Arginine as a Multifunctional Additive for High Performance S-Cathode

Advancement of sulfur (S) cathode of lithium-sulfur (Li-S) batteries is hindered by issues such as insulating nature of sulfur, sluggish redox kinetics, polysulfide dissolution and shuttling. To address these issues, we initiate a study on applying an important amino acid of protein, arginine (Arg), as a functional additive into S cathode. Based on our simulation study, the positively charged Arg facilitates strong interactions with polysulfides. The experimental results indicate that the interaction enable capability of trapping polysulfides within the S cathode, responsible for reducing shuttle effects. Furthermore, the positively charged Arg also promotes efficient ion diffusion and polysulfides conversion. The new findings include that, with addition of only 1 wt % Arg, the resultant cathode demonstrates effectively enhanced electrolyte wettability, polysulfide adsorption and redox kinetics, leading to enhanced rate performance and long-term cycling stability. This study highlights the great potential of amino acids being able to act as effective functional bio-additives in S cathode, paving a new way to high-performance and sustainable energy storage solutions.

Eco-friendly Lignin/N,N-dimethylacrylamide Hydrogel with Carrageenan and Polyvinylpyrrolidone for Amphoteric Adsorption of Methylene Blue and Congo Red: Optimization, Characterization, and Adsorption

This study presents a new approach for the preparation of N,N-dimethyl acrylamide (DMA), and lignin/DMA hydrogels using gamma radiation, highlighting the synergistic amphoteric adsorption of Methylene Blue (MB) and Congo Red (CR) facilitated by incorporating carrageenan and polyvinylpyrrolidone (PVP). The hydrogel formulation was optimized with a ratio of 2:1:0.75:5 for carrageenan:PVP:lignin:DMA and a radiation dose of 25 kGy, resulting in maximum gelation and adsorption efficiency. X-ray diffraction and spectroscopic analysis suggested that ionic interactions among carrageenan, PVP, and DMA and hydrogen bonding from lignin facilitated amphoteric adsorption via sulfate-mediated amide activation. The adsorption process followed a pseudo-first order kinetic model, with film-layer diffusion recognized as the primary transport mechanism. The maximum adsorption capacities were 405 mg·g-1 for MB and 417 mg·g-1 for CR, aligning with Freundlich isotherm behavior, while both the adsorptions were endothermic and thermodynamically spontaneous. The hydrogels were reusable for at least four adsorption-desorption cycles. Assessments of germination index indicated that the hydrogels are non-phytotoxic to Zea mays, with root elongation suggesting possible agricultural applications. Further research is necessary to evaluate the long-term viability of repurposing dye-desorbed hydrogels in agrarian systems. The findings indicate that gamma-irradiated hydrogels may serve as effective and reusable adsorbents for dye removal.

Uranium Extraction from Seawater: A Novel Approach Using Aluminum Fumarate-Based Metal-Organic Framework Aerogels

Efficient extraction of uranyl ions from seawater is crucial for the commercialization of nuclear technology. Metal-organic frameworks (MOFs), with their superior uranium extraction properties, face challenges in large-scale applications due to their powdery nature and the difficulty of assembling them into mechanically stable macroscopic composites. To address this, successfully synthesized 90 wt % nanoMOF (aluminum fumarate) loaded directional aerogels (AlFA-3-10) using polyvinyl alcohol (PVA) as an adhesive, which demonstrates robust strength longitudinally and transversely. Our uranium adsorption experiments reveal that at a pH of 8 (akin to that of seawater), the AlFA-3-10 achieves a maximum adsorption capacity of 1146.25 mg g-1, maintaining this exceptional performance over five cycles. Notably, in simulated seawater, AlFA-3-10 exhibits high selectivity for uranyl ions with minimal interference from other ions. The directional pores within AlFA-3-10 facilitate fluid transmission and exchange, ensuring optimal contact between the MOF and uranyl ions, thereby enhancing electrostatic attraction and electron transport for improved capture efficiency. This streamlined approach maximizes the intrinsic potential of nano-MOFs and heralds a new era for their integration into macroscopic composite materials.

Cellulose nanofibers/polyacrylic acid hydrogels integrated with a 3D printed strip: A platform for screening prostate cancer via sarcosine detection

Cellulose nanofiber/polyacrylic acid (CNF/PAA) hydrogel-based colorimetric sensor was fabricated for non-invasive screening of prostate cancer (PCa) via selective detection of sarcosine. The hydrogel was synthesized by photo-crosslinking of acrylic acid in the presence of CNF which acted as mechanical reinforcement and as color enhancer. The hydrogel exhibited a high aqueous absorption and high mechanical strength. A homogeneous distribution of CNF in the hydrogel was confirmed by TEM. A significant improvement in the compressive modulus and stress in the hydrogel were obtained after the incorporation of 0.25%wt CNF. The hydrogel sensor was integrated within a 3D printing strip on a diaper, and it offered a vivid color change from light yellow to blue for detecting sarcosine for PCa indication with a detection limit starting from 10 μM. The colorimetric results were semi-quantitatively evaluated by a spectrophotometer offering a linear range of 0-100 μM with R2 of 0.9901. Furthermore, the increase in CNF content significantly enhanced the sensor's sensitivity toward sarcosine. This sensor could open new avenues for non-invasive screening of prostate cancer in the future.

An Amidoxime-functionalized chitosan dual-network hydrogel: Enhanced uranium-water separation capacity

The source and after treatment of uranium, a key aspect of its use as a nuclear fuel, had been a topic of intense debate among developers. Therefore, a novel antimicrobial amidoxime-functionalized chitosan/polyacrylamide dual network hydrogel (CP-AO) had been developed utilizing a straightforward methodology. The results demonstrated excellent adsorption capacity and selectivity for uranium extraction under varying conditions, the U(VI) removal was above 94 % when pH was 4. Batch adsorption experiments revealed that CP-AO attained a maximum uranium adsorption capacity of 886.73 mg/g at 298 K, which was higher than most reported adsorbents. The kinetic and thermodynamic studies presented that adsorption process for CP-AO conformed to spontaneous monolayer chem-adsorption, and it can reach equilibrium quickly within 120 min. In addition, the adsorption mechanism revealed that the chemical-interaction between CP-AO hydrogel and U(VI) was attributed to -OH, -NH2 and amidoxime group. Notably, the hydrogel showed optimistic anti-biosludge performance against three common bacteria (E. coli, S. aureus and B. subtilis) owing to effects of chitosan. CP-AO also especially was susceptible to be recycled, its adsorption capacity was 2.8 mg/g and 38.67 mg/g in simulated and actual seawater, respectively. Hence, this work provides a promising material for the extraction of uranium resources and new insights.

