Adsorption of Neodymium(III) from Aqueous Solutions Using a Phosphorus Functionalized Adsorbent

Removal of fluoroquinolone antibiotic and sulfonated dye by functionalized Persea americana seed powder: Appraisal on phase transfer kinetics, equilibrium, economics, and applications in rural settings

The study focuses on reactive orange 16 (RO16), a sulfonated dye, and ciprofloxacin (CiP), a fluoroquinolone antibiotic treatment from aquatic surface by adsorption. The functionalized Persea americana seed powder (PASP) was developed by acid hydrolysis technique and investigated for RO16 and CiP removal in batch scale at different concentrations for CiP and RO16, pH (2-8), contact duration and temperature (303-318K). Utilizing a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDAX), the generated native PASP were assessed for their morphological characteristics. Fourier transform infrared (FTIR) spectroscopy was applied to examine the performing characteristics of PASP. Experimental findings with four kinetic mathematical models allowed the estimation of the process involved in the biosorption. The most effective agreement was explained by the pseudo-second-order model and Sips isotherm (Cip = 34.603 mg/g and RO16 = 30.357 mg/g) at 303K temperature. For Cip Process economics of the biosorbent was done, and it was observed that it was less than the readily market-available activated carbon.

Mussel-Inspired Nanocellulose Coating for Selective Neodymium Recovery

Neodymium (Nd) is one of the most in-demand rare earth elements (REEs) for developing the next generation of magnetic medical devices and clean energy. Eco-friendly and sustainable nanotechnology for REE recovery may be highly suitable to address the limited global supply while minimizing the environmental footprints of current practice, such as solvent extraction. Here, we present a novel one-step mussel-inspired nanocellulose coating (MINC) using bifunctional hairy cellulose nanocrystals (BHCNC), bearing dialdehyde and dicarboxylate groups. The dialdehyde groups enable dopamine-mediated orthogonal conjugation of BHCNC to substrates, such as microparticles, while the high content of dicarboxylate groups yields high-capacity and selective Nd removal against ferric, calcium, and sodium ions. To the best of our knowledge, the MINC-treated substrate provides the most rapid selective removal and recovery of Nd ions even at low Nd concentrations with a capacity that is among the highest reported values. We envision that the MINC will provide new opportunities in developing next-generation bio-based materials and interfaces for the sustainable recovery of REEs and other precious elements.

Photocatalytic Performance of Functionalized Biopolymer for Neodymium (III) Sorption and the Recovery from Leachate Solution

Successive grafting of new sorbent bearing amino phosphonic groups based on chitosan nano magnetite particles was performed through successive coupling with formaldehyde. The produced composite was characterized by the high sorption capacity toward rare earth elements (REEs) and consists of different types of functional groups (phosphonic, hydroxyls and amine groups) that are used for enhancing the sorption properties. The chemical modification and the sorption mechanism were investigated through different analytical tools; i.e., FTIR, SEM, SEM-EDX, TGA, BET (surface area) and pHpzc. The sorption was investigated toward Nd(III) as one of the REE(III) members under ultraviolet (UV) and visible light (VL) conditions. The optimum sorption was found at pH0 4 and the sorption capacity was recorded at 0.871 and 0.779 mmol Nd g−1 under UV and VL respectively. Sorption isotherms and uptake kinetics were fitted by Langmuir and Sips and by pseudo-first order rate equation (PFORE) for the functionalized sorbent, respectively. The sorbent showed a relatively high-speed sorption kinetic (20 min). The bounded metal ions were progressively eluted using 0.2 M HCl solution with a desorption rate 10–15 min, while the loss in the total capacity after a series of sorption recycling (sorption/desorption) (five cycles) was limited (around 3%) with 100% of the desorption efficiency, indicating the high stability of the sorbent toward an acidic medium. The sorbent was used for the recovery of REEs from leach liquor residue after pretreatment for the extraction of particular elements. From these results (high loading capacity, high selectivity and high stability against acid treatments), we can see that the sorbent is a promising tool for the selective recovery of rare earth elements in the field of metal valorization.

