Dry Air Conditions Research Articles

Oxygen Ion and Proton Transport in Alkali-Earth Doped Layered Perovskites Based on BaLa2In2O7

Inorganic materials with layered perovskite structures have a wide range of physical and chemical properties. Layered perovskites based on BaLanInnO3n+1 (n = 1, 2) were recently investigated as protonic conductors. This work focused on the oxygen ion and proton transport (ionic conductivity and mobility) in alkali-earth (Sr2+, Ba2+)-doped layered perovskites based on BaLa2In2O7. It is shown that in the dry air conditions, the nature of conductivity is mixed oxygen–hole, despite the dopant nature. Doping leads to the increase in the conductivity values by up to ~1.5 orders of magnitude. The most proton-conductive BaLa1.7Ba0.3In2O6.85 and BaLa1.7Sr0.15In2O6.925 samples are characterized by the conductivity values 1.2·10−4 S/cm and 0.7·10−4 S/cm at 500 °C under wet air, respectively. The layered perovskites with Ruddlesden-Popper structure, containing two layers of perovskite blocks, are the prospective proton-conducting materials and further material science searches among this class of materials is relevant.

Investigation of negative corona discharge Trichel pulses for a needle-plane geometry via two numerical 2D axisymmetric models

Trichel pulses for negative direct current corona discharge in a pin plate configuration under open dry air conditions are investigated using two numerical models. The first well known general model takes electrons and positive and negative ions into consideration. The second model, a more detailed one, takes electrons and other 16 nitrogen and oxygen species into consideration. Both models are able to capture the general evolution of the electrical discharge. However, the detailed model is able to also show the effect of behavior and contribution of specific species on the discharge. The results show that negative oxygen ions play a key role in the development of Trichel pulses. Furthermore, O2− and O3− ions develop in the interlayered spatial layers in the discharge gap, with the number of layers corresponding to the number of Trichel pulses. It is also shown that nitrogen ions are mostly generated in front of the negatively biased (−5.5 kV) pin.

Heat and Mass Transfer in Structural Ceramic Blocks: An Analytical and Phenomenological Approach

The ceramic industry is one of the pillars of the Brazilian economy, characterized by making low-cost products and an obsolete manufacturing process from a technological point of view. Among the various stages of production of ceramic materials, drying is one of the most energy-consuming and, in general, causes structural damage to the product, compromising its mechanical performance and final quality. Despite the relevance, studies on the drying of ceramic materials are mostly conducted at the experimental level and limited to some specific operational conditions. In this scenario, this research aims to theoretically study the heat and mass transfers in industrial ceramic blocks during drying. Based on the lumped analysis method, and considering the dimensional variations of the material, new phenomenological mathematical models and their respective analytical solutions are proposed to describe the kinetics of mass loss and heating of the material. The predicted results referring to the thermal and gravimetric behavior of the block during the oven drying process under different conditions are compared with the experimental data, obtaining excellent agreement between the results. Furthermore, the transport coefficients were estimated, proving the dependence of these parameters on the drying air conditions. The convective mass transfer coefficient ranged from 6.69 × 10–7 to 15.97 × 10–7 m/s on the outer surface of the block and from 0.70 × 10–7 to 1.03 × 10–7 m/s on the inner surface of the material when the drying air temperature ranged from 50 to 100 °C. The convective heat transfer coefficient ranged from 4.79 to 2.04 W/(m2.°C) on the outer surface of the block and from 1.00 to 0.94 W/(m2.°C) on the inner surface of the material when air temperature ranged from 50 to 100 °C.

An in vivo and in vitro study on the force degradation and surface morphology of the orthodontic elastic ligatures

The objective of this study was to investigate the characteristics of force degradation and surface morphology of 9 brands of elastic ligatures over 6 weeks, both invivo and invitro, to provide some reference for clinical selection of appropriate elastic ligatures and determination of appropriate follow-up visit time. Choosing 9 kinds of brands of elastic ligatures (American Orthodontics, Ormco, 3M Grey, TP Orthodontics, Xihu, Yahong, Creative, Protect, 3M dusty blue), which are common in the market. For the invivo study, 9 volunteers (5 males, 4 females, aged 22-26 years) were chosen to wear elastic ligature fixators, which were made to fix the elastic ligature in the mouth without bonding brackets on the teeth. The residual force and percentage of force degradation of elastic ligatures were estimated after 0, 1 hour, 2 hours, 8 hours, 1 day, 2 days, 1 week, 2 weeks, 4 weeks, and 6 weeks processed invivo and invitro (25°C dry air condition, 37°C artificial saliva, pH= 6.7 and oral environment); A 1-way analysis of variance and t test were used to identify statistical significance (P<0.05). The surface morphology of the initial state and after a 6-week process invivo and invitro were observed separately. The characteristics of force degradation and surface morphology of 9 brands of elastic ligatures were different over 6 weeks; With the extension of time, the tensile force declined, and the percentage of force degradation of all groups decreased sharply by about 9.1%-32.3% in the first day, then the rate reduced steadily. In addition, during the first day, the percentage of force degradation declined most sharply in the first hour (4.4%-16.5%). The percentage of force degradation of 9 elastic ligatures was reduced by about 11.3%-37.3% over 6 weeks in all groups. At the same time, the characteristics of force degradation in the same brand are that invivo> artificial saliva> air (P<0.05). After a 6-week process, the surface morphologic defects were aggravated under a scanning electron microscope, corresponding to the change of mechanical properties in each brand. The mechanical properties of elastic ligatures are reduced with time extension and decreased greater invivo than invitro; According to the characteristics of force degradation of different brands of elastic ligatures, clinicians can choose the proper elastic ligatures at different stages of treatment, and adjust the follow-up visit time appropriately. For example, in alignment and leveling, the elastic ligatures with slow force degradation, such as Ormco, TP, and so on, maybe more suitable to ensure close contact between the archwire and the bracket. In the space-closing stage, the elastic ligatures with fast force degradation may be more appropriate to reduce the friction between the archwire and the bracket, such as 3M Grey, Yahong, Protect, and so on.

