Imageable Brachytherapy with Chelator-Free Radiolabeling Hydrogel.

Brachytherapy stands as an essential clinical approach for combating locally advanced tumors. Here, an injectable brachytherapy hydrogel is developed for the treatment of both local and metastatic tumor. Fe-tannins nanoparticles are efficiently and stably radiolabeled with clinical used therapeutic radionuclides (such as 131I, 90Y, 177Lu and 225Ac) without a chelator, and then chemically cross-linked with 4-ArmPEG-SH to form brachytherapy hydrogel. Upon intratumoral administration, magnetic resonance imaging (MRI) signal from ferric ions embedded within the hydrogel directly correlates with the retention dosage of radionuclides, which can real-time monitor radionuclides emitting short-range rays in vivo without penetration limitation during brachytherapy. The hydrogel's design ensures the long-term tumor retention of therapeutic radionuclides, leading to the effective eradication of local tumor. Furthermore, the radiolabeled hydrogel is integrated with an adjuvant to synergize with immune checkpoint blocking therapy, thereby activating potent anti-tumor immune responses and inhibiting metastatic tumor growth. Therefore, this work presents an imageable brachytherapy hydrogel for real-time monitoring therapeutic process, and expands the indications of brachytherapy from treatment of localized tumors to metastatic tumors. This article is protected by copyright. All rights reserved.

Phosphate and illite colloid pose a synergistic risk of enhanced uranium transport in groundwater: A challenge for phosphate immobilization remediation of uranium contaminated environmental water.

The phosphorus-containing reagents have been proposed to remediate the uranium contaminated sites due to the formation of insoluble uranyl phosphate mineralization products. However, the colloids, including both pseudo and intrinsic uranium colloids, could disturb the environmental fate of uranium due to its nonnegligible mobility. In this work, the transport pattern and micro-mechanism of uranium coupled to phosphate and illite colloid (IC) were investigated by combining column experiments and micro-spectroscopic evidences. Results showed that uranium transport was facilitated in granular media by forming the intrinsic uranyl phosphate colloid (such as Na-autunite) when the pH > 3.5 and CNa+ < 10 mM. Meanwhile, the mobility of uranium depended greatly on the typical water chemistry parameters governing the aggregation and deposit of intrinsic uranium colloids. However, the attachment of phosphate on illite granule increased the repulsive force and enhanced the dispersion stability of IC in the IC-U(VI)-phosphate ternary system. The non-preequilibrium transport and retention profiles, HRTEM-mapping, as well as TRLFS spectra revealed that the IC enhanced uranium mobility by forming the ternary IC-uranyl phosphate hybrid, and acted as the coagulation preventing agent for uranyl phosphate particles. This observed facilitation of uranium transport resulted from the formation of intrinsic uranyl phosphate colloids and IC-uranyl phosphate hybrids should be taken into consideration when evaluating the potential risk of uranium migration and optimizing the in-situ mineralization remediation strategy for uranium contaminated environmental water.

Simultaneous Determination of Transuranium Radionuclides in Urine by Tandem Quadrupole ICP-MS/MS with Mass-Shift Mode Combined with Chemical Separation.

The urine bioassay method for transuranium nuclides (237Np, 239,240,241Pu, 241Am, and 244Cm) is needed to quickly assess the potential internal contamination in emergency situations. However, in the case that the analysis of multiple radionuclides is required in the same sample, time-consuming/tedious sequential analytical procedures using multiple chromatographic separation resins would have to be employed for the separation of every single radionuclide. In this work, a rapid method for the simultaneous determination of transuranium nuclides in urine was developed by using triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) combined with a single DGA resin column. The chemical behaviors of Np/Pu and Am/Cm on the DGA resin were consistent in 8-10 mol/L HNO3 and 0.005-0.02 mol/L NaNO2 when 242Pu and 243Am were selected as tracers for Np/Pu and Am/Cm yield monitoring. Based on their different reaction rates with O2, 237Np, 239,240,241Pu, 241Am, and 244Cm in the same solution were simultaneously measured by ICP-MS/MS in the same run. The elimination efficiency of 238U+ tailing (7.43 × 10-9), 238U1H16O2+/238U16O2+ (8.11 × 10-8) and cross contamination of 241Pu and 241Am (<1%) were achieved using 10.0 mL/min He-0.3 mL/min O2 even if the eluate was directly measured without any evaporation. The detection limits of transuranium nuclides were at the femtogram level, demonstrating the feasibility of ICP-MS/MS for simultaneous transuranic radionuclides urinalysis. The developed method was validated by analyzing the spiked urine samples.

