Toxic metal ion removal by terpolymer ion-exchanger from aqueous environments: synthesis,thermal degradation,batch separation,kinetic and isotherm studies

A novel chelating resin was synthesized and characterized by elemental, physico-chemical, GPC, NMR, and SEM analyses. Batch separation was adopted to study the recovery of selected metal ions with respect to the pH, time, concentrations, and electrolytes. From the results, it was observed that the order of the rate of metal ion uptake by the resin was Fe³⁺ > Cu²⁺ > Zn²⁺ > Ni²⁺ > Co²⁺ > Pb²⁺ ions. The adsorption kinetics follows first order, and isotherm models were also found to fit each other. The resin showed three-step thermal degradation, and its kinetic and thermodynamic parameters were also evaluated.     

Equilibrium and kinetic studies on the removal of some metal ions using biogenic amorphous silica

In the present study agricultural waste (rice husks) was used for the production of biogenic silica. The resulting material was obtained by incineration of rice husks at a temperature of 800°С and was characterized by means of XRD, FTIR, SEM-EDS, Hg-porosimetry and N₂-adsorption. The adsorption ability of the rice husks ash towards Fe(III), Pb(II), Cr(III) and Cu(II) ions in single- and multi-component aqueous solutions was studied in a batch system. The effects of contact time, acidity of initial solutions and metal ion concentrations were followed. Different models were used to determine the adsorption mechanism. Equilibrium experimental data were fitted to linear Langmuir and Freundlich models. The maximum adsorption capacities for single- and multi-component adsorption were calculated.     

Equilibrium and kinetics of heavy metal ion exchange

Ion exchange has a great potential to remove heavy metals from industrial wastewaters or heavy metal-containing sludge. In order to design and operate heavy metal removal processes, the equilibrium relationship between ions and resin must be known a prior. A series of ion-exchange equilibrium tests of Cu²⁺/H⁺, Zn²⁺/H⁺, and Cd²⁺/H⁺ systems using Amberlite IR-120 were performed. The equilibrium data were analyzed by the Langmuir isotherm, Freundlich isotherm, and selectivity coefficient approaches. The thermodynamic parameters such as Gibbs free energy change, enthalpy change, and entropy change were calculated. By comparison of the selectivity coefficients, the affinity sequence to IR-120 is Cu²⁺ > Zn²⁺ > Cd²⁺ > H⁺. Moreover, in order to understand the heavy metal extraction kinetics in the presence of Amberlite IR-120, the ion-exchange kinetics was also studied. The ion-exchange kinetic data were regressed by the pseudo first-order, second-order models, and a reversible reaction model. The activation energies calculated from the rate coefficients at different temperatures are 15.41, 7.04, and 17.01 kJ/mol for copper, zinc, and cadmium, respectively. Although the pseudo first- and second-order models are easier to use for data analysis, the resultant model parameters depend on operating conditions. The reversible reaction model is capable to predict the effects of resin to solution ratio, initial heavy metal concentration, and temperature on the ion-exchange kinetic curves.     

Adsorption of streptomycin on ion exchange resins: Equilibrium and kinetic studies

Equilibrium and kinetic studies of streptomycin adsorption from aqueous solutions of streptomycin sulphate were carried out using four weakly acidic ion exchange resins: Indion 236 [Ion Exchange (India) Ltd], Amberlite IRC-50 (Rohm and Haas Co, USA), KB-2 and KB4-P2 (both Russian resins), initially in the sodium form. The maximum amounts of streptomycin taken up by the exchangers were about 1640, 1560, 2050 1400 mg g^?1 dry resin (sodium form), respectively. The rate of adsorption of the antibiotic was highest with the ion-exchanger KB-2, and lowest with KB4-P2. The initial diffusivity values calculated for the four exchangers at a temperature of 9°C were 2.87 × 10^?8, 1.87 × 10^?8, 3.42 × 10^?8 and 0.468 × 10^?8 cm² s^?1, respectively.     

Synthesis of cationic polymeric adsorbent and dye removal isotherm,kinetic and thermodynamic

Poly(quaternary ammonium salt) (PQAS) as a cationic polymeric adsorbent was synthesized and characterized by FTIR. Isotherm, kinetic and thermodynamic of dye removal from single and binary systems was investigated. Acid Blue 25 (AB25) and Acid Red 18 (AR18) were used. The effect of operational parameters (adsorbent dose, pH, dye concentration and salt) on dye removal was studied. The dye removal followed the Langmuir isotherm and pseudo-first order kinetics. The adsorbent maximum dye adsorption capacity (Q₀) was 2000 and 1667 mg/g for AB25 and AR18, respectively. The thermodynamic data showed that dye adsorption was spontaneous, endothermic, and a physisorption reaction.     

