Preconcentration and Determination of Pb (II) in Aqueous Samples using Functionalized Dowex 1X8

Synthetic resin Dowex 1X8 was functionalized with α-Nitroso β-Naphthol (Dowex-αNβN) and with 8-Hydroxy Quinoline (Dowex-8HQ) to form chelating resin. The resultant chelating resins were characterized using scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The efficiency of these resins for the removal/preconcentration of Pb (II) from aqueous samples was evaluated. Optimum conditions of pH, time of equilibrium, and sample volume were investigated for maximum retention of Pb (II) from aqueous solutions. At optimum conditions, 100% adsorption was observed for the functionalized resins. Both Freundlich and Langmuir isotherms were applied to the adsorption data and it was observed that data fits well to Langmuir isotherm. Various parameters such as shaking time, type, and concentration of eluents were investigated for the recovery of Pb (II) from the chelating resins. For Dowex-αNβN and Dowex-8HQ, 100% recovery with a preconcentration factor of 100 was achieved with 0.5 and 2 M HCl, respectively. The selectivity and specificity of the functionalized resins was also evaluated by studying the effect of various foreign ions and the results have been compared with the unmodified Dowex.     

Comparison of several polymeric sorbents for selective boron removal from reverse osmosis permeate

Fibrous sorbents based on polypropylene and viscose fibers grafted with styrene or glycidyl methacrylate and functionalized with N-methylglucamine were compared with classical polystyrene/DVB bead sorbent with N-methylglucamine functional group. Tests were carried out in dynamic column mode. Model solution of reverse osmosis permeate containing 1.5 mg/L of boron was pumped through 5 mL of sorbent packed in glass column. Fibrous sorbents showed much faster sorption kinetics than bead sorbent, tolerating high specific flow-rates. Compared to bead sorbent, boron regeneration profiles of fibrous sorbents were narrower and they could be successfully regenerated with more diluted hydrochloric acid.     

Silica functionalized by pyridinecarboximidamides as a novel sorbent of heavy metals ions

ABSTRACT

Two novel sorbents, obtained as a result of surface modification of silica gel for the Cu(II), Co(II) and Ni(II) removal from aqueous solutions were proposed. For the modification, 3-chloropropyltrimethoxysilane, N’-hydroxy-N,N-dioctylpyridine-3-carboximidamide and N’-hydroxy-N,N-dioctylpyridine-4-carboximidamides were used. A series of basic tests on the sorption of Cu(II), Co(II) and Ni(II) were carried out and the presented results indicated that the novel sorbents were able to remove all tested metals ions from the aqueous solutions, and the removal efficiency was dependent on the functionalised agent structure, dosage, metal ions concentration and pH. The Langmuir model also assumed that a monolayer sorption occurred.     

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     

Copper Sorption from Aqueous Solutions by Plasma Modified Polyacrylonitrile Beads

Summary The adsorption of Cu(II) ions from aqueous solutions on acrylonitrile(AN) copolymer sorbents has been studied. Porous sorbents from acrylonitrile copolymer-90.6% acrylonitrile (AN), 8.1% methylmethacrylate (MMA) and 1.4% 2-acrylamido-methylpropensylfonic acid (AMPSA) have been prepared and modified by ammonia, air and ethylenediamine plasma. Fourteen types of sorbents have been obtained changing plasma agent and plasma vacuum. The Cu(II) ions uptake has been studied and the sorbent with best sorption characteristics determined. The best sorption uptake has been achieved for the modified sorbent obtained at ethylenediamine plasma modification under 5 Pa plasma vacuum (PAN1-1.20 mgeq/g). Effect of sorbents regeneration after different elution cycles has also been investigated . The sorbents showed high effectiveness of regeneration towards Cu(II) ions, which was above 50% after the IV cycle of elution.     

Soybean hull functionalized by phosphoric acid for sorption of copper from aqueous solution

One kind of potentially biodegradable cationic sorbent, which bears hydroxyl groups of phosphoric acid as its functional groups, with high sorption capacity of copper was prepared by thermochemically esterifying phosphoric acid (PA) onto soybean hull. Sorption of Cu(II) from aqueous solution onto modified soybean hull (MSH) was investigated in a batch system. The sorption experiments were performed under various conditions such as different initial pH, copper concentration, MSH dosage, and contact time. The maximum copper sorption was obtained when initial solution pH≥3.5. The isothermal data of copper sorption fitted the Langmuir model and the sorption process could be described by the pseudo-first-order kinetic model. The maximum sorption capacity (Q _m ) of MSH for Cu(II) was 31.55 mg/g. For 100 mg/l of Cu(II) solution, a sorption ratio above 91% could be achieved by 5.0 g/l of MSH. The equilibrium of Cu(II) sorption was reached within 50 min. The foreign cation and chelator in Cu(II) solution caused decline of Cu(II) sorption.     

