Highly efficient extraction of uranyl ions from aqueous solutions using multi-chelators functionalized graphene oxide

ABSTRACT

A novel nanocaptor (GO-HDX) was designed based on the graphene oxide nanosheets functionalized with hydroxamate moieties that enabled the selective removal and recovery of extremely radioactive uranyl ions from wastewater samples. The synthesized nanocaptor (GO-HDX) was well-characterized using elemental analysis, FT-IR and Raman spectroscopy, and X-ray diffraction (XRD). The U(VI) removal from aqueous solution with GO-HDX was investigated in terms of essential factors (initial pH, contact time and temperature), adsorption isotherm and thermodynamics were examined. The UO₂ ²⁺ ions adsorption under the studied conditions was well-?tted to the Freundlich model as well as to the pseudo-first-order model.     

Magnetic removal of crystal violet from aqueous solutions using polysaccharide‐based magnetic nanocomposite hydrogels

Magnetic Fe₃O₄@SiO₂ starch‐graft‐poly(acrylic acid) (SPAA) nanocomposite hydrogels were prepared and used as absorbents for removal of crystal violet from aqueous solutions. Dynamic swelling, effect of contact time, absorption kinetics and nanocomposite hydrogel mass for removal of crystal violet dyes from aqueous solutions were studied. Fourier transform infrared spectroscopy, scanning electron microscopy and vibrating sample magnetometer measurements were used for the characterization of the nanocomposite hydrogels. The nanocomposite hydrogels had high magnetic sensitivity under an external magnetic field, which allowed their magnetic separation from water, thus avoiding secondary pollution. The results obtained are very promising since: (i) high levels of colour removal (>85%) were achieved with low magnetic SPAA nanocomposite mass and (ii) the magnetic SPAA nanocomposites can be successfully used several times as absorbents of crystal violet in aqueous solution without needing filtration. © 2012 Society of Chemical Industry     

Preparation of magnetic zeolite/chitosan composite using silane as modifier for adsorption of Cr(VI) from aqueous solutions

This study aimed to prepare an efficient, cost-effective, and separable magnetic zeolite/chitosan composite (MZFA/CS) adsorbent from solid waste to deal with the water pollution of Cr(VI). The MZFA/CS was characterized by X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM) techniques. Then, the effect of pH, temperature, initial concentration of Cr(VI) ions, and contact time was considered in the study. For a sorbent dose of 0.1 g in 50 mL of a Cr(VI) solution, at a contact time of 30 min, temperature of 30°C, and a pH of 3, an adsorption capacity (q_e) of 16.96 mg g⁻¹ was achieved. Adsorption kinetics and isotherm data obtained for all adsorption systems were well-fitted by pseudo-second-order and Langmuir models, respectively. The thermodynamic study suggested that the adsorption process is spontaneous and endothermic in nature. In summary, the adsorbent with better separability (Ms = 16.83 emu g⁻¹) and adsorbability was successfully fabricated.     

Biosorption of anionic dyes from aqueous solutions using a novel magnetic nanocomposite adsorbent based on rice husk ash

This study investigated the potential use of an agricultural waste, rice husk ash, for the removal of methyl orange. The adsorbent was prepared via a simple one-pot synthesis of magnetic iron oxide nanoparticles (MIONs). The prepared magnetic nanocomposites were characterized using Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometer techniques. Bach adsorption experiments were carried out to evaluate the effects of initial dye concentration, pH and contact time as well as MION content on adsorption capacity. The mechanism of dye adsorption was well fitted to a pseudo-second-order kinetic model. Moreover, the equilibrium data fitted well with the Langmuir isotherm model.     

Single step modification of micrometer-sized polystyrene particles by electromagnetic polyaniline and sorption of chromium(VI) metal ions from water

This article describes a single-step reproducible approach for the surface modification of micrometer-sized polystyrene (PS) core particles to prepare electromagnetic PS/polyaniline–Fe₃O₄ (PS/PANi–Fe₃O₄) composite particles. The electromagnetic PANi–Fe₃O₄ shell was formed by simultaneous seeded chemical oxidative polymerization of aniline and precipitation of Fe₃O₄ nanoparticles. The weight ratio of PS to aniline was optimized to produce core–shell structure. PS/PANi–Fe₃O₄ composite particles were used as adsorbent for the removal of Cr(VI) via anion-exchange mechanism. The composite particles possessed enough magnetic property for magnetic separation. The adsorption was highly pH dependent. Adsorption efficiency reached 100% at pH 2 in 120 min when 0.05 g of composite particles was mixed with 30 mL 5 mg L⁻¹ Cr(VI) solution. The adsorption isotherm fitted best with Freundlich model and maximum adsorption capacity approached 20.289 mg g⁻¹ at 323 K. The prepared composite was found to be an useful adsorbent for the removal of soluble Cr(VI) ions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47524.     

