Volume Ratio Of H2O Research Articles

Simple synthesis of carbon dots/organosilicon composites with tunable solid-state emission and size for accurate latent fingerprint identification

The CDs–OSi composites with tunable emission and size were prepared by adjusting the volume ratio of H2O and EtOH in solvothermal. The CDs–OSi composites were applied in identification of latent fingerprint with effective definition and contrast.

Boosting the Performance of Zn Electrode in Aqueous Electrolytes via Trace Amount of Organic Molecules

AbstractThe poor performance of Zn electrode in aqueous electrolytes prevents the practical application of aqueous zinc‐ion batteries (AZIBs). Here, 2‐Pyrrolidinone (Pr) is introduced into conventional ZnSO4 electrolytes as additive and only 3 vol.% addition (Pr−to−H2O volume ratio) enables boosted performance. The Pr molecules are preferentially adsorbed on the surface of Zn electrodes to promote the uniform deposition of Zn ions and modulate the solvation structure of Zn2+ to inhibit the side reactions. As a result, the Zn electrode is boosted to run over 1200 h during charge/discharge cycling processes and delivers high average coulombic efficiency (CE) of 99.9 % under 1 mA cm−2, 1 mAh cm−2. Even under harsh testing conditions of 20 mA cm−2 and 20 mAh cm−2, Zn electrode still run over 100 h, which is much longer than that at pristine electrolyte (25 h). Moreover, the Zn||MnO2 full cells with the Pr additive exhibit a high capacity of 201 mAh g−1 and good capacity retention of 89 % after 550 cycles at 0.5 A g−1.

Efficient synthesis of Co2+–Co3+ hydrotalcite-like compounds via NaOH precipitation in methanol–water under mild alkaline conditions

Divalent/trivalent cobalt hydrotalcite-like compounds (Co2+–Co3+ HTlc) were synthesized via precipitation under mild alkaline conditions by using NaOH as precipitant and methanol–water as solvent. The influences of synthetic parameters including CH3OH:H2O volume ratio, precipitation pH, and hydrothermal treatment on the HTlc formation were investigated. The crystalline phase, morphology, and chemical composition of the synthesized samples were characterized by XRD, FTIR, SEM, TG–MS, and iodometric titration. The formation of Co2+–Co3+ HTlc was strongly affected by the methanol content and a single Co2+–Co3+ HTlc phase was obtained by raising the CH3OH:H2O ratio to 4:1–8:1. It was suggested that the presence of methanol increased the concentration of dissolved oxygen and promoted the oxidation of Co2+ into Co3+, leading to complete transformation of α-Co(OH)2 into Co2+–Co3+ HTlc. Moreover, single-phased Co2+–Co3+ HTlc was available at pH between 10 and 12, and they were hydrothermally stable by treatment at 60 °C for 24 h. Under the synthetic conditions, complete precipitation of cobalt ions was achieved. This highlights that the developed synthesis process is an efficiency way for quantitative synthesis of cobalt HTlc.

Anisotropic assembly and fluorescence enhancement of conjugated polymer nanostructures

AbstractThe electronic properties of conjugated polymers depend sensitively on their conformation and morphology. However, control over the morphology of conjugated polymers is highly challenging. Here, we demonstrate a facile approach for assembling conjugated polymers into anisotropic nanostructures. In a water–tetrahydrofuran (H2O–THF) binary solvent, we prepared ellipsoidal nanoparticles, which can subsequently self‐assemble into triangle‐ring and rod‐like nanostructures in a stepwise manner. The transitions among these morphologies can be rationally regulated by tuning the volume ratio of H2O to THF and the polymer concentration. The nanostructures show shape‐dependent absorption from 383 to 403 nm and significant fluorescence enhancement with a quantum yield up to 70%. The oxetane groups in the polymer side chains and the presence of surfactant in the solvent are decisive for the anisotropic assembly. We further demonstrate multicolor fluorescent nanowires with good structural integrity over doping of dye molecules or other fluorescent polymers. Single nanowires were characterized by high‐order super‐resolution optical fluctuation imaging, which revealed spatial distribution of the photooxidation sites along single nanowire for easily generating hole polarons.

