Influence Of Solution Concentration Research Articles

Spin coating deposition of tin oxide thin films: Influence of solution concentration

Tin oxide (SnO2) thin films were deposited on glass substrates using a cost-effective spin coating method. The effect of solution molarity on their microstructural, optical, and electrical properties was investigated. For this purpose, solutions of tin chloride salt were prepared with various molarity in the range of 0.1M to 0.25M. The synthesized films structure and morphology were characterized by different techniques such as X-ray diffraction and scanning electron microscopy. The optical and electrical properties were studied by mean of UV-Vis spectroscopy and four probes conductivity measurement. The X-ray diffraction patterns of all samples revealed well-crystallized and pure SnO2 films with tetragonal rutile structure. The scanning electron microscopy images reveal a smooth and dense film pinholes free. The optical analyses show that the films exhibit an optical transparency that reaches up to 98% in the visible range and that the optical band gap decreases from 3.97 to 3.82 eV when the concentration increases from 0.1M to 0.25M. The films’ electrical conductivity varies in the range from 76 to 100 (Ω cm)–1. The largest figure of merit of 9.8 × 10–3 was measured in the films prepared at low solution concentration.

Atomistic Simulation Study of Grain Boundary Segregation and Grain Boundary Migration in Ni-Cr Alloys

Using Molecular Dynamics (MD) and Monte Carlo (MC) simulations, we studied the grain boundary (GB) segregation under different temperatures and Cr concentrations in Ni-Cr alloys with two distinct grain-boundary structures, i.e., Σ5(310)[010] and Σ101(200)[100]. Temperature plays a minor influence on Cr segregation for Σ5(310)[010] GB, but Cr segregation rapidly diminishes with elevating temperatures for Σ101(200)[100] GB. We also used the synthetic driving force and corresponding identification methods to investigate the effect of Cr solute segregation on grain boundary stability. All Σ5(310)[010] models have multi-stage grain boundary migration at 800 K. In the first stage, the grain boundary’s slow acceleration time is related to solute concentration. The migration temperature can influence this phenomenon. As temperatures rise, the duration of this slow acceleration phase diminishes. No similar phenomenon was observed in the process of the grain boundary movement of Σ101(200)[100]. The influence of solute concentration on grain boundary migration is complicated. The segregation concentration at the grain boundary cannot be regarded as the only factor affecting the migration of the grain boundary because the Cr atom on the grain boundary does not move with the grain boundary. This work will also discuss the grain boundary migration‘s relationship with lattice distortion and grain boundary atom diffusion. The results and findings of this study provide further insights into the segregation-increase GB stabilization of NC Ni-Cr alloys.

The Influence of Solution Concentration and pH for Removal Indigo Carmine using Banana Stem as a Biosorbent

The textile industry is one sector that generates effluent containing a significant quantity of pollutants, including dyes, and thus has an effect on the environment. Synthetic dyes, which are toxic and difficult to degrade, are utilized extensively in the textile industry. Therefore, a new study utilizes banana stems as a cost-effective biosorbent to remove indigo carmine dye. This research aims to investigate the use of banana stem waste as a bisorobent in batch method to adsorption indigo carmine dye. The optimal concentration and pH values are 2 and 900 mg/L, respectively. The interaction between the indigo carmine dye and the banana stems is suggested by the FTIR analysis. The solution's indigo carmine dye may be adsorbed by banana stem.

How does the precursor backbone length affect the grafting efficiency and kinetics for bottlebrush polystyrenes prepared by graft-onto Strategy?