The isotherm,kinetic and thermodynamic studies of the cadmium uptake by colpomenia sinuosa

ABSTRACT

A number of isotherm models were studied and modeled for colpomenia sinuosa. The experimental data were fitted among the 12 biosorption kinetic models. Thermodynamic studies indicated a spontaneous and endothermic process. The morphology of the biosorption process was revealed by Fourier transfer infrared (FT-IR) analysis and scanning electron microscope (SEM). The isotherm and kinetic parameters were compared with other microorganisms.     

Equilibrium studies of ternary systems containing some selected transition metal ions, triazoles and aromatic carboxylic acids

Solution equilibria of the binary and ternary complex systems of the divalent transition metal ions Cu²⁺, Ni²⁺, Zn²⁺, and Co²⁺ with 1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole (TRZSH), and 3-amino-1,2,4-triazole (TRZAM) and aromatic carboxylic acids (phthalic, anthranilic, salicylic, and 5-sulfosalicylic acid) have been studied pH-metrically at (25.0±0.1) °C, and a constant ionic strength I=1×10^?1 mol L^?1 NaNO₃ in an aqueous medium. The potentiometric titration curves show that binary and ternary complexes of these ligands are formed in solution. The stability constants of the different binary and ternary complexes formed were calculated on the basis of computer analysis of the titration data. The relative stability of the different ternary complex species is expressed in terms of Δ log K values, log X and R. S.% parameters. The effect of temperature of the medium on both the proton-ligand equilibria for TRZAM and phthalic acid and their metal-ligand equilibria with Cu²⁺, Ni²⁺, and Co²⁺ has been studied along with the corresponding thermodynamic parameters. The complexation behavior of ternary complexes is ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV-visible spectrophotometry.     

啤酒酵母吸附Cr（VI）的动力学及热力学研究

研究啤酒酵母对溶液中铬(VI)的吸附效果和机理,通过红外对吸附前后菌体表面特征分析,表明Cr (VI)与菌体表面基团发生配位络合反应.结果表明,在温度为35 ℃,pH=2,Cr(VI)初始浓度为20 mg/L时达到最大吸附量,最大吸附量为4.19 mg/g.酵母菌对Cr(VI)的吸附行为基本符合Langmuir方程,并且在 25,30和35 ℃条件下的理论最大吸附量qmax分别为4.472,4.533,4.702 mg/g.动力学研究表明,反应在240 min吸附基本达到平衡状态,准二级动力学模型能够更好的描述吸附过程.不同温度下的吸附热力学显示,该吸附过程为自发的吸热反应.     

Assessment of kinetic and isotherm models for competitive sorption of Cs+ and Sr2+ from binary metal solution onto nanosized zeolite

This study examined the sorption performance of synthesized nanosized zeolite for the elimination of Cs⁺ and Sr²⁺ cations in a binary metal system. The influence of pH, sorbent amount, temperature, and contact time was studied. The relationship between each of these parameters and the removal efficiency was investigated. An analysis of the rate data was performed using both pseudo-first- and second-order reaction models. The ranking of three equilibrium sorption isotherm models used (Redlich–Peterson, Langmuir, and Freundlich) with a variety of numbers of parameters was determined using the corrected Akaike’s information criterion. The results demonstrate that a pseudo-second-order model fits the sorption kinetic data better than a pseudo-first-order model. The isotherm model rank order that best described the data statistically was Redlich–Peterson?>?Langmuir?>?Freundlich for the cesium ions and Langmuir?>?Redlich–Peterson?>?Freundlich for the strontium ions. Our results revealed that the existence of Sr²⁺ caused a significant reduction of Cs⁺ sorption in the binary metal mixture according to a lumped parameter model and vice versa. The results show that the synthesized material’s surface had a relatively stronger affinity for Cs⁺ than for Sr^2+.     

Improved sorption of reactive black 5 by date seed-derived biochar: isotherm,kinetic, and thermodynamic studies

ABSTRACT

In the present investigation, date seed-derived biochar was applied as economic and effective sorbent for remediation of reactive dye from contaminated solutions. Biochar produced at 350°C through pyrolysis process exhibited reactive black 5 (REB5) sorption capacity 2.7 times higher than virgin date seeds. The surface of biochar was analyzed through Fourier transform infrared and scanning electron microscope data. The maximum REB5 uptake determined through the Langmuir model was found to be 113.4 mg/g. The REB5 sorption kinetics were accurately described by the pseudo-first-order model than pseudo-second-order model. Thermodynamic parameters indicated that REB5 sorption was spontaneous, feasible, and endothermic process.     