Investigations on Preparation and Electrochemical Performance Optimization of LiMnPO4/C Composites with High Tap Density

AbstractIn this paper, the process route of synthesizing high tap density LiMnPO4 material by hydrothermal method with Li3PO4 as precursor is designed, and the microstructure and electrochemical properties of in situ carbon coated material are systematically studied. The phase, structure, morphology, and grain fineness distribution of the LiMnPO4/C are characterized by X‐ray diffraction, scanner transmission electron microscope, and laser particle size analyzer. There are a series of process parameters are optimized by orthogonal, such as reaction temperature, reaction time, polyethylene glycol 400 to H2O volume ratio and reactants concentration. The results show that, in the range of ≈2.5–4.5 V, the original charge–discharge volume of the prepared battery cathode material is shown as 123.7 mAh g−1 at a rate of 0.05 C. After 500 long cycles, the sample saves 95.55% (0.05 C) of the original capacity. At 550 °C, at different rates in the discontinuance voltage range of ≈2.5–4.5 V, the charge and discharge quantity of the cathode electrode raw materials obtained by individuals can be maintained at about 120.9 mAh g−1 (0.1 C), 119.0 mAh g−1 (0.5 C), 116.8 mAh g−1 (1 C), respectively.

Recycling Ag, As, Ga of waste light-emitting diodes via subcritical water treatment

From environmental security and resource recovery viewpoint, hydrothermal technology was adopted to recycle Ag, As, and Ga from waste LEDs in present study. Waste LEDs packaging materials (Polyphthalamide (PPA), epoxy resin, and brominated flame retardant (BFR)), which are difficult to degrade under normal conditions, can be effectively decomposed through two steps of hydrothermal treatment. As and Ga were leached and silver was successfully recovered. Under the optimal process parameters (300 ℃, 300r/min, 3% volume ratio of H2O2,400 min), the leaching rates of As and Ga are 98.4% and 80.5%, respectively. Ag and sapphire substrate were left and obtained together. Ag remains in the form of original metal, and almost no Ag ion was detected in the hydrothermal solution. In addition, As species in aqueous systems were simulated and inferred. The simulation results showed that As compounds that exist in the leaching solution is in liquid form and mainly exist as H2AsO4-. Under optimum processing conditions, almost 100% epoxy resin was decomposed. The degradation mechanism may be illuminated through the free radical reaction, and the possible decomposition pathways were speculated. The study proposed a process to recycle Ag, As, and Ga from scrapped LEDs and information could be useful for recycling other e-wastes.

Rapid synthesis and characterization of monolithic ambient pressure dried MTMS aerogels in pure water

In this work, monolithic silica aerogels were prepared in pure water within 4 h by using MTMS as the precursor under ambient pressure drying (APD). The effects of the volume ratio of H2O/MTMS, CTAB content and NH3·H2O concentration on the properties of MTMS-based aerogels (MSA) were investigated experimentally. The realization of the rapid synthesis of MSA under APD is attributed to getting rid of the aging process, solvent exchange and surface modification. It demonstrates that the microstructure of MSA is comprised of coralloid branches. Furthermore, the greater volume ratio of H2O /MTMS, larger CTAB content and smaller NH3·H2O concentration cause relatively slimmer coralloid branches, smaller pores and weakened connectivity of skeletons. It also finds that the MSA with a greater volume ratio of H2O/MTMS presents larger Young’s modulus and smaller compressive stress, which is because of the correspondingly different microstructures. The as-prepared MSA shows a low density of 0.064 g/cm3 and a contact angle as high as 143.4°, which provides their potentials for some engineering applications.

