pH Value Of Solution Research Articles

Damage constitutive model and mechanical properties of a concrete limestone composite after acid corrosion

Damage constitutive model and mechanical properties of a concrete limestone composite after acid corrosion

Rat Fecal Metabolomics-Based Analysis.

The gut's symbiome, a hidden metabolic organ, has gained scientific interest for its crucial role in human health. Acting as a biochemical factory, the gut microbiome produces numerous small molecules that significantly impact host metabolism. Metabolic profiling facilitates the exploration of its influence on human health and disease through the symbiotic relationship. Fecal metabolomics-based analysis is an indisputably valuable tool for elucidating the biochemistry of digestion and absorption in the gastrointestinal system, serving as the most suitable specimen to study the symbiotic relationship between the host and the intestinal microbiota. It is well-established that the balance of the intestinal microbiota changes in response to various stimuli, both physiological, such as gender, age, diet, and exercise, and pathological, such as gastrointestinal and hepatic diseases. Fecal samples have been analyzed using widely adopted analytical techniques, including NMR spectroscopy, GC-MS, and LC-MS/MS. Rat fecal samples are frequently used and particularly useful substrates for metabolomics-based studies in related fields.The complexity and diversity of fecal samples necessitate careful and skillful handling to extract metabolites, while avoiding their deterioration, effectively and quantitatively. Several determinative factors, such as the fecal sample weight to extraction solvent solution volume, the nature and pH value of the extraction solvent, and the homogenization process, play crucial roles in achieving optimal extraction for obtaining high-quality metabolic fingerprints, whether for untargeted or targeted metabolomics.

The Effect of Slope Chamfer on Hydroponic NFT (Nutrient Film Technique) System For Cultivitation Of Japan Spinach (Spinacia Oleracea L.)

NFT is a hydroponic cultivation system by putting the roots of plants in a thin layer of water where the plants get nutrients from the nutrient solution that flows through the gutters, the flow of nutrient on NFT hydroponic circulated continuously so that the plant's nutritional needs can be fulfilled. NFT hydroponic vegetables is suitable to be cultivated for leafy vegetables, like a Japanese spinach plant (Spinacia Oleracea L.). The purpose of these research was to test the design of NFT Hydroponic with slope 3%. In the testing performance of hydroponic NFT consist of three parameters. These parameters include the testing of irrigation efficiency, pH values ​​and Electrical Conductivity (EC) solution and the uniformity of crop productivity. Data obtained from this study were analyzed based on its design to determine the effect of each parameter on plant growth. The average irrigation efficiency value is 92.00%, the value of uniformity electrical conductivity (EC) reached 92.10% and the uniformity of solution pH value reaches 99.51%. For the final harvest that obtained from its various agronomical aspects result obtained is the uniformity of the result obtained in plan weight gained is the smallest weight 13 grams and the heaviest 70 grams. From 32 plants produced, uniformity values obtained of plant weight at 67.788% (chamfer 1), 68,388% (chamfer 2) and 68,388% (chamfer 3).

The Preparation of High-Performance MoO3 Nanorods for 2.1 V Aqueous Asymmetric Supercapacitor.

In order to broaden the working voltage (1.23 V) of aqueous supercapacitors, a high-performance asymmetric supercapacitor with a working voltage window reaching up to 2.1 V is assembled using a nanorod-shaped molybdenum trioxide (MoO3) negative electrode and an activated carbon (AC) positive electrode, as well as a sodium sulfate-ethylene glycol ((Na2SO4-EG) electrolyte. MoO3 electrode materials are fabricated by adjusting the hydrothermal temperature, hydrothermal time and solution's pH value. The specific capacity of the optimal MoO3 electrode material can reach as high as 244.35 F g-1 at a current density of 0.5 A g-1. For the assembled MoO3//AC asymmetric supercapacitor with a voltage window of 2.1 V, its specific capacity, the energy density, and the power density are 13.52 F g-1, 8.28 Wh kg-1, and 382.15 W kg-1 at 0.5 A g-1, respectively. Moreover, after 5000 charge-discharge cycles, the capacity retention rate of the device still reaches 109.2%. This is mainly attributed to the small particle size of MoO3 nanorods, which can expose more electrochemically active sites, thus greatly facilitating the transport of electrolyte ions, immersion at the electrolyte/electrolyte interface and the occurrence of electrochemical reactions.

