Enhanced generation of oxysulfur radicals by the BiOBr/Montmorillonite activated sulfite system: Performance and mechanism.

The easily synthesized, cost-effective, and stable photocatalysts for sulfite activation are always required for the enhancement of organic contaminants degradation. Herein, the facile coprecipitation synthesis of Bismuth oxybromide (BiOBr)/Montmorillonite (MMT) was reported, which could activate sulfite (SO32-/HSO3-) under sunlight and accelerate the catalytic performance more effectively than pristine BiOBr. After adding sulfite to the photocatalysis system, the photodegradation efficiency of atrazine (ATZ) achieved 73.7% ± 1.5% after 5 min and 94.4% ± 1.6% after 30 min of sunlight irradiation with BiOBr/MMT. The BiOBr/MMT-sulfite system also presented remarkable photocatalytic performance to eliminate various contaminants, including ciprofloxacin, sulfadiazine, tetracycline, and carbamazepine. The various features of the photocatalyst materials were studied, including their surface morphology, structure, optical properties, and composition. The results illustrated that by adding MMT, the bandgap of the pristine BiOBr was reduced and the surface area was increased, which led to an increased ability to adsorb materials. Results of various influence factors showed this enhanced system had satisfactory and stable removal performance of ATZ in the pH range of 3.0-6.5, but HPO42- had a strong negative effect on the system performance. Oxysulfur radicals (SO5·- and SO4·-), h+, and 1O2 were discovered as the prevailing active species in the BiOBr/MMT-sulfite system. The proposed degradation mechanism of this photocatalyst-enhanced system revealed that sulfite adsorption on the surface of the photocatalyst played a vital role during the initial phase, and the degradation pathway of ATZ was discussed. This study provides a new synthesis strategy of a photocatalyst for sulfite activation and expands the potential uses of Bi-based photocatalysts in degrading difficult-to-remove organic pollutants.

Terahertz Spectroscopy and Imaging Techniques for Herbal Medicinal Plants Detection: A Comprehensive Review.

Herbal medicine (HM), derived from various therapeutic plants, has garnered considerable attention for its remarkable effectiveness in treating diseases. However, numerous issues including improved varieties selection, hazardous residue detection, and concoction management affect herb quality throughout the manufacturing process. Therefore, a practical, rapid, nondestructive detection technology is necessary. Terahertz (THz) spectroscopy, with low energy, penetration, and fingerprint features, becomes preferable method for herb quality appraisal. There are three parts in our review. THz techniques, data processing, and modeling methods were introduced in Part I. Three primary applications (authenticity, composition and active ingredients, and origin detection) of THz in medicinal plants quality detection in industrial processing and marketing were detailed in Part II. A thorough investigation and outlook on the well-known applications and advancements of this field were presented in Part III. This review aims to bring new enlightenment to the in-depth THz application research in herbal medicinal plants.

Novel sodium percarbonate-MnO2 effervescent tablets for efficient and moderate membrane cleaning.

Membrane flux recovery efficiency and durability are two key factors closely associated with the practical application for membrane cleaning process. However, conventional chemical membrane cleaning method by soaking the whole membrane module in highly concentrated chemical reagents has prominent drawbacks including the low mass transfer efficiency of reagents, long period of washing time, and the potential threat to membrane structure. Herein, for the first time, we report a facile approach to fabricate the sodium percarbonate-MnO2 effervescent tablets which show bubbling reaction to release oxygen and free radicals when being dispersed in water for membrane cleaning. Due to the synergistic effect of MnO2 and sodium percarbonate, the tablets are highly effective to clean the membrane fouled by humic acid within 5 min, with the terminal membrane flux being recovered from 0.50 to 0.95, and the irreversible fouling resistance being reduced by more than 90%, which is prominently more efficient than the conventional chemical cleaning methods. Moreover, even by consecutive membrane fouling and cleaning for 6 times, the membrane flux and filtration efficiency of the membrane could still be kept almost constant, and the moderateness of this membrane cleaning method was also verified by the systematic microscopic analysis. For mechanism study, results of Electron Spin Resonance (ESR) and quenching experiments indicated that the high-efficiency and robust durability of sodium percarbonate-MnO2 (SPC-MnO2) system for membrane cleaning was mainly attributed to the abundantly generated hydroxyl radicals and secondary free radicals (i.e. carbonate radicals). Conclusively, compared with the conventional membrane cleaning method with liquid cleaning reagents, the novel SPC-MnO2 system with remarkable advantages in terms of convenience and membrane cleaning performance demonstrated high potential for the wide application in practice.