The clarification of the potential dependence of grafting efficiency on the backbone length during the graft-onto reaction process is extremely important for subsequent structure–property study. In this work, by using alkyne-functional polypropargyne acrylate (PPANb, Mw/Mn < 1.10 and Nb = 960, 193, 35) and azide-functional polystyrene (PSNs, Mw/Mn < 1.15 and Ns = 54, 38, 22) as the backbone and sidechain precursors, we have investigated the Nb-dependence of the grafting reaction during the graft-onto click process. Specifically, the influence of solution concentration and feed ratio are investigated, and a combination of SEC characterization, Gaussian fitting and theoretical analysis is used to estimate the Nb-dependent grafting reaction for the bottlebrush product (PPANb-g-PSNs). The main findings include: 1) when the reaction time (t) is sufficient long (t = 24 h), the grafting efficiency is found to be nearly irrelevant with Nb, even if we consider 2 ∼ 5 times of difference in the diffusion coefficient (D) based the well-known scaling relation of D ∼ Nb1/2 in the semidilute reaction solution; 2) the time-dependent kinetics investigation further shows abnormal and different pathways for different backbone lengths when 0 min < t < 10 min, but the final grafting efficiency determined at t = 300 min shows no much difference, going back to the preliminary result of equilibrium state at t = 24 h; 3) the origin of abnormal pathways may be attributed to the relatively poor signal-to-noise ratio and potential dependence of dn/dC of PPANb-g-PSNs product on the composition at low grafting density range, which needs clarification in future. For the first time, our result has unambiguously demonstrated that, for a mixed solution of reaction system composed of backbone precursors with their lengths differing by hundreds of times, the polydispersity effect of the backbone length does not affect the final grafting efficiency during the process, no matter for long or short sidechain grafts. The result implies that it is the local dynamics of chain segments, instead of the overall translational diffusion dominates the graft-onto process in the concentration-regime studied.

Technology of preparation of defective cocoons for reeling

In this article, one of the ways to effectively use non-smooth defective cocoons that cannot be used in reeling is covered. An analysis of the development of the silk industry and the scientific work currently being carried out in this direction is presented. Water and air permeability of defective cocoons produced during cocoon sorting, evaporation regimes, influence of solution concentration on cocooning was studied by single cocooning. It is based on the fact that the amount of raw silk can be increased by introducing the spinning of defective cocoons. In order to achieve the set goal, separate cooking and water filling regimes of defective cocoons depending on the type of defect were determined based on experiments. A new processing method is recommended for cooking defective cocoons. Recommended technological parameters and modes for workshops are presented in the tables. Defective cocoons with a new concentration based on the type of defect recommended.

Influence of solution concentration on recycled polycarbonate nanofibers produced by solution blow-spinning process: a short communication

The recycling of polymeric materials is a sustainable alternative to reduce the use of virgin raw materials and avoid unnecessary disposal. A good example is its reprocessing through the solution blow-spinning (SBS) processing, which might produce nanofibers for coatings. This reprocessing technique has several advantages, such as lower production costs, a relatively simple system, and excellent yield. In this short communication, for the first time, three different solution concentrations, 5, 10 and 15 g/L of recycled polycarbonate (RPC) were solubilized with tetrahydrofuran solvent to produce nanofibers using the SBS technique. The nanofiber morphology was investigated by scanning electron microscopy (SEM) analysis. SEM micrographs showed that at a concentration of 5 g/L RPC it was not possible to produce nanofibers. Although nanofibers were formed at 10 g/L RPC, the appearance of undesirable droplets was inevitable. The 15 g/L was found as the ideal lower concentration of RPC for production of nanofiber without droplets.

Influence of solution concentration and temperature on the repair effect for electrophoretic deposition of rust-cracked reinforced concrete