Adsorption of lead and copper on modified polyacrylonitrile bead

Porous sorbents were prepared from copolymer of acrylonitrile‐methylmethacrylate‐2‐acrylamidomethylpropensulfonic acid and copolymer of acrylonitrile with vinylimidazol. The sorbent obtained from the former copolymer was modified with hydroxylamine, sodium hydroxide, and hydrazinehydrochloride under optimal conditions to obtain amidooxyme, carboxylic, and hydrazide groups. These functional groups introduced in the modified sorbent and the imidazol group in the sorbent of acrylonitrile and vinylimidazol showed high ability to form complexes with heavy metals. The adsorption properties of the porous chelate‐forming sorbents obtained were studied with Pb(II) and Cu(II) ions. The order of the polymer sorbents toward sorption of Pb(II) and Cu(II) ions was determined. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 283–288, 2001     

Iminodiacetic acid‐containing polymer brushes grafted onto silica gel for preconcentration and determination of copper(II) in environmental samples

Silica gel has been modified by silylation with 3‐mercaptopropyltrimethoxysilane followed by graft polymerization of dimethylacrylamide and (N,N‐bis‐carboxymethyl)amino‐3‐allylglycerol‐co‐dimethylacrylamide, synthesized via the reaction of allyl glycidyl ether with iminodiacetic acid. The sorbent, poly(AGE/IDA‐co‐DMAA)‐grafted silica gel, has been characterized by FTIR, elemental analysis, thermogravimetric analysis (TGA), FT‐Raman, and scanning electron microscopy and studied for the preconcentration and determination of trace amounts of Cu(II) ion in environmental water samples. The optimum pH value for quantitative sorption of Cu(II) in batch mode was 5.5 and desorption was achieved, using 0.5 mol L^?1 nitric acid. The sorption capacity of functionalized sorbent is 32.3 mg g^?1. The chelating sorbent was reused for 15 sorption–desorption cycles without any significant change in sorption capacity. The profile of copper uptake by the sorbent reflected good accessibility of the chelating sites in the poly(AGE/IDA‐co‐DMAA)‐grafted silica gel. Scatchard analysis demonstrated homogeneous nature of binding sites. The equilibrium adsorption data of Cu(II) on modified sorbent were analyzed by Langmuir, Freundlich, Temkin, and Redlich–Peterson models. Based on equilibrium adsorption data, the Langmuir, Freundlich, and Temkin constants were determined as 0.0665, 4.26, and 8.34, respectively, at pH 5.5 and 20°C. Adsorption isotherms were analyzed at different temperatures to obtain free energy, enthalpy, and entropy of adsorption. The method was applied for Cu(II) determination in sea water samples. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Artificial neural network (ANN) approach for modeling Zn(II) adsorption in batch process

Artificial neural networks (ANN) were applied to predict adsorption efficiency of peanut shells for the removal of Zn(II) ions from aqueous solutions. Effects of initial pH, Zn(II) concentrations, temperature, contact duration and adsorbent dosage were determined in batch experiments. The sorption capacities of the sorbents were predicted with the aid of equilibrium and kinetic models. The Zn(II) ions adsorption onto peanut shell was better defined by the pseudo-second-order kinetic model, for both initial pH, and temperature. The highest R² value in isotherm studies was obtained from Freundlich isotherm for the inlet concentration and from Temkin isotherm for the sorbent amount. The high R² values prove that modeling the adsorption process with ANN is a satisfactory approach. The experimental results and the predicted results by the model with the ANN were found to be highly compatible with each other.     