Ternary Heterostructure Membranes with Two-Dimensional Tunable Channels for Highly Selective Ion Separation.

Selective ion separation from brines is pivotal for attaining high-purity lithium, a critical nonrenewable resource. Conventional methods encounter substantial challenges, driving the quest for streamlined, efficient, and swift approaches. Here, we present a graphene oxide (GO)-based ternary heterostructure membrane with a unique design. By utilizing Zn2+-induced confinement synthesis in a two-dimensional (2D) space, we incorporated two-dimensional zeolitic imidazolate framework-8 (ZIF-8) and zinc alginate (ZA) polymers precisely within layers of the GO membrane, creating tunable interlayer channels with a ternary heterostructure. The pivotal design lies in ion insertion into the two-dimensional (2D) membrane layers, achieving meticulous modulation of layer spacing based on ion hydration radius. Notably, the ensuing layer spacing within the hybrid ionic intercalation membrane occupies an intermediary realm, positioned astutely between small-sized hydrated ionic intercalation membrane spacing and their more extensive counterparts. This deliberate configuration accelerates the swift passage of diminutive hydrated ions while simultaneously impeding the movement of bulkier ions within the brine medium. The outcome is remarkable selectivity, demonstrated by the partitioning of K+/Li+ = 20.9, Na+/K+ = 31.2, and Li+/Mg2+ = 9.5 ion pairs. The ZIF-8/GO heterostructure significantly contributes to the selectivity, while the mechanical robustness and stability, improved by the ZA/GO heterostructure, further support its practical applicability. This report reports an advanced membrane design, offering promising prospects for lithium extraction and various ion separation processes.

High performance photocatalyst TiO2@UiO-66 applied to degradation of methyl orange.

MOFs have considerable adsorption capacity due to their huge specific surface area. They have the characteristics of photocatalysts for their organic ligands can absorb photons and produce electrons. In this paper, the photodegradation properties of TiO2 composites loaded with UiO-66 were investigated for the first time for MO. A series of TiO2@UiO-66 composites with different contents of TiO2 were prepared by a solvothermal method. The photocatalytic degradation of methyl orange (MO) was performed using a high-pressure mercury lamp as the UV light source. The effects of TiO2 loading, catalyst dosage, pH value, and MO concentration were investigated. The results showed that the degradation of MO by TiO2@UiO-66 could reach 97.59% with the addition of only a small amount of TiO2 (5 wt%). TiO2@UiO-66 exhibited significantly enhanced photoelectron transfer capability and inhibited efficient electron-hole recombination compared to pure TiO2 in MO degradation. The composite catalyst indicated good stability and reusability when they were recycled three times, and the photocatalytic reaction efficiencies were 92.54%, 88.76%, and 86.90%. The results provide a new option to design stable, high-efficiency MOF-based photocatalysts.

Thermally Induced Orderly Alignment of Porphyrin Photoactive Motifs in Metal-Organic Frameworks for Boosting Photocatalytic CO2 Reduction.

Efficient transfer of charge carriers through a fast transport pathway is crucial to excellent photocatalytic reduction performance in solar-driven CO2 reduction, but it is still challenging to effectively modulate the electronic transport pathway between photoactive motifs by feasible chemical means. In this work, we propose a thermally induced strategy to precisely modulate the fast electron transport pathway formed between the photoactive motifs of a porphyrin metal-organic framework using thorium ion with large ionic radius and high coordination number as the coordination-labile metal node. As a result, the stacking pattern of porphyrin molecules in the framework before and after the crystal transformations has changed dramatically, which leads to significant differences in the separation efficiency of photogenerated carriers in MOFs. The rate of photocatalytic reduction of CO2 to CO by IHEP-22(Co) reaches 350.9 µmol·h-1·g-1, which is 3.60 times that of IHEP-21(Co) and 1.46 times that of IHEP-23(Co). Photoelectrochemical characterizations and theoretical calculations suggest that the electron transport channels formed between porphyrin molecules inhibit the recombination of photogenerated carriers, resulting in high performance for photocatalytic CO2 reduction. The interaction mechanism of CO2 with IHEP-22(Co) was clarified by using in-situ electron paramagnetic resonance, in-situ diffuse reflectance infrared Fourier transform spectroscopy, in-situ extended X-ray absorption fine structure spectroscopy, and theoretical calculations. These results provide a new method to regulate the efficient separation and migration of charge carriers in CO2 reduction photocatalysts and will be helpful to guide the design and synthesis of photocatalysts with superior performance for the production of solar fuels.