Electrophoretic deposition is a new method for the repair of rust-expanded cracked reinforced concrete, which needs high performance epoxy resin repair solution. Selecting an appropriate solution concentration and temperature, clarifying the molecule electrophoretic deposition rule in the repair process, and revealing the influence mechanism of solution concentration and temperature on the repair effect will help maximize the application potential of the proposed method and control repair costs. In this study, four high-performance epoxy resin solutions with different concentration and temperature were prepared. The molecule electrophoretic deposition rule during the repair process was explored via macroscopic observation, mass increment, and resistance tests. The influence mechanism of solution concentration and temperature on the repair effect is discussed using microscopic observations combined with theoretical analysis. The results show that the waterproofing, carbonation resistance, and stray current erosion resistance of repaired specimens improve as the solution concentration increases. With the increase of solution concentration, the number of molecules per unit volume and the current density between electrodes increased, so the repair speed was faster and the repair effect was better under the condition of high concentration. The high temperature reduced the viscosity of the repair solution, which was conducive to the rapid deposition of molecules in the solution on the surface of the specimen at the early stage of the repair, but was not conducive to the film formation of epoxy resin on the surface of the specimen. Therefore, the waterproof and carbonization resistance of the repaired specimen decreased after the temperature increased.

Synthesize of ZnO Nanorods on Quartz Substrates with Seed Layer via Hydrothermal Method: Influence of Solution Concentration

Vertically oriented ZnO nanorods have been synthesized by hydrothermal method on quartz substrates with a seed layer. The influence of solution concentration on the morphology, structural and optical properties was analyzed. Results indicated that with the increase of solution concentration, the diameter and uniformity of ZnO nanorods increased. And the preferred orientation is obviously which shows better crystal quality. Typically, when the solution concentration is 0.03 mol/L, the nanorods exhibit a stronger UV emission peak located around 380 nm. In the visible region, all synthesized samples demonstrate more than 80% of optical transparency.

Hysteresis of soil water retention and shrinkage characteristics for various molar concentrations

Laboratory investigation on the influence of solute concentration on the soil water-retention curve (SWRC) and volumetric behaviour of expansive soils has received much attention in recent years due to increasing environmental pollution. However, most studies only considered applying wetting or drying path with almost no attention to hydraulic hysteresis. Furthermore, these studies have focused on examining expansive soils and only marginal effort has been devoted to collapsible soils. Therefore, the main objective of this study is to systematically explore the SWRC and shrinkage characteristics of an artificially made collapsible soil at various molar concentrations. The tests were conducted in a developed unsaturated automatic oedometer with enhanced measuring accuracy. The results reveal the distinct role of molarity on hysteresis with an ascending linear trend. In contrast to the air entry value, both desorption and adsorption rates increase with a rise in molarity, while compressibility reduces under both saturated and unsaturated conditions with clear reduction in yield suction and stiffness parameter. Microstructural photographs confirms the enlargement of macroporosity in contrast to microporosity as a consequence of solute−clay interactions. The results are interpreted in light of the theory of diffuse double layer and conceptual physics-based capillary and hysteresis models.

Performance investigation of a novel heating tower heat pump system with integrated air gap membrane distillation regenerator

Solution regeneration plays an important role in maintaining the frost-free operation of heating tower heat pump (HTHP). The traditional packed regenerator has limitation on thermal energy utilization due to its low regeneration efficiency. This paper suggests a novel HTHP system with integrated air gap membrane distillation regenerator (AGMD), using the sensible heat of high-temperature refrigerant gas at the compressor discharge to drive the regeneration process, realizing the cascade utilization of thermal energy and reducing the deterioration of COP (DCOP). Thermodynamic model of the novel system is developed and model simulations are carried out to study the system performance, meanwhile the comparison between the proposed system and conventional reverse-defrosting air source heat pump (ASHP) is performed. The results show that the DCOP of the novel system decreases from 4.4% to 2.6% as the evaporating temperature decreases from −15 °C to −25 °C under typical working condition. Decrease of evaporating temperature and increase of condensing temperature will greatly enhance the regeneration efficiency and reduce DCOP. The influence of solution concentration on DCOP is also distinct, which becomes greater as the water removal rate increases. The maximum coefficient of separation performance (COSP) increases from 0.0042 to 0.0052 kg/kJ as the ambient temperature decreases from 0 °C to −20 °C, while it decreases from 0.0031 kg/kJ to 0.0016 kg/kJ with a dramatic decline of 48% for the traditional reverse-defrosting ASHP, indicating that the novel system performs better than the traditional one and is more suitable to find applications at low ambient temperature conditions.

