Adsorption of Lead Ions from Aqueous Phase on Mesoporous Silica with P-Containing Pendant Groups

Lead Extraction in a Functionalized and Permeable Silica-Based Porous Liquid

Silica-based porous liquids (PLs) are innovative and versatile liquid materials with a high potential, although their application is often restricted to gas sorption. In this work, we propose to evaluate their potential to extract metals. For this goal, we have adapted their synthesis to provide PLs functionalized with thiols that are expected to chelate metallic contaminants, such as lead. As the accessibility of liquids and metals to the PL's porous network is one of the key points for their application, we developed an original small-angle neutron scattering experiment to verify that the PL is permeable to polar liquids. Then, preliminary extraction tests have successfully been carried out, with an extraction of lead cations by complexation on one-third of accessible thiol groups. This work demonstrates that the extraction of metal species by a PL is possible and opens many perspectives for optimization.

Design of Zr-MOFs by Introducing Multiple Ligands for Efficient and Selective Capturing of Pb(II) from Aqueous Solutions

The existence of lead ions seriously affects the quality of many metal products in metallurgical enterprises. Currently, the various methods of lead-ion removal tried by researchers will affect valuable metals in the removal process, thus resulting in low economic efficiency. In this study, a novel metal-organic framework adsorbent (UiO-FHD) which efficiently and selectively captures lead ions is developed by introducing multiple ligands. The maximum adsorption capacity of lead ions is 433.15 mg/g at pH 5. The adsorption process accords with the pseudo-second-order kinetic and the Langmuir isotherm models at room temperature. Thermodynamic experiments indicate that the removal of Pb(II) is facilitated by appropriate temperature reduction. The performance tests indicate that UiO-FHD maintains a high removal rate of 90.35% for Pb(II) after four consecutive adsorption-desorption cycles. The distribution coefficient of lead ions (26.7 L/g) shows that UiO-FHD has excellent selective adsorption for lead ions. It is revealed that the chelation of the sulfhydryl groups and the electrostatic interaction of the hydroxyl groups are the dominant factors to improve the removal rate of Pb(II) by density functional theory calculations. This study clarifies the value of self-designed novel organic ligands in metal-organic framework materials that selectively capture heavy-metal ions.

Systematic Modulation of Thiol Functionalities in Inexpensive Porous Polymers for Effective Mercury Removal

Through accumulation, mercury contamination in aquatic systems still poses serious health risks despite the strict regulations on drinking water and industrial discharge. One effective strategy against this is adsorptive removal, in which a suitably functionalized porous material is added to water treatment protocols. Thiol (SH) group-grafted structures perform commendably; however, insufficient attention is paid to the cost, scalability, and reusability or how the arrangement of sulfur atoms could affect the Hg^II binding strength. We used an inexpensive and scalable porous covalent organic polymer (COP-130) to systematically introduce thiol functional groups with precise chain lengths and sulfur content. Thiol-functionalized COP-130 demonstrates enhanced wettability and excellent Hg^II uptake of up to 936 mg g^-1 , with fast kinetics and exceptionally high selectivity. These Hg adsorbents are easily regenerated with HCl and can be used at least six times without loss of capacity even after treatment with strong acid, a rare performance in the domain of Hg-removal research.

Recent progress in the applications of silica-based nanoparticles

Functionalized silica nanoparticles (SiO2 NPs) have attracted great attention due to their promising distinctive, versatile, and privileged physiochemical characteristics. These enhanced properties make this type of functionalized nanoparticles particularly appropriate for different applications. A lack of reviews that summarizes the fabrications of such nanomaterials and their different applications in the same work has been observed in the literature. Therefore, in this work, we will discuss the recent signs of progress in the fabrication of functionalized silica nanoparticles and their attractive applications that have been extensively highlighted (advanced catalysis, drug-delivery, biomedical applications, environmental remediation applications, and wastewater treatment). These applications have been selected for demonstrating the role of the surface modification step on the various properties of the silica surface. In addition, the current challenges in the applications of functionalized silica nanoparticles and corresponding strategies to discuss these issues and future perspectives for additional improvement have been addressed.