Post-irradiation physicochemical features of polymer composite for the removal of Co(II) and Nd(III) from aqueous solutions

The scientific impact of this work is the protection of the environment from hazardous pollutants. Gamma irradiation was employed for the preparation of a new composite polymer by irradiating a mixture containing polyvinyl pyrrolidone (PVP), hydroxyethyl methacrylate (HEMA), and tannic acid (TA) to produce PVP-HEMA-TA. The sorption efficiency and capacity of PVP-HEMA-TA were evaluated by studying some factors affecting the sorption of Nd(III) and Co(II) from aqueous solutions. The results demonstrated that the maximum uptake was 92.4 and 75.3% for Nd(III) and Co(II), respectively. From the kinetic studies, the pseudo-second-order equation could better fit the data than the pseudo-first-order for the sorption of both ions. The sorption isotherm investigations illustrated that the Langmuir equation fits the gained data better than Freundlich equation. The Langmuir capacity was 64.5 and 60.8 mg/g for neodymium and cobalt ions, respectively. The applicability of Langmuir equation is strong evidence that the process is limited by a chemisorption mechanism. Findings of the work highlight the potential utilization of PVP-HEMA-TA as an effective and recyclable material for the elimination of Nd(III) and Co(II) from the aqueous phase.

Arsenate removal on the iron oxide ion exchanger modified with Neodymium(III) ions

In this study the iron oxide ion exchanger with the quaternary ammonium groups, Ferrix A33E was modified with neodymium (III) ions in order to obtain the new material Ferrix A33E-Nd(III) characterized by greater sorption efficiency of arsenate(V) ions. A33E-Nd(III) was described by various techniques including scanning electron microscopy SEM, nitrogen adsorption/desorption isotherms, Fourier transform infrared spectroscopy FTIR and X-ray photoelectron spectroscopy XPS. The point of zero charge, pH_PZC was also determined. The kinetic and thermodynamic parameters of the arsenate(V) sorption were calculated. The experimental data was fitted to the four isotherm models - Langmuir, Freundlich, Dubinin-Radushkevich and Halsey. Kinetic and equilibrium studies allowed to get to know the behaviour of arsenate(V) ions during the sorption on A33E-Nd(III). The obtained material A33E-Nd(III)- was found to possess a larger maximum sorption capacity than A33E, great stability and the possibility of regeneration at least 3 times without a significant decrease in efficiency. This allows for the complete removal of As(V) ions from a solution with a concentration of 50 mg/dm³ in just 30 min. The Nd(III)-modification improved the sorption properties of the tested ion exchanger.

Tailoring Nanoadsorbent Surfaces: Separation of Rare Earths and Late Transition Metals in Recycling of Magnet Materials

Novel silica-based adsorbents were synthesized by grafting the surface of SiO₂ nanoparticles with amine and sulfur containing functional groups. Produced nanomaterials were characterized by SEM-EDS, AFM, FTIR, TGA and tested for adsorption and separation of Rare Earth Elements (REE) (Nd³⁺ and Sm³⁺) and Late Transition Metals (LTM) (Ni²⁺ and Co²⁺) in single and mixed solutions. The adsorption equilibrium data analyzed and fitted well to Langmuir isotherm model revealing monolayer adsorption process on homogeneously functionalized silica nanoparticles (NPs). All organo-silicas showed high adsorption capacities ranging between 0.5 and 1.8 mmol/g, depending on the function and the target metal ion. Most of these ligands demonstrated higher affinity towards LTM, related to the nature of the functional groups and their arrangement on the surface of nanoadsorbent.

Fabrication, Characterization and Evaluation of an Alginate-Lignin Composite for Rare-Earth Elements Recovery

