Ammonium Removal from Aqueous Solutions Using Sulfonated Polystyrene Grafted Silica Gel Sorbent

Abstract

A novel non‐swelling sulfonated polystyrene grafted silica gel sorbent was synthesized for use in ammonium removal from aqueous solutions. The ammonium sorption equilibrium isotherm was determined at 298 K by batch experiments, and the effects of flow rate and initial solution pH on the sorption were measured by breakthrough experiments in a laboratory scale fixed bed column. The equilibrium data were fitted to the Langmuir, Freundlich, Langmuir‐Freundlich, and Toth isotherm models. The breakthrough data were fitted to a dynamic isothermal mathematical model with an axial dispersion term to obtain the effective diffusion coefficient. The sorption rate of the sulfonated polystyrene grafted silica gel is higher than that of ion‐exchange resins, which enables shorter cycle times in column processes for the grafted silica gel.     

Arsenate and Dichromate Removal Efficiency of a New Calix[4]arene Impregnated Resin

This article highlights a newly synthesized 5,11,17,23-tetra-tert.butyl-25,26,27,28-tetrakis(hydrazidecarbonylmethoxy)-calix[4]arene (3) impregnated resin 4 and it's sorption ability for the removal of selected oxoanions, i.e., (arsenate and dichromate) from aqueous environment. Resin 4 was characterized by using FT-IR spectroscopy, scanning electron microscope (SEM), elemental, and thermogravimetic (TGA) analyses techniques. Sorption study was carried out through static and dynamic methods with continuous flow operation to evaluate the potency of resin 4 under various conditions. Several parameters, such as effect of sorbent dosage, contact time, pH, and initial concentration were optimized through batch experiments. Results justify that % sorption of these oxoanions is highly dependent on pH of the solution. Equilibrium was achieved in 45 min, while sorption efficiency of resin 4 can be better explained by Langmuir and Temkin isotherm models. Furthermore, kinetically both oxoanions follow pseudo second order model. Additionally, sorption of arsenate more appropriately could be explained by Moris-Weber diffusion kinetic model. For the dynamic method, Thomas model was used to calculate the kinetic coefficient (k_TH) and maximum sorption capacity (q_o) of resin 4 which are 3.84 and 5.94 ml mg^?1 min^?1 and 0.185, 0.160 mg g^?1 for As (V) and Cr (VI) respectively. Furthermore, resin 4 has been found as potential sorbent for removal of these oxoanions from contaminated surface water samples.     

Retention,Thermodynamics and Adsorption Profile of Th(IV) Ions onto 1‐(2‐Pyridylazo)‐2‐Naphthol (PAN) Loaded Polyurethane Foam from Acetate Media and its Separation from Rare Earths

Abstract

The sorption behavior of 2.7×10^?5 M solution of Th(IV) ions on 1‐(2‐pyridylazo)‐2‐naphthol (PAN) loaded polyurethane foam (PUF) has been investigated. The quantitative sorption was occurred from pH 6 to 9 from acetate buffer solutions. The sorption conditions were optimized with respect to pH, shaking time, and weight of sorbent. The sorption data followed the Freundlich, Langmuir, and Dubinin‐Radushkevich (D‐R) isotherms very successfully at low metal ions concentration. The Freundlich isotherm constant (1/n) is estimated to be 0.22±0.01, and reflects the surface heterogeneity of the sorbent. The Langmuir isotherm gives the maximum monolayer coverage is to be 8.61×10^?6 mol g^?1. The sorption free energy of the D‐R isotherm was 17.85±0.33 kJ mol^?1, suggesting chemisorption involving chemical bonding was responsible for the adsorption process. The numerical values of thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) indicate that sorption is endothermic, entropy driven, and spontaneous in nature. The adsorption free energy (ΔG_ads) and effective free energy (ΔG_eff) are also evaluated and discussed. The effect of different anions on the sorption of Th(IV) ions onto PAN loaded PUF was studied. The possible sorption mechanism on the basis of experimental finding was discussed. A new separation procedure of Th(IV) from synthetic rare earth mixture using batch, column chromatography, and squeezing techniques were reported.     