Ultrastretchable and highly sensitive ionic conductive hydrogel for environmentally resistant all-in-one human-motion sensors

Conductive hydrogels have been considered ideal candidate materials for fabricating human-motion sensors due to their combination properties of electronic and tissue-like soft nature and the similar functions of human skin with mechanical and sensory properties. However, the perfect integration of multiple functionalities such as environmentally tolerant, stretchable, self-adhesive, self-healing, transparent, high sensitivity, and rapid response in one system (all-in-one) is still a significant challenge. Herein, a novel ionic conductive hydrogel platform with excellent comprehensive performance through multiple dynamic interactions was prepared by employing [BMIm]BF4/glycerol/water ternary solvent system. The dynamic hydrogen bonds, coordination bonds, and electrostatic interaction within the network endows the hydrogel excellent mechanical performance. The synchronous effect of ionic liquids and glycerol realized the high ionic conductivity, transparency, environmentally tolerance, and long-term stability. Sensors based on this hydrogel have a relatively high sensitivity, a fast response time, and a wide linear sensing range in monitoring human movements. It can also serve as electronic skin, like human skin, for touchscreen pen and writing. Thus, the all-in-one hydrogel was concluded to hold considerable promise for constructing the next generation of hydrogel platforms for human-motion sensors.

Gamma Radiation-Induced Synthesis of Carboxymethyl Cellulose-Acrylic Acid Hydrogels for Methylene Blue Dye Removal

This study aims to develop efficient and sustainable hydrogels for dye adsorption, addressing the critical need for improved wastewater treatment methods. Carboxymethyl cellulose (CMC)-based hydrogels grafted with AAc were synthesized using gamma radiation polymerization. Various AAc to CMC ratios (5:5, 5:7.5, 5:10, 5:15) were treated with 37% NaOH and exposed to 1-15 kGy radiation, with the optimal hydrogel obtained at 5 kGy. Swelling studies showed an increase in swelling with 5-7.5% AAc content, with the 5:7.5 hydrogel achieving the highest swelling at 18,774.60 (g/g). FTIR spectroscopy confirmed the interaction between AAc and CMC, indicating the successful formation of the hydrogel. DSC analysis revealed that higher AAc content led to increased glass transition and decomposition temperatures, thereby enhancing thermal stability. The swelling kinetics were linked to a reduction in pore size and improved AAc grafting. The 5:7.5 hydrogel demonstrated the highest adsorption capacity (681 mg/g) for methylene blue at 80 mg/L, achieving a desorption efficiency of 95% in 2M HCl. Kinetic analysis revealed non-uniform physisorption on a heterogeneous surface, which followed Schott's pseudo-second-order model. This study advances the development of efficient hydrogels for water purification, providing a cost-effective and environmentally friendly solution for large-scale applications.

Construction of a Fluorescence/Phase-Change Dual-Mode Sensor Based on Carbon Dots/Poly(acrylic acid) for Highly Selective and Sensitive Detection of Ferric Ions

Fe3+ is one of the crucial metal ions in biological systems, and its excess or deficiency in the body can trigger various diseases, posing a serious threat to human health. Moreover, improper handling or disposal of Fe3+ can lead to water pollution, thereby harming the environment. Therefore, the development of highly selective and sensitive Fe3+ detection probes is particularly urgent. In this paper, a dual-mode sensor based on sol-gel and fluorescence signal responses was developed for the visual detection of Fe3+. The visual sensing method based on the simultaneous response of Fe3+-triggered dual signals can minimize the interference from false-positive signals and enhance detection accuracy. The dual-mode sensor, denoted as PAA@CDs, was constructed by incorporating high-brightness (high fluorescence emission intensity) green-yellow carbon dots (CDs) into poly(acrylic acid) (PAA), which possesses a large number of carboxyl functional groups. Based on the interaction of Fe3+ with the surface functional groups of CDs, nonfluorescent complexes are formed, leading to nonradiative electron transfer, which induces fluorescence quenching and produces a fluorescence signal visible to the naked eye. Additionally, the interaction of Fe3+ with the carboxyl groups of PAA triggers the cross-linking of PAA, causing a sol-gel phase change signal. Consequently, the PAA@CDs exhibit a dual-response signal in Fe3+ detection. Based on the fluorescence method, the linear detection range of PAA@CDs for Fe3+ is 0.05-2.60 mM with a limit of detection (LOD) of 5.14 μM. Meanwhile, using the sol-gel method, the linear detection range is 0.02-2.20 mM, and the LOD is 42.5 μM. Furthermore, the PAA@CDs probes can be successfully applied to the detection of Fe3+ in real water samples, demonstrating their potential value in the analysis of real samples containing multiple ions.

Ultrasensitive Rapid Antigen Test by Geometric Lateral Flow Assays and Highly Doped Upconversion Nanoparticles

The paper-based lateral flow assay (LFA) testing strips are currently the most widely used for point-of-care testing (POCT), valued for their rapid result turnaround times in a few minutes. However, their sensitivity has been limited. Upconversion nanoparticles (UCNPs), especially highly doped ones, have emerged as promising luminescent reporters to enhance the LFA sensitivity. These UCNPs exhibit a nonlinear enhancement in luminescence with excitation power density, necessitating higher power densities for higher brightness. In this study, we utilized a geometric paper strip design to minimize the immune reaction area and maximize the excitation power density, enabling ultrasensitive detection of the SARS-CoV-2 nucleoprotein antigen. This design also slowed the antigen flow on the paper strip, extending the reaction time between antigen and antibody, thereby enhancing the efficiency of the immune reaction. Through this design, our approach achieved over a 100-fold enhancement in the limit of detection (LOD) compared with the widely used LFAs, based on gold colloidal nanoparticles and europium nanoparticles. This innovation expands the scope of LFA applications that require a low LOD.