The recent increase in interest in rare earth elements is due to their increasing use in many areas of life. However, along with their increasing popularity, the problem of their natural resources availability arises. In this study, an alginate–lignin composite (ALG-L) was fabricated and tested for adsorptive abilities of the rare earth elements (La(III), Ce(III), Pr(III), and Nd(III)) from aqueous solutions. The characterization of the newly synthetized calcium alginate–lignin composite was performed using ATR/FT-IR, SEM, EDX, OM, AFM, XRD, BET, sieve analysis and pH_pzc measurements. The adsorption mechanism of the ALG₅L₁ composite for REEs was analyzed through a series of kinetic, equilibrium and thermodynamic adsorption experiments. Under the optimum sorption conditions, i.e., sorbent mass 0.1 g, pH 5.0, temperature 333 K, the maximum adsorption capacities of the ALG₅L₁ composite for La(III), Ce(III), Pr(III), and Nd(III) reached 109.56, 97.97, 97.98, and 98.68 mg/g, respectively. The desorption studies indicate that the new calcium alginate–lignin composite is characterized by good recycling properties and can be also reused. To sum up the advantages of low cost, easy synthesis, high adsorption efficiencies and reusability indicate that the ALG₅L₁ composite has great application perspectives for REEs recovery.

Understanding the Adsorption of Rare-Earth Elements in Oligo-Grafted Mesoporous Carbon

Rare-earth elements (REEs) are 17 elements of the periodic table primarily consisting of lanthanides. In modern society, the usage of REEs is ubiquitous in almost all modern gadgets and therefore efficient recovery and separation of REEs are of high importance. Selective adsorption and chelation of REEs in solid sorbents is a unique and sustainable process for their recovery. In this work, single-stranded oligos with 100 units of thymine were grafted onto carboxylated mesoporous carbon to synthesize a sorbent with phosphorus and oxygen functionalities. The sorbent was characterized by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy-energy-dispersive X-ray spectroscopy. Three different REEs with varying atomic radii and densities, Lu, Dy, and La, were adsorbed onto the carbon from aqueous solutions. It was observed that the adsorbed amounts increased with the increase in the atomic radius or decrease in the atomic density. Calculation of the distribution coefficients for all the equilibrium adsorption amounts suggested that adsorption is more effective in the lower concentration region. The L₃-edge X-ray absorption near-edge structure confirmed a 3+ oxidation state of REEs in the adsorbed phase. Extended X-ray absorption fine structure (EXAFS) confirmed the binding of REEs with oxygen functionalities in the adsorbed phase. The radial distribution functions calculated from the EXAFS data suggest a longer RE-O distance for La compared to those for Lu and Dy. The coordination numbers and Debye-Waller factors have typical values of about 8-9 atoms and 0.01-0.02 Ų, respectively.

Efficient Recovery of Rare Earth Elements (Pr(III) and Tm(III)) From Mining Residues Using a New Phosphorylated Hydrogel (Algal Biomass/PEI)

With the target of recovering rare earth elements (REEs) from acidic leachates, a new functionalized hydrogel was designed, based on the phosphorylation of algal/polyethyleneimine beads. The functionalization strongly increased the sorption efficiency of the raw material for Pr(III) and Tm(III). Diverse techniques were used for characterizing this new material and correlating the sorption performances and mechanisms to the physicochemical structure of the sorbent. First, the work characterized the sorption properties from synthetic solutions with the usual procedures (study of pH effect, uptake kinetics, sorption isotherms, metal desorption and sorbent recycling, and selectivity from multi-element solutions). Optimum pH was found close to 5; sorption isotherms were fitted by the Langmuir equation (maximum sorption capacities close to 2.14 mmol Pr g−1 and 1.57 mmol Tm g−1). Fast uptake kinetics were modeled by the pseudo-second order rate equation. The sorbent was highly selective for REEs against alkali-earth and base metals. The sorbent was remarkably stable for sorption and desorption operation (using 0.2 M HCl/0.5 M CaCl2 solutions). The sorbent was successfully applied to the leachates of Egyptian ore (pug leaching) after a series of pre-treatments (precipitation steps), sorption, and elution. The selective precipitation of REEs using oxalic acid allows for the recovery of a pure REE precipitate.

