A novel magnetite nanorod-decorated Si-Schiff base complex for efficient immobilization of U(vi) and Pb(ii) from water solutions

Analyzing (3-Aminopropyl)triethoxysilane-Functionalized Porous Silica for Aqueous Uranium Removal: A Study on the Adsorption Behavior

This study synthesized (3-aminopropyl)triethoxysilane-functionalized porous silica (AP@MPS) to adsorb aqueous uranium (U(VI)). To comprehensively analyze the surface properties of the AP@MPS materials, a combination of SEM, BET, XPS, NMR, and zeta potential tests were conducted. The adsorption experiments for U(VI) revealed the rapid and efficient adsorption capacity of AP@MPS, with the solution condition of a constant solution pH = 6.5, an initial U(VI) concentration of 600 mg × L-1, a maximum U(VI) capacity of AP@MPS reaching 381.44 mg-U per gram of adsorbent, and a removal rate = 63.6%. Among the four types of AP@MPS with different average pore sizes tested, the one with an average pore size of 2.7 nm exhibited the highest U(VI) capacity, particularly at a pH of 6.5. The adsorption data exhibited a strong fit with the Langmuir model, and the calculated adsorption energy aligned closely with the findings from the Potential of Mean Force (PMF) analysis. The outcomes obtained using the Surface Complex Formation Model (SCFM) highlight the dominance of the coulombic force ΔG0coul as the principal component of the adsorption energy (ΔG0ads). This work garnered insights into the adsorption mechanism by meticulously examining the ΔG0ads across a pH ranging from 4 to 8. In essence, this study's findings furnish crucial insights for the future design of analogous adsorbents, thereby advancing the realm of uranium(VI) removal methodologies.

Insight into the performance and mechanism of persimmon tannin functionalized waste paper for U(VI) and Cr(VI) removal

Herein, using dialdehyde waste paper (DAWP) as a cross-linking agent to immobilize persimmon tannin (PT) was first used to remove the U(VI) and Cr(VI) via the "waste control by waste" concept. The microscopic and macroscopic surface properties of the as-prepared adsorbent was characterized by the advanced characterization techniques. Factors that affected the elimination process such as variable pH, coexistence ions and equilibrium time were investigated by batch techniques. The results showed that the maximal removal capacities of U(VI) and Cr(VI) on DAWP-PT were 242.3 mg/g (pH = 6.0) and 178.7 mg/g (pH = 2.0) at 298 K, which exhibited competitiveness with most of the reported solid materials. Meanwhile, adsorption data were fitted perfectly to the Langmuir and Pseudo-second-order equations, which indicated that the monolayer and homogenous chemisorption dominated the removal process. The SEM-EDX, DFT and XPS analysis conformed that adsorption of U(VI) was mainly via surface complexation, while the elimination of Cr(VI) was a redox reaction process, and about 65.33% of Cr(III) and 34.67% of Cr(VI) co-existed onto the surface of DAWP-PT. Thus, this study would provide a high-efficiency and low-cost adsorbent for radionuclide and heavy metal treatment.

Phosphate group functionalized magnetic metal-organic framework nanocomposite for highly efficient removal of U(VI) from aqueous solution

The phosphate group functionalized metal-organic frameworks (MOFs) as the adsorbent for removal of U(VI) from aqueous solution still suffer from low adsorption efficiency, due to the low grafting rate of groups into the skeleton structure. Herein, a novel phosphate group functionalized metal-organic framework nanoparticles (denoted as Fe₃O₄@SiO₂@UiO-66-TPP NPs) designed and prepared by the chelation between Zr and phytic acid, showing fast adsorption rate and outstanding selectivity in aqueous media including 10 coexisting ions. The Fe₃O₄@SiO₂@UiO-66-TPP was properly characterized by TEM, FT-IR, BET, VSM and Zeta potential measurement. The removal performance of Fe₃O₄@SiO₂@UiO-66-TPP for U(VI) was investigated systematically using batch experiments under different conditions, including solution pH, incubation time, temperature and initial U(VI) concentration. The adsorption kinetics, isotherm, selectivity studies revealed that Fe₃O₄@SiO₂@UiO-66-TPP NPs possess fast adsorption rates (approximately 15 min to reach equilibrium), high adsorption capacities (307.8 mg/g) and outstanding selectivity (S_u = 94.4%) towards U(VI), which in terms of performance are much better than most of the other magnetic adsorbents. Furthermore, the adsorbent could be reused for U(VI) removal without obvious loss of adsorption capacity after five consecutive cycles. The research work provides a novel strategy to assemble phosphate group-functionalized MOFs.