A Radioluminescent Metal-Organic Framework for Monitoring 225Ac in Vivo.

225Ac is considered as one of the most promising radioisotopes for alpha-therapy because its emitted high-energy α-particles can efficiently damage tumor cells. However, it also represents a significant threat to healthy tissues owing to extremely high radiotoxicity if targeted therapy fails. This calls for a pressing requirement of monitoring the biodistribution of 225Ac in vivo during the treatment of tumors. However, the lack of imageable photons or positrons from therapeutic doses of 225Ac makes this task currently quite challenging. We report here a nanoscale luminescent europium-organic framework (EuMOF) that allows for fast, simple, and efficient labeling of 225Ac in its crystal structure with sufficient 225Ac-retention stability based on similar coordination behaviors between Ac3+ and Eu3+. After labeling, the short distance between 225Ac and Eu3+ in the structure leads to exceedingly efficient energy transduction from225Ac-emitted α-particles to surrounding Eu3+ ions, which emits red luminescence through a scintillation process and produces sufficient photons for clearcut imaging. The in vivo intensity distribution of radioluminescence signal originating from the 225Ac-labeled EuMOF is consistent with the dose of 225Ac dispersed among the various organs determined by the radioanalytical measurement ex vivo, certifying the feasibility of in vivo directly monitoring 225Ac using optical imaging for the first time. In addition, 225Ac-labeled EuMOF displays notable efficiency in treating the tumor. These results provide a general design principle for fabricating 225Ac-labeled radiopharmaceuticals with imaging photons and propose a simple way to in vivo track radionuclides with no imaging photons, including but not limited to 225Ac.

Theoretical Insights on the Complexation of Americium(III) and Europium(III) with Diglycolamide- and Dimethylacetamide-Functionalized Calix[4]arenes.

Separation of minor actinides from lanthanides is one of the biggest challenges in spent fuel reprocessing due to the similar physicochemical properties of trivalent lanthanides (Ln(III)) and actinides (An(III)). Therefore, developing ligands with excellent extraction and separation performance is essential at present. As an excellent pre-organization platform, calixarene has received more attention on Ln(III)/An(III) separation. In this work, we systematically explored the complexation behaviors of the diglycolamide (DGA)/dimethylacetamide (DMA)-functionalized calix[4]arene extractants for Eu(III) and Am(III) using relativistic density functional theory (DFT). These calix[4]arene-derived ligands were obtained by functionalization with two or four binding units at the narrow edge of the calix[4]arene platform. All bonding nature analyses suggested that the Eu-L complexes possess stronger interaction compared to Am-L analogues, resulting in the higher extraction capacity of the these calix[4]arene ligands toward Eu(III). Thermodynamic analysis demonstrates that these pre-organized ligands on the calix[4]arene platform with four binding units yield better extraction abilities than the single ligands. Although DMA-functionalized ligands show stronger complexation stability for metal ions, in acidic solutions, the calix[4]arene ligands with DGA binding units have better extraction performance for Eu(III) and Am(III) due to the basicity of the DMA ligand. This work enabled us to gain a deeper understanding of the bonding properties between supramolecular ligands and lanthanides/actinides and afford useful insights into designing efficient supramolecular ligands for separating Ln(III)/An(III).

Speciation of Zn and Cd in sierozem soil, northwest China: bulk EXAFS and micro synchrotron X-ray fluorescence.

Previous research studies have confirmed that Zn and Cd are the most predominant heavy metals in the Baiyin district, Gansu province, China. Furthermore, the speciation of Zn and Cd is a key factor in controlling the mobility, bioavailability, and toxicity of metals in Zn/Cd co-contaminated soil. In this study, the speciation of Zn and Cd in different types of agricultural soils including the Yellow River irrigated soil (s3) and sewage irrigated soil (s1 and s2) was investigated and compared by a combination of sequential extraction, bulk X-ray absorption fine structure (XAFS), and micro-X-ray fluorescence (µ-XRF) techniques. The results of the speciation quantified by XAFS were in general agreement with those obtained by sequential extraction, and the combination of both approaches allowed a reliable description of Zn/Cd speciation in soil. The speciation of Zn in the s1 soil exposed around the smelter was similar to speciation of Zn in the sewage irrigated s2 soil. In both soils, Zn was predominantly present as Zn-Al LDH (31-36%), Zn adsorbed on calcite (37-47%), and primary minerals (14-18% sphalerite and 9% franklinite). In contrast, the proportions of organic Zn (23%) and Zn-Al LDH (53%) were significantly higher in the Yellow River irrigated s3 soil, while that of Zn-calcite (24%) was lower. This indicated that Zn in s3 was less mobile and bioavailable than that in s1 and s2 soils. The content of bioavailable Zn in s3 was much lower than the background value and Zn did not pose a threat to the Yellow River irrigated soil. In addition, Cd was strongly correlated with Zn content and exhibited a simpler speciation. Cd adsorbed on illite and calcite was found as the major species in both soil types, posing higher migration and toxicity to the environment. Our study reported the speciation and correlation of Zn/Cd in sierozem soil for the first time and provided a significant theoretical basis for remediation actions to minimize Zn/Cd risks.