Cyclic Sorption and Desorption of Cu(II) onto Coconut Shell and Iron Oxide Coated Sand

Sorption is a viable treatment technology for copper-rich gold mine tailings wastewater. For continuous application, the sorbent should be regenerated with an appropriate desorbent, and reused. In this study, the sequential sorption/desorption characteristics of Cu(II) on coconut shell (CS) and iron oxide coated sand (IOCS) were determined. In batch assays, CS was found to have a Cu(II) uptake capacity of 0.46 mg g^?1 and yielded a 93% removal efficiency, while the IOCS had a Cu(II) uptake capacity and removal efficiency of 0.49 mg g^?1 and 98%, respectively. Desorption experiments indicated that HCl (0.05 M) was an efficient desorbent for the recovery of Cu(II) from CS, with an average desorption efficiency of 96% (sustained for eight sorption and desorption cycles). HCl (0.05 M) did not diminish the CS's ability to sorb copper even after eight sorption/desorption cycles, but completely deteriorated the iron oxide structure of the IOCS within six cycles. This study showed that CS and IOCS are both good sorbents for Cu(II); but cyclical sorption/desorption using 0.05 M HCl is only feasible with CS.     

Biosorption of Cu(II) onto agricultural materials from tropical regions

BACKGROUND: In Ghana, the discharge of untreated gold mine wastewater contaminates the aquatic systems with heavy metals such as copper (Cu), threatening ecosystem and human health. The undesirable effects of these pollutants can be avoided by treatment of the mining wastewater prior to discharge. In this work, the sorption properties of agricultural materials, namely coconut shell, coconut husk, sawdust and Moringa oleifera seeds for Cu(II) were investigated. RESULTS: The Freundlich isotherm model described the Cu(II) removal by coconut husk (R² = 0.999) and sawdust (R² = 0.993) very well and the Cu(II) removal by Moringa oleifera seeds (R² = 0.960) well. The model only reasonably described the Cu(II) removal by coconut shell (R² = 0.932). A maximum Cu(II) uptake of 53.9 mg g^?1 was achieved using the coconut shell. The sorption of Cu(II) onto coconut shell followed pseudo‐second‐order kinetics (R² = 0.997). FTIR spectroscopy indicated the presence of functional groups in the biosorbents, some of which were involved in the sorption process. SEM‐EDX analysis confirmed an exchange of Mg(II) and K(I) for Cu(II) on Moringa oleifera seeds and K(I) for Cu(II) on coconut shell. CONCLUSION: This study shows that coconut shell can be an important low‐cost biosorbent for Cu(II) removal. The results indicate that ion exchange, precipitation and electrostatic forces were involved in the Cu(II) removal by the biosorbents investigated. Copyright © 2011 Society of Chemical Industry     

Poly(ethyleneimine) infused and functionalized Torlon-silica hollow fiber sorbents for post-combustion CO2 capture

Organic–inorganic hybrid materials functionalized with amine-containing reagents are emerging as an important class of materials for capturing carbon dioxide from flue gas. Polymeric silica hollow fiber sorbents are fabricated through the proven dry-jet/wet-quench spinning process. In our study, a new technique for functionalizing polymeric silica hollow fiber sorbents with poly(ethyleneimine), followed by a post-spinning infusion step was studied. This two step process introduces a sufficient amount of poly(ethyleneimine) to the polymeric silica hybrid material support to improve the CO₂ sorption capacity due to the added amine groups. The poly(ethyleneimine) infused and functionalized hollow fiber sorbents are also characterized by a thermal gravimetric analyzer (TGA) to assess their CO₂ sorption capacities.     

Alginate and Algal-Based Beads for the Sorption of Metal Cations: Cu(II) and Pb(II)

Alginate and algal-biomass (Laminaria digitata) beads were prepared by homogeneous Ca ionotropic gelation. In addition, glutaraldehyde-crosslinked poly (ethyleneimine) (PEI) was incorporated into algal beads. The three sorbents were characterized by scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX): the sorption occurs in the whole mass of the sorbents. Sorption experiments were conducted to evaluate the impact of pH, sorption isotherms, and uptake kinetics. A special attention was paid to the effect of drying (air-drying vs. freeze-drying) on the mass transfer properties. For alginate, freeze drying is required for maintaining the porosity of the hydrogel, while for algal-based sorbents the swelling of the material minimizes the impact of the drying procedure. The maximum sorption capacities observed from experiments were 415, 296 and 218 mg Pb g⁻¹ and 112, 77 and 67 mg Cu g⁻¹ for alginate, algal and algal/PEI beads respectively. Though the sorption capacities of algal-beads decreased slightly (compared to alginate beads), the greener and cheaper one-pot synthesis of algal beads makes this sorbent more competitive for environmental applications. PEI in algal beads decreases the sorption properties in the case of the sorption of metal cations under selected experimental conditions.     