Biosorption of Naphthalene from Refinery Simulated Waste-Water on Blank Alginate Beads and Immobilized Dead Algal Cells

Abstract

The potential use of blank alginate beads and immobilized dead algal cells for the removal of naphthalene from aqueous solutions was investigated in this study. The effects of contact time, solution pH, and naphthalene concentration on the sorption of naphthalene on blank alginate beads or immobilized dead algal cells were studied. The effect of the presence of other pollutants on the sorption of naphthalene on immobilized dead algal cells was also studied.

Batch adsorption experiments showed that the removal of naphthalene on both sorbents was pH dependent and significant removal of naphthalene was obtained at pH 4. Dynamic sorption experiments revealed that the biosorption of naphthalene on either sorbent was rapid where the equilibrium uptake occurred within 10 minutes, and the biosorption of naphthalene on either sorbent followed the pseudo-second order kinetics. Analysis of the equilibrium sorption data showed that naphthalene sorption on either sorbent could be fitted to the Langmuir, Freundlich, and Dubinin-Radushkevich (D–R) isotherm equations. Competitive biosorption experiments showed that biosorption of naphthalene on immobilized dead algal cells was adversely affected by the presence of either heavy metals such as copper and nickel, and chelating agents such as citric acid.     

Determination of Microbial Sorption Isotherms from Column Experiments

Abstract

Microbial sorption isotherms cannot be obtained using the traditional batch methods owing to the difficulty of distinguishing between reversible and irreversible sorption. In this research, we investigated microbial sorption isotherms of Pseudomonas fluorescens, Pseudomonas putida, and Pseudomonas sp. on an alluvial loam from the Central Oklahoma Aquifer (COA) using column experiments. All these three bacterial strains displayed a concave isotherm on COA, which can be described by the Freundlich sorption isotherms. We explained the concave‐shaped microbial sorption isotherms using the surface thermodynamic theory. In this study, we also investigated the impact of transport velocity on the microbial breakthrough curves. We found that the same bacterial strain had the same sorption isotherms but different deposition coefficient at different flow rates. The high solid to solution ratio of column experiments is close to that which is encountered in the natural systems, which makes this method a useful tool for guidance of in‐situ bioremediation.     

Modification of Langmuir model for simulating initial pH and temperature effects on sorption process

ABSTRACT

The present study modifies the sorption isotherm for simulating the influences of initial pH and temperature variations on the cadmium sorption from contaminated water using waste foundry sand based on Langmuir, Freundlich, and Temkin models. Results proved that the Langmuir expression is able to adopt these effects by relating sorption capacity and affinity constants with pH and temperature of aqueous solution through exponential relationships (determination coefficient = 0.9375). The present model is assumed that the sorption process occurs through acidic functional groups and this is consistent with FTIR outputs. Interaction of cadmium/WFS is found to be exothermic by thermodynamic analysis.     

Sorption of uranyl ions from aqueous solutions using crosslinked maleic anhydride‐octene‐styrene terpolymer

Maleic anhydride‐octene‐styrene terpolymer has been modified with allylic alcohol and methylmethacrylate to prepare a new crosslinked functional polymer sorbent. The sorption behaviors of uranyl ions on the optimum sorption conditions were determined. The synthesized crosslinked polymer sorbent has a network structure and contains carboxylic acid, carbonyl, and ester groups, all of which are capable of interacting with metal ions. The maximum experimental sorption capacity of the sorbent for uranyl ions has been measured as 1.25 mmol g^?1. Langmuir and Freundlich isotherm constants and correlation coefficients for the present system have been calculated and compared. Uranyl ions are desorbed from the sorbent by treatment with hydrocholric and nitric acids at various concentrations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Uptake of Traces of Selenite by Manganese Dioxide from Aqueous Solutions

