounds and solution temperatures. The pseudo-second-order equation successfully predicted the adsorption among the tried kinetics models (pseudo-first-order, pseudo-second-order and intraparticle diffusion). Langmuir, Freundlich and DR adsorption models were used to describe equilibrium isotherms and the isotherm constants were obtained. The increase in solution temperature caused a decrease in the adsorption capacity values found from Freundlich and DR isotherm. The adsorption type can be explained by combined ion exchange and physisorption. Thermodynamic parameters of adsorption of Promethazine hydrochloride (PHCl) onto KSF were also evaluated. The surface morphologies of KSF and PHCl loaded KSF were examined using a scanning electron microscope (SEM). FTIR measurements of samples were also conducted.     

H3PO4改性PS-EDTA树脂对水相中Cu2+、Zn2+和Cd2+的吸附性能研究

大孔氯甲基化聚苯乙烯小球先后与乙二胺、2-氯乙酸反应得EDTA型螯合树脂(PS-EDTA),再用磷酸在室温处理得PS-EDTA/P树脂。PS-EDTA/P树脂被用于水相中Cu2+、Zn2+和Cd2+的吸附净化处理,探讨了溶液的pH值、初始金属离子浓度、时间、温度等因素对吸附性能的影响,并研究了其对重金属离子的吸附动力学和热力学。结果表明,PS-EDTA/P树脂对Cu2+和Zn2+的吸附符合Langmuir等温式、对Cd2+的吸附符合Freundlich等温式,准二级吸附动力学方程能够很好地描述3种金属离子在树脂上的吸附动力学行为。同时,PS-EDTA/P树脂对重金属吸附的热力学参数表明,PS-EDTA/P树脂对Cu2+、Zn2+和Cd2+的吸附是一个自发的、吸热的过程。已吸附Cu2+、Zn2+和Cd2+的树脂可以用0.1mol/L HCl解吸,解吸后的树脂对Cu2+、Zn2+和Cd2+仍具有较高的吸附量。     

Kinetic modeling of liquid-phase adsorption of phosphate on dolomite

The adsorption of phosphate from aqueous solution on dolomite was investigated at 20 and 40 degrees C in terms of pseudo-second-order mechanism for chemical adsorption as well as an intraparticle diffusion mechanism process. Adsorption was changed with increased contact time, initial phosphate concentration, temperature, solution pH. A pseudo-second-order model and intraparticle diffusion model have been developed to predict the rate constants of adsorption and equilibrium capacities.The activation energy of adsorption can be evaluated using the pseudo-second-order rate constants. The adsorption of phosphate onto dolomite are an exothermically activated process. A relatively low activation energy and a model highly fitting to intraparticle diffusion suggest that the adsorption of phosphate by dolomite may involve not only physical but also chemisorption. This was likely due to its combined control of chemisorption and intraparticle diffusion. However, for phosphate/dolomite system chemical reaction is important and significant in the rate-controlling step, and for the adsorption of phosphate onto dolomite the pseudo-second-order chemical reaction kinetics provides the best correlation of the experimental data.     

黄姜黄色素在大孔树脂上的吸附动力学研究

采用静态法考察了8种大孔吸附树脂对黄姜黄色素的吸附及解吸特性,筛选出LX-18G树脂具有较高的吸附选择性和良好的脱附性能.以LX-18G树脂对黄姜色素的吸附平衡和吸附动力学进行了深入探讨,测定了不同温度下黄姜色素在该树脂上的吸附等温线,以及不同温度,初始液浓度和转速下的吸附动力学曲线.结果表明,Langmuir方程可更好地描述黄姜色素在该树脂上的吸附平衡.吸附动力学规律可用二级速率方程表示,液膜扩散和颗粒内扩散分别是吸附初期和吸附后期的主要速率控制步骤,吸附活化能为5.37kJ/mol.     

Kinetic and isotherm studies of Cu(II) adsorption onto H3PO4-activated rubber wood sawdust

Adsorption of Cu(II) from aqueous solution onto H(3)PO(4)-activated carbon using rubber wood sawdust (RSAC) was investigated in a batch system. Kinetic and isotherm studies were carried out by considering the effects of various parameters, such as initial concentration, contact time, pH, and temperature. The optimal pH value for Cu(II) adsorption onto RSAC was found to be 6.0. Thermodynamic parameters such as standard Gibbs free energy (DeltaG(0)), standard enthalpy (DeltaH(0)), and standard entropy (DeltaS(0)) were evaluated by applying the Van't Hoff equation. The thermodynamics of Cu(II) adsorption onto RSAC indicates its spontaneous and exothermic nature. Langmuir, Freundlich, and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The Langmuir isotherm fits the experimental data significantly better than the other isotherms. Adsorption kinetics data were tested using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Kinetic studies showed that the adsorption followed a pseudo-second-order reaction. The initial sorption rate, pseudo-first-order, pseudo-second-order, and intraparticle diffusion rate constants for different initial concentrations were evaluated and discussed. Adsorption mechanism studies revealed that the process was complex and followed both surface adsorption and particle diffusion. The rate-controlling parameter and effective diffusion coefficient were determined using the Reichenberg plot. It was found that the adsorption occurs through film diffusion at low concentrations and at higher concentration the particle diffusion becomes the rate-determining step.     