The Influence of the Structural Architecture on the Swelling Kinetics and the Network Behavior of Sodium-Alginate-Based Hydrogels Cross-Linked with Ionizing Radiation

The present work discusses the influence of the structural architecture of sodium alginate-co-acrylic acid-poly(ethylene) oxide hydrogels, crosslinked through electron beam (e-beam) radiation processing. The most important properties of the hydrogels were studied in detail to identify a correlation between the architecture of the hydrogels and their properties. Furthermore, the effect of sodium alginate (NaAlg) concentration, the amounts of the polymer blend, and the size of the samples on hydrogel properties were investigated. The results show that the hydrogels cross-linked (0.5% and 1% NaAlg) with 12.5 kGy exhibit improved physicochemical properties. High gel fraction levels (exceeding 83.5-93.7%) were achieved. Smaller hydrogel diameter (7 mm) contributed to a maximum swelling rate and degree of 20.440%. The hydrogel network was dependent on the hydrogels' diameter and the amount of polymer blend used. The hydrogels best suited the first-order rate constants and exhibited a non-Fickian diffusion character with diffusion exponent values greater than 0.5. This study indicates that the cross-linked hydrogel has good properties, particularly because of its high degree of swelling and extensive stability (more than 180 h) in water. These findings show that hydrogels can be effectively applied to the purification of water contaminated with metals, dyes, or even pharmaceuticals, as well as materials with a gradual release of bioactive chemicals and water retention.

Selective uranyl ion-imprinting with clickable amidoxime-functionalized pullulan

Manufacturing a highly effective sorbent for removing UO22+ ions from aqueous effluents is vital for safeguarding the environment and recovering valuable resources. This research presents an innovative strategy employing adsorbents derived from pullulan, specifically tailored with furfuryl-amidoxime (FAO), to improve their affinity for UO22+ ions. The formation of a UO22+ ion-imprinted sorbent (U-II-P) was achieved by crosslinking the UO22+/FAO-modified pullulan (FAO-P) complex with bis(maleimido)ethane (BME) via click Diels-Alder (DA) cyclization, enhancing its attraction and specificity for UO22+ ions. Detailed characterization of the synthesis was performed using NMR and FTIR spectroscopy, and the sorbent's external textures were analyzed using scanning electron microscopy (SEM). The U-II-P sorbent showcased outstanding preference for UO22+ over other metallic ions, with the most efficient adsorption occurring at pH 5. It exhibited a significant adsorption capacity of 262 mg/g, closely aligning with the predictions of the Langmuir adsorption model and obeying pseudo-second-order kinetic behavior. This investigation underlines the effectiveness of FAO-P as a specialized solution for UO22+ ion extraction from wastewater, positioning it as a viable option for the remediation of heavy metals.

Fabrication of cellulose-collagen based biosorbent as eco-friendly scavengers for uranyl ions

The aim of the present research is to fabricate a biosorbent using agricultural waste for removal of uranium from contaminated water i.e. "waste to wealth" approach. Cellulose extracted from wheat straw was mercerized and a novel semi-interpenetrating polymer network (semi-IPN) was fabricated through graft copolymerization of polyvinyl alcohol onto hybrid mercerized cellulose + collagen backbone. Response surface methodology was used for optimization of different reaction parameters as a function of % grafting (195.1 %) was carried out. Semi-IPN was found to possess higher thermal stability. Adsorption results revealed that the optimum parameters for the elimination of uranium using semi-IPN were: adsorbent dose = 0.15 g, pH = 6.0, contact time = 120 min and initial U (VI) concentration = 100 μg/L. The pseudo-second-order kinetic model gave the best description of the adsorption equilibrium data as the calculated qe value is nearest to the experimental qe for the different initial U(VI) concentrations. Adsorption experiments followed Langmuir isotherm with R2 = 0.999. Furthermore, recyclability and reusability studies showed that the adsorption efficiency of semi-IPN was 82 % after 5 cycles indicating the superior recycling execution of fabricated biosorbent. Thus, the fabricated ecofriendly device can be used effectively for the removal of uranium from contaminated wastewater sources.

Fabricating pentaazatetraethylene modified sulfonated polyacrylamide for dye adsorption from aqueous media: isotherms and kinetics models

In this study, pentaazatetraethylene-modified sulfonated polyacrylamide (PAm-SO3-N5) was synthesized and used as a novel efficient adsorbent to remove calmagite from aqueous media. To this end, a central composite design (CCD) was applied to reduce the number of reaction variables (i.e., adsorbent concentration, temperature, initial concentration, and pH) on calmagite removal. The results showed that calmagite was entirely adsorbed by the PAm-SO3-N5 within 30 min. In addition, a pseudo-second-order (PSO) model was prepared as the optimum formula to fit the kinetics information. The modeling results revealed that film diffusion and adsorption are rate-limiting stages to remove the dyes. Using a Langmuir isotherm to fit the equilibrium data, the highest equilibrium adsorption was calculated to be 1732.5 mg/g. In the present study, the ΔH value indicates that the adsorption is of chemical type. Also, the negative sign of ΔS° shows that PAm-SO3-N5 removes calmagite during a relatively stable process with randomness in the system. The increase in ΔG° values with increasing temperature indicates a descending trend in the feasibility degree of calmagite adsorption. Eventually, recycling the adsorbent for 7 cycles to adsorb calmagite dye showed no remarkable activity loss.

Toward the Development of Simplified Lateral Flow Assays Using Hydrogels as the Universal Control Line

Lateral flow assays (LFA) have been widely utilized as point-of-care testing devices in diverse fields. However, it is imperative to preprint costly bioreceptors onto the lateral flow nitrocellulose membrane at the control line. The complex manufacturing process and relatively limited detection capabilities of LFA have impeded their utilization in more challenging fields. Here, we propose a novel and simple strategy to simplify the manufacture of LFA while simultaneously improving the sensitivity by modifying the hydrogel line (HL). In our study, it was observed that the sensitivity of commercial LFA strips could be enhanced by 2-5-fold by incorporating an extra HL. Particularly, a universal control line was developed to accommodate multiple LFA detection modes by substituting the conventional antibody control line with a hydrogel control line (HCL). As a proof of concept, the HCL performance could be associated with the slowdown and interception effect toward fluid, which are dependent on the permeation and hydrophilicity of the hydrogel with varying concentrations in the nitrocellulose membrane. This new design builds the foundation to enhance the sensitivity and develop the simplified LFA sensing platform without additional complicated processes.

Investigation of Chelating Agents for the Removal of Thorium from Human Teeth upon Nuclear Contamination

Thorium-232 (232Th) is a radioactive heavy metal that is of increasing interest as a source of nuclear energy. However, upon nuclear incidents, the ingestion or inhalation of Th in major quantities can contribute to chemical and radiological health problems, including accumulation in the bone tissue and an increased risk of developing pancreatic, lung, and hematopoietic cancers. The major mineral component of the bone is hydroxyapatite (HAP)─also the major mineral component of the teeth. As such, the teeth are the first site of exposure upon oral ingestion of Th-contaminated materials, and Th can pose a potential risk to teeth development. In essence, in the case of human contamination, it is critical to identify effective chelating agents capable of removing Th. Using a batch study methodology, this present work investigates the uptake and the removal of Th from synthetic HAP and from teeth samples by diethylenetriamine pentaacetate (DTPA), ethylenediaminetetraacetic acid (EDTA), and other promising chelating agents. Th uptake over synthetic HAP exceeds 98% at physiological pH with <1 min of contact time and uptake exceeds 90% across the entire pH range. Regarding teeth, over 1 mg Th uptaken per gram of tooth is observed after 24 h. The overall effectiveness of chelating agents for the removal of Th from is as follows: DTPA > EDTA > NaF/mouthwash/3,4,3-LI(1,2-HOPO); this trend was observed both in synthetic HAP and Th-impregnated teeth samples.