Polyelectrolyte CASA hydrogels for uptake of uranyl ions from aqueous solutions

In this study, uranyl ion adsorption from aqueous solutions has been investigated by chemically crosslinked acrylamide/sodium acrylate (CASA) hydrogels. Adsorption studies were investigated by the spectroscopic method. CASA hydrogels with various compositions were prepared from ternary mixtures of acrylamide (A), sodium acrylate (SA), and water by free radical polymerization in aqueous solution, using multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA). Uranyl ion adsorption from aqueous solutions was studied by the batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of adsorbent on the uranyl ion adsorption were examined. In experiments of sorption, L‐type sorption in the Giles classification system was found. Some binding parameters, such as initial binding constant (K_i), equilibrium constant (K), monolayer coverage (n), site‐size (u), and maximum fractional occupancy (Ô) for the CASA hydrogel–uranyl ion binding system, were calculated using the Langmuir linearization method. Finally, the amount of sorbed uranyl ion per gram of dry hydrogel (q) was calculated to be 4.44 × 10^?4–14.86 × 10^?4 mol uranyl ion per gram for CASA hydrogels. Adsorption of uranyl ion (percentage) was changed within a range of 12.86–46.71%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 200–204, 2007     

Solid phase extraction and removal of 2,4-dichlorophenol from aqueous samples using magnetic graphene nanocomposite

A magnetic graphene nanocomposite (Fe₃O₄-GNC) was prepared and used for the solid phase extraction (SPE) and removal of 2,4-dichlorophenol from aqueous solutions. The physicochemical properties were investigated using SEM, EDX, FTIR, and TGA. Different factors affecting sorption capacity were studied systematically. Results for kinetics studies revealed that 2,4-dichlorophenol sorption followed pseudo-second-order kinetics and the q_e value (987.45 mg/g) was in close agreement with experimental value (1000 mg/g). Thermodynamic study showed that the sorption is endothermic (?Hº = +56.116 kJ/mol) and spontaneous. The desorption studies were carried out for the reusability and extraction of 2,4-dichlorophenol from aqueous samples and 94% recoveries were obtained. The method was found feasible for the removal and preconcentration of trace analysis of 2,4-dichlorophenol in environmental water samples.     

Efficient removal of Cr(VI) and Pb(II) from aqueous solution by magnetic nitrogen-doped carbon

The magnetic nitrogen-doped carbon (MNC) was prepared from polypyrrole by a simple high temperature calcination process in this paper. The structure and properties of MNC were analyzed by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, Brunner-Emmet-Teller, vibrating sample magnetometer, and X-ray photoelectron spectroscopy. The capacity of MNC to adsorb Cr(VI) and Pb(II) was evaluated. The effects of the initial pH, dosage, concentration and temperature on the adsorption capacity of MNC were measured. MNC had a large specific surface area and a special porous structure. Its nitrogen and carbon sources were rich, and the ratio of carbon to nitrogen was fixed. The maximum Cr(VI)-adsorption capacity and maximum Pb(II) adsorption capacity of MNC could reach 456.63 and 507.13 mg∙g⁻¹ at 318 K, respectively. The pseudo-second-order model was used to describe the adsorption kinetics of MNC, and the Freundlich model was employed to discuss its isotherms. The adsorption process was affected by the electrostatic force, the reducing reaction, pores and chelation. The results of this study suggest that MNC is a material with superior performance, and is very easily regenerated, reused, and separated in the adsorption process.     

