Selective retention properties to silver(I) and mercury(II) ions of poly(4‐vinylpyridine) methyl iodide studied by the liquid‐phase polymer‐based retention technique

The retention of various metal ions by water‐soluble poly(4‐vinylpyridine) methyl iodide in conjunction with ultrafiltration membrane was investigated. The method is based on the retention of inorganic ions by this polymer in a membrane filtration cell and subsequent separation of low‐molecular weight species from the polymer metal ion complex formed. It is shown that the polychelatogen can bind silver(I) and mercury(II) ions in aqueous solution at pH 1. At higher pH, the water‐soluble polymer can be applied to the separation and preconcentration of silver metal ions. Therefore, this polychelatogen is highly selective to Hg(II) at pH 1 with respect to metal ions such as Cd(II) and Zn(II). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2578–2582, 2001     

Selective Extraction of Mercury(II) by 1‐Naphthylthiourea–Methyl Isobutyl Ketone System

Abstract

Selective extraction of Mercury(II) using 1‐naphthylthiourea–methyl isobutyl ketone (ANTU‐MIBK) system from hydrochloric acid solutions (0.1–10 M) has been studied. Influence of foreign ions, acid and ligand concentrations has been investigated. Addition of ANTU in MIBK enhanced, extraction capacity of MIBK to several times. Low effect of foreign ions and high separation factors for a number of metal ions determined at 0.5 M hydrochloric acid concentration evaluated the proposed method efficient and selective. The experimental data obtained from application of the method for extraction of mercury from a synthetic aqueous solution reveal that more than 99% mercury can be separated from cadmium, zinc and selenium in a single step with five minutes equilibration.     

Transport of mercury(II) ion through a supported liquid membrane containing a triisobutylphosphine sulfide (Cyanex 471X) as a mobile carrier

Carrier‐facilitated transport of mercury(II) against its concentration gradient from aqueous 0.1 mol dm^?3 hydrochloric acid solution across a flat‐sheet supported liquid membrane (SLM) containing triisobutylphosphine sulfide (Cyanex 471X) as the mobile carrier in kerosene as diluent has been investigated. Dilute sodium thiocyanate solution (0.11 mol dm^?3) was the most efficient stripping agent among several aqueous reagents tested. Various parameters such as stirring rate, concentration of HCl in the feed solution, concentration of NaSCN in the strippant, concentration of Cyanex 471X in the membrane, and contact time were investigated. Under optimum conditions the transport of Hg(II) across the liquid membrane is about 100% after 6 h. The carrier, Cyanex 471X, selectively and efficiently transported Hg(II) ions in the presence of other associated metal ions. The method has been demonstrated to recover selectively mercury from waste samples and mercurochrome solution. © 2002 Society of Chemical Industry     

Adjusted pH for the Selective Separation of Cadmium from Lead by Nano-Active Silica-Functionalized-[Bmim+Tf2 N−] Ionic Liquid

A method is described for the selective separation and extraction of cadmium-lead from aqueous solutions by tuning the pH value between 1.0 and 7.0. A modified nano-active silica sorbent was loaded with 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide hydrophobic ionic liquid, [Bmim⁺Tf₂N^?] and used in this work. The pH value was found to play a significant role in the sorption capacity of Cd(II) and Pb(II). In pH 1.0, the metal capacity values were characterized as 1.40 and 0.30 mmol g^?1 for Cd(II) and Pb(II), respectively. In pH 7.0, Cd(II) and Pb(II) switched their capacity values to 0.65 and 1.00 mmol g^?1, respectively. An anion exchange mechanism was proposed in solution with pH 1.0 for exchange of chloroanionic cadmium species by [Tf₂N^?]. The sorptive separation processes of Cd(II) and Pb(II) were studied and evaluated under the influence of various controlling factors. The potential applications of modified nano-silica sorbent for selective sorptive removal and separation of Cd(II) from Pb(II) in water samples was successfully accomplished by adjusting the pH value of the contact solution between 1.0 and 7.0. The results of this study indicated an efficient extraction behavior of the two examined metal ions.     