Adsorption of Brilliant Yellow onto Sepiolite: Evaluation of Thermodynamics and Kinetics and the Application of Nonlinear Isotherm Models

We studied the adsorption of Brilliant Yellow (BY) from aqueous solutions onto sepiolite and determined the adsorption equilibrium isotherms. We applied pseudo-first-order and pseudo-second-order kinetic models; the adsorption of BY onto sepiolite was best described by the pseudo-second-order kinetic model. The experimental data obtained at different temperatures were analyzed using various isotherm models; the Koble–Corrigan isotherm model provided the best fits for the BY adsorption data at all temperatures. The thermodynamic parameters of the BY adsorption onto sepiolite indicated that the adsorption process is spontaneous and exothermic in nature.     

Adsorption of Zinc and Cyanide from Cyanide Effluents on Anionic Ion-exchange Resin

The adsorption of zinc and cyanide from cyanide effluents onto strong and weak basic anion exchange resins was studied in a batch adsorption system. Factors influencing the adsorption rates such as resin selection, resin amounts, contact time and temperature were studied and scanning electron microscopy-energy disperse spectroscopy(SEM-EDS) was used in the analysis. The present study shows that the adsorption capacity of resin 201×7 is better than that of resin 301. The adsorption process was relatively fast and came to equilibrium after 60 min. The kinetic data were analyzed with three models and the pseudo-second-order kinetic model was found to agree with the experimental data well. The equilibrium data could also be described well by Langmuir isotherm model. Thermodynamic parameters such as enthalpy change(ΔH⁰), free energy change(ΔG⁰) and entropy change(ΔS⁰) were calculated and the adsorption process was spontaneous and endothermic.     

D301R树脂对水溶液中硝基苯的吸附性质

研究了D301R弱碱性阴离子交换树脂对水中硝基苯的吸附作用,测定了不同温度下吸附的动力学曲线和吸附等温线,提出了吸附动力学模型,计算了平衡吸附量、吸附活化能和吸附焓等。 实验结果表明,吸附动力学符合表面过程控制的准二级反应模型,其速率常数k2在300 K时为3.74×10-2 g/(mg·min),并随温度的升高而升高;平衡吸附量在300 K时为5.02 mg/g,且随温度的升高而降低;吸附活化能为39.02 kJ/mol;吸附等温线符合Langmuir吸附模型,吸附焓为-22.47 kJ/mol,吸附作用力主要是氢键。     

Equilibrium and kinetics for the sorption of promethazine hydrochloride onto K10 montmorillonite

This study presents the adsorption of cationic drug, promethazine hydrochloride from aqueous solution onto K10 montmorillonite. The effects of pH and temperature on adsorption process were investigated. Maximum adsorption pH was obtained to be about 7.5. Thermodynamic parameters found in this study depict the exothermic nature of adsorption. The process was favorable and spontaneous. From kinetic studies, it was found that adsorption process obeyed the pseudo-second-order kinetic model. The Langmuir, Freundlich, Dubinin-Radushkevich (DR) models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The fit of the Langmuir and DR models appeared to be good. Physisorption mainly controls the whole adsorption process but chemisorption also shows a particular contribution.     

D-101树脂对胭脂虫红色素吸附特性的研究

绘制了胭脂虫红色素的标准曲线,从9种不同性质的大孔吸附树脂中筛选出D-101树脂用于分离胭脂虫红色素,研究了D-101树脂对胭脂虫红色素吸附动力学曲线和不同温度下的吸附等温线。实验结果表明:胭脂虫红色素溶液浓度与吸光度之间显示良好的线性关系;D-101树脂对胭脂虫红色素的吸附速率快,120min达到平衡,吸附量为143.17mg/g树脂,吸附动力学曲线符合二级吸附动力学模型;D-101树脂对胭脂虫红色素的吸附等温线符合Freundlich方程,低温有利于吸附;通过热力学计算得到H、G、S均小于0,说明吸附是放热过程且能自发进行,吸附后体系趋向有序。研究结果可为胭脂虫红色素的分离提供有益的参考。     

