Search

Aqueous hexavalent chromium (Cr(VI)) treatment and chromium resource recovery toward Cr-containing wastes are of significant importance and necessity to both wastewater remediation and resource recovery. Herein, via mild photoreaction conditions with isopropanol (IPA) as an electron donor, a catalyst-free strategy for aqueous Cr(VI) extraction to form an insoluble polyhydroxy Cr(V) complex is developed for the first time. Aqueous Cr(VI) with concentration from 5 to 150 ppm can be efficiently extracted with high selectivity even in the presence of coexisting ions, and the total Cr concentration in residue solution can be as low as 0.5 ppm. The Cr resource could be efficiently recovered as pure Cr

Photocatalytic oxidation of alcohols has received more and more attention in recent years following the numerous studies on the degradation of pollutants, hydrogen evolution, and CO2 reduction by photocatalysis. Instead of the total oxidation of organics in the degradation process, the photo-oxidation of alcohols aims at the selective conversion of alcohols to produce carbonyl/acid compounds. Promising results have been achieved in designing the catalysts and reaction system, as well as in the mechanistic investigations in the past few years. This review summarizes the state-of-the-art progress in the photo-oxidation of alcohols, including the development of photocatalysts and cocatalysts, reaction conditions including the solvent and the atmosphere, and the exploration of mechanisms with scavengers experiment, electron paramagnetic resonance (EPR) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The challenges and outlook for the further research in this field are also discussed.

Conjugated polymers have a broad application foreground in the field of photocatalytic organic synthesis to produce value-added chemicals due to their functional diversity, broad light responsive ability, high thermal and chemical stability, and tunable band structure. Herein, using mixed chloride salts (i.e., NaCl/LiCl) as building template, a series of porous conjugated polymers constructed by melamine and terephthalaldehyde monomers were obtained through a Schiff-base reaction in the absence of any external solvent. Melamine-terephthalaldehyde polymer (i.e., PMTPA-x, x represents the mass ratio of salt-mixture to mixed precursors of PMTPA) materials displayed porous morphologies and possessed different energy band structures via regulating the mass ratio of mixed-salt to monomers. Specifically, PMTPA-20 has a larger specific surface area and more suitable redox potential towards the photocatalytic oxidative coupling of amines to imines. Under visible light, with molecular oxygen as oxidant, PMTPA-20 achieves 97% conversion of benzylamine in 8 h which is 3.9 times higher than that of pristine PMTPA (25% conversion in 8 h). In addition, PMTPA-20 catalyst has good structure stability and reusability performance for photocatalytic reactions.

Cu doped SrTiO3 (Cu-STO) has been synthesized and investigated as the photocatalyst for selective alcohol oxidation under mild condition. Cu-STO samples demonstrate intense absorption to visible light and near-infrared light. Using water as the reaction solvent, Cu-STO samples can efficiently oxidize benzyl alcohol (BA) into benzyl aldehyde under both anaerobic and aerobic conditions with high selectivity. In aerobic condition, an apparent quantum efficiency as high as 43.22% at 420 nm has been reached for benzyl alcohol oxidation. More strikingly, the apparent quantum efficiency remains as high as 14.47% even at 700 nm, being the highest one reported to date under similar conditions. Further analysis indicates Cu dopants induces abundant oxygen vacancies and introduces interband springboard into SrTiO3, which effectively extend the light response of SrTiO3 to the visible and NIR region and enhance the separation of charge carriers, being critical to the highly selective and efficient conversion of alcohols.

Extraction of uranium from radioactive waste-water is of significant importance for environmental protection and the recovery of uranium resource. Different from the previous reports to use the solid absorbent/photocatalyst for U(VI) removal, herein, we proposed a new eco-friendly method for the rapid and selective extraction of uranium from aqueous solutions under visible light without solid materials. At optimal pH value and in the presence of organics like alcohols, the U(VI) could be extracted efficiently to form brown uranium solid over wide uranium concentrations under anaerobic condition and visible light, by utilizing the excitation of the given U(VI) species. With comprehensive modelling of the electronic ultraviolet-visible (UV-Vis) properties, it is proved that pH adjusting towards U(VI) could induce efficient ligand-to-metal-charge-transfer (LMCT) within the uranyl complex under visible light and the reduction of U(VI) to form U(V), which can be transformed into U(IV) via disproportionation reaction. The resulting U(IV) in solid phase makes the extraction much more convenient in operation. More importantly, the excellent selectivity for uranium extraction over interfering alkali metal ions, transition metal ions and the lanthanide metal ions shows a powerful application potential.