Comparative adsorption capabilities of rubbish tissue paper-derived carbon-doped MgO and CaCO3 for EBT and U(VI), studied by batch, spectroscopy and DFT calculations

Water pollution due to organic dyes and radionuclides is a challenging issue to the modern world. Cheap and efficient adsorbents are needed for their removal from wastewaters. Carbon-doped magnesium oxide (C-MgO) and calcium carbonate (C-CaCO₃) were synthesized by the in situ hydrothermal treatment of Mg(OH)₂ and Ca(OH)₂ with carbon, and applied for the removal of eriochrome black T (EBT) at pH = 2.0 and uranium (U(VI)) at pH = 6.0. The Langmuir monolayer adsorption capacities of C-MgO (3.62 × 10^-4 mol/g for EBT and 8.10 × 10^-4 mol/g for U(VI)) were higher than those of C-CaCO₃ (2.53 × 10^-4 mol/g for EBT and 5.92 × 10^-4 mol/g for U(VI)). The high adsorption capacity of C-MgO was also evidenced with DFT calculations which showed that the sorption energies (ΔE) of C-MgO for EBT (20.62 kcal/mol) and U(VI) (63.41 kcal/mol) were higher than those of C-CaCO₃ for EBT (10.21 kcal/mol) and U(VI) (34.29 kcal/mol). In all cases, the electrostatic interactions were involved in the adsorption process. The sorption kinetic data followed pseudo-second-order kinetics. The results demonstrate that both C-MgO and C-CaCO₃ are reusable and can be effectively applied for the elimination of EBT and U(VI) from 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.

A simple method for preparing ultra-light graphene aerogel for rapid removal of U(VI) from aqueous solution

In this study, graphene aerogel (GA) was successfully prepared through a simple hydrothermal method. The resulting GA exhibited a porous network structure with a large specific surface area (350.8 m²/g), ultra-light mass and easy separation from water. The pH_IEP value of the GA was estimated to be 3.5. The adsorption process and the factors that affect adsorption capacity were studied. The adsorption could be conducted in a wide pH range from 2.0 to 7.0. The maximum adsorption capacity of GA towards U(VI) at pH 4.0 and T = 298 K was 238.67 mg/g calculated from the Langmuir model. The GA had greatly rapid adsorption property for the removal of U(VI) at pH 4.0. Kinetic data showed good correlation with pseudo-second-order equation. Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry characterizations showed that GA adsorbed U(VI) through chemical interaction by oxygen-containing and nitrogen-containing groups functional groups. The results show that GA has excellent application potential as an adsorbent material for removing U(VI) from aqueous solution.

Chitosan/ nanofibrillated cellulose aerogel with highly oriented microchannel structure for rapid removal of Pb (II) ions from aqueous solution

