Kinetics of ester-105 degradation by La/TiO2 photocatalysis.

Lanthanum-doped titanium (La/TiO2) nano-photocatalysts were prepared using the sol-gel method and characterized by X-ray diffraction (XRD), zeta potential, and low-temperature nitrogen adsorption analyses. Ester-105, a flotation collector from beneficiation wastewater, was chosen as the target pollutant. The influence of the initial ester-105 concentration, pH, and photocatalyst dosage on the photocatalytic degradation of ester-105 was investigated. To examine the kinetics of the adsorption and photocatalytic degradation of ester-105, a Langmuir adsorption model and Langmuir-Hinshelwood kinetic models were established and discussed. The synthesized photocatalyst comprised anatase-phase TiO2, with an isoelectric point of pH = 6.5, specific surface area of 56.1626 m2·g-1, and average pore size of 7.78 nm. The maximum adsorption and the adsorption equilibrium constant of La/TiO2 for ester-105 were determined as 0.338 mg·g-1 and 1.008 L·mg-1, respectively. The first-order kinetic reaction rate constant (k) exhibited a linear relationship with the initial ester-105 concentration. The optimal pH for ester degradation was theoretically determined to be 6.95, and the optimum photocatalyst dosage was found to be 0.2739 g·L-1. Experiments confirmed that the photocatalytic degradation of ester-105 using La/TiO2 followed the Langmuir-Hinshelwood kinetics model, thereby providing a theoretical foundation for the photocatalytic degradation of ester-105 for industrial application.

Carbon sphere@Co9S8 yolk-shell structure with good morphology stability for improved lithium storage performance.

The poor electronic conductivity and huge volume expansion of cobalt sulfides upon cycling would lead to their poor electrochemical performances for Lithium-ion batteries. Here, we rationally design a yolk-shell carbon sphere@Co9S8 (C@CS) composite, which demonstrates improved kinetics and excellent morphology stability during cycling. This structure can keep Co9S8 shell from collapse and aggregation. After cycling, a layer of thin solid electrolyte interphase is coated on the Co9S8 shells and prevented them from dissolving in electrolyte, which is helpful for the electrochemical performances. As a result, the C@CS electrodes exhibit good lithium storage performances, including excellent cyclic stability up to 300 cycles at 1000 and 2000 mA g-1 and high-rate property of 4000 mA g-1 with a capacity of 489 mA h g-1.

Influence of alkali metal ions (K+ and Na+) on the preparation of magnesium hydroxide hexagonal flakes.

Magnesium hydroxide (Mg(OH)2), as a green halogen-free flame retardant, has attracted significant attention in the field of flame retardant composite materials. In addition to conventional indicators such as purity and whiteness, Mg(OH)2 is required to take the form of regular hexagonal sheets to ensure the dispersion of composite materials. We use irregular large particles of Mg(OH)2 prepared by the magnesium factory in western Qinghai as raw materials to study the influence of alkali metal ions K+ and Na+ mainly present in salt lakes on the physicochemical properties of Mg(OH)2. The products were characterized via X-ray diffraction, scanning electron microscopy, automatic nitrogen physical adsorption apparatus, and other modern characterization techniques. Results show that alkali metal ions K+ and Na+ considerably influence the crystal surface polarity, particle size, and morphology of the prepared Mg(OH)2. The mechanism analysis shows that the presence of K+ and Na+ alters the dissolution, recrystallization, and growth characteristics of Mg(OH)2. This study provides theoretical support for the realization of high-performance Mg(OH)2 using salt lake resources and demonstrates the value for promoting the large-scale industrial application of the salt lake industry.

MRI parameters predict central lumbar spinal stenosis combined with redundant nerve roots: a prospective MRI study.

Background: To observe changes in the cauda equina nerve on lumbar MRI in patients with central lumbar spinal stenosis (LSS). Methods: 878 patients diagnosed with LSS by clinical and MRI were divided into the redundant group (204 patients) and the nonredundant group (674 patients) according to the presence or absence of redundant nerve roots (RNRs). The anteroposterior diameter of the spinal canal (APDS) and the presence of multiple level stenosis, disc herniation, thickening of ligamentum flavum (LF) and increased epidural fat were assessed on MRI. Univariate and multivariate logistic regression analyses were performed to explore the predictors of LSS combined with RNRs. Results: Patients with LSS combined with RNRs had thicker epidural fat, smaller APDS and more combined multifaceted stenosis. Female patients and older LSS patients were more likely to develop RNRs; there was no difference between two groups in terms of disc herniation (p > 0. 05). Age, APDS, multiple level stenosis, and increased epidural fat were significantly correlated with the formation of LSS combined with RNRs (p < 0.05). Conclusion: A smaller APDS and the presence of multiple level stenosis, thickening of LF, and increased epidural fat may be manifestations of anatomical differences in patients with LSS combined with RNRs. Age, APDS, multiple level stenosis, and increased epidural fat play important roles. The lumbar spine was measured and its anatomy was observed using multiple methods, and cauda equina changes were assessed to identify the best anatomical predictors and provide new therapeutic strategies for the management of LSS combined with RNRs.

