Lavinia Lupa

Cs+ Removal from Aqueous Solutions through Adsorption onto Florisil® Impregnated with Trihexyl(tetradecyl)phosphonium Chloride

This research determined the adsorption performance of Florisil® impregnated with trihexyl(tetradecyl)phosphonium chloride (Cyphos IL-101) in the process of Cs+ removal from aqueous solutions. The obtained Florisil® impregnated with the studied ionic liquid was characterized through energy dispersive X-ray analysis and Fourier transform infrared spectroscopy in order to verify that the impregnation with the ionic liquid had occurred. The adsorption process has been investigated as a function of pH, solid:liquid ratio, adsorbate concentration, contact time and temperature. The isotherm data was well described by a Langmuir isotherm model. The maximum adsorption capacities of the Florisil® impregnated with the studied ionic liquid was found to be 3.086 mg Cs+/g of adsorbent. The results indicated that the adsorption fitted well with the pseudo-second order kinetic model.

Remediation of Rare Earth Element Pollutants by Sorption Process Using Organic Natural Sorbents

The effects of the sorption of environmental applications by various source materials of natural organic matter, i.e., bone powder, was examined. Sorption capacities and subsequent rare earth element retention characteristics of all metals tested were markedly increased by ionic task-specific. In this study, the abilities of three models’ isotherms widely were used for the equilibrium sorption data: Langmuir, Freundlich and Redlich-Peterson. For all studied metal ions the maximum adsorption capacity is close to those experimentally determined. The characteristic parameters for each isotherm and related coefficients of determination have been determined. The experimental data achieved excellent fits within the following isotherms in the order: Langmuir > Redlich-Peterson > Freundlich, based on their coefficient of determination values. The bone powder has developed higher adsorption performance in the removal process of Nd(III), Eu(III), La(III) from aqueous solutions than in the case of the removal process of Cs(I), Sr(II) and Tl(I) from aqueous solutions. The described relationships provide direct experimental evidence that the sorption-desorption properties of bone powder are closely related to their degree of the type of the metal. The results suggest a potential for obtaining efficient and cost-effective engineered natural organic sorbents for environmental applications.

Adsorption of As(III) Ions onto Iron-Containing Waste Sludge

The adsorption performance of a low-cost adsorbent (IS), viz. an iron-containing waste sludge arising during a hot-dip galvanizing process, towards the removal of As(III) ions from synthetic aqueous solutions and natural underground water was examined. The adsorption process was best described by the pseudo-second-order kinetic equation. The equilibrium adsorption data were well described by the Langmuir model. The value of the dimensional separation factor, RL, indicated favourable adsorption. The maximum adsorption capacity of IS was 625 μg As(III)/g. The variation in the extent of adsorption with temperature was used to evaluate the thermodynamic parameters for the adsorption process. The values of ΔH0 and ΔG0 obtained demonstrated that the adsorption process was exothermic and spontaneous. The studied material exhibited an excellent As(III) ion adsorption performance from both synthetic solutions and a natural water sample. Moreover, no secondary contaminated substances arise if the exhausted adsorbent is recycled (e.g. in glass applications).

Use of styrene–divinylbenzene grafted with aminoethylaminomethyl groups and various ionic liquids in the removal process of thallium and strontium

Abstract This work reports the adsorption of thallium and strontium from aqueous solutions onto styrene-divinylbenzene grafted with aminoethylaminomethyl groups which was impregnated with various ionic liquids [trihexyltetradecylphosphonium chloride ionic liquid – (Cyphos IL-101); 1-octyl-3-methylimidazolium tetrafluoroborate – (OmimBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate – (BmimPF6)]. The impregnation of the solid support with the studied ionic liquids was realized through ultrasonication method. The obtained impregnated materials have been subjected to Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Their adsorption performance in the removal process of thallium and strontium from aqueous solutions was studied as a function of the initial concentration of metal ions. Adsorption isotherms like Langmuir, Freundlich, Dubinin–Radushkevich (D–R) and Temkin were used to analyze the equilibrium data at different concentrations. The studied materials showed a better adsorption performance in the removal process of strontium ions compared to the adsorption performance obtained in case of thallium ions removal process. From the studied ionic liquids, (OmimBF4) presented the most efficient performance for the removal of the studied metal ions.