Preparation and characterization of a novel nanocomposite based on MnCr-layered double oxide and CoFe2O4 spinel ferrite for methyl orange adsorption

Herein, the adsorption of methyl orange (MO), a dangerous anionic dye, from an aqueous solution was investigated using a novel magnetic nanocomposite adsorbent. A nanocomposite entitled manganese chromium-layered double oxide/cobalt spinel ferrite, (MnCr)-LDO5wt.%/CoFe2O4, which links the interlayer structural characteristics of layered double oxides (LDOs) with the magnetic properties of spinel ferrites (SFs) was synthesized using the eco-friendly co-precipitation technique. Determination of structural parameters, crystallite size, and micro-strain was done using X-ray diffraction (XRD) analysis. Transmission electron microscopy (TEM) was used to determine grain shape and size. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) to identify elements and oxidation states present in the prepared nanocomposite. Vibrating sample magnetometer (VSM) was utilized to examine the magnetic characteristic. A comprehensive comparative study about the effectiveness and durability of CoFe2O4 and (MnCr)5wt.%/CoFe2O4 as nanoadsorbents for MO was conducted. Numerous variables, including contact time, MO concentration, adsorbent dosage, and pH were tested for their effects on the adsorption removal percentages. The findings showed that the maximum removal percentage was 86.1% for 25 ppm of MO was for 0.1 g/100 mL of (MnCr)-LDO5wt.%/CoFe2O4 at pH = 3. Investigations of isotherms and kinetics were conducted under batch conditions. The Langmuir isotherm matched the experimental data, for both nanoadsorbents, quite well due to the homogeneous distribution of active sites. Adsorption kinetics data were found to be compatible with intra-particle diffusion and pseudo-second order models for CoFe2O4 and (MnCr)5wt.%/CoFe2O4, respectively. A total of five adsorption-desorption cycles were performed to determine the prepared adsorbents' recyclable nature.

Efficacy and mechanisms of δ-MnO2 modified biochar with enhanced porous structure for uranium(VI) separation from wastewater

Even though uranium (U) is considered to be an essential strategic resource with vital significance to nuclear power development and climate change mitigation, U exposure to human and ecological environment has received growing concerns due to its both highly chemically toxic and radioactively hazardous property. In this study, a composite (M-BC) based on Ficus macrocarpa (banyan tree) aerial roots biochar (BC) modified by δ-MnO2 was designed to separate U(VI) from synthetic wastewater. The results showed that the separation capacity of M-BC was 61.53 mg/g under the solid - liquid ratio of 1 g/L, which was significantly higher than that of BC (12.39 mg/g). The separation behavior of U(VI) both by BC and M-BC fitted well with Freundlich isothermal models, indicating multilayer adsorption occurring on heterogeneous surfaces. The reaction process was consistent with the pseudo-second-order kinetic model and the main rate-limiting step was particle diffusion process. It is worthy to note that the removal of U(VI) by M-BC was maintained at 94.56% even after five cycles, indicating excellent reusability and promising application potential. Multiple characterization techniques (e.g. Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) and X-ray Photoelectron Spectroscopy (XPS)) uncovered that U(VI) complexation with oxygen-containing functional groups (e.g. O-CO and Mn-O) and cation exchange with protonated ≡MnOH were the dominant mechanisms for U(VI) removal. Application in real uranium wastewater treatment showed that 96% removal of U was achieved by M-BC and more than 92% of co-existing (potentially) toxic metals such as Tl, Co, Pb, Cu and Zn were simultaneously removed. The work verified a feasible candidate of banyan tree aerial roots biowaste based δ-MnO2-modified porous BC composites for efficient separation of U(VI) from uranium wastewater, which are beneficial to help address the dilemma between sustainability of nuclear power and subsequent hazard elimination.

3D Composite U(VI) Adsorbents Based on Alginate Hydrogels and Oxidized Biochar Obtained from Luffa cylindrica

3D naturally derived composites consisting of calcium alginate hydrogels (CA) and oxidized biochar obtained from Luffa cylindrica (ox-LC) were synthesized and further evaluated as adsorbents for the removal of U(VI) from aqueous media. Batch-type experiments were conducted to investigate the effect of various physicochemical parameters on the adsorption performance of materials. The maximum adsorption capacity (qmax) was 1.7 mol kg-1 (404.6 mg·g-1) at pH 3.0 for the CA/ox-LC with a 10% wt. ox-LC content. FTIR spectroscopy indicated the formation of inner-sphere complexes between U(VI) and the surface-active moieties existing on both CA and ox-LC, while thermodynamic data revealed that the adsorption process was endothermic and entropy-driven. The experimental data obtained from the adsorption experiments were well-fitted by the Langmuir and Freundlich models. Overall, the produced composites exhibited enhanced adsorption efficiency against U(VI), demonstrating their potential use as effective adsorbents for the recovery of uranium ions from industrial effluents and seawater.

Development of hydrogels based on xylan and poly (acrylic acid) for melamine adsorption in batch and continuous mode: experimental design, kinetics, isotherms, recyclability, and fixed-bed column