Oxidative Dissolution Process of Sphalerite in Fe2(SO4)3-O3 System: Implications for Heavy Metals Removal and Recovery.

Metal sulfides in waste rocks and tailings are susceptible to serious soil and water contamination due to the generation of acid mine drainage (AMD) during stockpiling. The hydrometallurgical process is one of the most essential heavy metal remediation technologies through harmless disposal and resource utilization of the waste sulfides. However, atmospheric hydrometallurgy of sulfides still faces great challenges due to low leaching efficiency and high cost. In this work, we proposed a cooperative leaching system (Fe2(SO4)3-O3) and investigated the oxidative dissolution process of sphalerite (ZnS). Under the optimal conditions, the extracted zinc reached 97.8%. Reactive oxygen species (ROS) (·OH, 1O2 and ·O2-) were identified in the radical quenching experiments. The dissolution of sphalerite did not show passivation due to the ozone's capability to oxidize the sulfur in sphalerite to sulfate. In addition, stirring rate, O3 inlet concentration, and Fe2(SO4)3 concentration had a significant effect on the dissolution of sphalerite. Meanwhile, the apparent activation energy was 24.11 kJ/mol based on kinetic fitting, which indicated that the controlling step of the reaction was mainly a diffusion process. This work demonstrated the cooperative effect of sphalerite leaching in the O3-Fe2(SO4)3 system and provided a theoretical reference for efficient and atmospheric dissolution of sphalerite.

Facile Synthesis with TiO2 Xerogel and Urea Enhanced Aniline Aerofloat Degradation Performance of Direct Z-Scheme Heterojunction TiO2/g-C3N4 Composite.

Different TiO2/g-C3N4 (TCN) composites were synthesized by a simple pyrolysis method with TiO2 xerogel and urea. The structure and physicochemical properties of TCN were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, ultraviolet-visible diffuse reflectance spectrum, X-ray photoelectron spectroscopy, N2-adsorption isotherms and electrochemical impedance spectroscopy. Aniline Aerofloat was chosen as a typical degradation-resistant contaminant to investigate the photodegradation activity of TCN under UV irradiation. The results indicated that TCN had higher light absorption intensity, larger specific surface area and smaller particle size compared to pure TiO2. Furthermore, TCN had great recycling photocatalytic stability for the photodegradation of Aniline Aerofloat. The photocatalytic activity depends on the synergistic reaction between holes (h+) and hydroxyl radicals (·OH). Meanwhile, the direct Z-scheme heterojunction structure of TiO2 and g-C3N4 postpones the recombination of h+ and electrons to enhance UV-light photocatalytic activity.

Sonochemical Synthesis of Vaterite-Type Calcium Carbonate Using Steamed Ammonia Liquid Waste without Additives.

Herein, metastable spheroidal vaterite calcium carbonate (CaCO3) was prepared using a simple ultrasound technique. The fabricated material comprises an irregular nanoparticle aggregate when steamed ammonia liquid waste, that is, (CaCl2) and (NH4)2CO3, is used as the raw material at atmospheric temperature, without any surfactants. The effects of ultrasound amplitude, probe immersion depth, and solution volume on particle properties were investigated. The obtained samples were identified and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and the Brunauer-Emmett-Teller technique. Our experiments show that the probe immersion depth and the reaction volume are the key parameters that impact the diameter size and size distribution of the fabricated spheroidal vaterite CaCO3 particles. The ultrasound amplitude considerably affected the particle size and the specific surface area. A possible formation mechanism for pure vaterite is proposed herein, which suggests that simple vaterite CaCO3 is formed owing to the special properties of steamed ammonia liquid waste and the synergistic effects of the ultrasonic system. This study may provide a new method for vaterite CaCO3 synthesis.

Investigation of calcium carbonate synthesized by steamed ammonia liquid waste without use of additives.