Heterogeneous photocatalysis has captured worldwide attention because of its tremendous potential in the field of solar energy conversion to solve energy and environmental issues. Efficient utiliza...

NaNbO3 enriched with oxygen vacancies by Ni doping was successfully synthesized via a polymerized complex method and applied as a photocatalyst in the oxidation of cinnamyl alcohol (CA) to cinnamal...

Designing and fabricating environmental friendly adsorbents with more accessible active sites and higher specific surface area for achieving rapid kinetics and high efficiency have become an impending challenge in radionuclides’ pollution remediation. To overcome these issues, we rationally designed the hierarchical structured layered double hydroxides with mesoporous carbon template (CMK-3@LDHs) by in situ hydrothermal method. The adsorption data could be well simulated with pseudo-second-order and Langmuir model, and the results indicated that the CMK-3@LDHs exhibited higher adsorption capacities (171 mg·g−1 for CMK-3@Mg-Al LDHs and 301 mg·g−1 for CMK-3@Ni-Al LDHs at pH = 5.0) and more rapid kinetics (achieved equilibrium within 30 min) than SBA-15@LDHs towards U(VI). The kinetic model simulation demonstrated that the adsorption rate was dominated by intra-particle and film diffusion models simultaneously. In addition, the interaction between U(VI) and LDHs was pH-dependent and weakly related with ionic strength at pH

Aluminosilicate clay mineral (ACM) is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring. In past two decades, in-depth understanding on unique layered structure and abundant surface properties endows ACM in the emerging research and application fields. In field of solar-chemical energy conversion, ACM has been widely used to support various semiconductor photocatalysts, forming the composites and achieving efficient conversion of reactants under sunlight irradiation. To date, classic ACM such as kaolinite and montmorillonite, loaded with semiconductor photocatalysts has been widely applied in photocatalysis. This review summaries the recent works on ACM-based composites in photocatalysis. Focusing on the properties of surface and layered structure, we elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM, i.e., type 1:1 and type 2:1. Not only large surface area and active surface hydroxyl group assist the substrate adsorption, but also the layered structure provides more space to enlarge the application of ACM-based photocatalysts. Besides, we overview the modifications on ACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process. This review could inspire more upcoming design and synthesis for ACM-based photocatalysts, leading this kind of economic and eco-friendly materials for more practical application in the future.

Background Diabetes has significant effects on bone metabolism. Both type 1 and type 2 diabetes can cause osteoporotic fracture. However, it remains challenging to diagnose osteoporosis in type 2 diabetes by bone mineral density which lacks regular changes. Seen another way, osteoporosis can be ascribed to the imbalance of bone metabolism, which is closely related to diabetes as well. Methods Here, to assist clinicians in diagnosing osteoporosis in type 2 diabetes, an efficient and simple SVM (support vector machine) model was established based on different combinations of biochemical indexes, which were collected from patients who did the test of bone turn-over markers (BTMs) from January 2016 to March 2018 in the department of endocrine, Zhongda Hospital affiliated to Southeast University. The classification was done based on a software package of machine learning in Python. The classification performance was measured by SKLearn program incorporated in the Python software package and compared with the clinical diagnostic results. Results The predicting accuracy rate of final model was above 88%, with feature combination of sex, age, BMI (body mass index), TP1NP (total procollagen I N-terminal propeptide) and OSTEOC (osteocalcin). Conclusions Experimental results show that the model showed an anticipant result for early detection and daily monitoring on type 2 diabetic osteoporosis.