Photocatalytic direct borylation of carboxylic acids.

The preparation of high value-added boronic acids from cheap and plentiful carboxylic acids is desirable. To date, the decarboxylative borylation of carboxylic acids is generally realized through the extra step synthesized redox-active ester intermediate or in situ generated carboxylic acid covalent derivatives above 150 °C reaction temperature. Here, we report a direct decarboxylative borylation method of carboxylic acids enabled by visible-light catalysis and that does not require any extra stoichiometric additives or synthesis steps. This operationally simple process produces CO2 and proceeds under mild reaction conditions, in terms of high step economy and good functional group compatibility. A guanidine-based biomimetic active decarboxylative mechanism is proposed and rationalized by mechanistic studies. The methodology reported herein should see broad application extending beyond borylation.

Cobalt-catalyzed chemoselective dehydrogenation through radical translocation under visible light.

The transformations that allow the direct removal of hydrogen from their corresponding saturated counterparts by the dehydrogenative strategy are a dream reaction that has remained largely underexplored. In this report, a straightforward and robust cobaloxime-catalyzed photochemical dehydrogenation strategy via intramolecular HAT is described for the first time. The reaction proceeds through an intramolecular radical translocation followed by the cobalt assisted dehydrogenation without needing any other external photosensitizers, noble-metals or oxidants. With this approach, a series of valuable unsaturated compounds such as α,ß-unsaturated amides, enamides and allylic and homoallylic sulfonamides were obtained in moderate to excellent yields with good chemo- and regioselectivities, and the synthetic versatility was demonstrated by a range of transformations. And mechanistic studies of the method are discussed.

Theoretical Probing of Size-Selective Crown Ether Macrocycle Ligands for Transplutonium Element Separation.

Effective separation and recovery of chemically similar transplutonium elements from adjacent actinides is extremely challenging in spent fuel reprocessing. Deep comprehension of the complexation of transplutonium elements and ligands is significant for the design and development of ligands for the in-group separation of transplutonium elements. Because of experimental difficulties of transplutonium elements, theoretical calculation has become an effective means of exploring transplutonium complexes. In this work, we systematically investigated the coordination mechanism between transplutonium elements (An = Am, Cm, Bk, Cf) and two crown ether macrocyclic ligands [N,N'- bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H2bp18c6) and N,N'-bis[(6-methylphosphinic-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H2bpp18c6)] through quasi-relativistic density functional theory. The extraction complexes of [Anbp18c6]+ and [Anbpp18c6]+ possess similar geometrical structures with actinide atoms located in the cavity of the ligands. Bonding nature analysis indicates that the coordination ability of the coordinating atoms in pendent arms is stronger than that in the crown ether macrocycle because of the limitation of the macrocycle. Most of the coordination atoms of the H2bp18c6 ligand have a stronger ability to coordinate with metal ions than those of the H2bpp18c6 ligand. In addition, the bonding strength between the metal ions and ligands gradually weakens from Am to Cf, which is mainly attributed to the size selectivity of the ligands. Thermodynamic analysis shows that the H2bp18c6 ligand has a stronger extraction capacity than the H2bpp18c6 ligand, while the H2bpp18c6 ligand is superior in terms of the in-group separation ability. The extraction capacity of the two ligands for metal ions gradually decreases across the actinide series, indicating that these crown ether macrocycle ligands have size selectivity for these actinide cations as a result of steric constraint of the crown ether ring. We hope that these results offer theoretical clues for the development of macrocycle ligands for in-group transplutonium separation.

Encapsulation of Polymetallic Oxygen Clusters in a Mesoporous/Microporous Thorium-Based Porphyrin Metal-Organic Framework for Enhanced Photocatalytic CO2 Reduction.

