Evaluation of Adsorption Characteristics of Malachite Green onto Almond Shell (Prunus dulcis)

The potential usage of almond shell (P. dulcis), which is an agricultural waste product, in the removal of malachite green from aqueous solutions was evaluated with respect to various experimental parameters including contact time, initial malachite green concentration, temperature, adsorbent concentration, etc. The adsorption kinetics of malachite green fitted well the pseudo-second-order kinetic model. The monolayer adsorption capacity of almond shell was found to be 29.0 mg g^?1. The adsorption of malachite green onto almond shell increased with raising the temperature. From the experimental results, almond shell could be employed as a low cost and easily available adsorbent for removal of malachite green in wastewater treatment process.     

Extraordinary adsorption of acidic fuchsine and malachite green onto cheap nano-adsorbent derived from eggshell

Removal of dyestuffs such as Acidic Fuchsine(AF) and Malachite Green(MG) being present in many forms in industries is vital to protect water reservoirs from their catastrophic effects on the ecosystem. This study attempts to effectively eliminate these dyes using a low-cost and eco-friendly material. Eggshell, as a biocompatible by-product,was initially characterized, then some modifications were conducted, and its morphology and chemical structure were then examined through(Atomic force microscopy) AFM,(Fourier-Transform Infrared Spectroscopy) FTIR,(Energy-Dispersive X-ray Spectroscopy) EDS and(Brunauer–Emmett–Teller) BET analyses. They revealed that the modifications on raw material gave rise to a natural nano-adsorbent presenting porous medium appropriate for targeted adsorbate molecules with the average particle size and average pore diameter of 54 and ～2 nm, respectively. Functional groups on the adsorbent surface were also of importance to assist the adsorption of AF and MG.The effect of contact time, adsorbent dose, solution p H and initial concentration was evaluated. Pseudo-second order model accurately correlated the experimental kinetic data for both dyes. Moreover, the participation of intra-particle diffusion along with film diffusion in controlling the process was suggested. Langmuir isotherm model fitted very well to the equilibrium data for both dyes and maximum monolayer adsorption capacity of AF and MG was accordingly calculated to be 5000 and 3333.33 mg·g~(-1) respectively. The inherent characteristics of eggshell make it a potential material to remove contaminants from wastewater in future applications.     

Adsorption of Furfural from Aqueous Solution onto Activated Carbon: Kinetic,Equilibrium and Thermodynamic Study

Abstract

The present study aims to evaluate the influence of various experimental parameters viz. initial pH (pH ₀), adsorbent dose, contact time, initial concentration and temperature on the adsorptive removal of furfural from aqueous solution by commercial grade activated carbon (ACC). Optimum conditions for furfural removal were found to be pH ₀ ≈ 5.9, adsorbent dose ≈ 10 g/l of solution and equilibrium time ≈ 6.0 h. The adsorption followed pseudo‐second‐order kinetics. The effective diffusion coefficient of furfural was of the order of 10^?13 m²/s. Furfural adsorption onto ACC was found to be best represented by the Redlich‐Peterson isotherm. A decrease in the temperature of the operation favorably influenced the adsorption of furfural onto ACC. The positive values of the change in entropy (ΔS ⁰); and the negatived value of heat of adsorption (ΔH ⁰) and change in Gibbs free energy (ΔG ⁰) indicated feasible, exothermic, and spontaneous nature of furfural adsorption onto ACC.     

Adsorption of malachite green onto bentonite: Equilibrium and kinetic studies and process design

The adsorption of malachite green onto bentonite in a batch adsorber has been studied. The effects of contact time, initial pH and initial dye concentration on the malachite green adsorption by the bentonite have been studied. Malachite green removal was seen to increase with increasing contact time until equilibrium and initial dye concentration, and the adsorption capacity of bentonite was independent of initial pH in the range 3–11. Four kinetic models, the pseudo first- and second-order equations, the Elovich equation and the intraparticle diffusion equation, were selected to follow the adsorption process. Kinetic parameters; rate constants, equilibrium adsorption capacities and correlation coefficients, for each kinetic equation were calculated and discussed. It was shown that the adsorption of malachite green onto bentonite could be described by the pseudo second-order equation. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich equations. Adsorption of malachite green onto bentonite followed the Langmuir isotherm. The thermodynamic parameters, such as ΔH, ΔS and ΔG, were also determined and evaluated. A single stage batch adsorber was designed for different adsorbent mass/treated effluent volume ratios using the Langmuir isotherm.     

