Adsorption studies of Cu(II) ions on dendrimer-grafted silica-based materials

Computational Insights on the Chemical Reactivity of Functionalized and Crosslinked Polyketones to Cu2+ Ion for Wastewater Treatment

Today, the high concentrations of copper found in water resources result in an urgent problem to solve since human health and aquatic ecosystems have been affected. Functionalized crosslinked polyketone resins (XLPK) have demonstrated high performance for the uptake of heavy metals in water solutions. In addition, its green chemical synthesis makes these resins very attractive as sorbents for metal ions contained in wastewater. XLPK are not soluble in aqueous media and do not require any catalyst, solvent, or harsh conditions to carry out the uptake process. In this paper, a series of functionalized XLPK with pending amino-derivatives namely; butylamine (BA), amino 2-propanol (A2P), 4-(aminomethyl) benzoic acid (HAMC), 6-aminohexanoic acid (PAMBA), and 1,2 diamino propane (DAP) directly attached to the pyrrole backbone of the polymers and crosslinked by di-amine derivatives was investigated using Density Functional Theory (DFT) calculations. Our computational analysis revealed that dipole-dipole interactions played a crucial role in enhancing the adsorption of Cu2+ ions onto XLPKs. The negatively charged ketone moieties and functional groups within XLPKs were identified as key adsorption sites for the selective binding of Cu2+ ions. Additionally, we found that XLPKs exhibited strong electrostatic interactions primarily through the -NH2 and -C=O groups. Evaluation of the adsorption energies in XLPK-Cu(II) complexes showed that the DAP-Cu(II) complex exhibited the highest stability, attributed to strong Cu(II)-N binding facilitated by the amino moiety (-NH2). The remaining XLPKs displayed binding modes involving oxygen atoms (Cu(II)-O) within the ketone moieties in the polymer backbone. Furthermore, the complexation and thermochemical analysis emphasized the role of the coordinator atom (N or O) and the coordinating environment, in which higher entropic effects involved in the adsorption of Cu2+ ions onto XLPKs describes a lower spontaneity of the adsorption process. The adsorption reactions were favored at lower temperatures and higher pressures. These findings provide valuable insights into the reactivity and adsorption mechanisms of functionalized and crosslinked polyketones for Cu2+ uptake, facilitating the design of high-performance polymeric resins for water treatment applications.

Graphene oxide-based dendritic adsorbent for the excellent capturing of platinum group elements

Herein, we report amino functionalized thermally stable graphene oxide-based dendritic adsorbent (GODA) with the highest sorption capacity ever recorded for platinum group elements (PGEs), including platinum (Pt(IV), PtCl₆^2-) and palladium (Pd(II), PdCl₄^2-), from highly acidic aqueous solutions. The GODA was designed and synthesized to have fully ionized amine binding sites and was characterized in detail. The detail batch adsorption experiment along with kinetic, isotherm, and thermodynamic studies were carried out to investigate the adsorption efficacy of GODA. For both Pt(IV) and Pd(II), the experimental data are more accurately fitted with the pseudo-second-order and the intraparticle diffusion kinetic models and Langmuir isotherm model as compared to the pseudo-first-order kinetic model and Freundlich and Temkin isotherm models, respectively. The material showed the highest ever adsorption capacities of 827.8 ± 27.7 mg/g (4.24 ± 0.00 mmol/g) and 890.7 ± 29.1 mg/g (8.37 ± 0.00 mmol/g) for Pt(IV) and Pd(II), respectively, at pH 1. The adsorption equilibriums were achieved within 70 min and 65 min for Pt(IV) and Pd(II), respectively. The thermodynamic parameters indicate that the adsorptions of both metals are spontaneous. The binding mechanisms are considered to be electrostatic interactions, hydrogen bonding, cationic-π bonding, and surface complexation between the sorbent and the sorbates. Furthermore, the as-prepared GODA exhibited high thermal stability and significant acid-resistance at pH 1. The GODA demonstrated excellent regeneration and reusability for Pt(IV) and Pd(II) over five adsorption/desorption cycles, indicating its excellence in practical applications.