Synthesis of cellulose/reduced graphene oxide/polyaniline nanocomposite and its properties

A series of conductive nanocomposites cellulose/reduced graphene oxide/polyaniline (cellulose/RGO/PANi) were synthesized via in situ oxidative polymerization of aniline on cellulose/RGO with different RGO loading to study the effect of RGO on the properties of nanocomposites. The results showed that when RGO is inserted into cellulose/PANi structure, its thermal stability and conductivity are increased. So that adding of only 0.3 wt% RGO into the cellulose/PANi structure, its conductivity is increased from 1.1 × 1 10^?1 to 5.2 × 110^?1 S/cm. Scanning electron microscopy results showed that the PANi nanoparticles are formed a continuous spherical shape over the cellulose/RGO template; this increases the thermal stability of nanocomposite.     

Chitosan/polyaniline hybrid for the removal of cationic and anionic dyes from aqueous solutions

Nanostructured chitosan/polyaniline (CH/PANI) hybrid was synthesized via in situ polymerization of aniline in the presence of chitosan. The CH/PANI hybrid was characterized by FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The CH/PANI hybrid had a nanofibrous structure with an average diameter of 70 nm. This hybrid was employed as an ecofriendly and efficient adsorbent with high adsorption capacity for the removal of Acid Green 25 (AG) and methylene blue (MB) from aqueous solutions. AG and MB were used as anionic and cationic model dyes, respectively. The CH/PANI adsorbent showed high dependence on the pH of the medium with an excellent adsorption performance and regeneration manner. The kinetics and adsorption isotherms were studied. The CH/PANI hybrid follows the pseudo second-order adsorption kinetics and Temkin isotherm model for the adsorption of both AG and MB dyes. This assumes that the enthalpy of dyes molecules decreases with the adsorption on heterogeneous surface with various kinds of adsorption sites and as well as the ability to form multilayers of the dye. Also, intraparticle diffusion was found to play an important role in the adsorption mechanism. The maximum adsorption capacity was found to be 240.4 mg g⁻¹ of AG at pH 4 and 81.3 mg g⁻¹ of MB at pH 11. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47056.     

Preparation and characterization of higher degree‐deacetylated chitosan‐coated magnetic adsorbent for the removal of chromium(VI) from its aqueous mixture

Chitosan (90% deacetylated) coated magnetic adsorbent prepared by coprecipitation method to remove Cr(VI) from its aqueous solution. The experimental studies depicts that the predominant option for removal of Chromium by adsorption from its aqueous phase using Magnetic‐Chitosan (MC). The subsequent physical, chemical, and magnetic properties of MC were characterized by X‐ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectrometer, vibrating sample magnetometer. The influence of batch process parameters such as contact time, initial concentration, pH, and coexisting anions were investigated. The Box‐Behnken experimental design in response surface methodology was performed to design the experiment optimal operating conditions. The maximum percentage reduction of Cr(VI) is 96.3 that was obtained by magnetic chitosan with the optimal operating conditions of 149.53 mg/L at pH of 5.32 at the contact time of 80 min and at the temperature of 303 K. The average diameter of the magnetic chitosan was calculated from X‐ray diffractometer analysis as 24.5 nm. The equilibrium adsorption isotherm models such as Langmuir and Freundlich and the adsorption kinetics such as pseudo first order, pseudo second order and intra‐particle diffusion kinetic model were analyzed. The experimental data's suited for the best fit with the Langmuir isotherm model and pseudo first order kinetic model. It also revealed that Cr(VI) adsorption on MC is intrinsically exothermic and spontaneous. The magnetic chitosan was also used to investigate for the removal of Cr(VI) from the real water sources such as surface, underground, and tannery wastewater. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45878.     

Synthesis of graphene oxide nanoribbons/chitosan composite membranes for the removal of uranium from aqueous solutions

In this study, a graphene oxide nanoribbons/chitosan (GONRs/CTS) composite membrane was successfully prepared by encapsulating CTS into GONRs, which were unzipped from multi-walled carbon nanotubes. The GONRs/CTS composite membrane so prepared was characterized using scanning electron microscopy, X-Ray diffraction and Fourier transform infrared spectroscopy. The effects of the experimental conditions such as the pH (2‒7), adsorbent dosage (10‒50 mg), experimental time (5 min–32 h), uranium concentration (25‒300 mg∙L⁻¹), experimental temperature (298 K‒328 K) on the adsorption properties of the composite membrane for the removal of U(VI) were investigated. The results showed that the U(VI) adsorption process of the GONRs/CTS composite membrane was pH-dependent, rapid, spontaneous and endothermic. The adsorption process followed the pseudo-secondary kinetics and Langmuir models. The maximum U(VI) adsorption capacity of the GONRs/CTS composite membrane was calculated to be 320 mg∙g⁻¹. Hence, the GONRs/CTS composite membrane prepared in this study was found to be suitable for separating and recovering uranium from wastewater.     

