Enhanced Versatility in Thorium Removal: Mesoporous Silica-Coated Magnetic Nanoparticles Functionalized by Phenanthroline Diamide as a Selective Adsorbent

In order to promote the sustainable development of nuclear energy through thorium (Th(IV)) recycling, we synthesized SiO2-coated magnetic functional nanocomposites (SiO2@Fe3O4) that were modified with 2,9-diamide-1,10-phenanthroline (DAPhen) to serve as an adsorbent for Th(IV) removal. SiO2@Fe3O4-DAPhen showed effective Th(IV) adsorption in both weakly and strongly acidic solutions. Owing to its porous structure that facilitated rapid adsorption kinetics, equilibrium was achieved within 5 and 0.5 min at pH 3 and 1 mol L-1 HNO3, respectively. In weakly acidic solutions, Th(IV) primarily formed chemical coordination bonds with DAPhen groups, while in strongly acidic solutions, the dominant interaction was electrostatic attraction. Density functional theory (DFT) calculations indicated that electrostatic attraction was weaker compared to chemical coordination, resulting in reduced diffusion resistance and consequently faster adsorption rates in strongly acidic solutions. Furthermore, SiO2@Fe3O4-DAPhen exhibited a high adsorption capacity for Th(IV); it removed Th(IV) through chelation and electrostatic attraction at pH 3 and 1 mol L-1 HNO3, with maximum adsorption capacities of 833.3 and 1465.7 mg g-1, respectively. SiO2@Fe3O4-DAPhen also demonstrated excellent tolerance to salinity, adsorption selectivity, and radiation resistance, thereby highlighting its practical potential for Th(IV) removal in diverse contaminated water sources. Hence, SiO2@Fe3O4-DAPhen represents a promising choice for the rapid and efficient removal of Th(IV).

Highly selective extraction of uranium from wastewater using amine-bridged diacetamide-functionalized silica

A major environmental concern related to nuclear energy is wastewater contaminated with uranium, thus necessitating the development of pollutant-reducing materials with efficiency and effectiveness. Herein, highly selective mesoporous silicas functionalized with amine-bridged diacetamide ligands SBA-15-ABDMA were prepared. Different spectroscopy techniques were used to probe the chemical environment and reactivity of the chelating ligands before and after sorption. The results showed that the functionalized SBA-15-ABDMA had a strong affinity for uranium at low pH (pH = 3) with desirable sorption capacity (68.82 mg/g) and good reusability (> 5). It showed excellent separation performance with a high distribution coefficient (K_d,U > 10⁵ mL/g) and separation factors SF_U/Ln > 1000 at a pH of 3.5 in the presence of lanthanide nuclides, alkaline earth metal and transition metal ions. In particular, SiO₂spheres-ABDMA was used as a column material, which achieved excellent recovery of U(VI) (> 98%) and good reusability for samples of simulated mining and nuclear industries wastewater. XPS and crystallography studies clearly illustrated the tridentate coordination mode of U(VI)/PEABDMA and the mechanism and origin behind the high selectivity for U.

An ion-imprinted imidazole-functionalized ordered mesoporous silica for selective removal of chromium(VI) from electroplating effluents

In this work, ion imprinted technology incorporated with mesoporous silica materials (MCM-41) to obtain the novel specific adsorbent, ion imprinted mesoporous silica. Cr(VI) imprinted mesoporous silica (Cr(VI)IMS) was synthesized and used for adsorption studies and waste water application. A synthesized imidazolyl silane agent act as the functional monomer in the imprinted process to build up highly ordered functionalized imprinted materials. The chemical composition, porosity, and highly ordered morphology were characterized by Fourier transform infrared spectroscopy (FTIR), solid state nuclear magnetic resonance (NMR), Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), respectively. The Brunauer-Emmett-Teller (BET) surface area was 1054.51 m² g^-1 in this study. The Cr(VI)IMS showed great adsorption capacity to hexavalent chromium ions in acidic solution up to 45.6 mg g^-1. Cr(VI)IMS reached the adsorption equilibrium in a short time (10 min) at acid and weak acid conditions, while most of adsorbents need more than 30 min to achieve adsorption equilibrium. Cr(VI)IMS displayed much higher adsorption capacity to Cr(VI) ions than other negative ions. The relative selectivity coefficient was 2.56, higher than those of other anions (below 1.5). After eight adsorption-regeneration cycles, the adsorption efficiency of Cr(VI)IMS still reached 92.5%. The Cr(VI)IMS was found to exhibit equivalent property after multiple cycles of experiments, indicating good repeatability and reproducibility.