生物吸附法去除水中重金属离子

生物吸附作为一种有效的去除水中重金属的方法引起人们的极大关注。近几年虽然提出了许多吸附模型,但生物体的吸附机理尚不完全清楚。生物吸附过程受生物体本身的性质、处理水的种类、离子强度、pH、反应动力学、反应设备等因素的影响。由于生物体在吸附和脱吸过程中具有非常好的可逆性．并且这种生物体大量存在,因此在水处理领域具有非常好的应用前景。作者主要介绍了近几年国外生物吸附法在水处理方面的研究成果。     

Selective biosorption of mixed heavy metal ions using polysaccharides

Although much research has been conducted on the separation of single species of heavy metal, the selective adsorption of two or more heavy metals in mixture is relatively little known. In this study, polysaccharide beads were prepared to selectively remove the targeted heavy metal ion from mixture. Among the biomasses, polysaccharide was examined due to its low cost and easy accessibility. In a single metal ion system, chitosan, λ-carrageenan, and alginic acid showed high affinity to mercury, copper, and lead, respectively. In the ion mixture, the same trend shown in the single metal ion solution was observed. The optimum electrolyte concentraion was investigated to adsorb the metal ion selectively, and it was possible to remove the targeted metal ion selectively with chitosan, alginic acid and λ-carrageenan at 1 mmol concentration of electrolyte. In order to demonstrate the feasibility of selective biosorption, two packed-bed reactors in series containing chitosan and alginic acid beads in each were studied and selective adsorption to Hg²⁺ and Pb²⁺, respectively, was observed.     

Synthesis,metal ion complexation and antibacterial activities of some thiapodands with lipophilic amide and ester end groups

A series of acyclic analogues of thiacrown ethers (podands) 7–12 with lipophilic amide and ester end groups were synthesized in high yield and in a simple way. Their transition metal ions complexation was studied using a conductometric method in acetonitrile at 25°C. Podands 7 and 11 showed a continuous decrease in the molar conductances in their complexation with Ag⁺, Cu²⁺, Cd²⁺, Hg²⁺, Zn²⁺ and Pb²⁺ which begins to level off at a mole ratio of 1:1 podand to metal indicating the formation of a stable 1:1 complexes. On the other hand, podand 9 also showed the formation of 1:1 complexes with above metal cations except with Hg²⁺ ion, which formed a 1:2 podand-to-metal ratio complex. An influence of end groups on metal ion selectivity is evident. Podands having ethoxy end groups (podands 8, 10 and 12 exhibit pronounced metal ion selectivity over podands having amino end groups (podands 7, 9 and 11). Compounds 10 and 12 with dithiaethylene units and ethoxy end groups provide the best selectivity for Hg²⁺ and Ag⁺ ions. These results suggest that podands 10 and 12 could be useful for the selective removal of Hg²⁺ and Ag⁺ ions from industrial waste that may contain a variety of toxic heavy and transition metal ions. The in vitro antibacterial activity of the investigated compounds was tested against several microorganisms such as Bacillus subtilis (ATCC 6633), Micrococcus luteus (ATCC 10240), Staphylococcus aureus (ATCC 43300), Escherichia coli (ATCC 25922) and Enterobacter aerogenes (ATCC 13048). The antibacterial activity of podand 10 is significant for M. luteus and B. subtilis compared with other podands under investigation.     

Equilibrium and kinetic studies of chromium ions adsorption on Co (II)-based phosphonate metal organic frameworks

Chromium is present in wastewaters resulted from a lot of industrial processes such as electroplating, dye, cement, leather tanning, and paint. Its presence at values higher than maximum admitted value of 0.05 mg/L can affect the human health and the environment. Therefore, it is essential to remove chromium from wastewaters before discharge. In this study, the adsorption potential of three types of Co (II)-based phosphonate metal organic frameworks, obtained by the reaction of CoSO₄.7H₂O with phosphonoacetic acid (CP), N,N-bis(phosphonomethyl)glycine (Gly), or vinyl phosphonic acid (VP) in hydrothermal conditions, has been investigated. The study involves batch types experiments investigating the effects of the solution pH, solid:liquid ratio, initial concentration of Cr(VI), and contact time upon the adsorption efficiency of the studied materials. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich were applied to adsorption equilibrium data to find the best among these models. The kinetics of adsorption was found to follow the pseudo-second-order model. It was found that the adsorption efficiency of the studied materials in the removal process of Cr(VI) ions from aqueous solutions is in the following order: Co-CP<Co-Gly< Co-VP.     