Highly efficient removal of p-arsanilic acid with Fe(II)/peroxydisulfate under near-neutral conditions.

As a common animal feed additive, p-arsanilic acid (p-AsA) is thought to be excreted with little uptake and unchanged chemical structure, threatening the environment by potentially releasing more toxic inorganic arsenic. We herein investigated the removal of arsenic by in situ formed ferric (oxyhydr)oxides with the promotion of p-AsA degradation in Fe(II)/peroxydisulfate (PDS) system. Results showed that under acid conditions, p-AsA degraded very quickly and over 99% of p-AsA (5 µM) was degraded within 10 min at the optimal dosage of Fe(II) (100 µM) and PDS (150 µM) at pH 3, while less than 66.4% of arsenic was removed at pH 3-5. Higher pH (3-7) would inhibit the degradation of p-AsA but promote the arsenic removal. At pH 6-7, over 98.5% of total arsenic was removed, while the degradation efficiency of p-AsA was lower than 52.4%. HPLC-ICP-MS results indicated that the arsenic group was cleaved from p-AsA in the form of As(III) and then rapidly oxidized to As(V). FTIR and XPS analysis indicated that both As(V) products and residual p-AsA were bonded to ferric (oxyhydr)oxides via hydroxyl groups. Common cations (e.g., Na+, Ca2+, Mg2+) and anions such as Cl-, SO42-, CO32- had no significant influence on arsenic removal, while SiO32-, PO43- and HA inhibited the removal of total arsenic, mainly by affecting the zeta potential of iron particles. In summary, the Fe(II)/PDS process, as an efficient method for partial oxidation and simultaneous adsorption of p-AsA under near-neutral conditions, is expected to control the potential environmental risks of p-AsA.

The effects of loading-direction and strain-rate on the mechanical behaviors of human frontal skull bone.

Most fatal human skull injuries occur under impact loading conditions, such as car collisions, where the strain rates fall in the range of intermediate (1/s-102/s) and high (102/s-103/s) rates. Therefore, knowledge of the mechanical behaviors of human cranial bone at higher strain rates, i.e., intermediate and high strain rates, may provide insight into the prevention of skull injuries and help the design of efficient head protection systems. In the present study, the compressive mechanical behaviors of human frontal skull bone along and perpendicular to its through-the-thickness direction were experimentally characterized at quasi-static (0.01/s), intermediate (30/s) and high (625/s) strain rates in this study. A total number of 75 specimens prepared from three male donors with ages of 70-74 were separated into three groups: quasi-static (N = 23), intermediate (N = 23), and high (N = 29) strain rates. Experiments at quasi-static and intermediate strain rates were performed using a hydraulically driven materials testing system (MTS), while a Kolsky compression bar was used to load the skull bone specimen at high strain rates. X-ray computed tomography was performed to obtain the structural parameters and visualize the microstructures of the skull bone. The in-situ failure processes of the specimens under high-rate loading were documented by a high-speed camera. The human skull exhibited a loading-direction dependent mechanical behavior, as higher ultimate strength and elastic modulus were found in the direction perpendicular to the thickness when compared with those along the thickness direction, exhibiting an increasing ratio as high as 2 and 3 for strength and modulus, respectively. High-speed images revealed that the specimens loaded along the thickness direction generally failed due to the crushing in diploë (the trabecular bone tissue) whereas separation of the entire architecture was observed as the main failure mode when compressed in the perpendicular direction. The effect of loading rate was also evident: the skull specimens were increasingly brittle as strain rate increased from quasi-static to high rate for both the loading directions. The elastic modulus increased by a factor of 4 in radial direction and it increased by a factor of 2.5 in the tangential direction across the quasi-static, intermediate and high strain rates. Significant differences were also found in ultimate strength and work to failure as loading rate increased from quasi-static to high rates. The results also suggested that the strength in the radial direction was mainly depended on the diploë porosity while the diploë layer ratio played the predominant role in tangential direction.

High-speed X-ray visualization of dynamic crack initiation and propagation in bone.