The design and synthesis of heterogeneous catalysts for environmental applications

With the rapid advancements in synthetic strategies, the field of heterogeneous catalysis has expanded enormously over the last few decades, and today it is one of the foremost areas in energy and environmental research. Various templating and non-templating routes for designing porous nanomaterial-based catalysts starting from precursor building blocks are highlighted here. CO₂ and biomass are two major abundant resources that can be utilized as feedstocks for various heterogeneous catalytic processes. These are described in brief, together with environmental clean-up applications and future perspectives for addressing environmental issues.

A promising and cost-effective biochar adsorbent derived from jujube pit for the removal of Pb(II) from aqueous solution

This study evaluated the Pb(II) sorption capacity of jujube pit biochar (JPB) in aqueous solution, which was derived from jujube pit by pyrolysis and used as a promising and economical adsorbent. More importantly, the utilization of JPB could realize the recycling of agricultural residues. The JPB was characterized using conventional science technologies, including SEM, BET and FT-IR, and the sorption capacity of JPB for lead ions was investigated according to different adsorption parameters, such as the kinetics data, solution pH, isotherms data, coexisting ions of Na⁺ and K⁺, desorption and reusability, and solution temperature. The results of kinetics data suggested that the lead ion adsorption process by JPB could be fast to reach equilibrium within 30 min. Additionally, the adsorption capacity of JPB for Pb(II) was calculated to be maximum for 137.1 mg/g at pH 6.0. More importantly, after five cycles of desorption and reuse, the JPB still reached 70% of its original adsorption capacity. All the results suggested that JPB had a broad application prospect for the purification of lead ions in practical.

Preparation of sulfhydryl functionalized magnetic SBA-15 and its high-efficiency adsorption on uranyl ion in solution

A novel assembly method was used to prepare the sulfhydryl functionalized magnetic SBA-15 (SH-M-SBA-15). The physicochemical properties of SH-M-SBA-15 were characterized by TEM, XRD, EDS, FT-IR, BET, and VSM. Batch adsorption experiments were conducted to investigate the influence of initial uranium concentration, dosage of adsorbent, pH values, contact time, and temperature on the adsorption efficiency and behaviors. The adsorption types were analyzed from the aspects of kinetic, isotherms, and thermodynamic. The results show that the specific surface area of SH-M-SBA-15 is 316.67 m²/g, which is smaller than that of SBA-15 (692.18 m²/g). However, compared with SBA-15, SH-M-SBA-15 has more surface sulfhydryl functional groups. The addition of this group can improve the adsorption of uranyl ions by SH-M-SBA-15. The optimal adsorption conditions were adsorption dosage 40 mg/L, pH 6, temperature 35 °C, contact time 180 min, and initial uranium concentration 35 mg/L. Under this condition, the maximum adsorption amount of uranyl ion by SH-M-SBA-15 can reach 804.79 mg/g, which is much higher than the highest adsorption capacity of uranyl ion by SBA-15 (146.23 mg/g). The adsorption process was better depicted by the Langmuir isotherm model. The process was consistent with the quasi-second-order model. ΔG was negative and ΔH was positive, indicating spontaneous and endothermic adsorption.

The preparation of organophosphorus ligand-modified SBA-15 for effective adsorption of Congo red and Reactive red 2

P,P-bis (2-oxooxazolidin-3-yl)-N-(3-(triethoxysilyl)propyl)phosphinic amide (APTES-BOP)-modified SBA-15 (SBA-15-BOP) was prepared by a post-synthesis grafting method for the removal of anionic azo dyes from aqueous solutions. The properties of the prepared adsorbent were characterized by PXRD, FT-IR, SEM, TEM, nitrogen sorption, and elemental analysis. Adsorption equilibrium and adsorption kinetic studies demonstrated that the experimental data fitted well with the Langmuir isotherm model and pseudo-second-order model. According to Langmuir fitting, SBA-15-BOP showed high adsorption capacity for CR and RR2 dyes, with the maximum adsorption capacities of 518.1 mg g⁻¹ and 253.8 mg g⁻¹, respectively. The thermodynamic study indicated that the adsorption processes of CR and RR2 dyes on SBA-15-BOP were spontaneous and exothermal. The prepared SBA-15-BOP can be a promising adsorbent for the removal of anionic dyes from aqueous solutions.