A comparison of isotherm and kinetic models for binary-solute adsorption to affinity membranes

Single-solute isotherms for pepsin (EC 3.4.23.1) and chymosin (EC 3.4.23.4) adsorption to affinity membranes were fitted using five of the most popular isotherm models. It was found that the single-solute Langmuir isotherm was the best two-parameter model, although the three-parameter models gave even better fitting. Experimental binary-solute adsorption isotherms were compared with four different types of binary-solute Langmuir models using the single-solute parameters. The results showed that the difference in the saturation capacities affected the adsorption equilibrium. Furthermore, three types of binary-solute Langmuir models were converted into the kinetic form and used to calculate the association rate constants of pepsin and chymosin from experimental data. The best-fitted rate constant values were found to be identical for different kinetic models. However, the model predictions of association curves were significantly influenced when the values of association rate constants were changed.     

A model for ph dependent equilibrium of heavy metal biosorption

Biosorption of heavy metals can be an effective process for the removal and recovery of heavy metal ions from aqueous solutions. The biomass of marine macro algae has been reported to have high uptake capacities for a number of heavy metal ions and the uptake capacities are strongly influenced by the value of the solution pH. In this paper, a modified Langmuir model was proposed for describing the pH dependent biosorption equilibrium and validated with isotherm data obtained from batch experiments and from the literature. The model assumes that the functional groups for heavy metal interactions are weakly acidic and the uptake capacities of the biomass are affected through the association and dissociation equilibrium between two apparent ionic forms. The model equations fitted the experimental data well, which supports the biosorption mechanism proposed.     

Diffusion kinetic study of cadmium(II) biosorption by Aeromonas caviae

The removal of cadmium from aqueous solution by sorption on Aeromonas caviae particles was investigated in a well‐stirred batch reactor. Equilibrium and kinetic experiments were performed at various initial bulk concentrations, biomass loads and temperatures. Biosorption equilibrium was established in about 1 h and biosorption was well described by the Langmuir and Freundlich biosorption isotherms. The maximum biosorption capacity was found as 155.32 mg Cd(II) g^?1 at 20 °C. The obtained sorption capacity is appreciably high for most experimental conditions; so A caviae may be considered as a suitable biosorbent for the removal of cadmium. Moreover, the sorption rate of cadmium onto A caviae particles was particularly sensitive to initial bulk concentration and solid load. A detailed analysis was conducted, examining several diffusion (external and intraparticle) kinetic models in order to identify a suitable rate expression. The results are discussed and indicate that biosorption of cadmium is a complex process that is described more correctly by more than one model. Copyright © 2004 Society of Chemical Industry     

Equilibrium,kinetic, diffusion and thermodynamic applications for dye adsorption with pine cone

ABSTRACT

In the present study, the adsorption of methylene blue onto pine cone was investigated. Adsorbent was characterized by XRD and SEM. The adsorption data follow the Langmuir isotherm model. Maximum adsorption capacity was calculated 125 mg.g^?1 . It was determined that the pseudo-second-order model was the best choice among all the available kinetic models to describe the adsorption behaviour. E_a was found to be 19.57 kJ mol^?1. This confirms the fact that the adsorption was a physical process. The negative free energy values indicate the feasibility of the adsorption process and its spontaneous nature.     

Adsorption and photocatalytic degradation of organic dyes onto crystalline and amorphous hydroxyapatite: Optimization,kinetic and isotherm studies

We evaluated the adsorptive/photodegradation properties of hydroxyapatite. Hydroxyapatite was synthesized by two different precipitation methods and examined for the removal of two kinds of textile dye. The physicochemical properties of the products were characterized using Fourier transform infrared, X-ray diffraction, inductively coupled plasma atomic emission spectroscopy and scanning electron microscopy. The effects of different parameters, including hydroxyapatite synthesis method and removal process type, pH, reaction time, temperature and amount of hydroxyapatite, were investigated and optimized by Taguchi design. The kinetics of adsorption and isotherm studies showed that the pseudo-second-order model and the Freundlich isotherm were the best choices to describe the adsorptive behavior of hydroxyapatite. Photocatalytic degradation of dye followed Langmuir-Hinshelwood mechanism, illustrated a pseudo-first-order kinetic model with the adsorption equilibrium constant and kinetic rate constant of surface reaction equal to 0.011 (l mg^-1) and 1.3 (mg l ^-1 min^-1), respectively.