Among the heavy metal ions, Pb (II) can cause serious diseases in the nervous and cardiovascular systems even at an ultralow concentration. Nowadays, various materials with high adsorption capacity have been developed for heavy metal ions adsorption. However, most of them have a low adsorption rate and may take a long time to achieve adsorption equilibrium. In this work, chitosan (CS)/ nanofibrillated cellulose (NFC) aerogel with oriented microchannel structure was developed via a directional freeze-drying approach. The structure of the CS/NFC aerogel was characterized and its adsorption performance for Pb (II) was also investigated. The results reveal that the maximum adsorption capacity for Pb (II) is 252.6 mg g^-1, much higher than most chitosan-based adsorbents reported in the literature. More impressively, the developed aerogel takes only 5 min to achieve 85% of equilibrium adsorption capacity for Pb (II) due to its highly oriented microchannel structure. Furthermore, the aerogel maintains a high removal efficiency (>85%) after 5 adsorption-desorption cycles. The obtained results demonstrate that the as-prepared CS/NFC aerogel can be used as an effective adsorbent for Pb (II) removal from aqueous solution.

Novel conjugated hybrid material for efficient lead(II) capturing from contaminated wastewater

An efficient material is always welcoming for the water treatment due to the need of clean water to safe the human health. The conjugate adsorbent (CJA) was fabricated by functional ligand embedded onto the highly porous silica material for selective lead (Pb(II)) ion monitoring and removal from wastewater. The study was achieved not only investigating the beginning material but also the performing extrusion as novel conjugate material, this defining the material novelty of this study considers to the modern state-of-art. The fabricated material was characterized in all aspects and then the experimental works for Pb(II) ion assessing were carried in batch mode. The CJA was exposed the color and signal intensity upon addition of Pb(II) ion from low to high concentrations. The optimum pH was considered at 5.50 based on the sensitivity, the color formation ability and high adsorption of Pb(II) ion. The determined limit of low detection was 0.18 μg/L, which was the extraordinary performance for the Pb(II) ion monitoring ability by the CJA. The adsorption efficiency, specific attention was remunerated to the influence of solution pH, reaction time, foreign ion, initial Pb(II) amounts and regeneration. The CJA was exhibited high kinetic performances and showed high adsorption Pb(II) ion compared with the different forms of material. The adsorption was completely fitted with the Langmuir adsorption as defining the monolayer coverage as expected of the homogeneous porosity of the CJA. The maximum adsorption was determined as high as 175.16 mg/g. In addition, the foreign ions were not affected in the Pb(II) adsorption by the CJA, and the adsorbent was regenerated using 0.20 M HCl for several cycles used without significant loss of the initial performance. Considering these advantages, the CJA demonstrated the potential low-cost material for competitive use in wastewater remediation, especially in the developing countries.

Highly Selective Removal of Pb(II) by a Pyridylpyrazole-β-ketoenol Receptor Covalently Bonded onto the Silica Surface

Efficient materials capable of capturing toxic metals from water are widely needed. Herein, a new pyridylpyrazole-β-ketoenol receptor, X-ray diffraction analyzed, was covalently incorporated into the silica surface to produce solid and recyclable adsorbent particles. The new material, fully characterized, revealed extremely efficient removal of toxic metals from water, with a selectivity order of Pb(II) > Zn(II) > Cu(II) > Cd(II). The adsorption was exceptionally rapid at optimum pH and concentrations, showing Pb(II) removal of 93 mg g-1 within 5 min and maximum Pb(II) adsorption of 110 mg g-1 after only 20 min. Sorption isotherms agreed well with the Langmuir model suggesting a monolayer adsorption, whereas kinetics agreed with the pseudo-second-order model suggesting a chemisorption binding mechanism. Thermodynamics of adsorption were fitted with an endothermic and spontaneous process. The material, recyclable for at least five cycles, is therefore promising for the cleanup of water polluted by toxic metals, especially lead.

Two-dimensional MAX-derived titanate nanostructures for efficient removal of Pb(ii)

Two-dimensional (2D) nanomaterials have been identified as one of the promising materials due to their great promise for waste treatment.

Preparation of a novel polyfunctional and high adsorption capacity adsorbent by laccase-catalyzed self-polymerization of GAL and cross-linking with PEI

A novel polyfunctional and high adsorption capacity adsorbent was prepared by laccase-catalyzed self-polymerization of GAL and cross-linking with PEI.