P,P-bis (2-oxooxazolidin-3-yl)-N-(3-(triethoxysilyl)propyl)phosphinic amide (APTES-BOP)-modified SBA-15 (SBA-15-BOP) was prepared by a post-synthesis grafting method for the removal of anionic azo dyes from aqueous solutions.

Preparation of a mesocellular siliceous foam supported lanthanide-sensitive polymer for the selective adsorption of lanthanides

A ship in bottle nanocomposite was fabricated as a novel adsorbent for lanthanides by immobilizing a lanthanide-sensitive polymer into mesocellular siliceous foam (MCF). The MCF was used as a novel carrier for immobilization of the polymer, and the polymer was synthesized via in situ ring-opening polymerization of 2-methyl-2-oxazoline (MOL) and divinylbenzene (DVB) in the presence of MCFs. The substantially physically modified MCF-based composite exhibited superior adsorptivity and selectivity to lanthanides due to its exceptional properties, which was employed for lanthanide adsorption from aqueous solution by a facile solid-liquid separation procedure. The adsorption of lanthanides by the composite was systematically studied including adsorption parameter investigation and adsorption mechanism evaluation. The adsorption isotherms and kinetics were also investigated and proved to follow the Langmuir model and the pseudo-second-order model. The adsorption thermodynamics study indicated that the adsorption process was thermodynamically favorable, endothermic and spontaneous. The prepared inorganic-organic hybrid composite has superior selectivity and specificity to lanthanides, which can be used for lanthanide enrichment and separation of lanthanides from actinides.

Large-Pore 3D Cubic Mesoporous (KIT-6) Hybrid Bearing a Hard-Soft Donor Combined Ligand for Enhancing U(VI) Capture: An Experimental and Theoretical Investigation

A preorganized tetradentate phenanthrolineamide (DAPhen) ligand with hard and soft donors combined in the same molecule has been found to possess high extraction ability toward actinides over lanthanides from acidic aqueous solution in our previous work. Herein we grafted phenanthrolineamide groups onto a large-pore three-dimensional cubic silica support by the reaction of DAPhen siloxane with KIT-6 substrate to prepare a novel uranium-selective sorbent, KIT-6-DAPhen. The as-synthesized sorbent was well-characterized by scanning electron microscopy, high-resolution transmission electron microscopy, N₂ adsorption/desorption, X-ray diffraction, FT-IR, ¹³C cross-polarization magic-angle spinning NMR, and TGA techniques, which confirmed the consummation of the functionalization. Subsequently, the effects of contact time, solution pH, initial U(VI) concentration, and the presence of competing metal ions on the U(VI) sorption onto KIT-6-DAPhen sorbent were investigated in detail. It was found that KIT-6-DAPhen showed largely enhanced sorption capacity and excellent selectivity toward U(VI). The maximum sorption capacity of KIT-6-DAPhen at pH 5.0 reaches 328 mg of U/g of sorbent, which is superior to most of functionalized mesoporous silica materials. Density functional theory coupled with quasi-relativistic small-core pseudopotentials was used to explore the sorption interaction between U(VI) and KIT-6-DAPhen, which gives a sorption reaction of KIT-6-DAPhen + [UO₂(H₂O)₅]²⁺ + NO₃^- ⇄ [UO₂(KIT-6-DAPhen)(NO₃)]⁺ + 5H₂O. The findings of the present work provide new clues for developing new actinide sorbents by combining new ligands with various mesoporous matrixes.

Preparation of an ion imprinted functionalized mesoporous silica for rapid and specific absorption Cr(iii) ions in effluents

We developed an effective and selective method to remove Cr(iii) ions in acidic effluents.