Two hydrogels were synthesized, characterized, and applied as alternative materials to remove melamine (MEL) from aqueous media by adsorption. For the first time, a complete study of MEL adsorption is presented, including optimization, kinetics, isotherm, reuse, and column studies with these new materials. One hydrogel is based on xylan and poly (acrylic acid) and was named HXy, and the other is based on the same components functionalized with activated carbon and was named HXy-AC. The materials were synthesized by free radical polymerization and characterized by FTIR, XRD, TGA, DSC, SEM, zeta potential, point of zero charge, N2 adsorption isotherms (BET), helium gas pycnometry, Archimedes method, swelling analysis, and stability tests. The characterization results confirmed the intended synthesis and showed the thermal, morphological, textural, structural, and compositional profile, as well as the adsorption characteristics of the materials. The adsorption studies in batch process included experimental design, kinetics, isotherms, and recyclability, and in continuous mode, the studies included fixed-bed column experiments. The full factorial design showed that adsorbent dosage, pH, and ionic strength are significant for adsorption capacity and removal percentage responses. Doehlert design enabled the definition of the values of adsorbent dosage and pH that were most suitable for MEL adsorption into the materials, indicating the optimal adsorption conditions. The kinetics were well described by the pseudo-first-order model, with R2 above 0.9920 for both materials at all concentrations tested. The isotherm obeyed the Langmuir model, with R2 above 0.9939 for both materials at all temperatures tested. Equilibrium was attained at 180 min, and the maximum experimental adsorption capacity was up to 132.46 and 118.96 mg g-1 at pH 7, with adsorbent dosage of 0.5 g L-1, and 298 K for HXy and HXy-AC, respectively. Furthermore, HXy and HXy-AC materials maintained about 58 and 70% of their initial adsorption capacity at the end of five adsorption/desorption cycles, respectively. Breakthrough curves were described by the Yan model and presented a maximum adsorption capacity of 30.2 and 30.4 mg g-1, treating 3.4 and 6.1 L of influent until the breakthrough point of 0.5 mg L-1 with HXy-AC using 2.0 and 4.0 g of material, respectively. These findings show that the hydrogels produced present the potential to be applied in the adsorption of basic molecules, such as MEL.

"One-can" strategy for the synthesis of hydrothermal biochar modified with phosphate groups and efficient removal of uranium(VI)

Significant selectivity, reasonable surface modification and increased structural porosity were three key factors to improve the competitiveness of biochar in the adsorption field. In this study, a hydrothermal bamboo-derived biochar modified with phosphate groups (HPBC) was synthesized using "one-can" strategy. BET showed that this method could effectively increase the specific surface area (137.32 m2 g-1) and simulation of wastewater experiments indicated HPBC had an excellent selectivity for U(VI) (70.35%), which was conducive to removal of U(VI) in real and complex environments. The accurate matchings of pseudo-second-order kinetic model, thermodynamic model and Langmuir isotherm showed that at 298 K, pH = 4.0, the adsorption process dominated by chemical complexation and monolayer adsorption was spontaneous, endothermic and disordered. Saturated adsorption capacity of HPBC could reach 781.02 mg g-1 within 2 h. The introduction of phosphoric acid and citric acid by "one-can" method not only provided abundant -PO4 to assist adsorption, but also activated oxygen-containing groups on the surface of the bamboo matrix. Results showed that adsorption mechanism of U(VI) by HPBC included electrostatic action and chemical complexation involving P-O, PO and ample oxygen-containing functional groups. Therefore, HPBC with high phosphorus content, outstanding adsorption performance, excellent regeneration, remarkable selectivity and green value provided a novel solution for the field of radioactive wastewater treatment.

Poly(Acrylic Acid)-Sodium Alginate Superabsorbent Hydrogels Synthesized by Electron Beam Irradiation Part I: Impact of Initiator Concentration and Irradiation Dose on Structure, Network Parameters and Swelling Properties

In the present paper, hydrogels based on acrylic acid (20%), sodium alginate (0.5%) and poly(ethylene oxide) (0.1%) were obtained by electron beam irradiation at room temperature with doses between 5 and 20 kGy, using potassium persulfate in concentrations up to 0.3% as a reaction initiator. The influence of initiator concentration and irradiation dose on hydrogel network parameters, swelling and deswelling behavior, gelation and degradation points, structure and morphology were investigated. Cross-link density increased with the irradiation dose and initiator addition, except at 20 kGy. The gel fraction was over 87.0% in all cases. Swelling experiments in distilled water showed swelling degrees of 40,000% at an irradiation dose of 5 kGy when a concentration of 0.1% initiator was added. A relationship between the swelling degree and irradiation dose, cross-linking degree (that increases from 0.044 × 10² to 0.995 × 10² mol/cm³) and mesh size (that decreases from about 220 nm to 26 nm) was observed. The addition of only 0.1% of PP led to the obtaining of hydrogels with a swelling degree of 42,954% (about 430 g/g) at an irradiation dose of 5 kGy and of 7206% (about 62 g/g) at 20 kGy, which are higher percentages than those obtained in the same irradiation conditions but without PP.

NaAlg-g-AA Hydrogels: Candidates in Sustainable Agriculture Applications

Nowadays, the degradation of agricultural soil due to various factors should be a major concern for everyone. In this study, a new sodium alginate-g-acrylic acid-based hydrogel was developed simultaneously by cross-linking and grafting with accelerated electrons to be used as soil remediation. The effect of irradiation dose and NaAlg contents on the gel fraction, network and structural parameters, sol-gel analysis, swelling power, and swelling kinetics of NaAlg-g-AA hydrogels have been investigated. It was demonstrated that NaAlg hydrogels show significative swelling power that is greatly dependent on their composition and irradiation dose; they keep the structure and are not degraded in different pH conditions and different water sources. Diffusion data revealed a non-Fickian transport mechanism (0.61-0.99) also specific to cross-linked hydrogels. The prepared hydrogels were proved as excellent candidates in sustainable agriculture applications.

Advanced Fabrication and Multi-Properties of Aluminum-Based Aerogels from Aluminum Waste for Thermal Insulation and Oil Absorption Applications

Metal-based aerogels have attracted numerous studies due to their unique physical, structural, thermal, and chemical properties. Utilizing aluminum waste, a novel, facile, environmentally friendly approach to aluminum-based aerogels is proposed. In this work, the aluminum-based aerogels produced do not use toxic chemicals unlike conventional aerogel production. Aluminum powder, with poly(acrylic acid) and carboxymethyl cellulose as binders, is converted into aluminum-based aerogels using the freeze-drying method. The aluminum-based aerogels have low density (0.08–0.12 g/cm3) and high porosity (93.83–95.68%). The thermal conductivity of the aerogels obtained is very low (0.038–0.045 W/m·K), comparable to other types of aerogels and commercial heat insulation materials. Additionally, the aerogels can withstand temperatures up to 1000 °C with less than 40% decomposition. The aerogels exhibited promising oil absorption properties with their absorption capacity of 9.8 g/g and 0.784 g/cm3. The Young’s modulus of the aerogels ranged from 70.6 kPa to 330.2 kPa. This study suggests that aluminum-based aerogels have potential in thermal insulation and oil absorption applications.