Polypyrrole nanospheres@graphene aerogel with high specific surface area, compressibility, and proper water wettability prepared in dimethylformamide-dependent environment

A polar functionalization modification is put forward to prepare polypyrrole nanospheres@graphene aerogel (PPys@GA) with high specific surface area, compressibility, and proper water wettability. Polarity of mixed solutions is regulated by controlling the volume ratio of H2O to N,N-dimethylformamide (DMF) to realize better dispersion of graphite oxide (GO), while PPys prepared by weak oxidant (FeCl2/H2O2) own excellent water wettability and can be easily adsorbed on GO sheets to restrain the aggregation of graphene sheets during the reduction self-assembly process more efficiently than PPys synthesized using strong oxidants. The finally resultant PPys@GA enjoys the advantages of high specific surface area (686 m2 g−1), ultralow density (7.8 mg cm−3), high Young's modulus (45.33 kPa) as well as proper wettability (a contact angle of 86°). And such excellent comprehensive properties for PPys@GA outperform many of their counterparts, which qualifies PPys@GA acting as a promising candidate for extensive applications such as adsorption, catalysis, sensors and energy storage materials.

Development of aqueous-based phase change amino acid solvents for energy-efficient CO2 capture: The role of antisolvent

The energy penalty is a primary limitation for the implementation of the aqueous solvents for large-scale post-combustion CO2 capture processes. In this study, a novel aqueous-based phase change solvent, composed of potassium glycinate (GlyK, reactive species), water (H2O, solvent) and dimethylformamide (DMF, antisolvent) was developed to improve the energy efficiency of CO2 capture. To examine the role of the antisolvent, a series of aqueous-based amino acid solvents (GlyK-X) with different DMF:H2O (X) volume ratios was prepared, fully characterized and assessed. It was observed that a CO2-free phase appeared at the top of the aqueous-based amino acid GlyK-X solvents after CO2 absorption which can be easily separated and recycled to the absorption column and save energy. The results showed that the GlyK-60 solvent with DMF:H2O volume ratio of 60:40 had a very high CO2-free phase volume (63%). Moreover, the GlyK-60 solvent exhibited 26.1% (0.433–0.546 mol CO2/mol GlyK) enhancement in CO2 absorption capacity, 38.5% (130–80 min) decrease in regeneration time and 59.1% reduction in relative heat duty compared to the conventional aqueous GlyK solvent. Overall, the outcomes confirmed that the aqueous-based phase change GlyK-60 solvent is a viable solvent option for large-scale CO2 capture with extra-low energy consumption and a key to the success of Paris Climate Accord.

Pharmaceutical wastewater treatment using UV-enhanced electro-Fenton process: Comparative study.

In this research, treatment of a pharmaceutical wastewater (PhW) obtained from a factory by electro-Fenton (EF) and photoelectro-Fenton (PEF) processes was investigated. The effects of several parameters involving pH, current density, H2 O2 /Fe2+ molar ratio, volume ratio of H2 O2 /PhW, UVA light, and time were studied. The experiments were designed by Design Expert software, and response surface methodology (RSM) was applied to determine the optimum conditions for the highest COD removal. According to the analysis of variance (ANOVA), time was the most significant parameter on the process response (COD removal) followed by current density. The optimal conditions for 86.85% of COD removal through the EF process were at pH of 2.96, current density of 42.90mA/cm2 , H2 O2 /Fe2+ molar ratio of 3.78, volume ratio of H2 O2 /PhW of 1.37ml/L, and reaction time of 58.49min, while the optimal conditions for 93.00% of COD removal through PEF process were at pH of 2.91, current density of 43.71mA/cm2 , H2 O2 /Fe2+ molar ratio of 4.29, volume ratio of H2 O2 /PhW of 1.67ml/L, UVA light of 6W, and reaction time of 54.24min. It was concluded that UVA light can increase the COD removal through PEF process around 7% more than that of the EF process at optimum conditions. PRACTITIONER POINTS: Treatment of a pharmaceutical wastewater by EF and PEF processes was investigated. Effects of several parameters were entirely studied on both the processes. RSM was applied to determine optimum conditions for the highest COD removal for both the processes. UVA light increased COD removal through PEF process (around 7%) at the optimum conditions.