Studies Regarding As(V) Adsorption from Underground Water by Fe-XAD8-DEHPA Impregnated Resin. Equilibrium Sorption and Fixed-Bed Column Tests

The characteristics of arsenic adsorption onto Fe-XAD8-DEHPA resin were studied on the laboratory scale using aqueous solutions and natural underground waters. Amberlite XAD8 resin was impregnated with di(2-ethylhexyl) phosphoric acid (DEHPA) via the dry method of impregnation. Fe(III) ions were loaded onto the impregnated resin by exploiting the high affinity of arsenic towards iron. The studies were conducted by both in contact and continuous modes. Kinetics data revealed that the removal of arsenic by Fe-XAD8-DEHPA resin is a pseudo-second-order reaction. The equilibrium data were modelled with Freundlich Langmuir and Dubinin Radushkevich (D-R) isotherms and it was found that the Freundlich model give the poorest correlation coefficient. The maximum adsorption capacity obtained from the Langmuir isotherm is 22.6 µg As(V)/g of Fe-XAD8-DEHPA resin. The mean free energy of adsorption was found in this study to be 7.2 kJ/mol and the ΔG° value negative (−9.2 kJ/mol). This indicates that the sorption process is exothermal, spontaneous and physical in nature. The studied Fe-XAD8-DEHPA resin showed excellent arsenic removal performance by sorption, both from synthetic solution and the natural water sample, and could be regenerated simply by using aqueous NaOH or HCl solutions.

Studies Regarding the Florisil Impregnation with Ionic Liquid through Ultrasonication

The paper presents the studies regarding the impregnation of Florisil with Cyphos IL-101 using a new method of impregnation instead of the classic methods: the ultrasonication. In order to determine the efficiency of the ultrasonication methods of impregnation, the work conditions were varied, and the obtained supported ionic liquids were characterized through scanning electron microscopy (SEM), energy dispersive XRay analysis (EDX) and FTIR- Fourier transform infrared spectroscopy. From the experimental data was observed that only the amplitude of ultrasonication had a significant influence onto the impregnation process efficiency. The impregnated material obtained in the optimum conditions showed good adsorption performance in the removal process of Cs + developing a maximum adsorption capacity of 2.95 mg/g. Index Terms—Ultrasonication, impregnation, ionic liquid, Cs + adsorption. The impregnation of a solid support, with various functionalized groups in order to enhance its adsorbent properties and selectivity, is a new trend in the removal process of various metals ions from aqueous solutions. In this way were developed four methods for the impregnation of the desired extractant into a solid support: the dry method, wet method, modifier addition method and dynamic column method (1)-(6). Instead of the traditional methods mentioned in the specialty literature for the impregnation of a solid support, we studied in this paper, the impregnation through ultrasonication. Due to their superior characteristic compared to organic extractants, the use of ionic liquids reached a higher attention, in special in the removal process of radionuclides from aqueous solutions (7)-(11). The immobilization of the ionic liquids in a suitable solid support prevents the drawbacks of the liquid-liquid extraction like: the loss of the ionic liquid in water and a possible ion-exchange occurrence between the metal ion and the ionic-liquids cation (12)-(15). Therefore the studies regarding the ultrasonication method of impregnation were realized for the system Cyphos IL-101 onto Florisil. We focused on this ionic liquid due to its commercial availability and low price, and also because in our

Synthesis, characterizations and Pb(II) sorption properties of cobalt phosphonate materials

Abstract Due to the large amount of industrial activity during the last century, heavy metal contamination of the environment has become a serious problem. Therefore, it is important to develop new and efficient methods of heavy metals removal from aqueous solutions. In this respect, three phosphonate metal organic frameworks were obtained in our labs by the reaction of divalent inorganic salt (CoSO4·7H2O), phosphonic acid [phosphonoacetic (CP), N,N-bis(phosphonomethyl)glycine (Gly) and vinylphosphonic (VP)] in hydrothermal conditions. The synthesized compounds were characterized by FTIR, X-Ray crystallography scanning electron microscopy and thermogravimetric analysis. These materials were used in the removal process of lead ions from aqueous solutions in order to determine the possibilities of their use as adsorbent materials. The effect of pH, lead initial concentrations and contact time upon the adsorption properties were investigated. From the experimental data it can be observed that the Co-Gly material developed a higher adsorption capacity for lead metal ions than the Co-VP and Co-CP, increasing following Co-CP