Synthesis of polyaniline nanoparticle grafted silica gel and study of its Cr(VI) binding property

Polyaniline nanoparticles have been synthesized through simple micelle technique and then grafted it with silanized silica gel to develop a novel hybrid material. The nanoparticles are characterized by UV‐Vis, TEM, CV, SEM, TGA, DTG, and DSC. Silanization and grafting reactions are evaluated by FTIR and chemical test. The Cr(VI) binding behavior of the composite is studied in various pH of the medium, and both competitive and noncompetitive conditions. The particle size, adsorption capacity, and surface area of the material are found to be 100 nm, 135 mg/g, and 720 m²/g, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Production of hydroxyapatite-based adsorbent for the removal of cobalt ions from the aqueous solution

The aim of the current study was to recover and separate cobalt ions from multielement solution, using hydroxyapatite (HAp) and magnetic nanocomposite of HAp/Fe₃O₄ as adsorbents. Cobalt ion adsorption process was conducted batchwise within the temperature 25˗55°C, exposure duration 5˗120 min by applying a dose of 0.25–5 g/L as the adsorbent at pH 2 to 9.  Adsorbent characterization was performed using advanced spectroscopic techniques such as Fourier Transform Infrared Spectroscopy, Scanning electron microscopy, and Energy-dispersive X-ray spectroscopy. The maximum ionic adsorption efficiency using HAp was 90.48% against 94.72% in the case of the magnetic nanocomposite of HAp, under optimal conditions. Various isotherm models were used to evaluate the adsorption capacity and equilibrium coefficients for adsorption of the cobalt ions by the prepared adsorbents. The isotherm models data showed that the adsorption process is desirable by the adsorbents and by adding nanoparticles of Fe₃O₄ the adsorption capacity improves.     

Biosorption of Pb(II) and Cd(II) ions from aqueous solution using polyaniline/chitin composite

In this study, chitin (Ch) was made composite with polyaniline (PANI) and used for the removal of Pb(II) and Cd(II) ions from aqueous solution. Characterization techniques such as Fourier transform infrared spectroscopy, scanning electron microscope, energy-dispersive X-ray analyser and X-ray diffraction were employed to characterize the prepared PANI/Ch composite. Influence of various equilibrium parameters on the adsorption of Pb(II) and Cd(II) ions onto PANI/Ch composite was investigated. The adsorption process followed the Freundlich isotherm model, and the calculated maximum monolayer sorption capacity of PANI/Ch composite for Pb(II) and Cd(II) ions is 7.03 and 6.05 mg g^?1 at 303 K. The kinetic data were well described by the pseudo-second-order model.     

Development of nanocomposites of bentonite with polyaniline and poly(methacrylic acid)

Nanocomposites of bentonite with polyaniline (PANI), poly(methacrylic acid) (PMAA), and poly(aniline‐co‐methacrylic acid) (PANI‐co‐PMAA) were prepared by in situ intercalative polymerization technique. The nanocomposites were characterized by FTIR and UV–visible spectroscopies, XRD, SEM, TEM, as well as TG‐DTA studies. The in situ intercalative polymerization of PANI, PMAA, and PANI‐co‐PMAA within bentonite layers was confirmed by FTIR, XRD, SEM, as well as TEM studies. XRD confirmed the intercalation of polymers and copolymer in bentonite. The average particle size of the nanocomposites was found to be in the range of 250–500 nm. The thermal stability was found be the highest for PANI‐co‐PMAA‐bentonite. The swelling behavior studies suggest that these nanocomposites hold potential for their utilization in absorption of toxic materials from waste water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3299–3306, 2007     

Adsorption of some heavy metal ions from aqueous solutions on Nafion 117 membrane