Preparation of sawdust functionalized with aspartic acid and its sorption capacity,kinetics and thermodynamics for basic dyes

An ion exchanger with carboxyl groups as active sites was prepared by activating sawdust with epichlorohydrin, followed by coupling the epoxy-activated sawdust with aspartic acid. The optimal sorption condition, sorption capacity, kinetics and thermodynamics of basic dyes on sawdust ion exchanger (SIE) from aqueous solution were investigated in a batch system. Two basic dyes, methylene blue (MB) and crystal violet (CV), were selected as sorbates. The optimal pH value of MB and CV solutions for favorable sorption was pH 4 and above. The removal ratios of MB and CV on SIE increased with increasing sorbent dose but decreased with increasing dye concentration. The isothermal data of MB and CV sorbed on SIE correlated basically with the Langmuir model. The maximum sorption capacity (Q _m ) of SIE for MB and CV was 222.22 and 232.56 mg/g, respectively. The sorption equilibriums of MB and CV on SIE were reached at about 9 h, and the sorption processes could be described by the pseudo-second-order kinetic model. The thermodynamic study indicated that the sorptions of MB and CV on SIE were spontaneous and endothermic at the predetermined temperatures. High temperatures were favorable for the sorption processes.     

Reactive polymers,XXXIV. Complexes of Ag(I) and Ag(II) with ligands bound to solid support

The sorption of Ag(I) ions on sorbents containing ethylenediamine (en) and iminodiacetate (ida) groups was investigated. The basic backbone consisted on macroporous glass coatd on its inner surface with poly(glycidylmethacrylate) (glass-GMA), copolymer glycidylmethacrylate-ethylenedimethacrylate (GMA-EDMA), and GMA-EDMA encapsulated in poly(-2-hydroxyethylmethacrylate). The rate of sorption of Cu(II) in sorbents modified with en decreased in the same order. For the sorption of Ag(II), a sorbent was synthesized by a reaction of GMA-EDMA with 3-aminopyridine, and the reaction with the ion was carried out in an oxidizing solution. The types of complexes formed in the sorption were determined spectroscopically in all cases.     

Removal of Ni(II), Cd(II), and Pb(II) from a ternary aqueous solution by amino functionalized mesoporous and nano mesoporous silica

In the present study, the application for the removal of Ni(II), Cd(II) and Pb(II) ions from aqueous solution by using mesoporous silica materials, namely, MCM-41, nanoparticle of MCM-41, NH₂-MCM-41 (amino functionalized MCM-41) and nano NH₂-MCM-41 was investigated. Suitable adsorbents preparation techniques were developed in the laboratory. The effects of the solution pH, metal ion concentrations, adsorbent dosages, and contact time were studied. It was found that NH₂-MCM-41 showed the highest uptake for metal ions in aqueous solution. The results indicated that the adsorption of Ni(II), Cd(II) and Pb(II) ions on the surface of the adsorbent was increased with increasing solution pH. The experimental data were analyzed using the Langmuir and Freundlich equations. Correlation coefficients were determined by analyzing each isotherm. It was found that the Langmuir equation showed better correlation with the experimental data than the Freundlich. According to the parameters of the Langmuir isotherm, the maximum adsorption capacity of NH₂-MCM-41 for Ni(II), Cd(II) and Pb(II) was found to be 12.36, 18.25 and 57.74 mg/g, respectively. The kinetic data of adsorption reactions and the evaluation of adsorption equilibrium parameters were described by pseudo-first-order and pseudo-second-order equations. The synthesized solid sorbents were characterized by Fourier transform infrared (FT-IR) spectrometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen sorption measurements.     

