Study on Dynamic Column Behavior and Complexation Mechanism of DBS-Modified Crown Ether-Based Silica to Sr.

A crown ether-loaded hybrid adsorbent suitable for the separation and enrichment of strontium from high-level liquid waste was synthesized. 4',4'(5″)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) and its modifiers dodecyl benzenesulfonic acid (DBS) and 1-dodecanol were impregnated into silica-based polymer support. The hybrid adsorbent exhibited excellent Sr(II) selectivity ability, and effective chromatographic separation and recovery of Sr(II) from simulated high-level liquid waste could be achieved with a (DtBuCH18C6 + DBS + dodec)/SiO-P packed column.

Competition between Loss of H versus H+H in the Fragmentation of the Fluorene Cation.

The fluorene cation is a frequently studied molecule in the context of fragmentation experiments. This is because of its potential role in interstellar chemistry, notably as a precursor of PAH cages. In this paper, we analyze H, H , H and losses from the fluorene cation using the SMF (Statistical Molecular Fragmentation) model.

Decomposition mechanisms of nuclear-grade cationic exchange resin by advanced oxidation processes: Statistical molecular fragmentation model and DFT calculations.

The treatment and disposal of radioactive waste are presently facing great challenges. Spent ion exchange resins have become a focus of attention due to their high production and serious environmental risks. In this paper, a simplified model of cationic exchange resin is proposed, and the degradation processes of cationic resin monomer initiated by hydroxyl radicals (·OH) are clarified by combining statistical molecular fragmentation (SMF) model and density functional theory (DFT) calculations.

Amino acids modified nanoscale zero-valent iron: Density functional theory calculations, experimental synthesis and application in the Fenton-like degradation of organic solvents.

To improve the adsorption and catalytic performance of heterogeneous Fenton-like catalysts for oil wastes, amino acids were used to modify nanoscale zero-valent iron (AA@Fe), which were applied in the Fenton-like degradation of organic solvents (tributyl phosphate and n-dodecane, named TBP and DD). Twelve amino acids, i.e.

Radiation Resistance and Adsorption Behavior of Aluminum Hexacyanoferrate for Pd.

Irradiation resistance is important for adsorbents used in radioactive environments such as high-level liquid waste. In this work, a silica-based composite adsorbent (KAlFe(CN)/SiO) was synthesized and γ-irradiated from 10 to 1000 kGy. The angles of the main X-ray diffraction peaks slightly decreased with the increase in irradiation dose, and a minor decomposition of CN occurred after irradiation to 1000 kGy, indicating that the KAlFe(CN)/SiO adsorbent could preserve structural integrity with a dose below 100 kGy.

"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.

Degradation of the mixed nuclear-grade cationic and anionic exchange resins using Fe/H homogeneous Fenton oxidation.

To further improve the treatment capacity of actual wastes, H was introduced into the homogeneous Fenton system as a co-catalyst for dissolution and degradation of the mixed nuclear-grade cationic and anionic exchange resins. The effects of acid type and concentration, catalyst type and concentration, HO dosage, initial temperature, antifoaming agent and resin ratio were studied. The concentration of inorganic acid, type and concentration of catalyst had significant influence on the decomposition of mixed resins.

Adsorption of Co and Sr in aqueous solution by a novel fibrous chitosan biosorbent.

In this study, a novel fibrous chitosan biosorbent was prepared using LiOH/KOH/urea/HO (4.5:7:8:80.5 by weight) as spinning solvent.

Degradation of the mixed organic solvents of tributyl phosphate and n-dodecane by heterogeneous Fenton-like oxidation using nanoscale zero-valent iron as the catalyst.

The treatment and disposal of spent radioactive organic solvents, i.e., tributyl phosphate (TBP) and diluent (such as kerosene, n-dodecane, etc.

Iron-Based Dual Active Site-Mediated Peroxymonosulfate Activation for the Degradation of Emerging Organic Pollutants.