The initiation and propagation of physiological cracks in porcine cortical and cancellous bone under high rate loading were visualized using high-speed synchrotron X-ray phase-contrast imaging (PCI) to characterize their fracture behaviors under dynamic loading conditions. A modified Kolsky compression bar was used to apply dynamic three-point flexural loadings on notched specimens and images of the fracture processes were recorded using a synchronized high-speed synchrotron X-ray imaging set-up. Three-dimensional synchrotron X-ray tomography was conducted to examine the initial microstructure of the bone before high-rate experiments. The experimental results showed that the locations of fracture initiations were not significantly different between the two types of bone. However, the crack velocities in cortical bone were higher than in cancellous bone. Crack deflections at osteonal cement lines, a prime toughening mechanism in bone at low rates, were observed in the cortical bone under dynamic loading in this study. Fracture toughening mechanisms, such as uncracked ligament bridging and bridging in crack wake were also observed for the two types of bone. The results also revealed that the fracture toughness of cortical bone was higher than cancellous bone. The crack was deflected to some extent at osteon cement line in cortical bone instead of comparatively penetrating straight through the microstructures in cancellous bone. STATEMENT OF SIGNIFICANCE: Fracture toughness is with great importance to study for crack risk prediction in bone. For those cracks in bone, most of them are associated with impact events, such as sport accidents. Consequently, we visualized, in real-time, the entire processes of dynamic fractures in notched cortical bone and cancellous bone specimens using synchrotron X-ray phase contrast imaging. The onset location of crack initiation was found independent on the bone type. We also found that, although the extent was diminished, crack deflections at osteon cement lines, a major toughening mechanism in transversely orientated cortical bone at quasi-static rate, were still played a role in resisting cracking in dynamically loaded specimen. These finding help researchers to understand the dynamic fracture behaviors in bone.

Mechanical Response of Human Muscle at Intermediate Strain Rates.

We experimentally determined the tensile stress-strain response of human muscle along fiber direction and compressive stress-strain response transverse to fiber direction at intermediate strain rates (100-102/s). A hydraulically driven material testing system with a dynamic testing mode was used to perform the tensile and compressive experiments on human muscle tissue. Experiments at quasi-static strain rates (below 100/s) were also conducted to investigate the strain-rate effects over a wider range. The experimental results show that, at intermediate strain rates, both the human muscle's tensile and compressive stress-strain responses are nonlinear and strain-rate sensitive. Human muscle also exhibits a stiffer and stronger tensile mechanical behavior along fiber direction than its compressive mechanical behavior along the direction transverse to fiber direction. An Ogden model with two material constants was adopted to describe the nonlinear tensile and compressive behaviors of human muscle.

Enhanced removal of arsenite and arsenate by a multifunctional Fe-Ti-Mn composite oxide: Photooxidation, oxidation and adsorption.

In order to attain a high-efficiency and low-cost adsorbent for both arsenate (As(V)) and arsenite (As(III)) removal from As-contaminated water, a novel nanostructured Fe-Ti-Mn composite oxide (FTMO) was fabricated through a one-step simultaneous oxidation and co-precipitation method. Batch control experiments and series of spectroscopy detection technologies were carried out to investigate the surface change of the FTMO adsorbent and the respective role of Fe, Ti and Mn content in the arsenic adsorption process. The results showed that the FTMO adsorbent had a high adsorption capacity for both As(V) and As(III) (especially for the latter one) via the formation of inner-sphere complexes at the water/oxide interface under both darkness and light conditions. The material could effectively oxidize As(III) to As(V) and light illumination could further apparently enhance the As(III) oxidation, thus achieving high adsorption efficiency of As(III). Combined with the characterizations from FTIR, ESR and XPS, it was assumed that the predominant As(III) removal mechanism could be attributed to the coupling of various processes including photooxidation, oxidation and adsorption. The Ti and Mn contents were dominant for the As(III) oxidation, while the Fe content mainly played an important role for the adsorption of newly formed As(V). However, the involvement of surface hydroxyl groups and the formation of inner-sphere surface complexes were primarily responsible for the As(V) adsorption mechanism. Moreover, the successful removal of arsenic from real water matrices made the FTMO a potentially attractive adsorbent for both As(V) and As(III) removal.

Development of a novel anoxic/oxic fed-batch membrane bioreactor (AFMBR) based on gravity-driven and partial aeration modes: A pilot scale study.