Improvement of heavy metal removal from urban runoff using modified pervious concrete

Heavy metals are one of the major chemical pollutant groups in urban runoff. The application of porous concrete is a potential alternative to conventional runoff management systems with the ability to remove heavy metals. Hence, a thorough understanding of the heavy metal removal mechanisms and constraints of conventional porous concrete opens a path for the development of effective modifications. This review critically discusses the major contributors in ordinary porous concrete which supports heavy metal removal. The effects of initial concentration, contact time and competing ions on heavy metal removal using porous concrete are also discussed. Additionally, the effect of decalcification, atmospheric carbonation, acid influent on heavy metal removal is reviewed. The major drawback of porous concrete is the high pH (>8.5) of the effluent water, decalcification of the porous concrete and leaching of adsorbed pollutants. Overall, the addition of adsorbent materials to the porous concrete increases removal efficiencies (7% - 65% increase) without neutralizing the effluent pH. Meanwhile, the addition of Reduced Graphene Oxide is successful in reducing the leachability of the removed heavy metals. The addition of pozzolanic materials can lower the effluent pH while maintaining similar removal efficiencies to unmodified porous concrete. Therefore, developing a novel method of neutralizing the effluent pH must be prioritized in future studies. Additionally, the toxicity that can occur due to the abrasion of modified porous concrete requires study in future research. Further, advanced characterization methods should be used in future studies to understand the mechanisms of removal via the modified porous concrete materials.

Removal of Pb(II) Ions from Aqueous Solution Using Modified Starch

In this study, two types of modified cassava starch samples (MCS and MWS) prepared from commercially available native cassava starch (NCS) and native cassava starch extracted using the wet method (NWS) were investigated for the removal of Pb(II) ions from aqueous solutions. MCS and MWS samples were synthesized under acidic conditions using Pluronic 123 as the structure-directing agent and tetraethylorthosilicate (TEOS) as the chemical modifying agent. Modified starch samples were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray Diffraction (XRD), and a nitrogen (N2) gas adsorption–desorption analyser. MCS and MWS showed enhanced thermal stabilities upon acid hydrolysis and chemical modification. The effects of contact time and initial Pb(II) concentration were studied through batch adsorption experiments. Adsorption kinetics followed the pseudo-second-order kinetic model. The equilibrium adsorption data were analysed and compared by the Langmuir and Freundlich adsorption models. The coefficient correlation (R2) was employed as a measure of the fit. The Langmuir model fitted well with equilibrium adsorption data, giving a maximum Pb(II) adsorption capacity of 370.37 and 294.12 mg/g for MWS and MCS, respectively. Modified samples exhibited a higher desorption efficiency of over 97%. This study demonstrated that modified starch could be utilized for Pb(II) removal from industrial wastewater.

High adsorption capacity and super selectivity for Pb(Ⅱ) by a novel adsorbent: Nano humboldtine/almandine composite prepared from natural almandine

This study firstly reported a novel nano humboldtine/almandine composite (NHLA composite) prepared directly from almandine through one-pot method based on the interaction of almandine and oxalic acid. The formation of humboldtine/almandine binary phase from natural almandine was determined by X-ray diffraction. Analysis of scanning & transmission electron microscope showed that large amount of nano humboldtine with uniform size (average size of 15.59 nm) were loaded on the almandine sheets. Compared with raw minerals, Pb(Ⅱ) removal capacity of synthesized composite was significantly increased, demonstrating that the main active ingredient for Pb(Ⅱ) removal was humboldtine phase rather than almandine itself. Pb(Ⅱ) adsorption capacity was increased with the increasing of initial pH value or temperature. Langmuir isotherm and Pseudo-second order kinetic equation were well fitted with experimental results and the maximum Pb(Ⅱ) adsorption capacity from Langmuir isotherm was 574.71 mg/g at temperature of 25 °C. In addition, heavy metal removal experiments in coexisting systems of multiple heavy metal ions manifested that the composite had a high selectivity for Pb(Ⅱ) adsorption. Ion exchange, surface complexation and electrostatic interaction have involved in the Pb(Ⅱ) adsorption. The synthesized composite was considered as a low cost, high efficiency, super selectivity and easy to mass production material for Pb(Ⅱ) adsorption from solution.