Solar-initiated CO2 reduction is significant for green energy development. Herein, we have prepared a new mesoporous/microporous porphyrin metal-organic framework (MOF), IHEP-20, loaded with polymetallic oxygen clusters (POMs) to form a composite material POMs@IHEP-20 for visible-light-driven photocatalytic CO2 reduction. The as-made composite material exhibits good stability in water from pH 0 to 11. After POMs were introduced to IHEP-20, they showed superior activity toward photocatalytic CO2 reduction with a CO production rate of 970 µmol·g-1·h-1, which is 3.27 times higher than that of pristine IHEP-20. This study opens a new door for the design and synthesis of high-performance catalysts for the photocatalytic reduction of CO2.

Co-transport and co-release of Eu(III) with bentonite colloids in saturated porous sand columns: Controlling factors and governing mechanisms.

Accurate prediction of the colloid-driven transport of radionuclides in porous media is critical for the long-term safety assessment of radioactive waste disposal repository. However, the co-transport and corelease process of radionuclides with colloids have not been well documented, the intrinsic mechanisms for colloids-driven retention/transport of radionuclides are still pending for further discussion. Thus the controlling factors and governing mechanisms of co-transport and co-release behavior of Eu(III) with bentonite colloids (BC) were discussed and quantified by combining laboratory-scale column experiments, colloid filtration theory and advection dispersion equation model. The results showed that the role of colloids in facilitating or retarding the Eu(III) transport in porous media varied with cations concentration, pH, and humic acid (HA). The transport of Eu(III) was facilitated by the dispersed colloids under the low ionic strength and high pH conditions, while was impeded by the aggregated colloids cluster. The enhancement of Eu(III) transport was not monotonically risen with the increase of colloids concentration, the most optimized colloids concentration in facilitating Eu(III) transport was approximately 150 mg L-1. HA showed significant promotion on both Eu(III) and colloid transport because of not only its strong Eu(III) complexion ability but also the increased dispersion of HA-coated colloid particles. The HA and BC displayed a synergistic effect on Eu(III) transport, the co-transport occurred by forming the ternary BC-HA-Eu(III) hybrid. The transport patterns could be simulated well with a two-site model that used the advection dispersion equation by reflecting the blocking effect. The retarded Eu(III) on the stationary phase was released and remobilized by the introduction of colloids, or by a transient reduction in cation concentration. The findings are essential for predicting the geological fate and the migration risk of radionuclides in the repository environment.

Insights into sorption speciation of uranium on phlogopite: Evidence from TRLFS and DFT calculation.

Knowledge of the sorption speciation of uranium at mineral/water interface is essential to construct reliable retention and migration models. In this work, the sorption speciation of U(VI) at the phlogopite/water interface was studied at trace concentrations by combining batch sorption, time-resolved luminescence spectroscopy, and theoretical calculation. Batch experiments showed that the sorption of U(VI) on phlogopite was strongly dependent on pH but weakly affected by ionic strength, implying that the inner-sphere surface complexation was mainly responsible for U(VI) sorption on phlogopite. The diverse luminescence spectral characteristics indicated the formation of multiple inner-sphere surface species at the phlogopite/water interface, whose abundances varied as a function of pH. A portion of U(VI) precipitated as uranyl oxyhydroxides such as metaschoepite and becquerelite at high pH. Density functional theory calculation revealed that the bidentate complex at the edge of phlogopite (≡AlO-MgO-UO2(H2O)3) was the most favorable sorption configuration for U(VI) at acidic condition. The increasing temperature enhanced the sorption of U(VI) on phlogopite without altering the sorption species, and such enhancement in U(VI) sorption was withdrawn once the temperature decreased. These findings are essential for understanding the immobilization mechanism of U(VI) in mica-rich granitic terrains at a molecular scale and building a reliable retention model.

Graphene Quantum Dots prepared by Electron Beam Irradiation for Safe Fluorescence Imaging of Tumor.

Graphene quantum dots (GQD) have attracted much attention due to their unique properties in biomedical application, such as biosensing, imaging, and drug delivering. However, scale preparing red luminescing GQD is still challenging now. Herein, with the help of electron beam irradiation, a simple, rapid, and efficient up-to-down strategy was developed to synthesize GQD with size of 2.75 nm emitting 610 nm luminescence. GQD were further functionalized with polyethylene glycol (PEG) and exhibited good solubility and biocompatibility. The potential in vivo toxicity of PEGylated GQD could completely be eliminated by the clinic cholesterol-lowering drug simvastatin. PEGylated GQD could selectively accumulate in tumor after intravenous injection as a security, reliable and sensitive tumor fluorescence imaging agent. Therefore, this work presented a new method preparing red luminescing GQD for biomedical application.