Selective binding of mercury ions by poly(4‐vinylpyridine) hydrochloride resin

The binding ability of poly(4‐vinylpyridine) hydrochloride resin for Cu(II), Cd(II), Zn(II), Hg(II), Pb(II), Cr(III), and U(VI) was investigated. All these ions, except Hg(II), could be not removed from aqueous solutions under the same conditions. The selective sorption of Hg(II) from mixtures of ions was observed. The elution of Hg(II) bound to the resin was also investigated using various concentrations of nitric acid and perchloric acid. Due to rapid complexation, a high mercury ion‐binding capacity, high selectivity, and ease of regenerability, the resin can be useful for the removal and recovery of mercury ions from aqueous solutions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1557–1562, 1999     

Removal of mercury(II) from aqueous solution on a carbonaceous sorbent prepared from flax shive

Treatment of flax shive with sulfuric acid produced a carbonaceous material which has been used to remove mercury(II) from aqueous solution. The kinetics of sorption follows a first order reaction equation with the rate of sorption being higher for the wet material than for that which had been previously dried. Sorption of mercury depends on the pH of the aqueous solution with maximum uptake occurring in the pH range 6–7. Sorption capacity also increases with the increase of temperature. The presence of other metal ions such as K⁺, Na⁺, Mg²+ and Ca²+ decreases Hg(II) uptake capacity. A high capacity which exceeds the cation exchange capacity was observed, cumulative Hg(II) sorption exceeding 1 gg⁻¹. This arises from the reduction of mercury(II) to mercury(I) chloride and elemental mercury from chloride media and to elemental mercury from nitrate media. This was confirmed from the identification of deposits on the carbon surface by scanning electron microscopy and X‐ray diffraction. The reduction of mercury was accompanied by the oxidation of the carbon which was confirmed by the evolution of carbon dioxide. This observation was also supported by changes in the infra‐red spectrum of the carbon after reaction. The sorption mechanism is discussed. © 2000 Society of Chemical Industry     

Polymer‐supported iminodiacetamides for selective mercury extraction

A new polymeric resin with iminodiacetamide functions has been prepared for the selective extraction of mercuric ions. This polystyrene sulfone amide‐based resin with a 9.6 mmol g^?1 amide content is able to selectively sorb mercury over many metal ions, including Cd(II), Zn(II), Fe(III), and Pb(II). Among these, Cd(II) and Zn(II) ions are not sorbed at all, and Fe(III) and Pb(II) ions show only trace absorptions (0.58 and 0.17 mmol/g, respectively) under the same conditions. The selectivity of the resin, its high mercury loading capacity (4.23 mmol g^?1), and its ability to regenerate via acetic acid make it a promising material for the large‐scale selective separation of mercuric ions from aqueous mixtures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1316–1321, 2003     

Predicting the dynamics and performance of a polymer–clay based composite in a fixed bed system for the removal of lead (II) ion

A polymer–clay based composite adsorbent was prepared from locally obtained kaolinite clay and polyvinyl alcohol. The composite adsorbent was used to remove lead (II) ions from aqueous solution in a fixed bed mode. The increase in bed height and initial metal ion concentration increased the adsorption capacity of lead (II) and the volume of aqueous solution treated at 50% breakthrough. However, the adsorption capacity was reduced by almost 16.5% with the simultaneous presence of Ca²⁺/Pb²⁺ and Na⁺/Pb²⁺ in the aqueous solution. Regeneration of the adsorbent with 0.1 M of HCl also reduced its adsorption capacity to 75.1%. Adsorption of lead (II) ions onto the polymer–clay composite adsorbent in the presence of Na⁺ and Ca²⁺ electrolyte increased the rate of mass transfer, probably due to competition between cationic species in solution for adsorption sites. Regeneration further increased the rate of mass transfer as a result of reduced adsorption sites after the regeneration process. The length of the mass transfer zone was found to increase with increasing bed height but did not change with increasing the initial metal ion concentration. The models of Yoon–Nelson, Thomas, and Clark were found to give good fit to adsorption data. On the other hand, Bohart–Adams model was found to be a poor predictor for the column operation. The polymer–clay composite adsorbent has a good potential for the removal of lead (II) ions from highly polluted aqueous solutions.     