The aim of this work is to study the effect of reaction conditions using steamed ammonia liquid waste without the use of additives on the crystallization of calcium carbonate. CaCO3 was prepared by steamed ammonia liquid waste (CaCl2) and (NH4)2CO3 solution. The produced crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR) and X-ray diffraction (XRD). We have investigated the effect of the concentration of reactants, stirring speed, Ca2+ : CO3 2- ratio, aging time and adding mode on the particle size and size distribution, final morphology and polymorph of calcium carbonate crystals during precipitation. The influence of concentration of reactants, stirring speed, Ca2+ : CO3 2- ratio, aging time and adding mode on the morphology, size and polymorph of CaCO3 particles and possible formation mechanism were discussed. The exploration provides the possibility for large-scale synthesis of CaCO3 materials with controllable morphology and crystallographic structure by steamed ammonia liquid waste without use of additives at room temperature.

Selective sulfide precipitation of copper ions from arsenic wastewater using monoclinic pyrrhotite.

Pyrrhotite is a potential source of S2- for the sulfide precipitation of nonferrous metal ions in hydrometallurgy and waste water treatment. In this study, different pyrrhotite crystals were prepared using zero-valent iron and sulfur to determine the effects of the pyrrhotite's structure on the sulfide precipitation of copper ions. The results indicate that the sulfide precipitation of copper ions highly depends on the crystal structure and crystallinity of pyrrhotite. Monoclinic pyrrhotite was found to be the most effective for copper sulfide precipitation, which can be used for the selective precipitation of copper ions from arsenic wastewater. More than 96% copper ions were removed with little loss of arsenic, contributing to a copper product of 20.2% Cu and 0.7% As, which can serve as raw materials of copper metallurgy. X-ray diffraction analysis showed the presence of CuS and (CuxFe1-x)S, indicating that most copper ions precipitated as CuS and some copper ions entered the FeS lattice by a lattice substitution reaction. Therefore, monoclinic pyrrhotite may provide an alternative solution for the selective precipitation of copper from arsenic wastewater.

Photodegradation Pathways of Typical Phthalic Acid Esters Under UV, UV/TiO2, and UV-Vis/Bi2WO6 Systems.

Photolysis and photocatalysis of typical phthalic acid esters (dimethyl phthalate, DMP; diethyl phthalate, DEP; dibutyl phthalate, DBP) were carried out in UV, UV/TiO2, and UV-Vis/Bi2WO6 systems. All of the selected phthalic acid esters and their decomposition byproducts were subjected to qualitative and quantitative analysis through HPLC and GC-MS. The results of 300 min of photolysis and photodegradation reaction were that each system demonstrated different abilities to remove DMP, DEP, and DBP. The UV/TiO2 system showed the strongest degradation ability on selected PAEs, with removal efficiencies of up to 93.03, 92.64, and 92.50% for DMP, DEP, and DBP in 90 min, respectively. UV-Vis/Bi2WO6 had almost no ability to remove DMP and DEP. However, all of the systems had strong ability to degrade DBP. On the other hand, the different systems resulted in various byproducts and PAE degradation pathways. The UV system mainly attacked the carbon branch and produced o-hydroxybenzoates. No ring-opening byproducts were detected in the UV system. In the photocatalytic process, the hydroxyl radicals produced not only attacked the carbon branch but also the benzene ring. Therefore, hydroxylated compounds and ring-opening byproducts were detected by GC-MS in both the UV/TiO2 and UV-Vis/Bi2WO6 photocatalytic systems. However, there were fewer products due to direct hole oxidation in the UV-Vis/Bi2WO6 system compared with the UV/TiO2 system, which mainly reacted with the pollutants via hydroxyl radicals.

catena-Poly[[tetra-aqua-zinc(II)]-µ-2,2'-dihydr-oxy-5,5'-diazenediyldibenzoato].

In the title compound, [Zn(C(14)H(8)N(2)O(6))(H(2)O)(4)](n), the 2,2'-dihydr-oxy-5,5'-diazenediyldibenzoate ligand acts as a carboxyl-ate bridge, leading to the formation of a polymeric chain running along the [10] direction. The Zn(II) atom is hexa-coordinated in a distorted octa-hedral geometry by six O atoms [Zn-O = 2.055 (4)-2.132 (3) Å] from two carboxylate ligands and four water mol-ecules. The crystal packing is stabilized by inter-molecular O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds, and two π-π inter-actions. The centroid-centroid distances are 3.803 (16) and 3.804 (17) Å.

Carbon-coated cobalt oxide porous spheres with improved kinetics and good structural stability for long-life lithium-ion batteries.