It is still a challenge to synthesize highly efficient and stable catalysts for the Fenton-like reaction. In this study, we constructed an integrated catalyst with highly dispersed iron-based dual active sites, in which FeN and single-atom Fe (SA-Fe) were embedded into nitrogen- and oxygen-co-doped graphitic carbon (Fe-N-O-GC-350). Extended X-ray absorption fine structure (EXAFS) confirmed the coordination structure of iron, and line combination fitting (LCF) demonstrated the coexistence of FeN and SA-Fe with percentages of 75 and 25%, respectively.

Multiple dehydrogenation of fluorene cation and neutral fluorene using the statistical molecular fragmentation model.

The statistical molecular fragmentation (SMF) model was used to analyze the 306 fragmentation channels (containing 611 different species) that result from the fluorene (C13H10+) cation losing up to three hydrogen atoms (neutral radicals and/or a proton). Breakdown curves from such analysis permit one to extract experimentally inaccessible information about the fragmentation of the fluorene cation, such as the locations of the lost hydrogen atoms (or proton), yields of the neutral fragments, electronic states of the residues, and quantification of very low probability channels that would be difficult to detect. Charge localization during the fragmentation pathways was studied to provide a qualitative understanding of the fragmentation process.

Construction of three-dimensional reduced graphene oxide wrapped nZVI doped with AlO as the ternary Fenton-like catalyst: Optimization, characterization and catalytic mechanism.

The rational design and synthesis of novel nanocomposites as effective heterogeneous catalysts is meaningful for the advances in Fenton-like technology. Herein, multiple variants of three-dimensional reduced graphene oxide wrapped nZVI doped with AlO (3D-RGO@nZVI/AlO) were prepared by three different self-assembly methods. The composites were characterized by field emission scanning electron microscopy, nitrogen adsorption/desorption isotherms, Raman spectrum analysis, X-ray diffraction, and X-ray photoelectron spectroscopy.

Reaction mechanism of chloramphenicol with hydroxyl radicals for advanced oxidation processes using DFT calculations.

The structure properties of chloramphenicol (CAP), including bond information and the Fukui function for the atoms in the main chain, were investigated computationally by density functional theory (DFT). The result shows that the chiral carbons in CAP offer the most active positions for chemical reactions, which is in good agreement with the experiment. The detailed degradation mechanism for CAP with hydroxyl radicals in advanced oxidation processes is further studied at the SMD/M06-2X/6-311 + G(d,p) level of theory.

Nanoscale Fe/Cu bimetallic catalysts for Fenton-like oxidation of the mixture of nuclear-grade cationic and anionic exchange resins.

Spent resins generated from the nuclear industrial processes are still difficult to be treated and disposed. Fenton-like processes have great application potential in the treatment of spent resins, but the Fenton reaction mechanisms and resin degradation pathways remain challenging. In this study, nanoscale Fe/Cu bimetallic catalysts were prepared and characterized for the Fenton-like degradation of the mixture of cationic and anionic resins.

Enhanced heterogeneous Fenton-like degradation of nuclear-grade cationic exchange resin by nanoscale zero-valent iron: experiments and DFT calculations.

Nanoscale zero-valent iron (nZVI) was prepared and used as a heterogeneous Fenton-like catalyst for the degradation of nuclear-grade cationic exchange resin. The properties of nZVI before and after reaction were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface area analysis. The results showed that nZVI-HO system exhibited the enhanced degradation of cationic resins, compared with Fe-HO, Cu-HO, and Fe/Cu-HO systems.

A Statistical Model and DFT Study of the Fragmentation Mechanisms of Metronidazole by Advanced Oxidation Processes.

The degradation pathway of the antibiotic metronidazole (MNZ) in wastewater was investigated computationally with a physical statistical method and a quantum chemical approach. In both cases, density functional theory (DFT) at the M06-2X/6-311+G(d,p) level was used to calculate the structures and property parameters of all molecules. On one hand, decay of the isolated MNZ molecule excited at a given excitation energy was studied using the statistical molecular fragmentation (SMF) model.

Three-dimensional macroporous graphene-wrapped zero-valent copper nanoparticles as efficient micro-electrolysis-promoted Fenton-like catalysts for metronidazole removal.