Equilibrium,Thermodynamic and Kinetic Studies on Biosorption of Mercury from Aqueous Solution by Macrofungus (Lycoperdon perlatum) Biomass

The present research is to investigate the possibility of macrofungus Lycoperdon perlatum biomass, which is an easily available, renewable plant, low-cost, as a new biomass for the removal of mercury (Hg(II)) ions from aqueous solutions. The effects of various parameters like pH of solution, biomass concentration, contact time, and temperature were studied by the using the batch method. The Langmuir model adequately described the equilibrium data. The biosorption capacity of the biomass was found to be 107.4 mg · g^?1 at pH 6. The mean free energy value (10.9 kJ · mol^?1) obtained from the D–R model indicated that the biosorption of Hg(II) onto fungal biomass was taken place via chemical ion-exchange. Thermodynamic parameters showed that the biosorption of Hg(II) onto L. perlatum biomass was feasible, spontaneous, and exothermic in nature. The kinetic results showed that the biosorption of Hg(II) onto fungal biomass followed second-order kinetics. This work also shows that L. perlatum biomass can be an alternative to the expensive materials like ion exchange resins and activated carbon for the treatment of water and wastewater containing mercury ions due to its ability of selectivity and higher biosorption capacity and also being low cost material.     

Synthesis and Surface Modification of Mesoporous Silicate SBA‐15 for the Adsorption of Metal Ions

Abstract

In this study surface modified SBA‐15, coated with octadecyltrichlorosilane (C18), is considered as an alternative adsorbent for metal ions in water. The SBA‐C18 was loaded with Bis(2,4,4-trimethylpentyl) phosphinic acid (cyanex 272) as the metal ion extractant. The adsorption characteristics of phosphinic acid loaded SBA‐C18 were evaluated for Cu(II) and Zn(II) ions in aqueous solution. Adsorption tests indicated that a contact time of 1 hour was sufficient for adsorption equilibrium to occur. The pH_1/2 values of Zn(II) and Cu(II) onto SBA‐C18, were found to be similar to published data for levextrel ion exchange resins and around 1 pH unit lower than published solvent extraction data for cyanex 272 in xylene.     

Application of N,N′‐Dimethyl‐N,N′‐Di(4‐Chlorophenyl)Tetradecyl Malonamide for the Selective Recovery of Iron(III) from Concentrated Chloride Solutions

Abstract

The feasibility of using two new diamides namely; N,N′‐dimethyl‐N,N′‐di(4‐chlorophenyl)malonamide (DMDPhClMA) and N,N′‐dimethyl‐N,N′‐di(4‐chlorophenyl)tetradecylmalonamide (DMDPhClTDMA), as agents for the selective extraction of iron(III) from chloride solution was investigated. A systematic investigation has been carried out on the detailed extraction properties of iron(III) with these extractants from chloride media. The extraction of iron(III) from an aqueous chloride solution in the presence of metal ions, such as Zn(II), Co(II), Mn(II) Cu(II), Pb(II), Ni(II) and Ag(I) was carried out using DMDPhClMA or DMDPhClTDMA in binary and multicomponent mixtures. The quantitative extraction of iron(III) with DMDPhClMA and DMDPhClTDMA in toluene is observed at 4 and 7 M HCl, respectively. The quantitative stripping of Fe(III), from the loaded organic phase was successfully achieved by simple contact with water.     