A novel method based on functionalized bimodal mesoporous silica nanoparticles for efficient removal of lead aerosols pollution from air by solid-liquid gas-phase extraction

In this study, the enrichment and novel sorbent based on functionalized bimodal mesoporous silica nanoparticles (HS-UVM7 and NH2-UVM7) was used for removal of lead aerosols pollution from air by solid liquid gas phase extraction method (SLGPE). In bench scale set up, the lead aerosols [(Pb (NO3)2, PbO] was generated by dispersive aerosols generator system (DAGS) and removed from air by reaction loop (RL) / impinger trap (IT) in a liquid phase which was mixed with nano adsorbent in optimized pH. The effect of parameters such as, flow rate, volume of liquid phase, time stirring, temperature, concentration, pH and amount of sorbent (mg) were studied and evaluated by flame atomic absorption spectrometry (FAAS). In optimized conditions, the adsorption capacity of HS-UVM7 and NH2-UVM7 for Pb(NO3)2 aerosols was obtained 255.6 mg g-1 and 177.6 mg g-1, respectively which was more than UVM7. The lead oxides aerosols (PbO) were extracted only by HS-UVM7 at acidic pH with the adsorption capacity of 271.2 mg g-1. The characterization of SEM, XRD, TEM, and FTIR showed that the HS-UVM7 has beneficial surfaces for removal of (Pb (NO3)2 and PbO aerosols from the air by SLGPE method at pH = 5. The method validation was confirmed by standard addition and NIOSH method. Graphical abstract.

Synthesis of Hematite Nanodiscs from Natural Laterites and Investigating Their Adsorption Capability of Removing Ni2+ and Cd2+ Ions from Aqueous Solutions

In this work, disc-like hematite (Fe2O3) nanoparticles were prepared using a readily available inexpensive earth material, ferruginous laterite, via a low-cost synthesis route. Prepared hematite nanoparticles were characterized using X-Ray diffraction (XRD), inductively coupled plasma mass spectroscopy (ICP-MS), particle size analyzer (PSA), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and nitrogen adsorption-desorption analyzer. The performance of hematite nanoparticles was evaluated as a heavy metal ion adsorbent. Batch adsorption experiments were conducted to study the adsorption behaviour of Ni2+ and Cd2+ ions as a function of the amount of adsorbent, contact time, and pH. Adsorption data fitted to the linearized Langmuir and Freundlich kinetic models were compared and discussed. The correlation coefficient (R2) was used to determine the best fit kinetic model. Our data fitted the Langmuir kinetic model well and the highest adsorption efficiencies were found to be 62.5 mg/g for Ni2+ and 200 mg/g for Cd2+, respectively. Due to high surface area, pore volume with active sites, and sorption capabilities, hematite nanoparticles can be used as efficient and economical nano-adsorbents for the removal of Ni2+ and Cd2+ ions from industrial wastewater.

Facile synthesis of amino-functional large-size mesoporous silica sphere and its application for Pb2+ removal

Amino-functional large-size mesoporous silica spheres (LMS-AP) were successfully synthesized through a one-step method with (3-aminopropyl) triethoxysilane (APTES) addition during the pseudomorphic transformation process. LMS-AP were characterized using thermogravimetry-differential thermal analysis, Nitrogen adsorption-desorption measurement, infrared spectroscopy, and X-ray photoelectron spectroscopy. The study found that -NH₂ was grafted into LMS, and the LMS-AP had a better thermal stability than other samples. The Pb²⁺ removal properties of LMS-AP were investigated using the static and dynamic experiments in simulated and real wastewater solutions. The kinetic and equilibrium experiments indicated that the adsorption process of LMS-AP fitted the Langmuir adsorption model and the pseudo-second-order kinetics model (R² > 0.98), respectively. The maximum Q_e (mg/g) was about 100 mg/g in the static adsorption condition. The adsorption mechanism of removal of Pb²⁺ was also investigated. In fix bed column experiments, LMS-AP exhibited excellent Pb²⁺ adsorption ability for simulated wastewater, with the maximum q_e (mg/g) of 48.7 mg/g for particle size under 1-3 mm. Meanwhile in actual industrial wastewater treatment process, LMS-AP had a better Pb²⁺, Zn²⁺ and Cr (VI) removal efficiency of 80% and As (V) of 30-40% removal efficiency at initial pH 4, suggesting selective adsorption property for different heavy metal ions.