Adsorption of Rare Earth Elements onto DNA-Functionalized Mesoporous Carbon

The recovery and separation of rare earth elements (REEs) are of national importance owing to the specific usages, high demand, and low supply of these elements. In this research, we have investigated the adsorption of rare earth elements onto DNA-functionalized mesoporous carbons with a BET surface area of 605 m²/g and a median mesopore width of 48 Å. Three types of single-stranded DNA, one with 100 base units of thymine, another with 20 units of thymine, and the third, a 2000 unit long DNA from salmon milt were grafted on the carboxylated mesoporous carbon surface. All of the DNA-functionalized mesoporous carbons demonstrated higher adsorption of REEs compared to pristine mesoporous carbon and DNA grafted with 100 units of thymine demonstrated slightly higher adsorbed amounts compared to others. Pure neodymium (Nd(III)) adsorption in the aqueous phase demonstrated an adsorbed amount of 110.4 mg/g with respect to the initial concentration of 500 mg/g. A pH variation study with pure Nd(III) demonstrated that the adsorbed amount is higher at elevated pH compared to that at lower pH, thereby suggesting possible recovery at lower pH. Adsorption of a mixture of 16 REEs, including Sc, Lu, Tm, Yb, Er, Ho, Tb, Dy, Y, Eu, Gd, Sm, Ce, Nd, Pr, and La revealed that the adsorbed amount increased with an increase in the atomic weight and metallic radii of elements within the lanthanides. The calculation of the distribution coefficients for all of the equilibrium adsorption amounts suggested that adsorption is more effective in the lower concentration region. The Nd L₃-edge X-ray absorption near edge structure (XANES) confirmed a 3+ oxidation state of Nd in the adsorbed phase. The extended X-ray absorption fine structure (EXAFS) confirmed the local atomic structure relaxation of Nd complexes in the adsorbed phase and shortening of the Nd-O bond distance by about 0.03-0.04 Å, which may be associated with their local complexation at the carbon surface.

Comparison of Jordanian and standard diatomaceous earth as an adsorbent for removal of Sm(III) and Nd(III) from aqueous solution

In this study, Jordanian diatomaceous earth (JDA) and commercial diatomaceous earth (standard diatomaceous earth, SDA) were used for adsorption of samarium (Sm)(III) and neodymium (Nd)(III) ions from aqueous solutions using batch technique as a function of initial concentration of metal ions, adsorbent dosage, ionic strength, initial pH solution, contact time, and temperature. Both adsorbents were characterized by Fourier transform infrared (FTIR), X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller surface area, and cation exchange capacity (CEC). Maximum metal ion uptake was observed after 100 min of agitation, and the uptake has decreased with increasing temperature and reached a maximum at pH ≈ 5. Different types of adsorption isotherms and kinetic models were used to describe the Nd(III) and Sm(III) ion adsorption. The experimental data fitted within the following isotherms in the order Langmuir > Dubinin-Radushkevich (DR) > Freundlich and the pseudo-second-order kinetic model based on their coefficient of determination (R²), chi-square (χ²), and error function (F_error%) values. Maximum adsorption uptakes, according to the Langmuir model, were obtained as 188.679 mg/g and 185.185 mg/g for Sm(III) and 169.492 mg/g and 149.254 mg/g for Nd(III) by JDA and SDA, respectively. The results of thermodynamic parameters showed that the adsorption of Sm(III) and Nd(III) ions onto JDA and SDA is a feasible, spontaneous, exothermic, and entropy driven. The best recovery for Sm(III) and Nd(III) was obtained when the 0.05 M EDTA + 0.05 M H₃PO₄ mixture was used as an eluent.

Porous Covalent Organic Polymers Comprising a Phosphite Skeleton for Aqueous Nd(III) Capture

In order to meet the ever-increasing industrial demand for rare-earth elements (REEs), it is desirable to separate and recycle them at low concentrations from various sources including industrial and urban wastes. Here, we introduced phosphorus binding sites on the hydrophobic surface of a robust and high-surface area porous polymer backbone for environmentally benign and selective recovery of REEs via adsorption. For this purpose, two porous covalent organic polymer (COP) materials incorporated with in-built phosphite functionality (P-COP-1 and P-COP-2) were synthesized and applied for the adsorptive separation of Nd(III) ions from aqueous solution. A strategy to develop a series of P-COPs via a simple Friedel-Crafts reaction was introduced, and their application to the selective adsorption of REEs was explored for the first time. The newly synthesized P-COPs were amorphous and/or weakly crystalline and showed excellent chemical stability and large specific surface area with sufficient mesoporosity for enhanced diffusion of REE ions. P-COP-1 exhibited an exceptionally high Nd(III) adsorption capacity of 321.0 mg/g, corresponding to the stoichiometric ratio of P/Nd(III) = 1:0.7 and high selectivity of >86% over other competing transition and alkaline earth metal ions, whereas P-COP-2 gave a Nd(III) adsorption capacity of 175.6 mg/g at 25 °C and pH 5. Moreover, P-COP-1 showed a distribution coefficient value of 5.45 × 10⁵ mL/g, which is superior to other benchmark adsorbent materials reported so far. Finally, the P-COPs were reusable for a minimum of 10 cycles without deterioration in adsorption capacities.