Magnetic nanocomposites based on Zn,Al-LDH intercalated with citric and EDTA groups for the removal of U(vi) from environmental and wastewater: synergistic effect and adsorption mechanism study

The efficient removal of U(vi) ions from contaminated natural waters and wastewaters of industrial processing plants by novel magnetic nanocomposites based on magnetite and Zn,Al-layered double hydroxides intercalated with citric and EDTA groups (Fe3O4/Zn,Al-LDH/Cit and Fe3O4/Zn,Al-LDH/EDTA) was shown. These adsorbents were obtained using co-precipitation and ion-exchange techniques. The infrared spectroscopy confirmed the existence of O-containing groups on the surfaces of Fe3O4/Zn,Al-LDH/Cit and Fe3O4/Zn,Al-LDH/EDTA, which could provide active sites in the interlayer of the adsorbents for the pollutants removal. The intercalation of Zn,Al-LDH with chelating EDTA-groups significantly increased the adsorption capacity toward U(vi) ions (131.22 mg g-1) compared to citric moieties in a wide range of pH (3.5-9.0). The maximum adsorption capacities of U(vi) at pH 7.5 were 81.12 mg g-1 for Fe3O4/Zn,Al-LDH/EDTA and 21.6 mg g-1 for Fe3O4/Zn,Al-LDH/Cit. The higher adsorption capacity of Fe3O4/Zn,Al-LDH/EDTA vs. the citric sample might be explained by high affinity of LDH-supports and high-activity of the chelating groups in formation of the complexes in the interlayer space of the magnetic nanocomposite. The removal of U(vi) by the magnetic nanocomposites occurred due to interlayer complexation and electrostatic interactions. The cations (Na+, K+, Ca2+), HCO3 - and fulvic acid anions being typical for natural waters were practically not affected upon the removal of U(vi) from aqueous media. The adsorption performance of Fe3O4/Zn,Al-LDH/EDTA nanocomposites was evaluated in the analysis of environmental and wastewater samples with recoveries in the range of 95.8-99.9%. This superior intercalation performance of LDH-supports provides simple and low-cost adsorbents, providing a strategy for decontamination of radionuclides from wastewater.

Synthesis and Characterization of a Novel Dual-Responsive Nanogel for Anticancer Drug Delivery

In this study, to reduce the side effects of anticancer drugs and also to increase the efficiency of current drug delivery systems, a pH and temperature-responsive polymeric nanogel was synthesized by copolymerization of N-vinylcaprolactam (VCL) and acrylic acid (AA) monomers (P(VCL-co-AA)) with a novel cross-linker, triethylene glycol dimethacrylate (TEGDMA), as a biocompatible and nontoxic component. The structural and physicochemical features of the P(VCL-co-AA) nanogel were characterized by FT-IR, DLS/Zeta potential, FE-SEM, and 1HNMR techniques. The results indicated that spherical polymeric nanogel was successfully synthesized with a 182 nm diameter. The results showed that the polymerization process continues with the opening of the carbon-carbon double bond of monomers, which was approved by C-C band removing located at 1600 cm-1. Doxorubicin (Dox) as a chemotherapeutic agent was loaded into the P(VCL-co-AA), whit a significant loading of Dox (83%), and the drug release profile was investigated in the physiological and cancerous site simulated conditions. P(VCL-co-AA) exhibited a pH and temperature-responsive behavior, with an enhanced release rate in the cancerous site condition. The biocompatibility and nontoxicity of P(VCL-co-AA) were approved by MTT assay on the normal human foreskin fibroblasts-2 (HFF-2) cell line. Also, Dox-loaded P(VCL-co-AA) had excellent toxic behavior on the Michigan Cancer Foundation-7 (MCF-7) cell line as model cancerous cells. Moreover, Dox-loaded P(VCL-co-AA) had higher toxicity in comparison with free Dox, which would be a vast advantage in reducing Dox side effects in the clinical cancer treatment applications.

Fe3O4-Mg(OH)2 nanocomposite as a scavenger for silver nanoparticles: Rational design, facile synthesis, and enhanced performance

Silver nanoparticles (AgNPs) are considered as emerging contaminants because of their high toxicity and increasing environmental impact. Removal of discharged AgNPs from water is crucial for mitigating the health and environmental risks. However, developing facile, economical, and environment-friendly approaches remains challenging. Herein, an Fe₃O₄-Mg(OH)₂ nanocomposite, as a novel magnetic scavenger for AgNPs, was prepared by loading Fe₃O₄ nanoparticles on Mg(OH)₂ nanoplates in a one-pot synthesis. Batch removal experiments revealed that the maximum removal capacities for the two model AgNPs (citrate- or polyvinylpyrrolidone-coated AgNPs) were 476 and 442 mg/g, respectively, corresponding to partition coefficients 8.03 and 4.89 mg/g/μM. Removal feasibilities over a wide pH range of 5-11 and in real water matrices and scavenger reusability with five cycles were also confirmed. Both Fe₃O₄ and Mg(OH)₂ components contributed to the removal; however, their nanocomposites exhibited an enhanced performance because of the high specific surface area and pore volume. Chemical adsorption and electrostatic attraction between the coatings on the AgNPs and the two components in the nanocomposite was considered to be responsible for the removal. Overall, the facile synthesis, convenient magnetic separation, and high removal performance highlight the great potential of the Fe₃O₄-Mg(OH)₂ nanocomposite for practical applications.

High-Performance Material for the Effective Removal of Uranyl Ion from Solution: Computationally Supported Experimental Studies

Adsorption is a widely used method for pollution removal and for the recovery of valuable species. In recent years, the use of metal-organic compounds among the adsorbents used in adsorption studies has increased. In this study, the performance of the water-insoluble Fe complex as a metal organic framework (MOF-Fe-Ta) of water-soluble tannic acid, which is not used as an adsorbent in uranium recovery and removal, was investigated. For the characterization of the new synthesized material, Fourier transform infrared, scanning electron microscopy, and X-ray diffraction analyses were performed. The changes in the adsorption process based on various parameters were investigated and discussed. The point of zero charges value of the adsorbent was found as 5.52. It was noticed that the adsorption increases as the pH increases. Analyzing the effect of concentration on adsorption, we determined which model explained the adsorption better. The monolayer capacity of the adsorbent determined in light of the Langmuir model was reported as 0.347 mol kg^-1. The Freundlich constant, namely the β value obtained in the Freundlich model, which is a measure of surface heterogeneity, was found to be 0.434, and the E_DR value, which was found from the Dubinin-Raduskevich model and accepted as a measure of adsorption energy, was 10.3 kJ mol^-1. The adsorption was kinetically explained by the pseudo-second-order model and the adsorption rate constant was reported as 0.15 mol^-1 kg min^-1. The effect of temperature on adsorption was studied; it was emphasized that adsorption was energy consuming, that is, endothermic and ΔH was found as 7.56 kJ mol^-1. The entropy of adsorption was positive as 69.3 J mol^-1 K^-1. As expected, the Gibbs energy of adsorption was negative (-13.1 kJ mol^-1 at 25 °C), so adsorption was considered as a spontaneous process. Additionally, the power and mechanism of the interaction between studied adsorbent and adsorbate are explained through density functional theory computations. Computationally obtained data supported the experimental studies.