One-Pot Synthesis of Layered Disodium Zirconium Phosphate: Crystal Structure and Application in the Remediation of Heavy-Metal-Contaminated Wastewater

Inorganic ion exchangers offer advantages whenever operation at high temperatures or in oxidizing environments is required. A novel two-dimensional disodium zirconium phosphate, Zr(NaPO₄)₂·H₂O, was reported and investigated as an ion exchanger for heavy metals. The material was synthesized by a novel minimalistic solventless approach, and its solid-state structure was determined from powder X-ray diffraction data. Zr(NaPO₄)₂·H₂O crystallizes in the space group P2₁/c with cell parameters a = 8.7584(1) Å, b = 5.3543(1) Å, c = 18.1684(3) Å, β = 109.053 (1)°, and Z = 4. Its layered structure is similar to that of α-zirconium phosphate, Zr(HPO₄)₂·H₂O. However, unlike α-zirconium phosphate which is limited in practical applications by its narrow interlayer spacing (d = 7.6 Å), the disodium zirconium phosphate has a larger spacing of 8.6 Å between planes. The material with inherent structural advantages displays excellent sorption for heavy metals such as Pb²⁺, Cu²⁺, Cd²⁺, and Tl⁺, maintaining its high selectivity with distribution coefficients, K_d, of 10⁴-10⁵ mL/g even in the presence of a large excess of Na⁺, K⁺, Mg²⁺, and Ca²⁺, which are commonly present in underground water. In particular, the maximum sorption capacity for the highly toxic Tl⁺ is a record high, 5.07 mmol/g (1036 mg/g). The fast reaction kinetics indicate that the exchangeable positions in Zr(NaPO₄)₂·H₂O are readily accessible, in contrast to Zr(HPO₄)₂·H₂O. The ease of preparation, benign nature, and advantageous ion-exchange properties make Zr(NaPO₄)₂·H₂O a highly promising sorbent for the treatment of water polluted with heavy metals.

Economic and Efficient phosphonic functional groups mesoporous silica for uranium selective adsorption from aqueous solutions

A novel mesoporous silica with enhanced phosphonic functional groups (PFGs) and without any silane agents was provided by Sol-Gel technique for selective adsorption of U(VI) from aqueous solutions (AqS). The absorbent was synthesized based on the achieving the four best performance characteristics including availability, economically, adsorption efficiency, and selectivity which are undoubtedly defined the usefulness of the adsorbents. The sorption results exhibited the highest uranium adsorption capacity, qe, of 820.7 mg/g at pH ≈ 8 which indicated the adsorbent is the best alternative for uranium adsorption from the nearly neutral solutions such as seawater. The recovery percentages by the adsorbent in the aqueous environments involving other elements such as Mg, Cd, Hg, As, Ca, Na, Ni and the salty environment with high concentration of Cl- ions are indicated that the adsorbent presents the acceptable selectivity for uranium adsorption from the AqS such as industrial wastewater. Several activities and factors including removing the silane agents, using sodium metasilicate as an available and low-cost source of silica, and using the Sol-gel method as an unexpansive synthesis technique caused to reduce the synthesis costs from 222.787 EUR/kg for the template method to 60.078 EUR/kg for Sol-gel method which confirm the synthesis of a cost-effective adsorbent.