Continuous packed bed column removal of Cr6+, Cd2+, and Pb2+ ions from synthetic wastewater using polymeric ultra‐permeable and biodegradable ferromagnetic nanocomposite membrane

AbstractWater purification techniques, including membrane technologies, ion exchange and adsorption, chemical/biochemical reduction, and electrochemical processes, have been developed to remove/recover metal ions species from polluted wastewater. This work assessed the efficiency of polymeric, biodegradable, ultra‐permeable and magnetic nanocomposite membrane (CNCs/N6@Fe3O4‐CT) in a continuous packed bed column for the removal of Cd(II), Cr(VI), and Pb(II) metal ions from synthetic wastewaters. The eco‐compatibility of CNCs/N6@Fe3O4‐CT was increased using chitosan biopolymer. Fe3O4 nanoparticles increased the surface area and improved the separation process. CNCs and N6 polymeric materials enhanced their strength, porosity, and additional binding sites. The CNCs/N6@Fe3O4‐CT nanocomposite membrane was employed as packing material in a fixed‐bed lab‐scale column (height 30 cm, diameter 1.5 cm) to constantly remove Cd(II), Cr(VI), and Pb(II) metal ions from synthetic wastewaters and actual hexavalent chromium tannery effluent. The studies were carried out with different initial metal ion concentrations (10, 20, and 30 mg/L), input flow rates (2, 4, and 6 mL/min), and solution pH values (2.0, 5.0, and 8.0). The obtained experimental data from the breakthrough curves was fitted to the traditional dynamic Thomas model, Yoon‐Nelson, and Bed Depth Service Time (BDST) model.

Preparation of bio‐based polyamide 56/chitosan heavy metal adsorbing nanocomposite fibers by electrospinning

AbstractElectrospinning technology can produce nanofibers with extremely high specific surface area. Bio‐based polyamide 56 (PA56) was combined with chitosan (CS) to prepare PA56/CS composite nanofibers. An in vitro mineralization experiment was conducted to obtain a super hydrophilic composite fiber (PA56/CS‐HAP) with hydroxyapatite deposited on the surface. The adsorption performance of the composite fiber (PA56/CS‐HAP) was evaluated by the adsorbent dosage, solution pH value, and adsorption kinetics. The curves obtained after fitting the kinetics and adsorption isotherms show that the adsorption behavior under pH = 6 is more consistent with the Langmuir adsorption model. The adsorption capacity in a 100 mg L−1 Pb2+ environment is more than 5 times that of 10 mg L−1. Bio‐based PA56/CS static‐spun nanocomposite fibers prepared by in vitro mineralization have great potential in environmental protection, sensors, chemical engineering, and other fields.Highlights PA/CS fibers were prepared by electrospinning. Hydroxyapatite was deposited by in vitro mineralization technique. PA/CS‐HAP fiber achieves super hydrophilic effect. The adsorption capacity of PA/CS‐HAP in 100 mg L−1 Pb(II) reached 27.5 mg g−1. After fitting, the adsorption process is consistent with Langmuir adsorption.

Performance Analysis of Effective Methylene Blue Immobilization by Carbon Microspheres Obtained from Hydrothermally Processed Fructose

Carbon microspheres have been synthesized by the hydrothermal method with fructose and a phosphoric acid solution at two different concentrations, which were used as precursors. The obtained materials were characterized by elemental analysis, X-ray powder diffraction (XRPD) analysis, scanning electron microscopy (SEM), nitrogen adsorption/desorption measurements, and Fourier transform infrared (FTIR) spectroscopy. Batch sorption experiments were performed to remove methylene blue (MB) from aqueous solutions by varying the initial concentration of MB (C0) from 50 to 500 mg/dm3, contact period, solution pH value, and temperature. Prepared sorbents consisted of microsphere particles with diameters in the range of 0.6–2.7 µm. The synthetic route was found to govern the microporous–mesoporous structure and surface acidic functional groups of the final product. A phosphoric acid concentration of 40 wt.% gave carbon material with a specific surface area of 932 m2/g and a total pore volume of 0.43 cm3/g. It was found that the extent of MB sorption by the obtained carbon microspheres increased with initial dye concentration, contact time, and especially solution pH but slightly decreased with increasing temperature. Kinetic studies showed that the dye sorption process followed pseudo-second-order kinetics.