Nafion 117 membrane was investigated for the removal of Ni(II), Co(II), Pb(II), Cu(II) and Ag(I) metal ions from their synthesized aqueous solutions. The different variables affecting the adsorption capacity of the membrane such as contact time, initial metal ion concentration in the feed solution, pH of the sorption medium and temperature of the solution were investigated on a batch sorption basis. The affinity of Nafion 117 membrane towards heavy metal ions was found to increase in the sequence of Cu(II), Ni(II), Co(II), Pb(II), and Ag(I) with adsorption equilibrium achieved after 30 min for all metal ions. Among all parameters, pH has the most significant effect on the adsorption capacity, particularly in the range of 3.1-5.9. The variation of temperature in the range of 25-65 °C was found to have no significant effect on the adsorption capacity. Nafion 117 membrane was found to have high stability combined with repeated regeneration ability and can be suggested for effective removal of heavy metal ions such as Cu(II), Ni(II) and Co(II) from aqueous solutions.     

Nano-TiO2 modified with 2-mercaptobenzimidazole as an efficient adsorbent for removal of Ag(I) from aqueous solutions

Nano-TiO₂ was modified with 2-mercaptobenzimidazole via surfactant activation and used as an adsorbent for the removal of Ag(I) under optimum conditions. The adsorbent was characterized using powder X-ray diffraction and FT-IR spectroscopy. The equilibrium data were fitted to the Langmuir, Freundlich and Temkin isotherm models. Langmuir isotherm describes the adsorption data better than Freundlich isotherm and Temkin. Kinetic studies showed that the pseudo second order kinetic model fits the adsorption kinetic processes well. Maximum adsorption capacity for Ag(I) was 128.2 mg g⁻¹ of nano-TiO₂. The method was successfully applied to the removal of silver from radiology film processing wastewater samples.     

Novel hexamethylene diamine‐functionalized macroporous copolymer for chromium removal from aqueous solutions

Macroporous copolymers of poly[(glycidyl methacrylate)‐co ‐(ethylene glycol dimethacrylate)] (PGME ) with various crosslinker (ethylene glycol dimethacrylate) concentrations and porosity parameters and additionally functionalized with hexamethylene diamine (PGME‐HD ) were tested as potential Cr(VI ) oxyanion sorbents from aqueous solutions. Kinetics of Cr(VI ) sorption was investigated in the temperature range 298–343 K and the results were fitted to chemical reaction and particle diffusion models. The Cr(VI ) sorption obeys the pseudo‐second‐order model with definite influence of pore diffusion. A temperature rise promotes chromium removal, with a maximum experimental uptake capacity of 4.21 mmol g^?1 at 343 K for the sample with the highest amino group concentration. Equilibrium data were analysed with Langmuir, Freundlich and Temkin adsorption isotherm models. Thermodynamic parameters, i.e. Gibbs free energy (ΔG ⁰), enthalpy (ΔH ⁰) and entropy change (ΔS ⁰) and activation energy of sorption (E _a), were calculated. The Cr(VI) adsorption onto PGME‐HD was found to be spontaneous and endothermic, with increased randomness in the system. Desorption experiments show that chromium anion sorption was reversible and the PGME‐HD sample GMA 60 HD was easily regenerated with 0.1 mol L^?1 NaOH up to 90% recovery in the fourth sorption/desorption cycle. In the fifth cycle, a substantial sorption loss of 37% was observed. © 2016 Society of Chemical Industry     

Application of polyaniline nanolayer composite for removal of tartrazine dye from aqueous solutions

In this research, polyaniline was synthesized chemically onto the surface of sawdust as a thin layer (termed as PAni/SD) and was then used for removal of tartrazine dye (a typical anionic azo dye) from aqueous solutions. Ammonium peroxodisulphate was used as chemical oxidant for polymerization of polyaniline directly on the surface of sawdust. The procedure involves sorption experiments were performed on both batch and column systems. The effects of some important parameters such as pH, initial concentration, sorbent dosage, exposure time and temperature on uptake of tartrazine dye were investigated. Adsorption studies have shown that pH of the tartrazine solution has influence on the dye removal capacity of PAni/SD. It was found that effective dye removal is occurred under neutral or acidic conditions. The treatments of the data were carried out using both Freundlich and Langmuir adsorption isotherms. Sorption/desorption studies showed that PAni/SD was fast, simple, inexpensive, highly efficient and potential re-usable adsorbent to remove tartrazine from aqueous solutions. Based on our kinetics and thermodynamic studies, it was found that sorption process was endothermic (ΔH > 0) and the experimental data fitted very well with pseudo second-order kinetic model.