The synthesis of PEI core@silica shell nanoparticles and its application for sensitive electrochemical detecting mi-RNA

Although the silica-based nanoparticles (NPs) have been widely explored as the labels for sensing different targets, the simple and novel scheme, to impose a large number of signal molecules inside silica NPs, is challenge. Herein, a new scheme for this purpose was developed. This new strategy was based on densely doped polyethyleneimine (PEI) inside silica nanoparticles and forming the PEI@silica nanoparticles. Then, the Cu²⁺ was selected as the electrochemical signal molecule model to be loaded in PEI@silica nanoparticles the based on the strong coordination reaction of Cu²⁺ with PEI and test its signal amplification ability. Our results showed that 7.6 × 10⁵ Cu²⁺signal ions could be loaded in a single PEI@silica nanoparticles. Thereafter, based on the discriminating interaction of this PEI/Cu²⁺/SiO₂ NPs towards both ssDNA probes and ssDNA probe/mi-RNA complex, as well as the specific adsorption effect of this NPs on chemically modified electrode, a highly sensitive electrochemical method for detecting mi-RNA was developed and successfully used to detect mi-RNA in the human serum samples.

Novel Ion-Imprinted Carbon Material Induced by Hyperaccumulation Pathway for the Selective Capture of Uranium

The development of nuclear energy is significant for resource sustainability. Uranium is the main nuclear fuel, and its effective absorption has captured the attention of researchers. In this study, the green technologies hyperaccumulation effect of the plant and ion-imprinted technology were used to prepare the uranium ion-imprinted hierarchically porous carbon material (II-HPC). At the same time, a nonimprinted hierarchically porous carbon (HPC) was prepared for comparison. The adsorption isotherm was fitted to the Langmuir model and maximum sorption capacity of II-HPC was 503.64 mg g^-1 at 298 K. The kinetic data followed the pseudo-second-order model, indicating a dominant role of chemisorption. Initial studies were performed on a lab-scale simulated continuous-flow system for the adsorption kinetics testing of II-HPC in simulated seawater. The results showed that the amount of uranium adsorbed after 35 days was 0.379 mg g^-1, which determined that II-HPC adsorbent is a potential material for enrichment of U(VI) from the seawater.

Hydrothermal synthesized magnetically separable mesostructured H2Ti3O7/γ-Fe2O3 nanocomposite for organic dye removal via adsorption and its regeneration/reuse through synergistic non-radiation driven H2O2 activation

Hydrogen titanate (H₂Ti₃O₇) nanotubes/nanosheets (HTN) are emerging class of adsorbent material which possess unique property of activating hydrogen peroxide (H₂O₂) to generate the reactive oxygen species (ROS), such as superoxide radical ions (O₂^.-) and hydroxyl radicals (·OH), effective in the decomposition of surface-adsorbed dye. However, HTN are non-magnetic which create hurdle in their effective separation from the treated aqueous solution. To overcome this issue, magnetic nanocomposites (HTNF) composed of HTN and maghemite (γ-Fe₂O₃) nanoparticles have been processed by subjecting the core-shell magnetic photocatalyst consisting of γ-Fe₂O₃/silica (SiO₂)/titania (TiO₂), having varying amounts of TiO₂ in the shell to the hydrothermal conditions. HTNF-5 magnetic nanocomposite consisting of 31 wt% H₂Ti₃O₇, typically having nanotube morphology with the highest specific surface area (133 m² g^-1) and pore-volume (0.22 cm³ g^-1), exhibits the highest capacity (74 mg g^-1) for the adsorption of cationic methylene blue (MB) dye from an aqueous solution involving the electrostatic attraction mechanism and pseudo-second-order kinetics. Very fast magnetic separation followed by regeneration of HTNF-5 magnetic nanocomposite has been demonstrated via non-radiation driven H₂O₂ activation. It has been ascertained for the first time that the underlying mechanism of dye decomposition involves the synergy effect between the constituents of HTNF magnetic nanocomposite.