Effect of hydro-chemical corrosion on mechanical properties of red sandstone under uniaxial and triaxial compression

The degradation of mechanical characteristics of sandstone, a common engineering material in acid environment, is directly related to the project service life forecast. In order to investigate the influence of water–rock interaction on the mechanical properties of red sandstone, a series of uniaxial and triaxial compression tests were conducted on sandstone immersed in solutions of different pH values and immersion times. Moreover, the effects of acid chemical corrosion on the microscopic structure of the sandstone were analyzed using scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) tests. A chemical damage strength model was then formulated within the theoretical framework of chemical reaction kinetics theory. The results indicate that the different hydro-chemical solutions have a significant deterioration effect on the sandstone. In immersion tests, the water–rock reaction of sandstone is essentially completed after 30 days of immersion. With increasing immersion time, the uniaxial compressive strength of sandstone immersed in neutral and weakly acidic saline solutions shows an initial rapid decrease followed by a slow increase, while sandstone immersed in distilled water and strongly acidic solutions shows varying degrees of decrease over time. High confining pressure weakens the corrosion effect of the solutions on the sandstone, particularly, the neutral solution. In the triaxial compression tests, strong acid has a great corrosion effect on sandstone. The average peak strength of sandstone immersed in pH2, pH4, pH7, and distilled water decreased by 30.2%, 28.7%, 25.1%, and 22.8%, respectively. The model considers calcium precipitation not only reflects the change in pH value of the immersion solution with time but also effectively predicts the strength of sandstone immersed in different solutions. The results deepen our understanding of the deterioration mechanism of silicon-based porous rock under different chemical solutions and would be of importance for the long-term stability analysis of rock engineering in complex groundwater environments.

Fabrication of Uniform Porous Anodic Aluminum Oxide by Anodizing Aluminum in Trisodium Phosphate with Higher pH Values

Anodizing of aluminum is an electrochemical process of surface oxidation to form an alumina layer. Porous anodic aluminum oxide (PAAO) possessing self-organized nanopores can be obtained by anodizing aluminum in several acidic electrolyte solutions, and it has been widely used to develop emerging applications, such as nano-filters and optical devices. Recently, we found that anodizing in several alkaline solutions caused the formation of PAAOs with unique nanostructures such as an extremely high porosity and ultra-flat barrier layer. However, the anodizing process in alkaline solutions with higher pH values produced a slightly non-uniform film due to the active dissolution environment of alumina. Herein, we report the fabrication of uniform PAAO film by anodizing aluminum in alkaline solutions and their unique nanostructures.High-purity aluminum specimens were electropolished in 78 vol% CH3COOH/ 22 vol% - 70% HClO4. The electropolished specimens, then, were anodized in a 0.3 M trisodium phosphate (Na3PO4) solution at 274 K (pH = 13.1) and a constant voltage of 2-100 V. A platinum plate was used as the cathode, and the aluminum specimen was placed parallel to and 22 mm from the platinum plate. We investigated the effect of various operating conditions on the formation of PAAO film. The growth behavior and internal structure of anodized specimens were examined by optical microscopy (OM), field-emission scanning electron microscopy (FE-SEM), and scanning transmission electron microscopy (STEM).Figure 1a shows the OM images of the aluminum specimen anodized in a 0.3 M Na3PO4 solution at 274 K and a constant voltage of 20 V for 60 min with and without stirring the solution. A non-uniform appearance with both weak white and metallic luster areas was obtained on the specimen anodized with stirring, whereas a uniform metallic luster can be observed without stirring. The SEM images of four different surface positions (2 mm intervals) of each anodized specimen are shown in Figure 1b. In the case of the stirring condition, the surface of PAAO on the left was dissolved due to the high pH value of the Na3PO4 solution and higher dissolution rate caused by stirring. On the other hand, a uniform PAAO film possessing similar nanoscale pores was successfully fabricated by suppressing non-uniform dissolution without stirring. The PAAO film grew by anodizing in the Na3PO4 solution at extremely low applied voltages less than 10 V. Figure 1