Abstract

Sorption of selenite onto manganese dioxide has been investigated with respect to shaking time, concentration of sorbent and sorbate, nature of electrolyte, and influence of cations and anions. The sorption of other metal ions has been studied using optimal conditions selected for maximum sorption of selenite. The surface area, average pore diameter, porosity, and solid phase density of the sorbent have been measured. The sorption data followed only the Dubinin–Radushkevich (D–R) sorption isotherm among all the isotherms tested. The sorption capacity of 51.2 nmol·g^?1 and a constant β related to sorption energy have been estimated to be ?0.007521 mol²·kJ^?2. The sorption energy is found to be 8.15 kJ·mol^?1. The kinetics of the sorption follows the Lagergren equation in the initial stages. The first-order rate constant, k′, was evaluated to be 0.498 min^?1 and of intraparticle diffusion rate 3.06 × 10^?5 mol·g^?1·min^?2. Among all the anions and cations tested, only carbonate, Fe(III), and citrate reduced the sorption significantly. The sorption data for other metal ions showed that Te(IV) can be separated from ions showing higher degree of sorption; especially Se(IV), As(III), Sb(V), and Eu(III). It can be concluded that manganese dioxide may be used for the separation of certain metal ions, their preconcentration from very dilute solutions, and for decontamination and treatment of industrial effluents.     

Removal of Mercury (II) Ions from Aqueous Solutions by the Polyacrylamidoxime Chelating Fiber

Abstract

A fibrous sorbent containing chelating amidoxime groups –C(NH₂)?NOH prepared from the Romanian commercial polyacrylonitrile ‐based fiber Melana was used for the removal of Hg²⁺ from aqueous solutions. The optimum conditions for the Hg²⁺ uptake were developed with respect to initial pH of solution, nature of anions, equilibration time, concentration of Hg²⁺, and temperature. The sorption was described quantitatively by fitting the equilibrium data to the Langmuir isotherm. The Langmuir parameters and thermodynamic quantities (ΔG, ΔH, ΔS) were calculated. The chelation mechanism of Hg²⁺ uptake on polyacrylamidoxime fiber was confirmed by IR spectroscopy. The experimental results point out the possibility of polyacrylamidoxime fiber to reversibly bind Hg²⁺ from wastewaters.     

Bestimmung der sorptionsisothermen lösungsmittelfeuchter sorbentien nach der durchströmungsmethodeDetermination of sorption isotherms of solvent wetted sorbents by the through flowing method

The sorption isotherm is defined as the equilibrium moisture content of a sorbent as a function of the relative humidity at constant temperature. It is a measure for the hygroscopic behavior of the sorbent. In this work a simple and reliable method for the determination of sorption isotherms of solvent wetted sorbents is described. The sorption isotherm is determined by passing a nitrogen stream with a given relative humidity through a U-tube filled with the sorbent (through flowing method). The sorption isotherms of gas concrete, brick and clay for the sorbates isopropyl alcohol and water at 20 °C were measured. The reliability of the method was tested by comparing it with two other methods.     

Bestimmung der sorptionsisothermen lösungsmittelfeuchter sorbentien nach der durchströmungsmethode

The sorption isotherm is defined as the equilibrium moisture content of a sorbent as a function of the relative humidity at constant temperature. It is a measure for the hygroscopic behavior of the sorbent. In this work a simple and reliable method for the determination of sorption isotherms of solvent wetted sorbents is described. The sorption isotherm is determined by passing a nitrogen stream with a given relative humidity through a U-tube filled with the sorbent (through flowing method). The sorption isotherms of gas concrete, brick and clay for the sorbates isopropyl alcohol and water at 20 °C were measured. The reliability of the method was tested by comparing it with two other methods.     

Separation and Recovery of Uranium from Wastewater Using Sorbent Functionalized with Hydroxamic Acid

A newly developed hydroxamic acids functionalized acrylic based solid phase sorbent, named as poly-acryl hydroxamic acid (PHOA) is used as an extractant for the recovery of uranium from nuclear waste solution. Various parameters such as sorbent solubility in different medium, effect of various cations on U(VI) sorption, desorption performance of different eluents with respect to U(VI) sorption has been investigated in detail. U(VI) sorption behaviors of the sorbent were studied in different concentration of competitive ions such as Mg²⁺, Fe³⁺, and NO₃^? and it was found that the sorbent was capable of removing the U(VI) efficiently in the presence of high concentration of these ions.     