Preparation and characterization of polyimide nanocomposites with different organo‐montmorillonites

Poly(amic acid) nanocomposites were synthesized from a dimethylacetamide (DMAc) solution with two organophilic montmorillonites (organo‐MMTs). It was then heated at various temperatures under vacuum, yielding 15–20 um thick films of polyimide/organo‐MMT hybrid with different clay contents (1–8 wt%). Dodecy‐lamine (C₁₂‐) and hexadecylamine (C₁₆‐) were used as aliphatic alkylamines in organo‐MMT. The ultimate strength monotonically increased with increasing clay content in the polymer matrix. Maximum enhancement in the initial modulus was observed for the blends containing 2 wt% clay with two kinds of organo‐clays, and values did not alter significantly with further increases in clay content. Additions of only 2 wt% C₁₂‐ and C₁₆‐MMT to the polyimide were shown to cause 94%‐95% reduction in oxygen gas permeability. This is caused by the barrier properties of the clay layers dispersed in the composite. In general, C₁₆‐MMT is more effective than C₁₂‐MMT in increasing both the tensile property and the gas barrier in a polyimide matrix. Intercalations of the polymer chains in clay were examined through wide‐angle X‐ray diffraction (XRD) and electron microscopies (SEM and TEM).     

Antipolyelectrolyte superabsorbing nanocomposites: Synthesis and properties

Novel polyampholytic superabsorbing nanocomposites based on the zwitterionic sulfobetaine monomer [3‐(methacrylamido)propyl)]dimethyl(3‐sulfopropyl)ammonium hydroxide were synthesized through in situ polymerization in aqueous solution with different contents of an organo‐modified clay (OMMT, Cloisite 30B). Structural and thermomechanical properties of hydrogels were characterized by FT‐IR, XRD, and DMTA, respectively. Swollen gel strength of hydrogels was determined by a rheological method. Storage modulus of the hydrogels was considerably improved in comparison with its the clay‐free counterpart. The nanocomposite hydrogel containing 15% OMMT possessed the highest gel strength. The glass transition temperature was increased from 58.4 to 67.0°C for the clay‐free and nanocomposite hydrogel containing 8% OMMT, respectively. The swelling behavior of the hydrogel in various salt solutions was investigated. Antipolyelectrolyte behavior was observed with enhancement of concentration of mono‐ and multivalent salts. Swelling in the various pH media was nearly pH‐independent over a wide range of pH. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Adsorption of Co(II) from Aqueous Medium on Natural and Acid Activated Kaolinite and Montmorillonite

Abstract

Hazardous metal cations enter water through the natural geochemical route or from the industrial wastes. Their separation and removal can be achieved by adsorptive accumulation of the cations on a suitable adsorbent. In the present work, toxic Co(II) ions are removed from water by accumulating them on the surface of clay minerals. Clay adsorbents are obtained from kaolinite, montmorillonite, and their acid activated forms, and are characterized with the measurement of XRD patterns, specific surface area, and cation exchange capacity. The adsorption experiments are carried out in a batch process in environments of different pH, initial Co(II) concentration, amount of clay, interaction time, and temperature. Adsorption of Co(II) on the clays increases continuously from pH 1.0 to 8.0 after which adsorption could not be carried out due to the decreasing solubility of Co(II). Under appropriate conditions, the adsorption of Co(II) is very fast at low coverage approaching equilibrium within 240 min and the interactions are best described by second order kinetics. Langmuir monolayer capacity has been computed in the range of 11.2 to 29.7 mg/g and Co(II) accumulation has the order of acid‐activated montmorillonite>montmorillonite>acid activated kaolinite>kaolinite. Adsorption of Co(II) on kaolinite and acid‐activated kaolinite is endothermic driven by entropy increase but the same process follows exothermically on montmorillonite and acid‐activated montmorillonite supported by entropy decrease. In both cases, spontaneous adsorptive accumulation is ensured by favorable Gibbs energy decrease. It is found that acid activation enhances the adsorption capacity of kaolinite and montmorillonite.     