Studies on adsorption of rare earth elements from nitric acid solution with macroporous silica-based bis(2-ethylhexyl)phosphoric acid impregnated polymeric adsorbent

For the adsorption and recovery of rare earth elements from aqueous nitric acid, solid-phase extraction resins were prepared by impregnating and immobilizing of bis(2-ethylhexyl)phosphoric acid extractant into the macroporous silica-based polymeric (SiO2-P) particles. It was found that bis(2-ethylhexyl)phosphoric acid/SiO2-P had higher adsorption distribution coefficient for heavy rare earth elements than for light rare earth elements. The adsorption capacity of Gd(III) was observed to be 0.315 mmol g−1 by bis(2-ethylhexyl)phosphoric acid/SiO2-P in 0.1 M HNO3 at 298 K, which increased slightly when increasing temperature from 298 to 323 K. The adsorption isotherms of Gd(III) matched well with the Langmuir and Freundlich models. The obtained thermodynamic parameters (ΔHo and ΔGo) showed that the adsorption of Gd(III) by bis(2-ethylhexyl)phosphoric acid/SiO2-P was a spontaneous and exothermic process. This study also evaluated the chemical stability of bis(2-ethylhexyl)phosphoric acid/SiO2-P treated with nitric acid at different temperatures and demonstrated that bis(2-ethylhexyl)phosphoric acid/SiO2-P had considerable stability against nitric acid and heat.

Efficient Recovery of Neodymium in Acidic System by Free-Standing Dual-Template Docking Oriented Ionic Imprinted Mesoporous Films

Neodymium (Nd) is critical component of sintered neodymium magnets. Separation of Nd from consumer magnets has attracted a widespread attention. In this paper, we presented free-standing ionic imprinted mesoporous film materials for facile and highly efficient targeted separation of Nd from permanent magnets by dual-template docking oriented ionic imprinting (DTD-OII) method. DTD-OII is based on dual-template docking oriented molecular imprinting. Compared with conventional imprinting, this novel strategy does not need extra steps, but significantly advance imprinted efficiency. With optimization of functional monomer, our free-standing dual-template docking oriented ionic imprinted mesoporous films exhibit excellent adsorption of Nd by solid-liquid extraction. The Nd adsorption capacity for optimized films was 34.98 mg g^-1 under pH = 3.0. The distribution coefficient of Nd was 636 mL g^-1, which indicates films possess significantly selectivity of Nd. In addition, efficient dual-template docking oriented ionic imprinting makes films demonstrating an outstanding of reusability by cycle test, which appreciating their potential for industrial application.

Calixarene-functionalized graphene oxide composites for adsorption of neodymium ions from the aqueous phase

Calixarene-functionalized graphene oxide (GO) composites were synthesized via esterification and polymerization of calix[n]arenes (n = 4, 6, 8) onto graphene oxide surfaces for the first time.

Cysteine-Functionalized Chitosan Magnetic Nano-Based Particles for the Recovery of Light and Heavy Rare Earth Metals: Uptake Kinetics and Sorption Isotherms

Cysteine-functionalized chitosan magnetic nano-based particles were synthesized for the sorption of light and heavy rare earth (RE) metal ions (La(III), Nd(III) and Yb(III)). The structural, surface, and magnetic properties of nano-sized sorbent were investigated by elemental analysis, FTIR, XRD, TEM and VSM (vibrating sample magnetometry). Experimental data show that the pseudo second-order rate equation fits the kinetic profiles well, while sorption isotherms are described by the Langmuir model. Thermodynamic constants (ΔG°, ΔH°) demonstrate the spontaneous and endothermic nature of sorption. Yb(III) (heavy RE) was selectively sorbed while light RE metal ions La(III) and Nd(III) were concentrated/enriched in the solution. Cationic species RE(III) in aqueous solution can be adsorbed by the combination of chelating and anion-exchange mechanisms. The sorbent can be efficiently regenerated using acidified thiourea.