Simplified Predictions of Breakthrough Fronts for Constant-Pattern Adsorption and Ion Exchange

Abstract

The loading cycle of many (perhaps most) commercial adsorption and ion exchange operations involves a favorable isotherm. Concentration fronts for favorable isotherms approach a constant pattern for long bed lengths, and most industrial adsorption and ion exchange operations use sufficiently deep beds that the constant-pattern conditions are approached. Once a constant pattern is established, the region around the front can be analyzed using conventional methods developed for continuous absorption/stripping operations, but the location of the feed and withdrawal points must be assumed to move down the bed at the same rate at which the front moves. Using this approach, the constant-pattern front can be calculated for any shape of constant-pattern isotherm. The dimensionless distance in the bed is expressed in terms of transfer units, and the shape of the front can be evaluated graphically even when the relations can not be integrated analytically. This procedure is illustrated for binary ion exchange isotherms. In the simplest cases, exchange of ions with like charge, the integration can be performed analytically. For other cases, numerical and graphical solutions are illustrated.     

Preconcentration and determination of Cu (II) from aqueous samples using functionalized sawdust and comparison with synthetic functionalized sorbents

The efficiency of indigenous functionalized sorbent (sawdust functionalized with polyaniline) was compared with synthetic functionalized sorbents (Dowex functionalized with 8-hydroxyquinoline (Dowex-8HQ) and α-nitroso-β-naphthol (Dowex-αNβN)) for preconcentration and determination of Cu (II) from aqueous samples. The synthetic functionalized sorbents and indigenous functionalized sorbent were characterized using FTIR. Different parameters like pH, equilibration time and sample volume were investigated for maximum sorption of Cu (II). Isotherm studies showed that the sorption data fitted well into Langmuir isotherm for the sawdust functionalized with polyaniline. Freundlich isotherm was followed for Dowex-8HQ and Dowex-αNβN. Four types of kinetic equations were applied to the data, and it was observed that sorption of Cu (II) followed second-order kinetics. Thermodynamically, the sorption of Cu (II) on these three sorbents was found to be exothermic and spontaneous. For maximum recovery of Cu (II) from loaded sorbents, different parameters like shaking time, eluent type, concentration and volume were investigated, and 89% Cu (II) was recovered from loaded sawdust functionalized with polyaniline and Dowex-8HQ. The interference studies showed the selectivity of sawdust functionalized with polyaniline for Cu (II) in comparison to synthetic functionalized sorbents. Thus, Cu (II) can be easily removed from aqueous samples in the presence of foreign ions.     

Removal of Lead from Water Samples by Sorption onto Powdered Limestone

Abstract

Bench scale batch adsorption experiments were performed, aiming at the removal of the Pb²⁺ ions from aqueous solutions and water samples by fine powdered Limestone (LS) as an effective inorganic sorbent, which is inexpensive, widespread, and cheap. The main parameters (i.e., solution pH, sorbent and lead concentrations, stirring times, and temperature) influencing the sorption process, in addition to the effect of some foreign ions, were investigated. The results obtained stated that the sorption of Pb²⁺ ions onto LS is well described by Freundlich model and deviated from that of Langmuir over the concentration range studied. Under the optimum experimental conditions employed, the removal of ca. 100% of Pb²⁺ ions was attained. The procedure was successfully applied to the removal of lead from aqueous and different natural water samples. Moreover, the adsorption mechanism is suggested.     

Sorption Behavior of In(III) Ions onto Cation-Exchange Carboxylic Resin in Aqueous Solutions: Batch and Column Studies

Indium and its compounds have numerous industrial applications in the manufacture of liquid crystal displays and semiconductors. They are considered hazardous substances. This article reports the research into the recovery of In(III) from aqueous solution by sorption. Cation-exchange carboxylic resin (D155 resin) was used as a sorbent for indium(III) ions extraction in this research. The factors of parameters, such as pH, kinetics, temperature and sorption isotherm, and column experiment were investigated. In batch system, D155 resin exhibited the highest In(III) ion uptake as 279 mg/g at 298 K with a pH value 5.00. The sorption data matched the Langmuir isotherms very well. The thermodynamic parameter ΔG was negative, and this result indicated that the sorption of In(III) ions on D155 resin was spontaneous. Furthermore, the positive value of ΔH showed that the sorption was endothermic in nature. In(III) ions can be eluted with 0.5 mol/L HCl solution. The Thomas model was applied to experimental column data to determine the characteristic parameters of the column which is useful for process design.     