The leakage of radionuclides poses a great threat to the global ecosystem, which has aroused world-wide continuous attention. Since sorption plays the most important role in their environmental fate and humic acid (HA) is a key factor to their migration behavior, it is necessary to develop highly-efficient adsorbents that can remove radionuclides from the contaminated water in the presence of HA. Herein, we reported a novel multi-shelled Fe3O4@MnOx, which showed considerable sorption capacities towards uranium (U(VI)) and europium (Eu(III)). From the systemic batch experiments, the sorption kinetics follows the pseudo-second-order model, and sorption thermodynamics are endothermic processes. The sorption edges are pH-dependent but independent of ionic strength. Furthermore, the sorption isotherms are well described by the Langmuir model, giving maximum sorption capacities of 106.72 mg·g−1 for U(VI) and 138.13 mg·g−1 for Eu(III) at 298 K. Based on the spectroscopic studies, U(VI) is mainly adsorbed on the MnIII-O-H site while Eu(III) shows higher affinity to the MnIV-O-H site. In the presence of humic acid (HA), the HAUO2+ and (HA)2Eu+ species can accelerate the sorption kinetics and enhance the sorption capacities. This work can not only boost the exploration of adsorbent systems in the field of materials, but also promote the investigations of the interface reaction mechanism in the field of radiochemistry.

Background: Diabetes has significant effects on bone metabolism. Both type 1 and type 2 diabetes can cause osteoporotic fracture. However, it remains challenging to diagnose osteoporosis in type 2 diabetes by bone mineral density which lacks regular changes. Seen another way, osteoporosis can be ascribed to the imbalance of bone metabolism, which is closely related to diabetes as well. Method: Here, to assist clinicians in diagnosing osteoporosis in type 2 diabetes, an efficient and simple SVM model was established based on different combinations of biochemical indices, including bone turnover makers, calcium and phosphorus, etc. The classification performance was measured using several evaluations. Results: The predicting accuracy rate of final model is above 88%, with feature combination of Sex, Age, BMI, TP1NP and OSTEOC. Conclusion: Experimental results show that the model has come to an anticipant result for early detection and daily monitoring on type 2 diabetic osteoporosis.

The progress of efficient and low-cost materials for environmental remediation is highly desirable but remains challenging. Herein, we fabricated magnetic bimetal oxide MnFe2O4 nanocubes (NCs) by co-precipitation phase inversion method. Characterization of the as-prepared nanomaterials revealed that MnFe2O4 NCs had an average size of 50–70 nm and possessed unique magnetic properties for adsorbent separation. The adsorption behavior and interaction mechanism of U(VI)/Eu(III) on MnFe2O4 were explored by batch experiment and spectroscopy analysis combined with density functional theory (DFT) calculations. Batch experimental results showed that U(VI)/Eu(III) sorption onto MnFe2O4 were independent of ionic strength, indicating the formation of inner-sphere surface complexes. The maximum sorption capacities of MnFe2O4 calculated from Langmuir isotherm model at 298.15 K were 119.90 mg·g−1 for U(VI) at pH 5.0 and 473.93 mg·g−1 for Eu(III) at pH 7.0, respectively. Furthermore, the excellent regeneration and reusability of MnFe2O4 could support long-term application in wastewater and sewage treatment. The analysis of FT-IR and XPS in combination with DFT calculations revealed that the interaction of U(VI)/Eu(III) onto MnFe2O4 was mainly ascribed to the strong ionic bonds (M O) and hydroxyl ( OH) groups via electrostatic interaction and surface complexation. The resulting MnFe2O4 further exhibited high effective retention and recovery for U(VI)/Eu(III) from synthetic water systems and real seawater. This work highlighted that MnFe2O4 NCs were exceptionally capable in rapidly and efficiently sequestering U(VI)/Eu(III) from natural water and sewage, which would be a great prospect and further widely used in other lanthanides/actinides remediation.

Selective photocatalytic oxidation of alcohols into value-added aldehydes or ketones is a promising alternative for alcohol oxidation concerning the mild reaction conditions and the controllable selectivity. To increase the activity, defective Bi2WO6 with abundant oxygen vacancies (OVs) was synthesized via substitution of W by Ta. The resulting Ta-doped Bi2WO6 loaded with Pt nanoparticles as co-catalyst efficiently converted aromatic and aliphatic alcohols into the corresponding carbonyl compounds with high selectivity (>99%) in aqueous solution under visible-light irradiation and anaerobic conditions, with equivalent H2 as a coupled product. The optimal amount of benzyl alcohol converted by the Ta-doped catalyst was two times higher than that of the undoped catalyst. Surface OVs were found to favor the dissociative adsorption of the alcohols and to prolong the life time of the charge carriers. More importantly, isotopic labelling experiments confirmed that over Pt-loaded pristine undoped Bi2WO6, the coupled H2 product results from water reduction, while over Pt-loaded Ta-doped Bi2WO6, the produced H2 originates from benzyl alcohol, implying that benzyl alcohol can be photo-oxidized via a complete dehydrogenation pathway. Thus, enriched surface OVs in photocatalysts can activate α-C-H bonds in alcohols, boosting the photocatalytic oxidation performance.