Zn(II) ion removal from aqueous solution by using a polyaniline composite

The aim of this research was to investigate the sorption characteristics of polyaniline/sawdust (PAn/SD) for the removal of Zn(II) ions from aqueous solutions. Batch sorption studies were carried out to determine the effect of initial concentration of the sorbate, agitation time, adsorbent dose, and pH on the removal of Zn(II). The sorptive removal was found to be strongly pH‐dependent. The experimental data fitted well to the Freundlich isotherm. The products were investigated in terms of morphology and chemical structure by using scanning electron microscopy and Fourier‐transform infrared spectroscopy, respectively. Also, PAn/SD was used for the removal of heavy metals from urban waste water. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Synthesis and characterization of starch‐g‐Poly(acrylic acid)/Organo‐Zeolite 4A superabsorbent composites with respect to their water‐holding capacities and nutrient‐release behavior

Novel superabsorbent composites were prepared using starch, acrylic acid, and organo‐zeolite 4A micropowder via aqueous solution graft copolymerization. The effects of organo‐zeolite 4A content on water absorbency were tested to determine the optimum conditions that ensure a high swelling ability. Under these conditions, the maximum swelling ability in distilled water was determined to be 511 g/g when the amount of organo‐zeolite 4A in the feed was 10 wt%. The prepared samples were characterized with Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscope (SEM). The SEM characterization of the samples indicated that the superabsorbent composites had more pores and water than zeolite‐free superabsorbents. The swelling capacities in distilled water, various salt solutions, and aqueous urea were studied. The on–off switching behavior and the release of urea from the loaded starch‐g‐ poly(acrylic acid)/organo‐zeolite 4A were also determined. The results indicated that the novel composite was responsive to salts and exhibited on–off switching behavior, as evidenced by reversible swelling and de‐swelling. In addition, the slow nutrient release makes this material suitable for many potential applications in the fields of agriculture and horticulture. POLYM. COMPOS., 38:1838–1848, 2017. © 2015 Society of Plastics Engineers     

A novel synthesis of reactive nano‐clay polyurethane and its physical and dyeing properties

This study is about polyurea prepolymer, which was synthesized from the extender (N‐(2‐hydroxyethyl) ethylene diamine, HEDA or ethylene diamine, EDA) with 4,4′‐diphenylmethane diisocyanate (MDI), as an intercalative agent to intercalate the organic modified montmorillonite clay. Then, it is further reacted with the polyurethane prepolymer, which is polymerized from the polytetramethylene glycol (PTMG) and MDI, to proceed the intercalative polymerization to form a polyurethane/clay nanocomposite polymer. The experimental parameters contain the use of polyurea intercalative prepolymer extender and also the contents of organo‐clay in the prepolymer etc. We expect to get better mechanical property and also to improve the dyeing properties of nano‐clay polyurethane. The polyurethane/clay polymer is synthesized using two‐step method: synthesizing the polyurethane prepolymer from PTMG and MDI and then extended with the polyurea prepolymer modified with the organo‐clay. Because the extender HEDA contains side chain of hydroxyl groups, the modified PU can further react with the reactive dye. From the experimental results of the fine structure (X‐ray and FT‐IR) and mechanical analysis, it is found that the intercalation is successfully achieved. Thedistance of interlayer spacing is manifestly enlarged. The mechanical properties are significantly improved as the content of organo‐clay is increased. Besides, although thedye up‐take is decreased with the increasing content oforgano‐clay, but the water‐resistant fastness is improved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Optimization of kinetic data for two‐stage batch adsorption of Pb(II) ions onto tripolyphosphate‐modified kaolinite clay