Biosorption of Uranium from aqueous solution by green microalga Chlorella sorokiniana

Uranium and its compounds are radioactive and toxic, as well as highly polluting and damaging the environment. Novel uranium adsorbents with high biosorption capacity that are both eco-friendly and cost-effective are continuously being researched. The non-living biomass of the fresh water green microalga Chlorella sorokiniana was used to study the biosorption of uranium from aqueous solution. The biosorption of uranium from aqueous solutions onto the biomass of microalga C. sorokiniana was investigated in batch studies. The results showed that the optimal pH for uranium biosorption onto C. sorokiniana was 2.5. Uranium biosorption occurred quickly, with an equilibrium time of 90 min. The kinetics followed a pseudo-second-order rate equation, and the biosorption process fit the Langmuir isotherm model well, with a maximum monolayer adsorption capacity of 188.7 mg/g. The linear plot of the DKR model revealed that the mean free energy E = 14.8 kJ/mol, confirming chemisorption adsorption with ion exchange mode. The morphology of the algal biomass was investigated using a scanning electron microscope and energy dispersive X-ray spectroscopy. The FTIR spectroscopy analysis demonstrated that functional groups (carboxyl, amino, and hydroxyl) on the algal surface could contribute to the uranium biosorption process, which involves ion exchange and uranium absorption, and coordination mechanisms. Thermodynamic simulations indicated that the uranium biosorption process was exothermic (ΔH = -19.5562 kJ/mol) and spontaneous at lower temperatures. The current study revealed that C. sorokiniana non-living biomass could be an efficient, rapid, low-cost, and convenient method of removing uranium from aqueous solution.

Sulfur edge in molybdenum disulfide nanosheets achieves efficient uranium binding and electrocatalytic extraction in seawater

Electrochemical extraction of uranium in seawater provides a promising strategy for the persistent supply of fuel in the nuclear industry. However, current operation voltage for the electrochemical extraction of uranium in seawater generally requires a high applied voltage (∼-5 V). Herein, we constructed S-terminated MoS₂ nanosheets with abundant electrochemically active S-edge sites for efficient binding and reduction of uranium. In 100 ppm of uranium-spiked seawater at an applied voltage of -3 V, the S-terminated MoS₂ nanosheets exhibited a considerable extraction capacity of 1823 mg g^-1. After 30 min electrolysis in 100 mL of real seawater with 100 times concentrated uranium (330 ppb), the extracted uranium (29.5 μg) consumes electricity of 8.7 mW h. Moreover, we concentrated 12 L of real seawater (3.3 ppb) into 20 mL of aqueous solution containing 1752.6 ppb U by adding a reverse potential. In the mechanistic study, we directly observed the uranium clusters and single atoms confined by the S-edge at atomic resolution, which served as the intermediate and accounted for the boosted uranium extraction in seawater.

Controllable Fabrication of Molecularly Imprinted Microspheres with Nanoporous and Multilayered Structure for Dialysate Regeneration

Adsorption of urea from dialysate is essential for wearable artificial kidneys (WRK). Molecularly imprinted microspheres with nanoporous and multilayered structures are prepared based on liquid–liquid phase separation (LLPS), which can selectively adsorb urea. In addition, we combine the microspheres with a designed polydimethylsiloxane (PDMS) chip to propose an efficient urea adsorption platform. In this work, we propose a formulation of LLPS including Tripropylene glycol diacrylate (TPGDA), ethanol, and acrylic acid (30% v/v), to prepare urea molecularly imprinted microspheres in a simple and highly controllable method. These microspheres have urea molecular imprinting sites on the surface and inside, allowing selective adsorption of urea and preservation of other essential constituents. Previous static studies on urea adsorption have not considered the combination between urea adsorbent and WRK. Therefore, we design the platform embedded with urea molecular imprinted microspheres, which can disturb the fluid motion and improve the efficiency of urea adsorption. These advantages enable the urea absorption platform to be highly promising for dialysate regeneration in WRK.

Simple one-pot synthesis of manganese dioxide modified bamboo-derived biochar composite for uranium(VI) removal

Exploitation of bamboo-derived biochar offers a lucrative opportunity for using moso bamboo due to its short growth cycle, large quantity and universality. Novel MnO2 modified bamboo-derived biochar composites (MnO2@BBC) were...

Green Hydrogel-Biochar Composite for Enhanced Adsorption of Uranium

Uranium is the backbone of the nuclear fuel used for energy production but is still a hazardous environmental contaminant; thus, its removal and recovery are important for energy security and environmental protection. So far, the development of biocompatible, efficient, economical, and reusable adsorbents for uranium is still a challenge. In this work, a new orange peel biochar-based hydrogel composite was prepared by graft polymerization using guar gum and acrylamide. The composite's structural, morphological, and thermal characteristics were investigated via Fourier transform infrared (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) methods. The composite's water absorption properties were investigated in different media. The performance of the prepared composite in adsorbing uranium (VI) ions from aqueous media was systematically investigated under varying conditions including solution's acidity and temperature, composite dose, contact time, and starting amount of uranium. The adsorption efficiency increased with solution pH from 2 to 5.5 and composite dose from 15 to 50 mg. The adsorption kinetics, isotherms, and thermodynamics parameters were analyzed to get insights into the process's feasibility and viability. The equilibrium data were better described through a pseudo-second-order mechanism and a Langmuir isotherm model, indicating a homogeneous composite surface with the maximum uranium (VI) adsorption capacity of 263.2 mg/g. The calculated thermodynamic parameters suggested that a spontaneous and endothermic process prevailed. Interference studies showed high selectivity toward uranium (VI) against other competing cations. Desorption and recyclability studies indicated the good recycling performance of the prepared composite. The adsorption mechanism was discussed in view of the kinetics and thermodynamics data. Based on the results, the prepared hydrogel composite can be applied as a promising, cost-effective, eco-friendly, and efficient material for uranium (VI) decontamination.