We provide a distinct understanding on the role of oxygen vacancies (OVs) for visible light-triggered aerobic oxidation of alcohols via comparative studies on three kinds of Nb2O5, i.e., undoped, Ti-doped and Ce-doped Nb2O5. With benzyl alcohol and 5-hydroxymethylfurfural as representative alcohol substrates, we show that fast alcohol oxidation with high selectivity can be achieved on these doped Nb2O5 containing abundant OVs. However, the functionality of OVs is dependent on the properties of dopants as Ce-doped Nb2O5 exhibits a better performance than Ti-doped one. Investigations indicate that the Ce dopants incur little distortion to the structure of Nb2O5 and induce more accessible OVs than Ti dopants for the dissociative chemisorption of alcohol molecules which supports favorable interfacial electron migration process. The present work not only reveals the difference of oxygen vacancies caused by varied metal doping but provides a unique insight in the relation between OVs structure and photocatalytic alcohol oxidation.

Herein the novel natural bimetallic oxides of perovskite oxides (CaTiO x ) and calcium aluminum oxides (CaAlO x ) were fabricated by one-step calcination-oxidation process under air conditions and were characterized using zeta potential, FT-IR, SEM, TEM, XRD, and XPS techniques. Porous and cotton-shaped irregular surface morphologies of CaTiO x and CaAlO x could provide excellent active sites and large specific surface area for the removal of U(VI) from wastewater. Based on FT-IR, XRD and XPS analyses, the enrichment of U(VI) was attributed to the abundant adsorption sites (e.g., M-O groups) of CaTiO x and CaAlO x . The consequences demonstrated that the sorption of U(VI) on CaTiO x and CaAlO x were strongly dependent on pH and weakly dependent on ionic strength at pH 4.0. The accordance of sorption kinetic data with the pseudo-second order model suggested that the sorption reaction was multi-stage controlled chemical process. The sorption isotherms of U(VI) can be satisfactorily simulated by the Langmuir model and the maximum monolayer sorption capacities of U(VI) were 241.71 mg·g −1 on CaTiO x and 258.29 mg·g −1 on CaAlO x at 298.15 K. In addition, the thermodynamic results pointed out that the sorption reaction was spontaneous and endothermic process. The sorption mechanism was interpreted as surface complexation and electrostatic interactions. The results demonstrated that CaTiO x and CaAlO x could be widely used as promising and cost-effective materials for the treatment of U(VI) of aqueous solutions in environmental management and pollution prevention and cure.

Novel rod-like ternary nanoscale layered double hydroxides (Ca-Mg-Al-LDH) and their bimetal derivatives (Ca-Mg-Al-LDOx, x: 200, 300, 400, 500, and 600 °C) were fabricated with a simple-green hydrothermal and calicination process. The interaction mechanism and adsorption property of U(VI) on Ca-Mg-Al-LDH and Ca-Mg-Al-LDOx were investigated by a batch technique and spectroscopy analysis, and the results indicated that U(VI) could form strong and stable surface complexes on Ca-Mg-Al-LDH and Ca-Mg-Al-LDOx surfaces. The adsorption capacity of U(VI) on various adsorbents could be controlled and adjusted through changing the calcination temperature, which was attributed to the different contents of various metal–oxide bonds (e.g., Ca–O, Mg–O, and Al–O). The adsorption capacities of U(VI) on these adsorbents were in the order of Ca-Mg-Al-LDO500 (486.8 mg/g) > Ca-Mg-Al-LDO600 (373.4 mg/g) > Ca-Mg-Al-LDO400 (292.5 mg/g) > Ca-Mg-Al-LDO300 (260.0 mg/g) > Ca-Mg-Al-LDO200 (223.5 mg/g) > Ca-Mg-Al-LDH (132.5 mg/g), which...