BACKGROUND: Most adsorption studies consider only the adsorption of pollutants onto low cost adsorbents without considering how equilibrium and kinetic data can be optimized for the proper design of adsorption systems. This study considers the optimization of kinetic data obtained for the removal of Pb(II) from aqueous solution by a tripolyphosphate modified kaolinite clay adsorbent. RESULTS: Modification of kaolinite clay with pentasodium tripolyphosphate increases its cation adsorption capacity (CEC) and specific surface area (SSA) from 7.81 to 78.9 meq (100 g)^?1 and 10.56 to 13.2 m² g^?1 respectively. X‐ray diffraction patterns for both unmodified and tripolyphosphate‐modified kaolinite clay suggest the modification is effective on the surface of the clay mineral. Kinetic data from the batch adsorption of Pb(II) onto the tripolyphosphate‐modified kaolinite clay adsorbent were optimized to a two‐stage batch adsorption of Pb(II) using the pseudo‐second‐order kinetic model. Mathematical model equations were developed to predict the minimum operating time for the adsorption of Pb(II). Results obtained suggest that increasing temperature and decreasing percentage Pb(II) removal by the adsorbent enhanced operating time of the adsorption process. The use of two‐stage batch adsorption reduces contact time to 6.7 min from 300 min in the single‐stage batch adsorption process for the adsorption of 2.5 m³ of 500 mg L^?1 Pb(II) under the same operating conditions. CONCLUSION: Results show the potential of a tripolyphosphate‐modified kaolinite clay for the adsorption of Pb(II) from aqueous solution and the improved efficiency of a two‐stage batch adsorption process for the adsorption of Pb(II) even at increased temperature. Copyright © 2009 Society of Chemical Industry     

Removal of Copper (II) Ions from Aqueous Solutions using Na‐mordenite

Abstract

The potential to remove copper (II) ions from aqueous solutions using Na‐mordenite, a common zeolite mineral, was thoroughly investigated. The effects of relevant parameters solution pH, adsorbent dose, ionic strength, and temperature on copper (II) adsorption capacity were examined. The sorption data followed the Langmuir, Freundlich, and Dubinin‐Radushkevich (D‐R) isotherms. The maximum sorption capacity was found to be 10.69 mg/g at pH 6, initial concentration of 40 mg/dm³, and temperature of 40°C. Different thermodynamic parameters viz., changes in standard free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰) have also been evaluated and the results show that the sorption process was spontaneous and endothermic in nature. The dynamics of the sorption process were studied and the values of rate constant of adsorption, rate constant of intraparticle diffusion were calculated. The activation energy (E_a) was found to be 11.25 kJ/mol in the present study, indicating a chemical sorption process involving weak interactions between sorbent and sorbate. The interaction between copper (II) ions and Na‐mordenite is mainly attributable to ion exchange. The sorption capacity increased with the increase of solution pH and the decrease of ionic strength and adsorbent dose. The Na‐mordenite can be used to separate copper (II) ions from aqueous solutions.     

Behaviors of Acrylamide/Itaconic Acid Hydrogels in Uptake of Uranyl Ions from Aqueous Solutions

Abstract

In this study, adsorptions of uranyl ions from two different aqueous uranyl solutions by acrylamide-itaconic acid hydrogels were investigated by a spectroscopic method. The hydrogels were prepared by irradiating with γ-radiation. In the experiment of uranyl ions adsorption, Type II adsorption was found. One gram of acrylamide-itaconic acid hydrogels sorbed 178–219 mg uranyl ions from the solutions of uranyl acetate, 42–76 mg uranyl ions from the aqueous solutions of uranyl nitrate, while acrylamide hydrogel did not sorb any uranyl ion. For the hydrogel containing 40 mg of itaconic acid and irradiated to 3.73 kGy, swelling of the hydrogels was observed in water (1660%), in the aqueous solution of uranyl acetate (730%), and in the aqueous solution of uranyl nitrate (580%). Diffusions of water onto hydrogels were a non-Fickian type of diffusion, whereas diffusions of uranyl ions were a Fickian type of diffusion.