Phosphonium grafted styrene–divinylbenzene resins impregnated with iron(III) and crown ethers for arsenic removal

Abstract In the present work a polymer with phosphonium pendant groups impregnated with crown ether (dibenzo-18-crown-6) and loaded with iron ions was investigated for arsenic removal through adsorption from aqueous solutions. The impregnated polymer was loaded with iron ions due to the high affinity of arsenic to it. The characterization of the surface modification of the obtained new adsorbent material was performed on the basis of energy dispersive X-ray analysis; scanning electron microscopy and Fourier transform infrared spectroscopy. The arsenic adsorption was investigated, including effect of pH, arsenic initial concentration, the shaking time and temperature. The effect of the pH was examined over the range 2–11. The adsorption of As(V) increases with pH increasing reaching a maximum at pH higher than 8. Equilibrium, kinetic and thermodynamic studies were carried out to study the adsorption performance of the obtained material in the removal process of arsenic from aqueous solutions. For the studied materials the equilibrium data closely fitted Langmuir model and was achieved a maximum adsorption capacity of 32.6 μg As(V)/g of material. The pseudo-second order kinetic model is suitable for describing the adsorption system. The obtained results show that the studied adsorbent can be used with efficiency in the arsenic removal from underground water even from low influent arsenic concentration solutions.

Thallium removal through adsorption onto ionic liquid-impregnated solid support: influence of the impregnation conditions

Abstract This article presents the use of ionic liquid in the removal process of thallium ions using solid–liquid extraction by impregnating ionic liquid (1-n-hexyl-3-methylimidazolium chloride) onto an inorganic solid support (Florisil). The influence of impregnation was studied in order to improve the adsorption capacity of the material obtained. Impregnation was realized with the help of a rotavapor. Stirring time and temperature used were varied. Ionic liquid-impregnated materials obtained at different conditions of impregnation were characterized using scanning electron microscopy, energy-dispersive X-ray analysis, and Fourier transform infrared spectroscopy. In order to determine the most efficient adsorbent material, the materials obtained were used in the removal process of thallium ions from aqueous solutions, varying the initial concentration of thallium ions and the stirring time used in the adsorption process. It was observed that for the improving the adsorption capacity of the obtained ionic liquid-impregnated material, it is not necessary to increase the stirring time of the impregnation process but to increase the temperature. The experimental data obtained in the adsorption process were fitted with the Langmuir isotherm. Adsorption of thallium ions onto Florisil impregnated with 1-n-hexyl-3-methylimidazolium chloride ionic liquid corresponds to a pseudo-second-order kinetic model.

Thermal and spectroscopic analysis of Co(II)–Fe(III) polyglyoxylate obtained through the reaction of ethylene glycol with metal nitrates

The synthesis and thermal and spectroscopic studies of a new CoII–FeIII heteropolynuclear coordination compound are presented. The in situ oxidation product of ethylene glycol plays the role of ligand. Under specific working conditions, the reaction of ethylene glycol with FeIII and CoII nitrates in dilute acid solutions occurs with the oxidation of the former to glyoxylic acid, coordinated to the CoII and FeIII cations as glyoxylate anion (C2H2O42−), with simultaneous isolation of the heteropolynuclear coordination compound. In order to separate and identify the ligand, the synthesized coordination compound, having the composition formula Co4Fe10(L)9(OH)20(H2O)32·14H2O, where L is the glyoxylate anion, has been treated with R–H cationite (Purolite C-100). After the retention of the metal cations, the resulting glyoxylic acid was confirmed by measuring its physical constants, by specific reactions and through spectroscopic methods. The synthesized coordination compound was characterized by physical–chemical analysis, electronic spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and thermal analysis. Cobalt ferrite impurified with ferric oxide was obtained following the thermal decomposition of CoII–FeIII polyhydroxoglyoxylate. The oxides obtained through thermolysis were studied by FTIR, XRD, scanning electron microscopy (SEM) and elemental analysis.