Controlled synthesis of NbO-type metal-organic framework nano/microcrystals with superior capacity and selectivity for dye adsorption from aqueous solution

Abstract NbO-type MOF nano/microcrystals were facilely achieved by tuning the volume ratio of DMF and H2O mixed solvent under solvothermal conditions. It was found that NOTT-102 rhombohedral sample obtained with DMF:H2O volume ratio of 15:5 has the largest BET surface area (3006 m2 g−1), compared to the samples with the DMF:H2O volume ratio of 12:8 (2263 m2 g−1) and 20:0 (1962 m2 g−1) as well as the bulk NOTT-102, namely [Cu2(QPTC)] (H4QPTC = [1,1':4′,1″:4″,1‴-quaterphenyl]-3,3‴,5,5‴-tetracarboxylic acid), crystals (2942 m2 g−1). Furthermore, dye adsorption results indicate that NOTT-102 rhombohedral sample exhibits superior adsorption capacity (850 mg g−1) and adsorption selectivity for methylene blue (MB) in contrast to methyl orange, rhodamine B, and acid chrome blue K dyes, which may be one of the promising candidates for potential application in removal of organic dyes from aqueous solution.

Physicochemical and FTIR Study of Diesel-Hydrogen Peroxide Fuel Blend

Physicochemical properties of combustion fuels play a key role in determining the qualitative and quantitative characteristics, reliability and health effects associated with emissions. This paper reports the preparation of polysaccharide (PS) based emulsifier for stable blending of petroleum diesel-hydrogen peroxide (H2O2) and investigated the influence of H2O2 as diesel fuel blends on the physicochemical properties and characteristics. The quantity of PS-emulsifier was kept at 5 volume % (vol. %) and the volume ratio of H2O2 were varied 5-15 vol. % to reference diesel (RD), respectively. The blended diesel/H2O2 fuel were prepared under inert oxygen (O2) gas closed heating system; afterthought, physiochemical properties of diesel/H2O2 blend were evaluated at standard ASTM D-975 testing method. The kinetic properties show the interaction of RD and H2O2 blend at presence of PS emulsifier which exhibit the phenomenon to diminish the interfacial tension among the two different phases to form a homogenized stable solution. Results revealed that H2O2 is capable of enhancing the diesel fuel properties and showed that the addition of H2O2 in a diesel fuel blend are lied within the ranges of standard ASTM D-975. Due to further oxygen atom present in H2O2, it can facilitate the combustion process which ultimately effect on exhaust emission.

Aggregation induced emission-excited state intramolecular proton transfer based “off-on” fluorescent sensor for Al3+ ions in liquid and solid state

Benzophenone azine based schiff base exhibiting AIE and ESIPT phenomenon has been synthesised and studied the photophysical behaviour towards detection of Al3+ ions. The results showed that compound 2 exhibit feeble excited state intramolecular proton transfer emission in CH3CN and undergo aggregation induced emission in >70% H2O-CH3CN. The compound 2 shows significant hydrodynamic diameter change from 20 nm to 200 nm upon increasing the H2O volume ratio in CH3CN. Compound 2 shows colorimetric and “off-on” emission response for Al3+, with detection limit of 2.7 × 10−7 M in CH3OH. The association of compound 2 to Al3+ also causes restriction in intramolecular motion induced emission. The hydrodynamic diameter of compound 2 increases from 335 nm to 625 nm in the presence of Al3+ ion in CH3OH.

Room-temperature processing of CdSe quantum dots with tunable sizes

In this work, CdSe quantum dots (QDs) with tunable sizes have been fabricated via photo-induced chemical etching at room temperature, and the related reaction mechanism was investigated. The surface of QDs was oxidized by the holes generated through photon irradiation of oxygen species, and the obtained oxide layer was dissolved in an aqueous solution of 3-amino-1-propanol (APOL) with an APOL:H2O volume ratio of 5:1. The generated electrons promoted QD surface interactions with amino groups, which ultimately passivated surface defects. The absorption and photoluminescence emission peaks of the produced QDs were clearly blue-shifted about 26 nm with increasing time, and the resulting quantum yield for an 8 h etched sample was increased from 20% to 26%, as compared to the initial sample.