Current anode materials for lithium-ion batteries (LIBs) mainly suffer from poor electronic conductivity and large volume expansion upon cycling. Improving kinetics and designing good morphology structural stability of electrode materials can effectively enhance the lithium storage performances of LIBs. In this study, we successfully synthesized hierarchical carbon-coated cobalt oxide (C@CoO) porous spheres with improved kinetics and good structural stability, which were investigated by ex situ electrochemical impedance spectrometry, scanning electron microscopy, and powder X-ray diffraction. We also optimized the preparation conditions of the C@CoO porous spheres. The C@CoO350 porous spheres exhibited good electrochemical performances including the high 2nd specific capacity of 811mAhg-1 at 0.1Ag-1 and good rate property of 450mAhg-1 at 4Ag-1. Furthermore, it demonstrated an excellent cyclic stability with a high capacities of 669mAhg-1 after 400 cycles at 0.5Ag-1. Results demonstrated that C@CoO350 porous spheres are promising LIBs anodes.

Sludge Biochar Amendment and Alfalfa Revegetation Improve Soil Physicochemical Properties and Increase Diversity of Soil Microbes in Soils from a Rare Earth Element Mining Wasteland.

Long-term unregulated mining of ion-adsorption clays (IAC) in China has resulted in severe ecological destruction and created large areas of wasteland in dire need of rehabilitation. Soil amendment and revegetation are two important means of rehabilitation of IAC mining wasteland. In this study, we used sludge biochar prepared by pyrolysis of municipal sewage sludge as a soil ameliorant, selected alfalfa as a revegetation plant, and conducted pot trials in a climate-controlled chamber. We investigated the effects of alfalfa revegetation, sludge biochar amendment, and their combined amendment on soil physicochemical properties in soil from an IAC mining wasteland as well as the impact of sludge biochar on plant growth. At the same time, we also assessed the impacts of these amendments on the soil microbial community by means of the Illumina Miseq sequences method. Results showed that alfalfa revegetation and sludge biochar both improved soil physicochemical properties and microbial community structure. When alfalfa revegetation and sludge biochar amendment were combined, we detected additive effects on the improvement of soil physicochemical properties as well as increases in the richness and diversity of bacterial and fungal communities. Redundancy analyses suggested that alfalfa revegetation and sludge biochar amendment significantly affected soil microbial community structure. Critical environmental factors consisted of soil available K, pH, organic matter, carbon⁻nitrogen ratio, bulk density, and total porosity. Sludge biochar amendment significantly promoted the growth of alfalfa and changed its root morphology. Combining alfalfa the revegetation with sludge biochar amendment may serve to not only achieve the revegetation of IAC mining wasteland, but also address the challenge of municipal sludge disposal by making the waste profitable.

Characterization and Computation of Yb/TiO2 and Its Photocatalytic Degradation with Benzohydroxamic Acid.

Yb-doped TiO2 (Yb/TiO2) compositions were synthesized by sol-gel method, and the prepared materials were characterized by X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse-reflectance spectrum (UV-Vis DRS), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM), energy dispersive spectrometer (EDS), and N2 adsorption. A beneficiation reagent of benzohydroxamic acid (BHA) was used to test the photocatalytic activity of Yb/TiO2. The characterizations indicate that the doping of Yb could inhibit the crystal growth of TiO2, enhance the specific surface area, increase the binding energy of Ti2p, and also slightly expand the adsorption ranges to visible light. Furthermore, the computation of band structure also indicates that Yb-doped TiO2 could make the forbidden band narrower than pure anatase TiO2, which presents a red shift in the absorption spectrum. As a result of the photodegradation experiment on BHA, Yb/TiO2 (0.50% in mass) sintered at 450 °C displayed the highest catalytic activity for BHA when compared with pure TiO2 or other doped Yb/TiO2 compositions, and more than 89.2% of the total organic carbon was removed after 120 min. Almost all anions, including Cl-, HCO3-, NO3-, and SO42-, inhibited the degradation of BHA by Yb/TiO2, and their inhibition effects followed the order of HCO3- > NO3- > SO42- > Cl-. Cations of Na⁺, K⁺, Ca2+, and Mg2+ displayed a slight suppressing effect due to the impact of Cl- coexisting in the solution. In addition, Yb/TiO2 maintained a high photocatalytic ability with respect to BHA after four runs. It is hypothesized that ·OH is one of the main species involved in the photodegradation of BHA, and the mutual transformation of Yb3+ and Yb2+ could promote the separation of electron-hole pairs.

Effects of Biochar-Derived Sewage Sludge on Heavy Metal Adsorption and Immobilization in Soils.