Synthesis of hyperbranched polyamine dendrimer/chitosan/silica composite for efficient adsorption of Hg(II)

The pollution of water system with Hg(II) exerts hazardous effect to ecosystem and public health. Adsorption is considered to be a promising strategy to remove Hg(II) from aqueous solution. Herein, hyperbranched polyamine dendrimer/chitosan/silica composite (SiO₂-FP) was synthesized for the adsorption of aqueous Hg(II). The adsorption performance of SiO₂-FP was comprehensively determined by considering various influencing factors. SiO₂-FP displays good adsorption performance for Hg(II) with the adsorption capacity of 0.79 mmol·g^-1, which is higher than the corresponding chitosan functionalized silica (SiO₂-CTS) by 46.30 %. The optimal solution pH for the adsorption of Hg(II) is 6. Adsorption kinetic indicates the adsorption for Hg(II) can reach equilibrium at 250 min. Adsorption kinetic process can be well fitted by pseudo-second-order (PSO). Adsorption isotherm reveals the adsorption for Hg(II) can be promoted by increasing initial Hg(II) concentration and adsorption temperature. The adsorption isotherm indicates the adsorption process can be described by Langmuir model and the adsorption is a spontaneous, endothermic and entropy-increased process. SiO₂-FP displays excellent adsorption selectivity and can 100 % adsorb Hg(II) with the coexisting of Ni(II), Zn(II), Pb(II), Mn(II), and Co(II). Adsorption mechanism demonstrates -NH-, -NH₂, CN, CONH, -OH, and CO participated in the adsorption. SiO₂-FP exhibits good regeneration property and the regeneration rate can maintain approximately 90 % after five adsorption-desorption cycles.

Elevated Adsorption of Lead and Arsenic over Silver Nanoparticles Deposited on Poly(amidoamine) Grafted Carbon Nanotubes

An efficient adsorbent, CNTs-PAMAM-Ag, was prepared by grafting fourth-generation aromatic poly(amidoamine) (PAMAM) to carbon nanotubes (CNTs) and successive deposition of Ag nanoparticles. The FT-IR, XRD, TEM and XPS results confirmed the successful grafting of PAMAM onto CNTs and deposition of Ag nanoparticles. The absorption efficiency of CNTs-PAMAM-Ag was evaluated by estimating the adsorption of two toxic contaminants in water, viz., Pb(II) and As(III). Using CNTs-PAMAM-Ag, about 99 and 76% of Pb(II) and As(III) adsorption, respectively, were attained within 15 min. The controlling mechanisms for Pb(II) and As(III) adsorption dynamics were revealed by applying pseudo-first and second-order kinetic models. The pseudo-second-order kinetic model followed the adsorption of Pb(II) and As(III). Therefore, the incidence of chemisorption through sharing or exchanging electrons between Pb(II) or As(III) ions and CNTs-PAMAM-Ag could be the rate-controlling step in the adsorption process. Further, the Weber-Morris intraparticle pore diffusion model was employed to find the reaction pathways and the rate-controlling step in the adsorption. It revealed that intraparticle diffusion was not a rate-controlling step in the adsorption of Pb(II) and As(III); instead, it was controlled by both intraparticle diffusion and the boundary layer effect. The adsorption equilibrium was evaluated using the Langmuir, Freundlich, and Temkin isotherm models. The kinetic data of Pb(II) and As(III) adsorption was adequately fitted to the Langmuir isotherm model compared to the Freundlich and Temkin models.

The Adsorption of Heavy Metal Ions by Poly (Amidoamine) Dendrimer-Functionalized Nanomaterials: A Review

Rapid industrialization has resulted in serious heavy metal pollution. The removal of heavy metal ions from solutions is very important for environmental safety and human health. Poly (amidoamine) (PAMAM) dendrimers are artificial macromolecular materials with unique physical and chemical properties. Abundant amide bonds and amino functional groups provide them with a high affinity for heavy metal ions. Herein, PAMAM-functionalized adsorbents are reviewed in terms of different nanomaterial substrates. Approaches in which PAMAM is grafted onto the surfaces of substrates are described in detail. The adsorption isotherms and kinetics of these adsorbents are also discussed. The effects of PAMAM generation, pH, adsorbent dosage, adsorption time, thermodynamics, and ionic strength on adsorption performance are summarized. Adsorption mechanisms and the further functionalization of PAMAM-grafted adsorbents are reviewed. In addition to the positive results, existing problems are also put forward in order to provide a reference for the optimization of PAMAM-grafted adsorbents of heavy metal ions.