Falling film evaporation in a vertical tube with a new type of liquid distributor designed using the brachistochrone principle

A new-type brachistochrone distributor is proposed which creates much more uniform film on the tube wall than the conventional ones. Performance of the new distributor is tested for deionized water, 95% ethanol, 25% NaCl solution and realistic industrial wastewater, the result indicates that it consistently reduces the critical flowrate of liquid to form fully covered film. With the brachistochrone distributor, film thickness increases but tends to be stable with higher flowrate. Increasing gas velocity produces thinner film due to interfacial shear force. Parametric study of liquid flowrate, liquid initial temperature, heat flux and vacuum degree proves that heat transfer rate of film highly depends on flow regime and film thickness. Thicker film produces larger thermal resistance, while it allows for turbulence to occur which helps improve convective and evaporative heat transfer. Furthermore, the influence of solute concentration is investigated which implies that higher contents of NaCl in the water leads to lower heat transfer rate, which is attributed to the higher viscosity that increases film thickness and the higher surface tension that suppresses turbulence of film flow.

One-step method for the fabrication of high-quality perovskite thin-films under ambient conditions: Stability, morphological, optical, and electrical evaluation

Stability is still a property that limits the commercialization of perovskite solar cells. Thus, with the development of continuous deposition methods, it is essential to determine their feasibility in terms of stability, and not only on the efficiency of the devices produced. In this work, a hot air blow-drying (HABD) method is proposed as an alternative for the deposition of CH3NH3PbI3 (MAPbI) perovskite thin-films. The ability of HABD to produce homogeneous and stable thin-films was systematically studied and compared with those produced with air at standard conditions (25 °C, 25% relative humidity). The MAPbI thin-films were characterized by infrared spectroscopy and X-ray diffraction revealing that air temperature rules the film hydration. Partial degradation after using air at standard conditions was observed in contrast with the stable and pure perovskite phase obtained when using air heated at 90 C°. The influence of solution concentration on the surface coverage was determined by scanning electron and atomic force microscopies. It was found that 4 µL of precursors solution (0.434 M) produced a homogeneous MAPbI thin-film with ~180 nm thickness and roughness of (Rq ~ 29 nm) covering a 6.25 cm2 area. Moreover, the outstanding optical and electrical properties of MAPbI were not affected by the deposition procedure. Remarkably, degradation tests demonstrate that our HABD method is capable of producing stable MAPbI thin-films with excellent resistance to degradation at ambient conditions (up to 15 days), which makes it a promising low-cost and easy to use method for the continuous fabrication of perovskite solar cells.

The rejection of mono- and di-valent ions from aquatic environment by MWNT/chitosan buckypaper composite membranes: Influences of chitosan concentrations

Owing to the scarcity of proper drinking water is an urgent problem, MWNT/Chitosan membrane is greeting to reject mono- and di-valent ions from water. MWNT/Chitosan membrane was fabricated through the dispersion of Multi-walled carbon nanotubes (MWNTs) in an aqueous solution containing different concentrations of chitosan. The influence of solution concentration on membrane salt rejection properties, as well as contact angle, electrical conductivity, water permeability, mechanical properties, zeta potential, surface area and internal pores morphologies has been investigated. The resulting buckypaper demonstrate that the contact angle (91° ± 4° to 124° ± 3°), electrical conductivity (17 ± 1 to 83 ± 3 S/cm), water permeability (0.59 ± 0.04 to 5.73 ± 0.3 L/m2 h bar), surface area and internal pores morphologies of the buckypaper membranes were decreased by increasing the concentration of chitosan. While, the mechanical properties (tensile strengths varied between 35 ± 2 and 75 ± 3 MPa) and zeta potential of these buckypaper membranes were found to increase with increasing the amounts of chitosan. A buckypaper fabricated from MWNTs and a high concentration of chitosan (0.4% w/v) showed a higher rejection efficiency for these salts, possibly due to their smaller internal pore volumes and lower specific surface area.