The object of this study was to evaluate the effect of sewage sludge biochar on adsorption and mobility of Cr, Mn, Cu, and Zn. Biochar (BC400) was produced via pyrolysis of municipal sewage sludge at 400 °C. Maximum adsorption capacities (qm) for Zn, Cr, Mn, and Cu were 5.905, 5.724, 5.681, and 5.342 mg·g-1, respectively, in the mono-metal solution and 2.475, 8.204, 1.01, and 5.415 mg·g-1, respectively, in the multi-metal solution. The adsorption capacities for Mn, Cu, and Zn decreased in the multi-metal solution due to competitive adsorption, whereas the capacity for Cr increased. Surface precipitation is an important mechanism in the sorption of these metals on BC400. The 360-day incubation experiment showed that BC400 application reduced metal mobility in contaminated soils, which was attributed to the substantial decreases in the acid-soluble fractions of Cr, Mn, Cu, and Zn (72.20%, 70.38%, 50.43%, and 29.78%, respectively). Furthermore, the leaching experiment using simulated acid rain indicated that the addition of BC400 enhanced the acid buffer capacity of contaminated soil, and the concentration of Cr, Mn, Cu, and Zn in the leachate was lower than in untreated soil. Overall, this study indicates that sewage sludge biochar application reduces the mobility of heavy metal in co-contaminated soil, and this adsorption experiment is suitable for the evaluation of biochar properties for remediation.

Degradation and Mineralization of Benzohydroxamic Acid by Synthesized Mesoporous La/TiO2.

Rare earth element La-doped TiO2 (La/TiO2) was synthesized by the sol-gel method. Benzohydroxamic acid was used as the objective pollutant to investigate the photocatalytic activity of La/TiO2. The physicochemical properties of the prepared materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, specific surface area and porosity, scanning electron microscopy and transmission electron microscopy. As a result, the doping of La could inhibit the crystal growth of TiO2, increase its specific surface area and expand its response to visible light, thus improving its photocatalytic activity. La/TiO2 with the doping ratio of 0.75% calcined at 500 °C, showing the highest photocatalytic activity to degrade benzohydroxamic acid under the irradiation of 300 W mercury lamp. About 94.1% of benzohydroxamic acid with the original concentration at 30 mg·L-1 was removed after 120 min in a solution of pH 4.4 with an La/TiO2 amount of 0.5 g·L-1. Furthermore, 88.5% of the total organic carbon was eliminated after 120 min irradiation. In addition, after four recycling runs, La/TiO2 still kept high photocatalytic activity on the photodegradation of benzohydroxamic acid. The interfacial charge transfer processes were also hypothesized.

Water-equivalent fiber radiation dosimeter with two scintillating materials.

An inorganic scintillating material plastic optical fiber (POF) dosimeter for measuring ionizing radiation during radiotherapy applications is reported. It is necessary that an ideal dosimeter exhibits many desirable qualities, including water equivalence, energy independence, reproducibility, dose linearity. There has been much recent research concerning inorganic dosimeters. However, little reference has been made to date of the depth-dose characteristics of dosimeter materials. In the case of inorganic scintillating materials, they are predominantly non water-equivalent, with their effective atomic weight (Zeff) being typically much greater than that of water. This has been a barrier in preventing inorganic scintillating material dosimeter from being used in actual clinical applications. In this paper, we propose a parallel-paired fiber light guide structure to solve this problem. Two different inorganic scintillating materials are embedded separately in the parallel-paired fiber. It is shown that the information of water depth and absorbed dose at the point of measurement can be extracted by utilizing their different depth-dose properties.

Characterization of La/Fe/TiO2 and Its Photocatalytic Performance in Ammonia Nitrogen Wastewater.

La/Fe/TiO2 composite photocatalysts were synthesized by Sol-Gel method and well characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen-physical adsorption, and UV-Vis diffuse reflectance spectra (UV-Vis DRS). It is interesting that the doped catalysts were in anatase phase while the pure TiO2 was in rutile phase. In addition, the composites possessed better physical chemical properties in photocatalytic activity than pure TiO2: stronger visible-light-response ability, larger specific surface area, and more regular shape in morphology. The photodegradation results of ammonia nitrogen indicate that: the La/Fe/TiO2 had higher catalytic activity to ammonia nitrogen waste water compared pure TiO2 and the other single metal-doped TiO2. pH 10 and 2 mmol/L H2O2 were all beneficial to the removal of ammonia nitrogen by La/Fe/TiO2. However, the common inorganic ions of Cl(-), NO3(-), SO4(2-), HCO3(-)/CO3²(-), Na⁺, K⁺, Ca(2+) and Mg(2+) in water all inhibited the degradation of ammonia nitrogen. By balance calculation, at least 20% of ammonia nitrogen was converted to N2 during the 64.6% removal efficiency of ammonia nitrogen.

Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization.

Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO3(-)-N, less into NO2(-)-N, not into N2.