Stress Corrosion Cracking of Nasicon Pellets in Aqueous Electrolytes

Recent efforts have explored the use of sodium super ionic conductors (NaSICON) in aqueous redox flow batteries (RFBs) because of their ability to selectively conduct sodium ions while effectively preventing the crossover of active species, thereby enhancing the performance and longevity of RFBs. However, despite the potential of NaSICON membranes in enhancing the electrochemical performance of RFBs, the use of dense and thick ceramic membranes results in increased cell resistances. Modak et al. recently suggested that NaSICON membranes with thicknesses below 100 mm may achieve equivalent power densities to RFBs with polymer membrane and meet the resistance criterion.1 Therefore, to realize the commercial application of these thin ceramic films, careful attention must be paid to the membrane’s mechanical properties, especially fracture strength and toughness.Stress-corrosion cracking (SCC) is particularly important for ceramics when they are exposed to water,2 which is defined as the growth of cracks due to the simultaneous action of a stress and a reactive environment. During cell operation, the NaSICON membrane is immersed in corrosive liquid electrolytes and is simultaneously subject to a pressure gradient due to the uneven electrolyte flow. Consequently, understanding the interaction at solid-liquid interface and its impact on NaSICON is crucial as it may affect the fracture toughness of NaSICON and cause unexpected failure.In this study, the toughness of the samples was determined using Vickers indentation. The indentations were imaged using an optical microscope, allowing for measurement of the crack lengths. To assess the evolution of fracture toughness of NaSICON in the presence of typical RFB reactants, the pellets were soaked in selected aqueous solutions. The influence of solution composition, pH value, and molarity are investigated as well as soaking time. Significant crack propagations were observed in all pellets when immersed in solutions, suggesting a decrease in the fracture toughness of the NaSICON pellet after interacting with these liquids. Measurable crack growth was observed to occur mainly within the first 24 hours of immersion, suggesting a equilibrium had been reached between the driving forces for crack propagation (such as stress intensity and corrosive environment) and the resisting material properties (material toughness). To model the influence of SCC during operation of an aqueous RFB, theoretical analysis was conducted to quantify the relationships between the pressure gradient that a NaSICON membrane can withstand under a given geometry, and the evolution of its fracture toughness. These fundamental mechanical studies will provide valuable insights to understand and manage stress corrosion cracking of NaSICON membranes in contact with liquid electrolytes. Modak, S., Valle, J., Tseng, K. T., Sakamoto, J. & Kwabi, D. G. Correlating Stability and Performance of NaSICON Membranes for Aqueous Redox Flow Batteries. ACS Appl Mater Interfaces 14, 19332–19341 (2022).Spearing, S. M., Zok, F. W. & Evans, A. G. Stress Corrosion Cracking in a Unidirectional Ceramic‐Matrix Composite. Journal of the American Ceramic Society 77, 562–570 (1994).

Mechanical properties and energy evolution law of marble under the coupled effects of chemical corrosion and dry-wet cycles.