CO2 capture and preparation of spindle-like CaCO3 crystals for papermaking using calcium carbide residue waste via an atomizing approach

Spindle-like CaCO3 crystals with controllable sizes for papermaking were successfully prepared using CO2 (8% CO2/N2 mixture gas) and calcium carbide residue (CCR) waste, a by-product of acetylene gas and polyvinyl chloride production, as the raw materials by an atomization method at room temperature. The influences of solution concentration, reaction temperature, and gas/liquid flow rate ratios on the properties of the CaCO3 crystal were systematically investigated, and a possible atomization mechanism was proposed. The size of the as-prepared CaCO3 crystal with pure calcite phase was turned from 4.71×4.02 µm to 1.82×1.12 µm by adjusting the reaction conditions. The application of the as-prepared CaCO3 crystals from CCR waste as a filler for papermaking was explored. The R475 blue light whiteness of paper was increased from 77.3 to 80.6 with 11.4% CaCO3 crystals.

Influence of Solute Concentration on Meniscus‐Guided Coating of Highly Crystalline Organic Thin Films

AbstractMeniscus‐guided coating methods are a successful approach to precipitate highly crystalline organic thin films at the tip of a receding meniscus. Their optimization nevertheless requires better understanding of the underlying fluid‐ and thermodynamics. Here, the systematic investigation of the impact of solute concentration is reported on the morphology and electrical characteristics of highly crystalline films of two benchmark organic semiconductors: C8‐BTBT and TIPS‐Pentacene. Building on the previous model that predicts the ideal coating speed by balancing substrate motion with solvent evaporation, the approach combines a complete fluid dynamics simulation, including solute transport and precipitation, with a broad set of experimental results. The fluid dynamics modeling confirms that precipitation is strongly enhanced at the tip of the meniscus, regardless of the solute concentration in the bulk of solution. This relative independence explains why the film morphology is little affected by the solute concentration. On the other hand, a rise in concentration results in thicker films. This is rationalized by the mass balance during precipitation. Furthermore, a rise in concentration generally results in films with better electrical characteristics, while the presence of the solute has limited impact on the optimal coating speed that remains close to the ideal balanced speed.

Influences of solute concentration on uniform elongation and dislocation characteristics of Al–Mg and Al–Si alloys

Influences of solute concentration on uniform elongation and dislocation characteristics of Al–Mg and Al–Si alloys

Preparation of pH-responsive DOX-loaded chitosan nanoparticles using supercritical assisted atomization with an enhanced mixer

Chemotherapeutics are used extensively in cancer and encapsulating the drug in nanoparticles is an effective method to enhance therapeutic efficacy and reduce side effect. In this work, DOX-loaded chitosan nanoparticles were prepared using supercritical fluid assisted atomization introduced by a hydrodynamic cavitation mixer (SAA-HCM) from aqueous solution. The influences of solution concentration, CO2/solution ratio, mixer pressure, chitosan/DOX ratio and chitosan molecular weight on particle morphologies and sizes were investigated in detail. Well defined spherical nanoparticles with average diameter ranging from 120 nm to 250 nm were obtained, and the loading efficiency was up to 90%. FT-IR result showed that the structure of DOX was not changed after the SAA-HCM process. Zeta potential of the nanoparticles was about +50 mV. The in vitro drug release behavior conducted in the media with pH of 4.5, 6.5 and 7.4 respectively showed strongly pH responsive. In vitro cytotoxicity profiles revealed that the activity of DOX was well maintained after loaded into chitosan nanoparticles. The SAA-HCM process was demonstrated to be a promising technique for one-step production of polymer/drug composite nanoparticles suitable for cancer drug delivery from aqueous solution.