Colorimetric and Electrochemiluminescence Dual-Mode Sensing of Lead Ion Based on Integrated Lab-on-Paper Device

A highly selective two-point separation strategy was designed based on a cross-like all-in-one lab-on-paper analytical device. The stable and cleavable enzyme-coated reduced graphene oxide (rGO)-PdAu probe was fabricated as the signal reporter to enable the visualization and electrochemiluminescence (ECL) dual-mode sensing of Pb²⁺. Concretely, the experimental workflow consists of the following process: (i) fabrication of the lab-on-paper device and growth of Au nanoparticles on ECL detection zone, (ii) immobilization of Pb²⁺-specific DNAzyme, and (iii) hybridization between DNAzyme and rGO-PdAu-glucose oxidase (GOx) labeled oligonucleotide to form the double-stranded DNA. Upon addition of Pb²⁺ into the prepared system, the double-helix structure of the DNA was destroyed, resulting in the release of cleaved rGO-PdAu-GOx probe to visualization bar to promote the effective oxidation and color change of 3,3',5,5'-tetramethylbenzidine. As a consequence, the color change can be recognized by naked eye, meanwhile GOx on an uncleaved signal probe can oxidize glucose along with the H₂O₂ production. As a co-reaction reagent for luminol ECL system, the concentration of H₂O₂ is proportional to the ECL intensity, which constitutes a new mechanism for colorimetric and ECL dual mode to detect Pb²⁺. With the method developed here, the concentration of Pb²⁺ could be easily determined by the naked eye within a linear range from 5 to 2000 nM, as well as by monitoring the decreased ECL intensity of luminol in a linear range of 0.5-2000 nM. This work not only constructs a simple and versatile platform for on-site visible monitoring of Pb²⁺ in tap water and river water but also furnishes a strategy for designing a dual-mode sensing toward different heavy metal ions based on specific DNAzyme in the fields of environmental monitoring-related technologies.

P, Balakrishna GR, M. S. J. La activated high surface area titania float for the adsorption of Pb(ii) from aqueous media

Smaller particle size with higher surface area La-TiO₂ fabricated float depicts enhanced adsorption of hazardous heavy metal ion Pb²⁺, present in the aqueous media and the float makes the process easy and reusable.

Synthesis of enhanced phosphonic functional groups mesoporous silica for uranium selective adsorption from aqueous solutions

Enhanced phosphonic functional group (PFG)-based mesoporous silicas (MSs) were synthesized by hydrothermal method for uranium [U(VI)] selective adsorption from aqueous solutions. Considering that PFGs are directly related to U(VI) adsorption, the main idea of this research was to synthesize enhanced PFG-MSs and consequently enhance U(VI) adsorption. We synthesized two kinds of MSs based on acetic and phosphoric acids at weakly acidic pH, which allows high-loading phosphonic functionality. The main sodium and phosphonic functionality sources were sodium metasilicate and diethylphosphatoethyltriethoxysilane (DPTS). Adsorption experiment results exhibit enhanced U(VI) adsorption capacity from 55.75 mg/g to 207.6 mg/g for acetic and phosphoric acids, respectively. This finding was due to the enhancement of PFGs by phosphoric acids. The highest adsorption selectivity was 79.82% for U(VI) among the six different elements, including Pb, As, Cu, Mo, Ni, and K. Structural characterization of the samples was performed by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller analysis methods. Element concentrations were measured by inductively coupled plasma optical emission spectrometry. Several parameters affecting adsorption capacity, including pH, contact time, initial U(VI) concentration and solution volume, and adsorbent concentration, were also investigated.

Multifold enhanced synergistic removal of nickel and phosphate by a (N,Fe)-dual-functional bio-sorbent: Mechanism and application

A novel (N,Fe)-dual-functional biosorbent (N/Fe-DB) capable of efficient synergistic removal of Ni(II) and H₂PO₄^- from aqueous solution was synthesized. The adsorption capacities of Ni(II) and H₂PO₄^- were both remarkably enhanced over 3 times compared with those in single systems. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that complexation of amino groups and ligand exchange of hydrous ferric oxide in N/Fe-DB played dominant roles. The electric double layer compressing and chelating ligand of deprotonated H₂PO₄^- accounted for the enhanced removal of Ni(II) in binary system, while cation bridge interaction promoted uptake of H₂PO₄^-. Furthermore, the coadsorbates were sequentially recovered, with the ratios of more than 99.0%. Besides, the recovered N/Fe-DB remained stable and applicable to the treatment of real electroplating wastewater even after six adsorption-regeneration cycles. Since the electroplating industry is springing up, effective control of heavy metals and phosphate has attracted global concerns. Based on the enhanced coremoval properties and superb regenerability, N/Fe-DB is potentially applicable to practical production.