The main factors affecting the safety of underground structures are groundwater chemical corrosion and water level fluctuations. To investigate the mechanical properties of marble and the energy evolution pattern during the failure process under the coupled effects of chemical corrosion and dry-wet cycling, samples were subjected to 5, 10 and 20 cycles of dry-wet ageing in chemical solutions with pH values of 4, 7 and 10, respectively, followed by mechanical property testing. The energy evolution pattern during the failure process of the specimens was also studied. It was found that there is a strong correlation between number of dry-wet cycles and pH value of chemical solution. Chemical corrosion at the early stage of dry-wet cycling has the greatest effect on the deterioration of the rock. As the number of dry-wet cycles increases, the degree of corrosion in acidic solutions is most evident, with the uniaxial compressive strength and elastic modulus decreasing by 27.88% and 33.52% respectively, followed by alkaline solutions, and the degree of corrosion in neutral solutions is the lowest. In addition, dry-wet cycling and chemical corrosion lead to an increase in the internal pores of the rock samples and a decrease in the energy storage capacity. Nevertheless, the proportion of energy loss increases with the number of dry and wet cycles, with the proportion of energy loss in acidic media increasing from 35.61% to 41.63%, indicating that the plastic deformability of marble increases under the action of chemical corrosion and dry and wet cycles. The research results have certain guiding significance for the design, construction and maintenance reinforcement of underground structures under the conditions of chemical corrosion and dry-wet cycling.

Effect of CuSO4 content and pH on the mechanical properties and antibacterial ability of copper-plated cement-based material

Microbial induced concrete corrosion (MICC) is the main deterioration mode of concrete corrosion in concrete wastewater transportation system. Protective coating is one of the commonly used microbial corrosion protection technologies for concrete. In this study, the effects of CuSO4 concentration and pH value of electroless plating solution on the preparation of copper-plated hardened cement paste (HCP) were investigated, and the antibacterial properties of HCP surface were optimized by electroless copper plating. The main components of the coating were copper and its oxide particles. When HCP was plated at the CuSO4 concentration of 10 g/L, the copper coating with high mass gain (0.3 %) and Vickers hardness (212.0 HV) was obtained. In addition, cubic copper structure constituted a compact copper coating HCP. The plating solution with pH of 9 was helpful to obtain the best quality gain and Vickers hardness of the coating. The microscopic morphology analysis showed that the coating had a relatively dense structure. Besides, antibacterial test indicated that copper-plated HCP had a significant improvement in antibacterial performance.

Efficient Preparation of S-Scheme Ag/AgBr/BiOBr Heterojunction Photocatalysts and Implications for Degradation of Carbendazim: Mechanism, Pathway, and Toxicology.

Carbendazim (CBZ), as a highly effective benzimidazole fungicide, has a good control effect on various crops caused by fungi. However, excessive use of CBZ in water, atmosphere, soil, and crops has serious effects. The efficient degradation of CBZ is an effective way to reduce its toxic effect. In this work, the type of S-scheme Ag/AgBr/BiOBr heterojunction photocatalyst was effectively prepared by a simple one-step solvothermal in situ method and first applied to the mineralization and degradation of CBZ. The effects of the molar ratio of AgBr to BiOBr, catalyst dosage, CBZ concentration, pH value of the original solution, and inorganic salt ions on the photocatalytic degradation performance of CBZ were comprehensively studied. The results showed that, under visible light irradiation, 0.9-Ag/AgBr/BiOBr (0.9-AAB) exhibited the best photocatalytic degradation performance (88.9%) against the concentration at 10 mg/L of CBZ in original solutions with pH of 10. However, the degradation effect was also good at pH 7. After 90 min, the degradation efficiency reached 86.0%, corresponding to a TOC removal efficiency of 84.0%. The results indicate that the main active species are 1O2 and •O2- free radicals according to the free radical quenching experiments and electron spin resonance spectra. Combined with the XPS characterization results, the electron transfer mechanism of the S-scheme heterojunction was deeply revealed. Additionally, the degradation pathway of CBZ was proposed through both the intermediate identification and the theoretical calculation derived from the DFT Fukui index. Finally, the toxicity of CBZ and the degradation intermediates were predicted based on the T.E.S.T.

On the mechanism for work function change of gold electrodes by ultrathin polyethyleneimine (PEI) films: Effect of molecular order.