Influence of solution concentration and temperature on the dissolution process and the internal structure of glauberite

Although transport in porous media under the influence of chemistry and temperature is a common phenomenon, the dissolution and internal structure evolution of glauberite during in-situ mining have been unique and challenging. This uniqueness indicates the complexity of mineral dissolutions, whereas the challenge represents the characterization of pore development and evolution during the dissolution processes. To investigate the microstructure development of glauberite under the influence of chemistry and temperature, experimental studies were performed with fine cuboid specimens of 4 mm × 4 mm × 9 mm soaked in solutions of different concentrations (fresh water, half-saturated, and saturated brine). The evolutions of internal structures were monitored through a micro computed tomography system. The statistical analysis indicated that the concentration and temperature of solutions significantly influenced the evolutions of pore size, porosity, and specific surface area of glauberite. The results showed that the increase in the rates of pore size, porosity, and specific surface area declined with time when glauberite was saturated in fresh water. The main reason for pore parameter variation is the differential concentration of solution. However, in the half-saturated and saturated solutions, the increase in rate increased with time. These observations suggest that the chloride ions contained in the saline solution could facilitate the dissolution of glauberite, whereas the existence of salt effect could contribute to the dissolution of calcium sulfate. Compared with the results at 20°C and 65°C, the studied parameters of glauberite have dramatically decreased when the mineral was soaked in the solutions at high temperature (95°C). This function was most striking in fresh water. The dissolution of glauberite soaked in fresh water or half-saturated brine solution was conditioned by the temperature and solution concentration. However, the dissolution of glauberite was less influenced by temperature at high concentrations. These findings may feature significant implication for the effective recovery of mineral resources by in-situ solution mining method.

The Influence of Operating Parameters on Membrane Performance in Used Lube Oil Processing

Membrane process is an attractive technology for used lube oil treatment due to the advantages, i.e. relatively low energy consumption, intensive process, higher separation efficiency, and the improvement of final product quality. The performances of membrane processes depend on several factors such as feed characteristic, membrane properties, and operating parameter. In this work, the influences of solute concentration and applied pressure on the performance of hollow fiber polypropylene membrane during used lube oil filtration are investigated. The osmotic pressure model is used to simulate the influence of operating parameter on membrane performances and it results in good agreement with experimental data. By using the osmotic pressure model, the intrinsic properties of the membrane, namely membrane resistance (Rm) and mass transfer coefficient (k) are 5x106 atm.s/m and 5x10-9 m/s, respectively. Generally, the flux increases with applied pressure and decreases with solute concentration. However, when the osmotic pressure builds up, the flux decreases gradually reaching a limiting value. At this condition, increasing an applied pressure gives an insignificant effect and the flux is in the limiting flux region. When the permeate flux reaches a limiting flux, the flux will be 5% of or less than the pure solvent permeability.

The influence of solute concentration and temperature of drilling fluids on wellbore failure in tight formation

The performance of drilling fluids influences the efficiency of drilling operations. The near-wellbore pore pressure and stress distribution will change with time due to the hydraulic, chemical and thermal potential gradients between the drilling and formation fluids, resulting in wellbore instability during drilling a tight formation. The pore pressure diffusion equation, which considers the effects of hydraulic diffusion, thermal diffusion, and solute diffusion, is presented and the analytic expressions of the near-wellbore pore pressure and stress distribution induced by pore pressure change and temperature stress are presented. An example is used to study the influence of the temperature and solute concentration on the near-wellbore pore pressure and effective stress and the degree of wellbore failure with time. The results show that increasing the solute concentration of drilling fluid reduces the pore pressure but increases the radial and tangential effective stress. In addition, decreasing drilling fluid temperature reduces the pore pressure and tangential effective stress but increases the radial effective stress, both of which are beneficial to wellbore stability. When wellbore failure occurs, increasing the drilling fluid temperature will cause a slight increase of wellbore failure and decreasing the solute concentration may cause a more serious failure in early time.