Recovery of Tantalum from Waste Tantalum Capacitors by Supercritical Water Treatment

Recycling e-waste has been a significant topic for environmental protection and also for resource recovery. Waste tantalum capacitors (WTCs), widely existing in discarded small appliances, are rich in high quality tantalum (Ta) resources. However, recovering Ta from WTCs is difficult due to the tightly covered mold resin. This study proposes an efficient and environmentally friendly process using supercritical water (SCW) to decompose the organics and recover Ta from WTCs. Two methods of SCW were studied: SCW depolymerization (SCWD) and SCW oxidation (SCWO). The results indicated that the mold resin (packing) of WTCs were effectively decomposed by SCW treatments. The organic decomposition efficiency in SCWD was lower than that in SCWO. The optimal parameters for SCWD and SCWO were, respectively, considered to be 425 °C, 25 MPa, and 120 min and 400 °C, 25 MPa, and 90 min, adding a 10% volume ratio of H2O2. After SCWO treatment, Ta electrodes were directly recovered, and the purity of Ta could reach 93.18%....

Tuning pore size of mesoporous silica nanoparticles simply by varying reaction parameters

Mesoporous silica nanoparticles (MSN) with tunable pore size have been proved to be excellent potential in molecular-related applications. Herein, in this study, we designed to synthesize MSN with tunable pore size by varying the n-octadecyltrimethoxysilane (C18TMS)/tetraethylorthosilicate (TEOS) molar ratio or the ethanol (EtOH)/H2O volume ratio in a water-ethanol-ammonia system, where C18TMS acted as structure-directing agent, TEOS as silica source, ammonia as catalyst, EtOH and H2O as solvents. The as-obtained MSN were characterized by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption-desorption analysis. The results showed that the as-synthesized MSN possessed spherical morphology with diameter ranging from 100 to 200nm, and the pore size of MSN could be easily tailored from 2.4 to 6.5nm simply by varying the C18TMS/TEOS molar ratio from 0.32 to 0.74 and the EtOH/H2O volume ratio from 3.6 to 7.5. Meanwhile, the pore volume also could be adjusted from 0.6 to 1.0cm3/g by this strategy. These results suggested that our strategy could effectively enlarge and adjust the mesopores of the MSN. We supposed our approach may provide a platform of nanotechnology for preparation of porous silica materials with adjustable mesopores which would be great potential in practical applications where different sizes of molecules were involved.

Effect of Imidazolium-Based Surface-Active Ionic Liquids on the Orientation of Liquid Crystals at Various Fluid/Liquid Crystal Interfaces.

A series of imidazolium-based surface-active ionic liquids (IM-SAILs), viz., single-chained IM-SAILs, 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br, n = 12, 14, 16), 1-dodecyl-3-methylimidazolium salicylate ([C12mim]Sal), 1-dodecyl-3-methylimidazolium 3-hydroxy-2-naphthoate ([C12mim]HNC), 1-dodecyl-3-methylimidazolium cinnamate ([C12mim]CA), 1-dodecyl-3-methylimidazolium para-hydroxy-cinnamate ([C12mim]PCA), gemini IM-SAIL, and 1,2-bis(3-dodecylimidazolium-1-yl)ethane bromide ([C12-2-C12im]Br2), along with three short-chained ionic liquids (ILs) [ethylammonium nitrate (EAN), propylammonium nitrate (PAN), and butylammonium nitrate (BAN)] were synthesized and applied to nematic liquid crystal (LC)/fluid interfaces. First, we evaluated the influence of the length and number of aliphatic chains as well as the counterion in the IM-SAIL structures on the anchoring of LCs at the aqueous/LC interface. It was observed that the threshold concentration of [Cnmim]Br (n = 12, 14, 16) decreased with the increase in aliphatic chain length. And double-chained [C12-2-C12im]Br2 has a far lower threshold concentration than single-chained [C12mim]Br. But the alteration of counterions (e.g., Br- and aromatic counterions) scarcely affected the anchoring of LCs at the interface. Second, we investigated the alignment of LCs at the diverse IL/LC interfaces in the presence of IM-SAILs. It is found that the variations in both aliphatic chain length and number can remarkably change the trigger points of the orientational transition of LCs at the EAN/LC interface. Specifically, with a slight increase in the alkyl chain length of short-chained ILs, as the fluid medium, the orientation of LCs varied tremendously at the IL/LC interface. Therefore, the higher threshold concentration of IM-SAILs and the corresponding greater stability in the optical appearance of LCs at the EAN/LC interface compared to that of the aqueous/LC interface can be ascribed to the discrepancy in the microstructure of water and IL. Finally, we verified that the volume ratio of H2O to EAN could more dramatically affect the alignment of LCs than the change in IM-SAIL concentration in aqueous solution. This work first illustrated the impact of SAIL structure on the LCs orientation at the aqueous/LC, IL/LC, and H2O-IL mixture/LC interfaces, which will inspire us to obtain a stabilized molecular alignment of LCs at the IL/LC interfaces and to further design novel functionalized SAIL molecules for various chemical and biological applications.