Adsorption of Cu2+ from aqueous solution onto iron oxide coated eggshell powder: Evaluation of equilibrium,isotherms, kinetics,and regeneration capacity

This study explored the adsorption behavior of Cu²⁺ onto iron oxide coated eggshell powder (IOESP) from aqueous solution. The effect of various operational parameters such as pH, contact time, initial adsorbate concentration, surfactant, and temperature on adsorption of Cu²⁺ ions was investigated using batch adsorption experiments. The optimum pH for Cu²⁺ adsorption was found to be 6.0. Kinetics of adsorption was found to follow the pseudo-second-order rate equation. The suitability of Langmuir and Freundlich adsorption models to the equilibrium data was investigated. The adsorption was well described by the Freundlich isotherm model indicating the presence of heterogeneous sites for Cu²⁺ adsorption. The adsorption of Cu²⁺ was increased in the presence of anionic surfactant (SDS) while cationic surfactant (CTAB) shows no significant change in adsorption capacity. Thermodynamic parameters showed that the adsorption of Cu²⁺ onto IOESP was feasible, spontaneous, and exothermic. Regeneration studies were performed using HCl, HCOOH, EDTA, and NaOH as eluting agent for Cu²⁺ desorption from saturated IOESP and the maximum regeneration was observed with HCl.     

Preparation of a novel chelating resin for the removal of Ni2+ from water

A new chelating resin DVB-MA-HDA modified with hydroxamic acid groups was prepared for the fast removal of Ni2＋ from water. SEM, BET, elemental analysis, FT-IR spectroscopy and XPS were used to characterize this new adsorbent. Batch adsorption experiment indicated that the equilibrium adsorption capacity of DVB-MA-HD for Ni2＋ was more than 130mg/g, and the adsorption isotherm can be well fitted by the Langmuir model. The adsorption kinetic curve indicates that more than 60% of the adsorption amount of Ni2＋ at equilibrium occurred within the initial 20 rain. 0.1 mol/L EDTA solution could desorb Ni2＋ from DVB-MA-HDA effectively.     

Preparation of chemically oxidized porous carbon and its adsorption of uranium(VI) from aqueous solution

The chemically oxidized porous carbon (m-a-NC) materials were prepared by oxidation and activation of N-doped carbon (NC) materials which were produced from the glucose-urea resin primary carbon. Simultaneously, the batch experiments were carried out to investigate the adsorption of U(VI) onto the m-a-NC materials. The m-a-NC materials exhibit the maximum adsorption capacity of 397 mg/g towards U(VI) at 298.15 K and pH = 4.5. The adsorption kinetics was well fitted by the pseudo-second-order kinetic model, and the adsorption isotherm was better described by the Langmuir model. The possible adsorption mechanism of the m-a-NC for U(VI) was ion-exchange and coordination.

     

均苯四甲酸酐修饰壳聚糖微球对Pb2+和Cd2+的吸附

用交联的壳聚糖微球 (CTS) 与均苯四甲酸酐在无水条件下反应,合成均苯四甲酸酐修饰壳聚糖微球,并用FT-IR和XPS表征产物的结构。研究它对水溶液中Pb2+和Cd2+的吸附行为。考察溶液的pH,吸附时间及Pb2+和Cd2+的初始浓度对吸附金属离子的影响。吸附等温线可以用Langmuir 方程较好的描述,当pH 5.0时,该吸附剂对Pb2+和Cd2+的最大吸附量分别为296.7mg g-1和149.9mg g-1。动力学过程用二级吸附动力学模拟具有很好的线性相关性,从而确定了吸附过程为化学吸附。采用0.2mol L-1的EDTA为解析剂,Pb2+和Cd2+分别获得92.4%和85.3%的解析率。表明该吸附剂有再生性能。应用于电镀废水中铅的处理,结果满意。     

Estimation of radiological indices in Indian Sundarbans: a mangrove habitat

Stereoscopic porous microspheres based gellan gum (GG–Ca) were successfully prepared by sol–gel method using ethyl acetate as porogen and glutaraldehyde as crosslinker. The obtained GG–Ca microspheres were mainly of mesoporous with the average pore diameter was about 4 nm. It displayed a higher ability for uranium removal. In addition, the uranium adsorption process was endothermic and spontaneous following a pseudo-second-order and the adsorption isotherm was the best fit with the Freundlich model with maximum uranium capacity of 202.26 mg g⁻¹. The UO²⁺ adsorption mechanism is ion-exchange with Ca²⁺ based on SEM, EDX and XPS data analysis.