A novel pilot gravity-driven anoxic/oxic fed-batch membrane bioreactor (AFMBR) was developed to treat real domestic wastewater. In this process, the anoxic and oxic stages created favorable conditions for stable and continuous nitritation-denitritation/denitrification-nitrification links without adding external carbon source. Excellent removals of organic carbon/nitrogen (NH4+-N: 71-97%, COD: 78-96%, UV254: 70-95%, TN: 20-60%) and spontaneous permeability recovery were achieved simultaneously. It was assessed at micro levels by characterizing sludge particle morphologies, microbiota functional evolutions, fouling layer properties and energy consumptions. It was demonstrated that the aerobic granular sludge (AGS) was cultivated successfully. Notable differences of microbial diversity were observed in different regions of AFMBR. The SEM and AFM spectra suggested the loose cake layers can shed automatically due to low pressure and continue flushing. The energy consumption in AFMBR was around 0.042 kWh/m3, far lower than that of conventional MBR. Overall, the AFMBR has a potential on improvement of domestic wastewater treatment.

Heterogeneous catalytic ozonation of ciprofloxacin in aqueous solution using a manganese-modified silicate ore.

Manganese modified silicate ore (MnSO) prepared using an impregnation method was used as a heterogeneous ozonation catalyst, and the catalytic activity was evaluated by the degradation of ciprofloxacin (CIP). The results showed that the manganese oxide was successfully loaded onto natural silicate ore (SO). The degradation and mineralization efficiencies of CIP were considerably improved in the presence of MnSO. Under optimal conditions, the CIP removal process followed the pseudo-first-order reaction model well. The degradation rate constant of MnSO/O3 was 1.7 times and 3.3 times higher than those of SO/O3 and only O3, respectively. During the ozonation of the CIP aqueous solution in the presence of MnSO, the TOC removal rate reached 61.2% at 60 min, but was only 30.8% using ozonation alone. The addition of tert-butanol (TBA) significantly inhibited the degradation efficiency of CIP, which indicated that catalytic ozonation of MnSO followed a hydroxyl radical (·OH) reaction mechanism. Furthermore, MnSO showed great stability and durability over several reaction cycles.

Improved pretreatment (coagulation-floatation and ozonation) of younger landfill leachate by microbubbles.

A novel microbubble air/ozone floatation device, TCRI, was developed to enhance the combination of the coagulation and ozonation processes as the pretreatment of landfill leachate. In the coagulation process, microbubble floatation reduced the coagulant dosage. The removal efficiencies of chemical oxygen demand (COD), color, nitrate, and ammonia for the coagulation microbubble floatation were 97, 20, 47, and 163% higher, respectively, than those of the coagulation-sedimentation process; in the ozonation process, the removal efficiencies of ammonia and COD in microbubble ozonation were increased by 300 and 200%, respectively, compared with a conventional ozonation contactor when the ozonation time was 60 minutes. The results showed that microbubbles could reach a higher ozone-transfer rate (microbubbles = 0.3018 min(-1) > conventional ozone bubbles = 0.2014 min(-1)). Therefore, the application of the microbubble technology in the coagulation and ozonation combination process may provide an effective and low-cost approach for wastewater treatment.

Enhanced mechanism of catalytic ozonation by ultrasound with orthogonal dual frequencies for the degradation of nitrobenzene in aqueous solution.

The experiments have been performed with a semi-continuous batch reactor to investigate the degradation efficiency of nitrobenzene in aqueous solution by ultrasound with the different orthogonal dual frequencies catalytic ozonation. The introduction of ultrasound can enhance the degradation efficiency of nitrobenzene compared to the results obtained from the processes of ozonation alone and ultrasound alone. The degradation of nitrobenzene is found to be zero-order in the two systems of ultrasound alone, and the reactions follow the pseudo-first-order kinetic model in the processes of ozone alone and ozone/ultrasound. The investigation confirms that the degradation of nitrobenzene follows the mechanism of hydroxyl radical ((*)OH) oxidation, and the enhancement function is even more pronounced in the presence of ultrasound with the greater difference between the orthogonal dual frequencies due to the obvious synergetic effect between ozone and ultrasound, which increases the utilization efficiency of ozone, and accelerates the initiation of (*)OH and the formation of H(2)O(2), resulting in the rapid formation of an increasing diversity of byproducts and the advancement degree of mineralization of total organic carbon (TOC). The oxidative byproducts have been, respectively identified in the different processes selected, including o, p, m-nitrophenols, phenol, malonic acid, 4-nitrocatechol, nitrate ion, maleic acid, oxalic acid, hydroquinone, p-quinone, 1,2,3-trihydroxy-5-nitrobenzene and acetic acid.