孔雀绿褪色光度法研究麦壳对SDBS的吸附性能

采用麦壳为生物吸附剂,研究其对十二烷基苯磺酸钠（SDBS）的吸附作用。结果表明：麦壳能迅速有效地吸附SDBS,40min基本达到平衡;增大SDBS的初始浓度,吸附量随之增大;增加吸附剂的用量,吸附量随之减小;SDBS溶液pH值在5~8范围内,吸附效果较好;升高温度对吸附有利;麦壳对SDBS的吸附符合Langmuir等温模型。     

改性超细煤粉对甲基橙的吸附行为研究

The adsorption of methyl orange onto ultrafine coal powder (UCP) and modified ultrafine coal powder (MUCP) from aqueous solutions were studied, in which the influence of contact time, dosage, temperature, pH, and methyl orange concentration in the solution were investigated. The adsorption kinetics of methyl orange by UCP and MUCP can be described by the Lagergren first-order and pseudo second-order kinetic models, respectively. The adsorption isotherms of methyl orange onto MUCP at 303, 313 and 323 K follow the Freundlich and Langmuir isotherm equation. Values of G0 for methyl orange adsorption onto MUCP are -22.55, -23.10 and -23.79 kJ•mol－1 at 303, 313, and 323 K, respectively. The values of ΔH0 and ΔS0 are -3.74 kJ•mol－1 and 61.99 J•mol－1, respectively. The adsorption process is spontaneous and exothermic.     

Adsorption of Cu(II) and Cr(VI) onto Treated Shorea dasyphylla Bark: Isotherm,Kinetics, and Thermodynamic Studies

The efficacy of treated Shorea dasyphylla bark for Cu(II) and Cr(VI) adsorption was assessed in a batch adsorption system as a function of pH, agitation period, and initial metal concentration. The equilibrium nature of Cu(II) and Cr(VI) adsorption was described by the Freundlich, Langmuir, and Dubinin-Radushkevich isotherms. The maximum monolayer capacities of treated Shorea dasyphylla bark, estimated from the Langmuir equation were 184.66 and 42.72 mg/g for Cu(II) and Cr(VI), respectively. The experimental results were fitted using pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models; the pseudo-second order showed the best conformity to the kinetic data. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) were determined by applying the Van't Hoff equation. The adsorption of Cu(II) and Cr(VI) onto treated Shorea dasyphylla bark was found to be spontaneous and exothermic. The adsorption mechanism was confirmed by means of Fourier transform infrared (FTIR) and Energy dispersive X-ray (EDX) spectroscopy. The dimensionless constant separation factor (R _L), indicated that treated Shorea dasyphylla bark was favorable for Cu(II) and Cr(VI) adsorption.     

Adsorption Equilibrium and Kinetics of Toxic Dye-Erythrosine B Adsorption onto Montmorillonite

Erythrosine B is extensively used in the textile and food industry. It is reported to be a neurotoxicant and is carcinogenic in nature. It can induce DNA damage in the gastrointestinal organs even at low doses. In this study, adsorption efficiency of montmorillonite (MMT) has been investigated for the removal of erythrosine B (EB) from aqueous solution. The batch adsorption model was developed to predict the equilibrium adsorption capacity with respect to the pH of the dye solution, contact time, initial dye concentration, and adsorbent dosage. A maximum monolayer adsorption capacity of 578.03 mg/g was obtained at the original pH (7.5) of the aqueous dye solution within 5 minutes of contact time. It was found that the Langmuir adsorption isotherm yielded the most favorable representation of the adsorption behavior of EB. The dye was found to be chemisorbed on the adsorbent as confirmed by the FTIR spectral analysis. Although anionic in nature, the dye was found to be intercalated into the clay interlayers as suggested by the X-ray diffraction studies.     

Isotherm,Kinetic, and Thermodynamic of Cationic Dye Removal from Binary System by Feldspar

In this paper, the isotherm, kinetic, and thermodynamic of cationic dye removal onto inorganic adsorbent (Feldspar) were investigated in single and binary systems. Basic Red 18 (BR18) and Basic Blue 41 (BB41) were used as cationic dyes. The characterization of the Feldspar was carried out using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques. The effect of operational parameters such as adsorbent dosage, initial dye concentration, pH, ionic strength, and temperature on dye removal was studied. It was found that the adsorption of BR18 and BB41 onto Feldspar followed with Langmuir and extended Langmuir isotherms in single and binary systems, respectively. Adsorption kinetic of dyes was found to conform to pseudo-second order kinetic in single and binary system. The thermodynamic data showed that dye adsorption onto Feldspar was spontaneous, endothermic, and physisorption reaction. Based on the data of the present investigation, one could conclude that the Feldspar as an eco-friendly and low-cost adsorbent might be a suitable alternative to remove dyes from colored aqueous solutions containing cationic dyes.     