Development of a novel nano-biosorbent for the removal of fluoride from water

The study was designed to investigate the use of two sorbents namely (i) Fe₃O₄ nanoparticles immobilized in sodiumalginate matrix (FNPSA) and (ii) Fe₃O₄ nanoparticles and saponified orange peel residue immobilized in sodium alginate matrix (FNPSOPR) as sorbents for fluoride removal from contaminated water. The synthesized nanoparticles were analyzed and characterized by dynamic light scattering, X-ray diffraction, vibrating sample magnetometry, and scanning electron microscopy with energy dispersive X-ray spectroscopy and Fourier transform-infrared spectrometry. The sorbentmatriceswere prepared in the formof beads and surface functionalized to enable enhanced sorption of fluoride ions. Batch sorption studieswere carried out and the sorption isotherm and reaction kinetics were analyzed. Both the sorbents followed Langmuir model of isotherm and fitted well with Pseudo first order reaction. The maximum sorption capacity exhibited by FNPSA and FNPSOPR was 58.24 mg·g^-1 and 80.33 mg·g^-1 respectively. Five sorption–desorption cycles exhibited 100%, 97.56%, 94.53%, 83.21%, and 76.53% of regeneration of FNPSOPR. Accordingly, it is demonstrated that FNSOPR could be used as a promising sorbent for easy and efficient removal of fluoride from contaminated water with good reusability. The current work suggests a simple and effective method to remove fluoride from contaminated water.     

Synthesis and application of amine functionalized silica mesoporous magnetite nanoparticles for removal of chromium(VI) from aqueous solutions

In this research, novel nanoparticles of Kit-6 mesoporous silica magnetite were synthesized with 9.6 nm pore diameter and 241.68 m² g^?1 surface area. The synthesized mesoporous magnetite nanoparticles (MMNPs) were functionalized with amine groups. Scanning electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy and nitrogen adsorption–desorption method confirmed the morphology and structure of the synthesized nanoparticles. The amine functionalized MMNPs were used for sorption of toxic chromate ions from aqueous samples. The effect of various experimental parameters (four factors at three levels) on the sorption efficiency of Cr(VI) was studied and optimized via Taguchi L₉ (3⁴) orthogonal array experimental design. At optimum conditions, the sorption of the Cr(VI) was best described by a pseudo second-order kinetic model with R² = 0.9999 and q_eq = 129.8 mg g^?1, suggesting chemisorption mechanism. Adsorption data were fitted well to the Langmuir isotherm and the synthesized sorbent showed complete ion removal with 185.2 mg g^?1sorption capacity.     

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.     

Adsorption Studies of Volatile Organic Compound (Naphthalene) from Aqueous Effluents: Chemical Activation Process Using Weak Lewis Acid,Equilibrium Kinetics and Isotherm Modelling

This study deals with the preparation of activated carbon (CDSP) from date seed powder (DSP) by chemical activation to eliminate polyaromatic hydrocarbon—PAHs (naphthalene—C₁₀H₈) from synthetic wastewater. The chemical activation process was carried out using a weak Lewis acid of zinc acetate dihydrate salt (Zn(CH₃CO₂)₂·2H₂O). The equilibrium isotherm and kinetics analysis was carried out using DSP and CDSP samples, and their performances were compared for the removal of a volatile organic compound—naphthalene (C₁₀H₈)—from synthetic aqueous effluents or wastewater. The equilibrium isotherm data was analyzed using the linear regression model of the Langmuir, Freundlich and Temkin equations. The R² values for the Langmuir isotherm were 0.93 and 0.99 for naphthalene (C₁₀H₈) adsorption using DSP and CDSP, respectively. CDSP showed a higher equilibrium sorption capacity (q_e) of 379.64 µg/g. DSP had an equilibrium sorption capacity of 369.06 µg/g for C₁₀H₈. The rate of reaction was estimated for C₁₀H₈ adsorption using a pseudo-first order, pseudo-second order and Elovich kinetic equation. The reaction mechanism for both the sorbents (CDSP and DSP) was studied using the intraparticle diffusion model. The equilibrium data was well-fitted with the pseudo-second order kinetics model showing the chemisorption nature of the equilibrium system. CDSP showed a higher sorption performance than DSP due to its higher BET surface area and carbon content. Physiochemical characterizations of the DSP and CDSP samples were carried out using the BET surface area analysis, Fourier-scanning microscopic analysis (FSEM), energy-dispersive X-ray (EDX) analysis and Fourier-transform spectroscopic analysis (FTIR). A thermogravimetric and ultimate analysis was also carried out to determine the carbon content in both the sorbents (DSP and CDSP) here. This study confirms the potential of DSP and CDSP to remove C₁₀H₈ from lab-scale synthetic wastewater.