Strengthened erosion resistance of compacted bentonite by layered double hydroxide: A new electrostatic interaction-based approach.

For the geological repository of high-level radioactive waste (HLW) built in granitic host rock，the control of buffer material (compacted bentonite) erosion and subsequent loss caused by groundwater in granite fissures is an unresolved problem of major concern. We propose here new insight into enhancing the erosion resistance of compacted bentonite by means of its electrostatic interaction with oppositely-charged layered double hydroxide (LDH). The interaction between bentonite and LDH was studied by dropwise addition of colloidal LDH into colloidal bentonite suspension, during which the variation in electrical conductivity, zeta potential and particle size proved a strong interaction between these two materials. Interestingly, in addition to their aggregation, intercalated structures of LDH and montmorillonite were found in the composite (BEN@LDH) by a combined characterization of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM), and were confirmed by density functional theory (DFT) calculation. Colloid generation of compacted BEN@LDH under ultrasonic conditions is negligible comparing with that of compacted bentonite, indicating a significantly higher erosion resistance. Besides, a small amount of LDH by mechanically mixing with bentonite (mass ratio 1:99) can also effectively improve the erosion resistance of compacted bentonite. Moreover, BEN@LDH displayed stronger retention performance towards U(VI) and Se(IV) than bentonite under near-neutral/weakly alkaline conditions. Our results indicate that LDH is a promising additive in compacted bentonite, and this approach may be extended to common geotechnical structures built with clays and soils.

Facile Vacuum Annealing-Induced Modification of TiO2 with an Enhanced Photocatalytic Performance.

In this work, the photocatalytic performance enhancement of hydrothermally prepared TiO2 was achieved by facile vacuum annealing treatment. Calcination of TiO2 powder in air (CA-TiO2) maintained its white color, while gray powder was obtained when the annealing was performed under vacuum (CV-TiO2). Fourier transform infrared, total organic carbon, X-ray photoelectron spectroscopy, and electron paramagnetic resonance analyses proved that vacuum annealing transformed ethanol adsorbed on the surface of TiO2 into carbon-related species accompanied by the formation of surface oxygen vacancies (Vo). The residual carbon-related species on the surface of CV-TiO2 favored its adsorption of organic dyes. Compared with TiO2 and CA-TiO2, CV-TiO2 exhibited an improved charge carrier separation with surface Vo as trapping sites for electrons. Vacuum annealing-induced improvement of crystallinity, enhancement of adsorption capacity, and formation of surface Vo contributed to the excellent photocatalytic activity of CV-TiO2, which was superior to that of commercial TiO2 (P25, Degussa). Obviously, vacuum annealing-triggered decomposition of ethanol played an important role in the modification of TiO2. In the presence of ethanol, vacuum annealing was also suitable for the introduction of Vo into P25. Therefore, the current work offers an easy approach for the modification of TiO2 to enhance its photocatalytic performance by facile vacuum annealing in the presence of ethanol.

Mechanisms of bentonite colloid aggregation, retention, and release in saturated porous media: Role of counter ions and humic acid.

In the subsurface environment, colloids play an important role in pollutant transport by acting as the carriers. Understanding colloid release, transport, and deposition in porous media is a prerequisite for evaluating the potential role of colloids in subsurface contaminant transport. In this work, the aggregation, retention, and release of bentonite colloid in saturated porous sand media were investigated by kinetic aggregation and column experiments, the correlation and mechanism of these processes were revealed by combining colloid filtration theory, interaction energy calculation and density functional theory. The results showed that the retention and release of colloids were closely related to the dispersion stability and filtration effect. Multivalent cations with higher mineral affinity reduced the colloid stability, and the dispersion stability and mobility of the colloid were greatly improved by humic acid due to the enhancement of electrostatic repulsion and steric hindrance effects. The primary minimum interaction was found to contribute more to irreversible colloid retention in a Ca2+ system, while the secondary energy minimum was found to be responsible for colloid release with the occurrence of transient solution chemistry. The deposited colloid aggregates could be redistributed and released when the solution chemistry became favorable towards dispersion. These findings provide essential insight into the environmental colloid fate as well as a vital reference for the risk of colloid-driven transport of contaminants in the subsurface aquifer environment.