Polyethyleneimine (PEI) is a widely used cationic polyelectrolyte. In organic electronics, it is a universal surface modifier for shifting the electrode work function (Φ) and improving charge injection into electronic devices. This effect may depend on the conformation and dipolar order of the PEI ultrathin film, but their detailed experimental evaluation has not yet been reported. Thus, we used sum-frequency generation (SFG) spectroscopy to probe the net orientation of polar groups of PEI films on glass and gold. The films were fabricated by spin-coating from alcoholic solutions or by dip-coating from aqueous solutions of various pH values, with both branched (b-PEI) and linear (l-PEI) structures. The obtained SFG spectra and atomic force microscopy (AFM) images indicated that the conformational ordering of the PEI layers increases over the period of 14 days after fabrication, being slightly more pronounced for l-PEI vs b-PEI, and for dip-coating vs spin coating fabrication. Furthermore, both the pH of the dip-coating solutions and the substrate nature influence the final morphology and order of the adsorbed films. On glass, they are optimized at an intermediate pH 5, while on gold, the greatest homogeneity is observed at pH 2 and the largest dipolar order is observed at pH 10. The pH dependence of changes in the work function of gold by PEI (|ΔΦ|) suggests that the electronic contribution is dominant. Nevertheless, the evolution of the PEI dipolar ordering was accompanied by small variations of |ΔΦ|, suggesting that it does have a significant contribution, especially at conditions for which the electronic contribution is reduced.

Red radish anthocyanin-based intelligent starch/pectin films for shrimp sub-freshness monitoring: effect of adjusting pH value of the film-forming solution

Red radish anthocyanin-based intelligent starch/pectin films for shrimp sub-freshness monitoring: effect of adjusting pH value of the film-forming solution

Performance improvement tactics of sensitized solar cells based on CuInS2 quantum dots prepared by high temperature hot injection

To reveal the ways and causes of conversion efficiency enhancement for quantum dot-sensitized solar cells (QDSSCs), chalcopyrite structure CuInS2 quantum dots (QDs) was synthesized in oil phase by the high temperature hot injection method. Then, QDs were transferred from oil phase to water phase with 3-mercaptopropionic acid as a ligand exchange reagent and loaded inducer of QDs. 3-mercaptopropionic acid coated QDs in water phase were sensitized on TiO2 nanocrystalline thin films to fabricate QDSSCs. The sensitization time of QDs and pH value in QDs solution are two important factors to affect the loading amounts of QDs and performance of the final assembled QDSSCs. Long-time sensitization of QDs on the TiO2 porous thin film will cause QDs to agglomerate and stack on the film. The pH of QDs aqueous solution influences the stable existence in solution of QDs and adsorption on the surface of TiO2. By balancing the influence of the above two factors, the optimal sensitization condition of CuInS2 QDs is adsorption in pH = 11 QDs solution for 2 h. In addition, the interface between QD-sensitized TiO2 porous thin film and FTO is another factor to affect the photoelectric conversion efficiency of QDSSCs. By adding Zn-doped TiO2 compact layer with high conductivity and electron mobility on QDSSCs to modify this interface, the photoelectric conversion efficiency of QDSSCs was further increased by 66.4 %.

Growth of novel tin oxide nanocrystals under different pH: Structure evolution, broad spectrum response and photocatalytic activity

Two-dimensional (2D) van der Waals (vdW) heterostructures are highly attractive for fabricating nanodevices due to their high surface-to-volume ratio and good compatibility with device design. In this work, without using any surfactant, the different mixed valence tin oxides were prepared by controlling the pH value of the precursor solution under simple hydrothermal condition. When the pH is at 3.22, Sn3O4 2D vdW nanocrystals will be produced, which have the characteristic of layered structure with mixed valence as confirmed by HRTEM and XPS analysis. The Sn3O4 nanocrystals show excellent adsorption and photocatalytic activity under the visible and infrared light, which is attributed to two-dimensional layered morphology, especial electrical structure and large mesopores structure. As the pH is increased to 9.72, SnO 2D nanocrystals with a layered structure similar to Sn3O4 could be generated, which have an obvious infrared response. Moreover, while the pH is decreased to 0.89, the tetragonal rutile phase SnO2-x nanocrystals with rich oxygen vacancies can be obtained. These tin oxides with different structures exhibit broad photo-response and high photocatalytic performance respectively.