A Review: Adsorption and Removal of Heavy Metals Based on Polyamide-amines Composites

In recent years, the problem of heavy metal pollution has become increasingly prominent, so it is urgent to develop new heavy metal adsorption materials. Compared with many adsorbents, the polyamide-amine dendrimers (PAMAMs) have attracted extensive attention of researchers due to its advantages of macro-molecular cavity, abundant surface functional groups, non-toxicity, high efficiency and easy modification. But in fact, it is not very suitable as an adsorbent because of its solubility and difficulty in separation, which also limits its application in environmental remediation. Therefore, in order to make up for the shortcomings of this material to a certain extent, the synthesis and development of polymer composite materials based on PAMAMs are increasingly prominent in the direction of solving heavy metal pollution. In this paper, the application of composites based on PAMAMs and inorganic or organic components in the adsorption of heavy metal ions is reviewed. Finally, the prospects and challenges of PAMAMs composites for removal of heavy metal ions in water environment are discussed.

Kinetics, thermodynamics, equilibrium, surface modelling, and atomic absorption analysis of selective Cu(ii) removal from aqueous solutions and rivers water using silica-2-(pyridin-2-ylmethoxy)ethan-1-ol hybrid material

The removal of heavy metals is attracting considerable attention due to their undesirable effects on the environment. In this investigation, a new adsorbent based on silica functionalized with pyridin-2-ylmethanol (SiPy) was successfully synthesized to yield to a hybrid material. FTIR, SEM, TGA, and specific surface area analysis were used to characterize the structure and morphology of the SiPy hybrid material. Various heavy metal ions such as Cu(ii), Zn(ii), Cd(ii), and Pb(ii) were selected to examine the adsorption efficiency of the newly prepared adsorbent, optimized at varying solution pH, contact time, concentration, and temperature. The adsorbent SiPy displayed good adsorption capacity of 90.25, 75.38, 55.23, and 35.12 mg g⁻¹ for Cu(ii), Zn(ii), Cd(ii), and Pb(ii), respectively, at 25 min and pH = 6. The adsorption behaviors of metal ions onto the SiPy adsorbent fitted well with the pseudo-second-order kinetic mode and the isotherm was better described by the Langmuir isotherm. The thermodynamic studies disclose spontaneous and endothermic adsorption process. Furthermore, the SiPy adsorbent retained good selectivity and regeneration properties after five adsorption–desorption cycles of Cu(ii). A computational investigation of the adsorption mechanism indicates that the N-pyridine, O-hydroxyl, and ether O-atoms play a predominant role during the capture of Cu(ii), Zn(ii), Cd(ii), and Pb(ii). This study proposes the SiPy adsorbent as an attractive material for the selective removal of Cu(ii) from real river water and real industrial wastewater.

The removal of heavy metals is attracting considerable attention due to their undesirable effects on the environment.

The Electrospray (ESI) and Flowing Atmosphere-Pressure Afterglow (FAPA) Mass Spectrometry Studies of Nitrophenols (Plant Growth Stimulants) Removed Using Strong Base-Functionalized Materials