β-FeOOH Nanorods/Carbon Foam-Based Hierarchically Porous Monolith for Highly Effective Arsenic Removal

Arsenic pollution in waters has become a worldwide issue, constituting a severe hazard to whole ecosystems and public health worldwide. Accordingly, it is highly desirable to design high-performance adsorbents for arsenic decontamination. Herein, a feasible strategy is developed for in situ growth of β-FeOOH nanorods (NRs) on a three-dimensional (3D) carbon foam (CF) skeleton via a simple calcination process and subsequent hydrothermal treatment. The as-fabricated 3D β-FeOOH NRs/CF monolith can be innovatively utilized for arsenic remediation from contaminated aqueous systems, accompanied by remarkably high uptake capacity of 103.4 mg/g for arsenite and 172.9 mg/g for arsenate. The superior arsenic uptake performance can be ascribed to abundant active sites and hydroxyl functional groups available as well as efficient mass transfer associated with interconnected hierarchical porous networks. In addition, the as-obtained material exhibits exceptional sorption selectivity toward arsenic over other coexisting anions at high levels, which can be ascribed to strong affinity between active sites and arsenic. More importantly, the free-standing 3D porous monolith not only makes it easy for separation and collection after treatment but also efficiently prevents the undesirable potential release of nanoparticles into aquatic environments while maintaining the outstanding properties of nanometer-scale building blocks. Furthermore, the monolith absorbent is able to be effectively regenerated and reused for five cycles with negligible decrease in arsenic removal. In view of extremely high adsorption capacities, preferable sorption selectivity, satisfactory recyclability, as well as facile separation nature, the obtained 3D β-FeOOH NRs/CF monolith holds a great potential for arsenic decontamination in practical applications.

Preparation and characterization of novel phthalhydrazide-functionalized MCM-41 and its application in the one-pot synthesis of coumarin-fused triazolopyrimidines

Preparation and characterization of novel phthalhydrazide-functionalized MCM-41 and its application in the one-pot synthesis of 4-hydroxycoumarin-fused triazolopyrimidines.

Pore-Free Matrix with Cooperative Chelating of Hyperbranched Ligands for High-Performance Separation of Uranium

A new strategy combining a pore-free matrix and cooperative chelating was proposed in the present paper in order to effectively avoid undesired nonselective physical adsorption and intraparticle diffusion caused by pores and voids in porous sorbents, and to greatly enhance uranium-chelating capability based on hyperbranched amidoxime ligands on the surface of nanodiamond particles. Thus, a pore-free, amidoxime-terminated hyperbranched nanodiamond (ND-AO) was designed and synthesized. The experimental results demonstrate that the strategy endows the as-synthesized ND-AO with the following expected features: (1) distinctively high uranium selectivity (S_U = q_e-U/q_e-tol × 100%) from over 80% to nearly 100% over the whole weak acidity range (pH < 4.5); especially, the S_U can reach up to unprecedented >91% at pH 4.5, more than 20% of selectivity increment over any analogous sorbent materials reported so far, with a uranium sorption capacity of 121 mg/g in simulated nuclear industry effluent samples containing 12 coexistent nuclide ions; (2) superfast equilibrium sorption time of <30 s; and (3) one of the highest distribution coefficients (K_d) of ∼3 × 10⁶ mL/g for U(VI) as well as a fairly high sorption capacity of 212 mg/g at pH 4.5 in pure uranium solution. The strategy could also provide an optional approach for the design and fabrication of other new high-performance sorbing materials with prospective applications in selective separation of other interested metal ions.

Enhanced photodegradation of dyes and mixed dyes by heterogeneous mesoporous Co–Fe/Al2O3–MCM-41 nanocomposites: nanoparticles formation, semiconductor behavior and mesoporosity

Fabrication of mono and bimetallic nanoparticles by in situ sol–gel cum hydrothermal method for photo degradation of dyes and mixed dyes.