Synergetic effect of ultrasound with dual fields for the degradation of nitrobenzene in aqueous solution.

Experiments have been performed with a semicontinuous batch reactor to compare the degradation efficiency of nitrobenzene in aqueous solution by the ultrasonic processes of single field, opposite dual fields, and orthogonal dual fields. Ultrasound with dual fields can improve the degradation efficiency of nitrobenzene compared to that of single field, and the improvement phenomenon is even more pronounced in the orthogonal dual-field system. The degradation reactions of nitrobenzene in the three processes all follow the pseudofirst-order kinetic model. The mechanism investigation indicates the degradation proceeds via hydroxyl radical (*OH) oxidation. The enhancement efficiency of orthogonal dual fields is attributed to an obvious synergetic effect, which accelerates the *OH initiation from 0.28 micromol L(-1) min(-1) for a single field to 0.98 micromol L(-1) min(-1) compared with 0.42 micromol L(-1) min(-1) for opposite dual fields, resulting in rapid formation of an increased diversity of byproducts and an advanced degree of mineralization of total organic carbon (TOC). The introduction of an ultrasonic field placed in the different spatial position causes a variable kinetic order during the removal of TOC. The degradation byproducts are identified by gas chromatography mass spectrometry and ion chromatography, including p-, m-nitrophenol, malonic acid, nitrate ion, 4-nitrocatechol, phenol, maleic acid, oxalic acid, hydroquinone, 1,2,3-trihydroxy-5-nitrobenzene, and acetic acid.

Preliminary kinetic study on the degradation of nitrobenzene by modified ceramic honeycomb-catalytic ozonation in aqueous solution.

The kinetics of degradation of nitrobenzene in aqueous solution was investigated in the processes of ozone alone, ozone/ceramic honeycomb (CH), ozone/modified ceramic honeycomb (MCH). The results indicated that all reactions followed the pseudo-first-order kinetic model, and the degradation rate of nitrobenzene was accelerated in the presence of CH or MCH catalyst, and the more pronounced degradation rate was achieved in O(3)/MCH system. Under the experimental conditions of reaction temperature 293 K and initial pH 6.87, the rate constants were determined to be 5.21 x 10(-2)min(-1) for O(3) alone, 7.99 x 10(-2)min(-1) for O(3)/CH and 15.45 x 10(-2)min(-1) for O(3)/MCH. The influencing factors, such as applied ozone concentration (0.987-2.732 mg L(-1)), initial concentration of nitrobenzene (50-250 microg L(-1)) and amount of catalyst (0-5 blocks) could yield respectively the positive effect on the pseudo-first-order rate constants for degradation of nitrobenzene in the three processes mentioned above. The results suggested that the modification process promoted the catalytic activity of raw CH catalyst, namely the impregnation of metals (Mn, Cu and K) maybe enhance the initiation of hydroxyl radical (OH).

Mechanism of influence of initial pH on the degradation of nitrobenzene in aqueous solution by ceramic honeycomb catalytic ozonation.

The influences of initial pH on the degradation efficiency of nitrobenzene in aqueous solution were investigated with a semicontinuous batch reactor in the processes of ozone alone, ozone/ceramic honeycomb, and adsorption of ceramic honeycomb. The results indicated that initial pH significantly affected the concentrations of offgas, residual ozone, and the utilization efficiency of ozone. The experiments also detected the generation of hydroxyl radicals (*OH), the removal of TOC, and the formation and evolution of byproduct at different initial pHs in the ceramic honeycomb catalytic ozonation process. It was found that the systems of different initial pHs exhibited the different extent of the conversion of pH, the leaching of effective components, and the establishment of pH at the point of zero charge (pH(PZC)) in the catalytic oxidation process. The experimental findings presented a good correlation between initial pH and terminal pH and the establishment of pHpzc with terminal pH, and indicated the relationship between the absolute value of the difference between terminal pH and terminal pH(PZC) (A) and the density of surface hydroxyl groups. Based on the correlation between the density of surface hydroxyl groups in the neutral state and A, possible mechanism of influence of initial pH on the degradation of nitrobenzene in aqueous solution by ceramic honeycomb catalytic ozonation was proposed, suggesting that the conversion of initial pH determines the establishment of pHpzc, and the synergistic effect of pH terminal and pHpzc terminal affects the density of surface hydroxyl groups in the neutral state, which controls the concentration of *OH, determining the degradation of nitrobenzene and the formation of byproduct.