The functional silica-based materials functionalized with a strong nitrogen base TBD (SiO₂-TBD) deposited via a linker or with a basic poly(amidoamine) dendrimer containing multiple terminal amine groups -NH₂ (SiO₂-EDA) and functional polymers containing a strong phosphazene base (Polymer-Phosphazene) or another basic poly(amidoamine) dendrimer (PMVEAMA-PAMAM) were tested as sorbents dedicated to a mixture of nitrophenols (p-nitrophenol and 2-methoxy-5-nitrophenol), which are analogs of nitrophenols used in plant growth biostimulants. The adsorptive potential of the studied materials reached 0.102, 0.089, 0.140, and 0.074 g of the nitrophenols g⁻¹, for SiO₂-TBD, SiO₂-EDA, polymer-phosphazene, and PMVEAMA-PAMAM, respectively. The sorptive efficiency of the analytes, i.e., their adsorption on the functional materials, the desorption from the obtained [(sorbent)H⁺ − nitrophenolates^–] complexes, and interactions with the used soil, were monitored using mass spectrometry (MS) technique with electrospray (ESI) and flowing atmosphere-pressure afterglow (FAPA) ionizations, for the analysis of the aqueous solutions and the solids, respectively. The results showed that the adsorption/desorption progress is determined by the structures of the terminal basic domains anchored to the materials, which are connected with the strength of the proton exchange between the sorbents and nitrophenols. Moreover, the conducted comprehensive MS analyses, performed for both solid and aqueous samples, gave a broad insight into the interactions of the biostimulants and the presented functional materials.

A Highly Efficient Environmental-Friendly Adsorbent Based on Schiff Base for Removal of Cu(II) from Aqueous Solutions: A Combined Experimental and Theoretical Study

Removal of heavy metals from drinking water sources and rivers is of strategic health importance and is essential for sustainable ecosystem development, in particular in polluted areas around the globe. In this work, new hybrid inorganic-organic material adsorbents made of ortho- (Si-o-OR) or para-Schiff base silica (Si-p-OR) were synthesized and characterized in depth. These hybrid adsorbents show a high selectivity to Cu(II), even in the presence of competing heavy metals (Zn(II), Cd(II), and Pb(II)), and also demonstrate great reusability after five adsorption-desorption cycles. Maximum sorption capacity for Cu(II) was found for Si-o-OR (79.36 mg g⁻¹) and Si-p-OR (36.20 mg g⁻¹) in no less than 25 min. Energy dispersive X-ray fluorescence and Fourier transform-infrared spectroscopy studies demonstrate that this uptake occurs due to a chelating effect, which allows these adsorbents to trap Cu(II) ions on their surfaces; this result is supported by a theoretical study for Si-o-OR. The new adsorbents were tested against real water samples extracted from two rivers from the Oriental region of Morocco.

Adsorption and selectivity studies of direct and magnetite-cored molecularly imprinted polymers (MIPs and magMIPs) towards chosen chalcones investigated with various analytical methods

The following article presents a method for obtaining molecularly imprinted polymers (MIPs) dedicated to trans-chalcone (TC) and 2',4'-dihydroxy-3-methoxychalcone (DHMC). The synthetic protocol optimized with a choice of the most suitable functional monomer led to the synthesis of MIPs and their non-imprinted equivalents (NIP) performed via direct polymerization or on the surface of magnetite nanoparticles. The characterized materials were investigated for adsorption isotherms of TC and DHMC, which led to satisfactory values of maximal adsorption capacity, reaching 131.58 and 474.71 mg g^-1, respectively. Moreover, all the polymers were studied for the adsorption kinetics and the selectivity towards four structurally different chalcones, which proved the proper selectiveness towards the template molecules. Also, the kinetic profiles of chalcones' adsorption on the synthesized MIPs showed a quasi-plateau reached already after 2 hours, indicating high sorption effectiveness. The studies involved the use of various analytical techniques, which afforded a comprehensive and reliable description of the materials' adsorption efficacy. It was found that the materials successfully bind the MIP-complementary analytes and also structurally similar chalcones, with slightly lower intensity.

Dendritic Polymers as Promising Additives for the Manufacturing of Hybrid Organoceramic Nanocomposites with Ameliorated Properties Suitable for an Extensive Diversity of Applications

As the field of nanoscience is rapidly evolving, interest in novel, upgraded nanomaterials with combinatory features is also inevitably increasing. Hybrid composites, offer simple, budget-conscious and environmental-friendly solutions that can cater multiple needs at the same time and be applicable in many nanotechnology-related and interdisciplinary studies. The physicochemical idiocrasies of dendritic polymers have inspired their implementation as sorbents, active ingredient carriers and templates for complex composites. Ceramics are distinguished for their mechanical superiority and absorption potential that render them ideal substrates for separation and catalysis technologies. The integration of dendritic compounds to these inorganic hosts can be achieved through chemical attachment of the organic moiety onto functionalized surfaces, impregnation and absorption inside the pores, conventional sol-gel reactions or via biomimetic mediation of dendritic matrices, inducing the formation of usually spherical hybrid nanoparticles. Alternatively, dendritic polymers can propagate from ceramic scaffolds. All these variants are covered in detail. Optimization techniques as well as established and prospected applications are also presented.