One‐step immersion method for fabricating superhydrophobic aluminum alloy with excellent corrosion resistance

This work develops a facile one‐step immersion method for preparing the superhydrophobic aluminum alloy, i.e. the aluminum alloy is treated with stearic acid (STA)–ethanol–H2O solution at 60 °C for 35 h. Results show that the aluminum alloy achieves flower‐like structure with both a great deal of pillars and pores, while the long hydrophobic alkyl chains are chemically grafted onto the hierarchical surface. Meanwhile, the water contact angle at the aluminum alloy surface gradually enhances with the decrease of the ethanol–H2O volume ratio, and the water contact angle and rolling angle of 156.2° and 5°, respectively, are obtained when the ethanol–H2O volume ratio is 1:3. Moreover, results show that the higher water contact angle at the aluminum alloy, the better corrosion resistance of the aluminum alloy. Consequently, the aluminum alloy with the superhydrophobic property has the best corrosion resistance, durability, and stability in corrosive environments. Copyright © 2016 John Wiley & Sons, Ltd.

Synthesis of large-sized mesoporous silica spheres by pseudomorphic transformation of commercial silica spheres

Large-sized spherical mesoporous silica (LMS > 3 mm) has been synthesized through a pseudomorphic transformation method. For this, cetyltrimethylammonium bromide (CTAB) was selected as a templating agent and commercial silica spheres were used as the parent silica material. The effects of synthesis parameters, such as NaOH:SiO2 molar ratio, reaction time, and ethanol:H2O volume ratio, have been quantitatively investigated. The structure and morphology of the spheres have been investigated by N2 sorption–desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. The pore structure of LMS obtained from a molar ratio of 140H2O:0.1NaOH:0.27CTAB after 48 h was examined with the addition of ethanol, and the optimal volume ratio of ethanol:H2O was identified as 0.252. Under the optimum conditions, high-quality mesoporous silica spheres were synthesized with a high specific surface area (about 1078.19 m2/g) after post-hydrothermal treatment. The ordered pore structure was maintained over four cycles in recyclability experiments on the reaction solution. The large-sized particles showed improved capacity for Pb2+ removal, suggesting that they might be applied as a basic material for heavy metal adsorption in treating industrial or natural waste water.

The Optimum of Preparation and Characterization of Aerogels like Hydrophobic Titania by Ambient Pressure Drying

The influence of different factors in the alcogel preparation process and ambient pressure drying process on packing density of hydrophobic TiO2 aerogel synthesized by ambient pressure drying (APD) and the optimum preparation conditions were investigated by the orthogonal test with four-factor and three-level L9(34), respectively. The morphology and structural properties of hydrophobic TiO2 aerogels with different density were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetry (TG), N2 adsorption-desorption measurement and Scanning Electron Microscope (SEM). The results showed that the most important factors in the preparation process for TiO2 aerogels with low-density under ambient pressure are aging time, the volume ratio of C2H5OH to TBT, ethanol immersion time and hydrophobic modification time. The optimized preparation conditions are that aging time is 24 h, the volume ratio of C2H5OH to TBT is (7+7) : 5, the volume ratio of H2O to TBT is 1.7 : 5, the volume ratio of HAc to TBT is 1.7 : 5, ethanol immersion time is 24 h, hydrophobic modification time is 48 h, hexane solvent replacement time is 24 h and the drying temperature is 393 K. TiO2 aerogels with density of 460 kg/m3 was obtained at the optimized conditions. TiO2 aerogel with lower density displays higher specific surface area, porosity and pore volume as well as the larger pore size.