Capture of actinides (Th4+, [UO2]2+) and surrogating lanthanide (Nd3+) in porous metal–organic framework MIL-100(Al) from water: selectivity and imaging of embedded nanoparticles

Aluminium-based metal–organic framework MIL-100 was utilized for the capture of actinide ([UO₂]²⁺, Th⁴⁺) and lanthanide (Nd³⁺) cations.

Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater

U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), (13)C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100-200nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production.

Microwave-induced synthesis of pyrophosphate Zr1-xTixP2O7 and TiP2O7 with enhanced sorption capacity for uranium (VI)

A series of nanostructured pyrophosphates Zr1-xTixP2O7 (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0), have been prepared via a facile microwave induced route in which zirconium hydroxide, titanium hydroxide and phosphoric acid were used as Zr, Ti and P sources, respectively. It is demonstrated the isomorphous substitution of Zr(4+) by Ti(4+) results in a decrease of the size and an enhancement of the adsorption capacity of the obtained particles for U(VI) in aqueous solution. The maximum amount of TiP2O7 for U(VI) reached up to 309.8 mgg(-1) under the experimental conditions (pH=5, t=60min and T=303K). The as-obtained specific metal pyrophosphates exhibit a considerably higher adsorption capability for U(VI) in aqueous solution compared with Zr1-xTixP2O7 prepared by calcined method, showing a high potential for U(VI) sequestration applications. The adsorption kinetics and thermodynamic analysis of Zr1-xTixP2O7 on adsorption of U (VI) were performed, and a possible adsoprtion mechanism was also proposed.

The removal of aqueous uranium by SBA-15 modified with phosphoramide: a combined experimental and DFT study

Phosphoramide-modified SBA-15 materials were prepared via a two-step process involving: (1) the synthesis of phosphoramide via amidation of phosphoryl chloride with a primary amine and (2) modification of the phosphoramide onto SBA-15.

New insights into the uranium adsorption behavior of mesoporous SBA-15 silicas decorated with alkylphosphine oxide ligands

Alkylphosphine oxide functionalized mesoporous silicas were prepared by co-condensation and further addition reaction with secondary n-propylphosphine oxide and are promising candidates for the preconcentration and adsorption of uranium from acidic aqueous solutions.

Theoretical study on complexation of U(vi) with ODA, IDA and TDA based on density functional theory

Precise structures of U(vi) complexes with ODA, IDA and TDA in different binding modes.

Facile functionalized of SBA-15 via a biomimetic coating and its application in efficient removal of uranium ions from aqueous solution

A novel dopamine-functionalized mesoporous silica (DMS), synthesized by grafting dopamine onto a mesoporous molecular sieve (SBA-15), was developed as a sorbent to extract U(VI) from aqueous solution. The method used to modify SBA-15 was simple, facile and cost-effective. The DMS was characterized by SEM, TEM, XRD and BET, showing that the material had an ordered mesoporous structure and a large surface area. The effect of contact time, pH, ionic strength, temperature, and solid-liquid ratio on the sorption process was investigated. It was demonstrated that the adsorption of U(VI) by DMS was fast and that it can be described by the pseudo-second order-equation where the equilibrium time was 20 min. Additionally, the adsorption isotherm data were fitted well by the Langmuir model with the maximum adsorption capacity of DMS of 196 mg/g at pH 6.0. Furthermore, the influence of the K(+) and Na(+) concentrations and solid-to-liquid ratio on the sorption was very weak, and the values of the thermodynamic parameters revealed that the sorption process was exothermic and spontaneous. All the results suggested that the DMS could be used as an excellent adsorbent to remove U(VI) from aqueous solution.

Sensing Properties of GO and Amine-Silica Nanoparticles Functionalized QCM Sensors for Detection of Formaldehyde

In the current work, graphene oxides (GO) and Amine-Functionalized Silica Nanoparticles ( NH 2-SNs) were used as sensing layer on quart crystal microbalance (QCM) for detection of HCHO gas. The GO and NH 2-SNs functionalized QCM resonators all had a significant response to HCHO gas. The sensitivity of GO functionalized QCM resonator is 0.04 Hz/(μg⋅ppm), which is four times as high as that of NH 2-SNs functionalized QCM resonator (0.01 Hz/(μg⋅ppm)). The GO functionalized QCM resonators would be of benefit in area of environmental applications.