Efficient and Environmentally Friendly Adsorbent Based on β-Ketoenol-Pyrazole-Thiophene for Heavy-Metal Ion Removal from Aquatic Medium: A Combined Experimental and Theoretical Study

A new sustainable and environmentally friendly adsorbent based on a β-ketoenol-pyrazole-thiophene receptor grafted onto a silica surface was developed and applied to the removal of heavy-metal ions (Pb(II), Cu(II), Zn(II), and Cd(II)) from aquatic medium. The new material SiNPz-Th was well characterized and confirms the success of covalent binding of the receptor on the silica surface. The effect of environmental parameters on adsorption including pH, contact time, temperature, and the initial concentration were investigated. The maximum adsorption capacities of SiNPz-Th for Pb(II), Cu(II), Zn(II), and Cd(II) ions were 102.20, 76.42, 68.95, and 32.68 mg/g, respectively, at 30 min and pH = 6. The adsorption isotherms, kinetics, and thermodynamic process were investigated and showed efficiency and selectivity toward Pb(II) and good regeneration performance. Density functional theory, noncovalent-interaction, and quantum theory of atoms in molecules calculations were used to study and to gain a deeper understanding of both the adsorption mechanism and selectivity of metal ions onto the adsorbent. Accordingly, metal ions such as Pb(II), Cu(II), and Zn(II) were bidentate coordinated with the adsorbent by nitrogen and oxygen atoms of the Schiff base C=N and hydroxyl group -OH, respectively, to form stable complexes. Whereas Cd(II) was coordinated in a monodentate fashion with oxygen atom of the hydroxyl group. Furthermore, the affinity of SiNPz-Th toward the metal ions was decreased in the order of Pb(II) > Cu(II) > Zn(II) > Cd(II), in good agreement with the experimental results. All these results highlight that SiNPz-Th has good potential to be an advanced adsorbent for the removal of lead ions from real water.

Biocompatible chitosan-zinc oxide nanocomposite based dispersive micro-solid phase extraction coupled with HPLC-UV for the determination of rosmarinic acid in the extracts of medical plants and water sample

In the present research, a procedure was described for the recovery of rosmarinic acid (RA) from medical extract samples using chitosan‑zinc oxide nanoparticles as a biocompatible nanocomposite (CS-ZnO-NC). The dispersive micro-solid phase extraction (D-μ-SPE) of RA from the medical extract samples was investigated by using the prepared biocompatible composite as a solid phase. The HPLC-UV method was used for measuring the extracted RA. The important variables (pH, biocompatible composite mass, contact time, and volume of eluent) associated with the extraction process were analyzed by the application of central composite design (CCD). The achieved optimum values for the mentioned variables were 7.0, 10 mg, 4 min, and 180 μL, respectively. The extraction recovery (99.68%) obtained from the predicted model was in agreement with the experimental data (98.22 ± 1.33%). In addition, under the obtained optimum conditions and over the concentration in the range of 2-3500 ng mL-1, a linear calibration curve was obtained with R2 > 0.993. The limit of detection (LOD) and quantification (LOQ) values were computed, and the obtained ranges were respectively from 0.060 to 0.089 ng mL-1 and 0.201 to 0.297 ng mL-1. In addition, the enrichment factors were obtained in the range of 93.7-110.5 with preconcentration factor of 83.3. Therefore, the D-μ-SPE-HPLC-UV method could be used for analyzing RA in the samples of the extracts obtained from the medical plants and water with the recovery values of the analyte in the range of 96.6%-105.4% and the precision with relative standard deviation <5.7%.