Parametric Analysis of the Propagation of Uncertainties in Sorption Measurements Made with a Pressure-Decay Apparatus

ABSTRACT

The general formulation for the propagation of statistical uncertainties is presented for the dual volume pressure decay method of measuring sorption capacity in polymers and other solid sorbents. These relationships are then used to determine the percent uncertainty in the calculated sorption coefficient (or capacity) with respect to ranges of values for several parameters that relate to choices in equipment design and operating conditions, and properties of the sorbent. These parameters include the ratio of system volumes, the relative volume of the sorbent, the accuracy and resolution of the sensors, the operating pressure, and the nominal sorption capacity of the sorbent. This analysis provides guidance for determining the uncertainty in the calculated sorption capacity and minimizing that uncertainty within whatever logistical and resource constraints may exist.     

Sorption of textile dye from aqueous solution by macroporous amino‐functionalized copolymer

Macroporous poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME) was synthesized by suspension copolymerization and functionalized with diethylene triamine (PGME‐deta). The effect of pH, contact time, and sorbent mass on sorption efficiency of initial and functionalized copolymer sample for removal of Acid Orange 10 dye from aqueous solutions was studied. No dye was sorbed by nonfunctionalized copolymer, indicating that sorption of Acid Orange 10 by PGME‐deta is specific, through amino groups. The isotherm data are best fitted by Langmuir model, indicating homogeneous distribution of active sites in PGME‐deta as well as monolayer sorption. Sorption kinetics study showed that the sorption of Acid Orange 10 by PGME‐deta obeys the pseudo‐second‐order kinetic model. It was shown that PGME‐deta selectively sorbs Acid Orange 10 from binary solution with Bezaktiv Rot reactive dye. The comparison of sorption characteristics of PGME‐deta with activated carbon showed that this functionalized copolymer might be used as an alternative sorbent for textile dyes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Extraction and Adsorption Behavior of Co(II) on HTTA-Impregnated Polyurethane Foam

Abstract

The batch extraction of Co(II) from aqueous solutions with open cell polyethertype HTTA-loaded polyurethane (PU) foam has been studied using a radiotracer technique. The effect of pH, shaking time, and loading capacity has been investigated. The membrane properties of loaded PU foam sorbent offer unique advantage of adsorption. The fundamental studies of adsorption show that the classical Freundlich and Langmuir isotherms are followed in the entire concentration range of a 10^?5 to 10^?2 M solution of cobalt. The sorption mean free energy from the Dubinin-Radushkevich isotherm is found to be 13.8 kJ·mol^?1 and the loading capacity 4.44 mg·g^?1, suggesting that the ion-exchange or chemisorption mechanism operates. The kinetic parameters of adsorption also support a chemisorption mechanism and the first-order rate law. The rate constants and activation energies of sorption and desorption have been evaluated. The thermodynamic function of adsorption of ΔH, ΔS, ΔG, and equilibrium constant K _c have been calculated. The process of adsorption is established to be endothermic and chemisorption, stabilized through thermodynamic functions.     

Preparation and sorption studies of microsphere copolymers containing β-cyclodextrin and poly(acrylic acid)

Microsphere polymeric materials containing β-cyclodextrin (β-CD) and poly(acrylic acid) (PAA) with tunable morphologies were prepared in order to improve their sorption characteristics in aqueous solution. The microsphere polymeric materials were prepared using a (water/oil) micro-emulsion-evaporation technique to condense β-cyclodextrin (β-CD) with PAA at various comonomer ratios and mixing speeds. The β-CD microsphere copolymers were characterized using FTIR, TGA, DSC, SEM, elemental (C and H) microanalyses, and solid state ¹³C-NMR spectroscopy. The sorption properties of the polymeric materials at 295 K in aqueous solution containing p-nitrophenol (PNP) were studied using a dye-based method with UV–Vis spectrophotometry at pH 4.6 and 10.3. The sorption isotherms of copolymer/PNP systems were evaluated with various isotherm models (e.g., Langmuir, BET, Freundlich, and Sips). The Sips isotherm showed the best overall agreement with the experimental results and the sorption parameters provided estimates of the sorbent surface area (12.0–331 m²/g) and the sorption capacity (Q_m = 0.359–2.20 mmol/g at pH = 4.6; Q_m = 0.070–0.191 mmol/g at pH = 10.3) for the microsphere copolymer/PNP systems in aqueous solution. The nitrogen adsorption properties of the microporous copolymers in the solid state were obtained at 77K with BET surface areas ranging from 0.275 to 4.47 m²/g. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012