Adsorption equilibrium,thermodynamics, kinetics,mechanism and process design of zinc(II) ions onto cashew nut shell

Cashew nut shell (CNS) is an agricultural waste was investigated as a new adsorbent for the removal of zinc(II) from aqueous environment. Effects of solution pH, CNS dose, contact time, initial zinc(II) concentration and temperature on removal efficiency were tested and optimum conditions were evaluated. The equilibrium data were fitted well with Langmuir isotherm model and pseudo‐second‐order kinetic model. Langmuir monolayer adsorption capacity of CNS was examined as 24.98 mg/g. Changes in standard Gibbs free energy (?G°), standard enthalpy (?H°) and standard entropy (?S°) showed that the sorption of zinc(II) ions onto CNS are spontaneous and exothermic at 303–333 K. Sorption process was found to be controlled by both surface and pore diffusion. A batch adsorber was designed for different CNS dose to effluent volume ratios using Langmuir equation. Effective diffusivity values were found to be 1.927 × 10^?11 (10 mg/L), 2.135 × 10^?11 (20 mg/L), 2.267 × 10^?11 (30 mg/L), 2.305 × 10^?11 (40 mg/L) and 2.362 × 10^?11 (50 mg/L) m²/s. © 2011 Canadian Society for Chemical Engineering     

Aqueous Phase Adsorption of Cephalexin onto Bentonite and Activated Carbon

The adsorption of cephalexin in aqueous solution has been investigated using bentonite and activated carbon as the adsorbents. Batch kinetics and isotherm studies were carried out to evaluate the effect of contact time, adsorbent dosage, pH, particle size, and temperature. Adsorption equilibrium data were well represented by the Langmuir and Freundlich isotherm models. The adsorption intensity was found to be increased as the aqueous phase pH increased, and had a maximum at pH = 6.1. The pseudo-first order, pseudo-second order, and intraparticle diffusion kinetic models were used to describe the kinetic data. The experimental data fitted very well with the pseudo-second-order kinetic model and also followed the simple external and intraparticle model.     

Adsorption Kinetics and Equilibria of Strontium onto Kaolinite

Adsorption of Sr²⁺ onto kaolinite has been studied by means of a radiotracer technique using the ⁹⁰Sr isotope. Bangham’s and McKay models have been applied to kinetic results in Sr²⁺ concentrations between trace ?0.1 mol.L^?1. The magnitudes of film and intra-particle diffusion coefficients are 10?10 and 10?14 m²·s^?1, respectively. Concentration dependence of diffusion coefficients indicated that Sr²⁺ ions are adsorbed on two different adsorption sites by an exothermic and spontaneous process. The Freundlich isotherm parameters and exchange equilibrium constants derived from selectivity coefficients indicate that Sr adsorption are depressed by competing cations in the order of Na⁺< Mg²⁺< Al³⁺.     

Equilibria,Kinetics, and Mechanisms for the Adsorption of Four Classes of Phenolic Compounds onto Synthetic Resins

The adsorption of five phenolic compounds of four different classes from aqueous batch solutions onto four styrene-divinylbenzene and acrylic resins (EXA 90, EXA 118, XAD 7, and XAD 16) was investigated regarding their equilibria, kinetics and surface-energy heterogeneity, and mechanisms of adsorption. The experimental equilibrium data were very well fitted to Langmuir and Freundlich models (R ² > 0.900). Three kinetic models (pseudo-first-order, pseudo-second-order, and an intra-particle diffusion model) were suitable for describing the experimental data, the pseudo-second-order kinetic model being the best one (p < 0.001). The adsorption energy values were low (<19.00 kJ/mol), suggesting a physical adsorption process. Driving forces involved in the adsorption of the phenolic compounds onto the resins were hydrogen bonding, π ? π stacking and hydrophobic interactions.     

ZH-03树脂对苯酚和2,4-二氯苯酚的吸附机理研究

在静态条件下,研究了水溶液中新型树脂ZH-03吸附苯酚和2,4-二氯苯酚的热力学特性,测定了在288k、303k、318k和下降到288k温度下的吸附等温线。结果表明,在稀溶液中ZH-03吸附剂对苯酚和2,4-二氯苯酚的吸附同时符合Langm u ir和F reund lich模型。该树脂对苯酚的吸附是一个放热过程,而对2,4-二氯苯酚的吸附属于吸热过程,同时不同温度下的吸附等温线和热力学计算结果都证明了在树脂ZH-03对2,4-二氯苯酚吸附行为中存在着化学吸附。     

Removal of Acid Violet 17 from Aqueous Solutions by Adsorption onto Activated Carbon Prepared from Pistachio Nut Shell

Adsorbents prepared from pistachio nut shell, an agricultural waste biomass, were successfully used to remove Acid Violet 17 from an aqueous solution. The activated carbons PNS1, PNS2, and PNS3 were characterized by scanning electron microscope (SEM), Fourier Transform – Infra Red spectroscopy (FTIR) and (BET). The effect of pH, adsorbent dosage, and temperature on dye removal was studied. Maximum color removal was observed at pH 2. The adsorption increased with the increase in adsorbent dosage. As the adsorption capacity increased with the increase in temperature, the process was concluded to be endothermic. The experimental data were analyzed by the Langmuir and Freundlich isotherm models of adsorption. Equilibrium data fitted well with the Langmuir model. The rates of adsorption confirmed the pseudo-second order kinetics with good correlation values. The results indicated that the activated carbon prepared from pistachio nut shell can be effectively used for the removal of Acid Violet 17 from aqueous solution.     