Three-dimensional macroporous graphene-wrapped zero-valent copper nanoparticles (3D-GN@Cu) were synthesized using a self-assembly process of liquid-phase reduction and characterized by field emission scanning electron microscopy, nitrogen adsorption/desorption isotherms, X-ray diffraction, Raman spectrum analysis, and X-ray photoelectron spectroscopy. The catalytic activity of 3D-GN@Cu was evaluated in view of the effects of various systems, the pH value, catalyst dosage, initial metronidazole concentration and temperature, and it showed a high efficiency for removing metronidazole with saturated dissolved oxygen (without adding extra HO) in a wide range of pH value from 3.2 to 9.

Mechanism of Co(II) adsorption by zero valent iron/graphene nanocomposite.

Nanoscale zero valent iron (ZVI)/graphene (GF) composite was prepared and characterized by Brunauer-Emmett-Teller (BET) surface area measurement and zeta potential determination. The adsorption isotherm of Co(II) in aqueous solution, as well as the influence of pH values and ionic strengths was studied. The mechanism of Co(II) adsorption by GF was investigated through analyzing the sorption products at initial pH of 3.

Degradation of 4-Chloro-3,5-Dimethylphenol by a Heterogeneous Fenton-Like Reaction Using Nanoscale Zero-Valent Iron Catalysts.

Degradation of 4-chloro-3,5-dimethylphenol (PCMX) by a heterogeneous Fenton-like process using nanoparticulate zero-valent iron (nZVI) and hydrogen peroxide (HO) at pH 6.3 was investigated. Interactive effects of three factors-initial PCMX concentration, nZVI dosage, and HO concentration-were investigated using the response surface method based on the Box-Behnken design.

Magnetic nanoscaled Fe3O4/CeO2 composite as an efficient Fenton-like heterogeneous catalyst for degradation of 4-chlorophenol.

Magnetic nanoscaled Fe(3)O(4)/CeO(2) composite was prepared by the impregnation method and characterized as a heterogeneous Fenton-like catalyst for 4-chlorophenol (4-CP) degradation. The catalytic activity was evaluated in view of the effects of various processes, pH value, catalyst addition, hydrogen peroxide (H(2)O(2)) concentration, and temperature, and the pseudo-first-order kinetic constant of 0.11 min(-1) was obtained for 4-CP degradation at 30 °C and pH 3.

A heterogeneous Fenton-like system with nanoparticulate zero-valent iron for removal of 4-chloro-3-methyl phenol.

The removal of biocide 4-chloro-3-methyl phenol (CMP) was investigated by heterogeneous Fenton-like system using nanoparticulate zero-valent iron (nZVI) as catalyst. The properties of nZVI before and after reaction were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of pH value, initial concentration of CMP, nZVI dose and hydrogen peroxide (H(2)O(2)) concentration were determined.

Mechanism of the anodic oxidation of 4-chloro-3-methyl phenol in aqueous solution using Ti/SnO2-Sb/PbO2 electrodes.

Electrochemical oxidation of 4-chloro-3-methyl phenol (CMP) was examined using Ti/SnO(2)-Sb/PbO(2) anodes. The physicochemical properties of the electrodes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. The degradation was studied by monitoring the total organic carbon (TOC) removal of CMP, and variation of the concentration of intermediates by high-performance liquid chromatography (HPLC), ion chromatography (IC) and gas chromatography/mass spectrometry (GC/MS).

Preparation of a titanium dioxide photocatalyst codoped with cerium and iodine and its performance in the degradation of oxalic acid.

A novel class of visible light-activated photocatalysts was prepared by codoping TiO(2) with cerium and iodine (Ce-I-TiO(2)). The particles were characterized using the Brunauer-Emmett-Teller method, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Visible light absorption. Particles of Ce-I-TiO(2) had greater photoabsorption in the 400-800 nm wavelength range than iodine-doped TiO(2) (I-TiO(2)).

Mechanism of the photocatalytic degradation of C.I. Reactive Black 5 at pH 12.0 using SrTiO3/CeO2 as the catalyst.

The photocatalytic degradation mechanism of an azo dye, C.I. Reactive Black 5 (RB5), has been investigated in an aqueous suspension of SrTiO3/CeO2 composite under 250 W UV irradiation at pH 12.