Americium(III) capture using phosphonic acid-functionalized silicas with different mesoporous morphologies: adsorption behavior study and mechanism investigation by EXAFS/XPS

Efficient capture of highly toxic radionuclides with long half-lives such as Americium-241 is crucial to prevent radionuclides from diffusing into the biosphere. To reach this purpose, three different types of mesoporous silicas functionalized with phosphonic acid ligands (SBA-POH, MCM-POH, and BPMO-POH) were synthesized via a facile procedure. The structure, surface chemistry, and micromorphology of the materials were fully characterized by (31)P/(13)C/(29)Si MAS NMR, XPS, and XRD analysis. Efficient adsorption of Am(III) was realized with a fast rate to reach equilibrium (within 10 min). Influences including structural parameters and functionalization degree on the adsorption behavior were investigated. Slope analysis of the equilibrium data suggested that the coordination with Am(III) involved the exchange of three protons. Moreover, extended X-ray absorption fine structure (EXAFS) analysis, in combination with XPS survey, was employed for an in-depth probe into the binding mechanism by using Eu(III) as a simulant due to its similar coordination behavior and benign property. The results showed three phosphonic acid ligands were coordinated to Eu(III) in bidentate fashion, and Eu(P(O)O)3(H2O) species were formed with the Eu-O coordination number of 7. These phosphonic acid-functionalized mesoporous silicas should be promising for the treatment of Am-containing radioactive liquid waste.

Electrochemical and thermodynamic properties of Ln(III) (Ln = Eu, Sm, Dy, Nd) in 1-butyl-3-methylimidazolium bromide ionic liquid

The electrochemical behavior and thermodynamic properties of Ln(III) (Ln = Eu, Sm, Dy, Nd) were studied in 1-butyl-3-methylimidazolium bromide ionic liquid (BmimBr) at a glassy carbon (GC) electrode in the range of 293–338 K. The electrode reaction of Eu(III) was found to be quasi-reversible by the cyclic voltammetry, the reactions of the other three lanthanide ions were regarded as irreversible systems. An increase of the current intensity was obtained with the temperature increase. At 293 K, the cathodic peak potentials of −0.893 V (Eu(III)), −0.596 V (Sm(III)), −0.637 V (Dy(III)) and −0.641 V (Nd(III)) were found, respectively, to be assigned to the reduction of Ln(III) to Ln(II). The diffusion coefficients (D_o), the transfer coefficients (α) of Ln(III) (Ln = Eu, Sm, Dy, Nd) and the charge transfer rate constants (k_s) of Eu(III) were estimated. The apparent standard potential (E⁰*) and the thermodynamic properties of the reduction of Eu(III) to Eu(II) were also investigated.

Mesoporous silica SBA-15 functionalized with phosphonate derivatives for uranium uptake

Good selective sorption ability of SBA-15-PA for U(VI).

Specific salt and pH effects on foam film of a pH sensitive surfactant

Steady state foams made of a pH sensitive surfactant, nonaoxyethylene oleylether carboxylic acid, with ion complexing properties was studied using small angle neutron scattering (SANS). The effect of pH variation and salt addition on the foam film thickness was investigated and discussed in terms of the influent parameters stabilizing the foam such as surface properties and electrostatic effects determined by tensiometry and zeta potential measurements. The decrease in the film thickness by adding mono (Na(+)) and divalent (Ca(2+)) salts is classically explained by screening of the double layer in foam films (transverse interactions). On the contrary, addition of acid or complexing ion (Nd(3+)) results in an increase in the film thickness and can be analyzed in terms of cohesive forces between surfactants at the liquid/gas interface (lateral interactions). pH and specific salt effects revealed that foams produced by nonaoxyethylene oleylether carboxylic acid are of interest in the potential use of this surfactant in ion separation process.