核桃壳接枝聚合物的制备及其吸附性能

以核桃壳、2-溴异丁酰溴制备的核桃壳大分子化合物为引发剂,Fe Cl3·6H2O/PPh3、VC为催化体系,采用电子活化再生原子转移自由基聚合(AGET ATRP)法制备了核桃壳接枝聚丙烯酰胺(核桃壳-g-PAM)、聚甲基丙烯酸甲酯(核桃壳-g-PMMA)两种复合材料。利用红外光谱、差热分析及扫描电镜对复合材料的结构和形貌进行了表征。结果表明:两种复合材料对水中Pb(Ⅱ)、Cu(Ⅱ)的吸附量均高于核桃壳。293 K时,10 mg核桃壳-g-PAM、核桃壳-g-PMMA对pH=5、50 mg/L Pb(Ⅱ)的吸附量分别为40.5、53.7 mg/g,吸附机理均符合拟二级动力学模型,等温吸附过程可用Langmuir方程较好地描述。核桃壳-g-PAM、核桃壳-g-PMMA再生4次对Pb(Ⅱ)的最低解吸率分别为93.4%、93.1%,表明核桃壳复合材料具有较好的再生能力。     

Kinetic,equilibrium and thermodynamic studies on removal of Cr(VI) by activated carbon prepared from Ricinus communis seed shell

A study on the removal of hexavalent chromium ions from aqueous solution by using activated carbon prepared from Ricinus communis has been done. In this process, it was carbonised and activated by treating with concentrated sulphuric acid followed by heating for 5 h at 500°C. Batch adsorption experiments are also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature. The experimental data are fitted well to the Freundlich adsorption isotherm. Thermodynamic parameters such as ΔH°, ΔS° and ΔG° are calculated, which indicated that the adsorption is spontaneous and endothermic in nature. Adsorbent used in this study is characterised by FT‐IR and SEM before and after the adsorption of Cr(VI). © 2011 Canadian Society for Chemical Engineering     

核桃壳炭的制备及其对氨氮废水的吸附性能研究

为解决当前氨氮废水污染问题,以自制核桃壳炭为吸附剂,以NH4+为模型吸附分子,考察了核桃壳预处理方式、焙烧温度、焙烧时间和铵根离子初始浓度等对氨氮废水吸附的影响,并采用多种手段对核桃壳炭进行表征.研究结果表明:经H3PO4预处理后于700 ℃焙烧2h制备的核桃壳炭对低浓度的NH4+具有优异的吸附能力;当铵根离子初始质量...     

Application of Kinetic,Isotherm, and Thermodynamic Models for Atrazine Adsorption on Nanoporous Polymeric Adsorbents

Adsorption of atrazine on nanoporous polymeric adsorbents, PAD 400 and PAD 610, was investigated. The effect of particle size, pH, ionic strength, and temperature along with kinetic, equilibrium, and thermodynamic studies reveal the efficiency of PAD 400 with a higher adsorption capacity than PAD 610. The equilibrium data obey the Freundlich isotherm and the kinetic data were well described by the pseudo-second-order model. Spontaneous, endothermic, and random characteristics of the process were confirmed by thermodynamic analysis.     

Adsorption of bark derived polyphenols onto functionalized nanocellulose: Equilibrium modeling and kinetics

This article describes the kinetics and capacity of adsorbing condensed conifer tannins onto cationic cellulose nanocrystals (CCNCs). Batch adsorption experiments were carried as a function of pH, contact time, and initial tannin concentration with constant cationic cellulose nanocrystal concentration (0.01%). The adsorption process was highly pH dependent as adsorption capacities ranged from 13.2 mg/g to 112.7 mg/g at pH of 3–10. The amount of tannin adsorbed per unit mass of the cationic cellulose nanocrystals increased with increasing of tannin concentration until equilibrium was attained. The experimental data followed the Langmuir adsorption model, and the maximum experimental and theoretical adsorption capacities for the cationic nanocrystals reached 1,008 mg/g and 1,111 mg/g, respectively. The kinetics of adsorption was described best by the pseudo-second-order kinetics indicating a chemisorption process. The inherent adsorption has interesting applications for CCNC-complexes with natural polyphenolics in green chemical applications for adhesives, adsorbents, preservatives, and packaging materials.