Development of porous material via chitosan-based Pickering medium internal phase emulsion for efficient adsorption of Rb+, Cs+ and Sr2

The radioactive Rb⁺, Cs⁺ and Sr²⁺ have serious threat for the aquatic life and human health, its removal has been granted increasing concern. Hence the adsorbent with excellent adsorption performance and favourable reusability is strongly demanded. This work prepared a novel porous polymer of chitosan-g-polyacrylamide (CTS-g-PAM) by grafting the acrylamide (AM) onto the chitosan (CTS) with sufficient pore structure via an eco-friendly surfactant-free (corn oil)-in-water Pickering medium internal phase emulsion (O/W Pickering MIPE), solely stabilized by CTS. Interestingly, its pore structure could be tuned by varying the emulsion character via changing the molecular weight and concentration of CTS, as well as the pH values. Due to the abundant -COO^- and -NH₂ functional groups in the porous material of CTS-g-PAM, the high adsorption capacities of 195.43, 237.44 and 185.63 mg/g for Rb⁺, Cs⁺ and Sr²⁺ could be reached within 40, 30 and 20 min, respectively. Moreover, the CTS-g-PAM had excellent regeneration ability and reusability. Herein, we provided a feasible and low-cost pathway for preparation of the porous adsorbent with tunable porous structure for adsorption and separation application.

Hydrolytically stable foamed HKUST-1@CMC composites realize high-efficient separation of U(VI)

HKUST-1@CMC (HK@CMC) composites that show good acid and alkali resistance and radiation resistance were successfully synthesized by introducing carboxymethyl cellulose (CMC) onto the surface of HKUST-1 using a foaming strategy. For the first time, the composites were explored as efficient adsorbents for U(VI) trapping from aqueous solution, with encouraging results of large adsorption capacity, fast adsorption kinetics, and desirable selectivity toward U(VI) over a series of competing ions. More importantly, a hybrid derivative film was successfully prepared for the dynamic adsorption of U(VI). The results show that ∼90% U(VI) can be removed when 45 mg L-1 U(VI) was passed through the film one time, and the removal percentage is still more than 80% even after four adsorption-desorption cycles, ranking one of the most practical U(VI) scavengers. This work offers new clues for application of the Metal-organic-framework-based materials in the separation of radionuclides from wastewater.

Sonochemical recovery of uranium from nanosilica-based sorbent and its biohybrid

Use of nanomaterials to remove uranium by adsorption from nuclear wastewater is widely applied, though not much work is focused on the recovery of uranium from the sorbents. The present work reports the recovery of adsorbed uranium from the microstructures of silica nanoparticles (SiO2M) and its functionalized biohybrid (fBHM), synthesized with Streptococcus lactis cells and SiO2M, intensified using ultrasound. Effects of temperature, concentration of leachant (nitric acid), sonic intensity, and operating frequency on the recovery as well as kinetics of recovery were thoroughly studied. A comparison with the silent operation demonstrated five and two fold increase due to the use of ultrasound under optimum conditions in the dissolution from SiO2M and fBHM respectively. Results of the subsequent adsorption studies using both the sorbents after sonochemical desorption have also been presented with an aim of checking the efficacy of reusing the adsorbent back in wastewater treatment. The SiO2M and fBHM adsorbed 69% and 67% of uranium respectively in the second cycle. The adsorption capacity of fBHM was found to reduce from 92% in the first cycle to 67% due to loss of adsorption sites in the acid treatment. Recovery and reuse of both the nuclear material and the sorbent (with some make up or activation) would ensure an effective nuclear remediation technique, catering to UN's Sustainable Development Goals.

Antioxidant and anti-aging carbon quantum dots using tannic acid

Overexpression of collagenase, elastase, and tyrosinase is caused by external factors such as ultraviolet (UV) radiation and stress, resulting in wrinkle formation and freckles through the loss of skin elasticity and skin pigmentation. In this study, we developed novel carbon quantum dots (CQDs) with antioxidant and anti-aging properties using tannic acid as a carbon source through a simple microwave-assisted pyrolysis method. The synthesized tannic acid-derived CQDs (T-CQDs) showed bright blue fluorescence (QY = 28.2 ± 4.0%), exhibiting maximum emission at 430 nm under 350 nm excitation. Even though small amount of the T-CQDs (3μg ml^-1) was used, they exhibited excellent free radical scavenging ability (82.8 ± 4.3%). Also, the T-CQDs (10μg ml^-1) revealed remarkable inhibitory activity against skin aging-related collagenase (77.6 ± 4.8%), elastase (52.6 ± 1.0%), and tyrosinase (44.2 ± 1.3%), demonstrating their antioxidant and anti-aging effects. Furthermore, their antioxidant and anti-aging properties were superior to those of tannic acid, L-ascorbic acid, and quercetin used as positive controls. Finally, the T-CQDs effectively suppressed UV-induced reactive oxygen species generation by 30% at the cellular levels and showed high cell viability (99.7 ± 0.8%) even at 500μg ml^-1. These results demonstrate that the T-CQDs with superior antioxidant, anti-aging properties, and low cytotoxicity can be utilized as novel anti-aging materials in cosmetic and nanomedicine fields.

Enhanced uranium removal from acidic wastewater by phosphonate-functionalized ordered mesoporous silica: Surface chemistry matters the most

The removal of uranium species from aqueous phases using non-hazardous chemicals is still an open challenge, and remediation by adsorption is a prosperous strategy. Among the most crucial concerns regarding the design of an efficient material as adsorbent are, except the cost and the green character, the feasibility to be stable and effective under acidic pH, and to selectively adsorb the desired metal ion (e.g. uranium). Herein, we present a phosphonate functionalized ordered mesoporous silica (OMS-P), prepared by a one-step co-condensation synthesis. The physicochemical features of the material were determined by HR-TEM, XPS, EDX, N₂ sorption, and solid NMR, while the surface zeta potential was also measured. The removal efficiency was evaluated at two different temperatures (20 and 50 °C) in acidic environment to avoid interferences like solid phase formation or carbonate complexation and the adsorption isotherms, including data fitting with Langmuir and Freundlich models and thermodynamic parameters are presented and discussed. The high and homogeneous dispersion of the phosphonate groups within the entire silica's structure led to the greatest reported up-todays capacity (345 mg/g) at pH = 4, which was achieved in less than 10 min. Additionally, OMS-P showed that the co-presence of other polyvalent cation like Eu(III) did not affect the efficiency of adsorption, which occurs via inner-sphere complex formation. The comparison to the non-functionalized silica (OMS) revealed that the key feature towards an efficient, stable, and selective removal of the U(VI) species is the specific surface chemistry rather than the textural and structural features. Based on all the results and spectroscopic validations of surface adsorbed U(VI), the main interactions responsible for the elevated uranium removal were proposed.