High-Selective Separation Recovery of Ni, Co, and Mn from the Spent LIBs Via Acid Dissolution and Multistage Oxidation Precipitation.

For recovering Ni, Co, and Mn from lithium-ion batteries, traditional chemical precipitation methods demonstrate low selectivity and significantly contribute to environmental pollution. This study proposes a separation recovery technique for transition metals, specifically Ni, Co, and Mn, from spent LIBs, involving "acid dissolution" and "multistage oxidation precipitation". More than 98 % of transition metals can be extracted from spent LIBs using a low acid concentration (0.5 M) without reducing agents. The feasibility of separating different metals via multistage oxidation precipitation, based on their different electrode potentials for oxidizing Me2+ (Me=Mn/Co/Ni), was confirmed. The combination of oxidizing agent S2O8 2- and the precipitant OH- was universally applied to the fractional precipitation of Mn, Co, and Ni respectively. About 99 % of Mn, 97.06 % Co, and 96.62 % Ni could be precipitated sequentially by changing the concentrations of S2O8 2- and the pH value of solution. XRD, XPS, XRF, ICP-MS and other methods were employed to elucidate the mechanism behind the multistage oxidation precipitation of target metal compounds, exploiting the differential electrode potentials for oxidizing Me2+ ions. This technique surpasses traditional solvent extraction in cost-effectiveness and selectivity, showing promise for large-scale industrial applications in recovering Mn, Co, and Ni.

Investigation of H-Bonding and pH on the Fluorescence Spectral Behavior of Valsartan.

The photophysical properties of valsartan (VAL), a potent phenyl tetrazole derivative sartan, were investigated. Valsartan has absorption bands at 230nm and 255nm and a fluorescence band at about [Formula: see text] = 346nm in butanol which is red shifted depending on the H-bonding capability of the solvent. The role of H-bonding in the excited state was approved through the linear correlation of the emission energy of VAL with Camlet-Taft acidity and basicity parameters, α and β, of polar protic solvents. The position and intensity of fluorescence emission bands of VAL are found to be pH dependent, shifting from 425nm at pH 2 to 375nm at pH 4 with enhancement of intermolecular H-bonding and fluorescence intensity depletion beyond pH 5 with formation of tetrazole anion. The results were supported by time-resolved fluorescence measurements which indicated the presence of different species with different lifetimes in the excited state depending on solution pH value. Computational results based on time dependent density functional methods (TDDFT) show that the tetrazole moiety is involved in the [Formula: see text] absorption transitions, while natural bond analysis (NBO) shows that VAL adopts a dimer conformation in water because of effective intermolecular H-bonding.

Effective abatement of naphthalene from flue gas by V-W/Ti catalyst: Study of vanadium species and reaction mechanism

The removal of naphthalene is important but deficient, so that the available V-W/Ti catalysts (1.0 wt% V2O5/TiO2) were prepared for its efficient abatement in this work. Especially, influences of different existence status of vanadium species on naphthalene elimination were investigated via changing the pH value of precursor solution. With the increase of precursor solution acidity, more highly polymeric vanadium species were formed on the catalyst surface. The redox capability was enhanced markedly as a consequence of the stronger electron transfer between V/W and Ti that induced more surface active oxygen and V5+, whereas the catalytic activity was obviously boosted and almost 90 % conversion of naphthalene was achieved at 293 °C. Moreover, the weaker chemisorption between naphthalene and V-W/Ti catalyst allowed the deeper conversion to COx. GC–MS manifested that naphthalene seemed to be an organic component that was difficult to be totally degraded. Naphthalene oxidation was in the following pathway of naphthalene → 1,4-naphthoquinone → phthalic anhydride → phthalates → benzene → benzoquinone → maleic anhydride → COx/H2O. The opening of aromatic ring in phthalic anhydride and benzene ring in benzene were proven to be the rate-controlling step based on in-situ DRIFTS results. The key of naphthalene oxidation was the complete degradation of various intermediates.