Investigating the Physicochemical Property Changes of Plastic Packaging Exposed to UV Irradiation and Different Aqueous Environments

A wide range of weathering processes contributes to the degradation of plastic litter items which leads to the formation of microplastics that may be detrimental to marine ecosystems and the organisms inhabiting them. In this study, the impact of UV exposure on the degradation of clear polypropylene (CPP), black polypropylene (BPP), and polyethylene terephthalate (PET) packaging materials was investigated over a period of 6 weeks under dry air conditions representing the terrestrial environment. The exposure was conducted using differently sized and shaped samples at irradiation intensities of 65 W/m2 and 130 W/m2. Results indicated that UV irradiation led to changes in the properties of PET, BPP, and CPP that were proportional to the intensity delivered, leading to a higher level of mass loss, carbonyl indices, crystallinities, and microhardness in all polymer types at 130 W/m2 relative to 65 W/m2. However, material shape and size did not have a significant influence on any property for any of the test materials. Increased mass loss over time was accompanied by considerable increases in carbonyl index (CI) for both PPs. Clear PP (CPP) underwent the most severe degradation, resulting in the highest mass loss, increase in crystallinity, and CI. BPP was less degraded and modified by the UV irradiation than the CPP, indicating that the colorant, carbon black, provided some degree of protection to the bulk polymer material. PET was the least degraded of the three materials, suggesting this polymer type is more resistant to UV degradation. The differences in the degradation behaviours of the three test materials under dry environmental conditions indicate that the UV exposure history of plastic litter might play an important role in its potential for further degradation once it reaches the marine environment. Furthermore, analysis of samples exposed to UV in aqueous media reveals a more irregular set of trends for most material properties measured. Overall, the degree of degradation resulting from UV irradiation in dry environments was more pronounced than in aqueous environments, although the most significant property changes were observed for materials without previous UV exposure histories. Samples with previous UV histories showed higher resistance to further crystallinity changes, which appeared to be due to crosslinking in the pretreatment exposures inhibiting chain alignment into crystalline structures. The effect of solution medium was insignificant, although the presence of water allowed hydrolytic degradation to proceed simultaneously with UV degradation for PET. The reduction of CI in pretreated materials in the aqueous exposures, combined with the mass loss, suggest that the degraded surface layer erodes or products dissolve into surrounding solution medium, leaving a fresh surface of plastic exposed.

Humidity Resistant Carbon Nanotubes‐Styrene Methyl‐Methacrylate Polymer Composite for Ultrafast Laser

AbstractCarbon nanotube (CNT)–polymer composite films are key elements in widespread photonic and optoelectronic applications. One particular successful application is to produce ultrashort optical pulses in the laser cavity. Nevertheless, such composite film may suffer from severe humidity/water degradation, from which the laser may even stop generating regular pulses. Here, surfactant‐free CNT–styrene methyl‐methacrylate polymer composite film is fabricated. Based on such film‐type saturable absorber, a self‐starting passively mode‐locked erbium‐doped fiber laser with the capability of generating ≈1 ps pulses is demonstrated. From the perspective of experimental measurements and numerical simulations, the effectiveness of a saturable absorber in generating ultrashort pulses is confirmed. The operating composite film can survive under fully immersed water condition for 30 days. More importantly, after the non‐operating composite film has been fully soaked in the water tank for 2 days, it can still mode‐lock the laser as it is in dry air condition, confirming the humidity resistance capability. In addition, it is experimentally found that the mechanical packaging of the composite film has an impact on the survival time of composite film under water immersion.

Comparison of Tool Wear Mechanisms During Drilling of Aluminium Alloy 7075 in Dry and Chilled Air Conditions

Aluminium alloys are widely used in manufacturing industry due to the need of lightweight components and low production cost. However, mechanical assembly of the alloy which requires drilling operations is challenging due to chip accumulation and heat at the cutting tool and workpiece interface. This often causes material adhesion on cutting edges, built-up edge, accelerated tool wear, shorter tool life and poor drilled hole quality. This paper investigates the effect drilling conditions (dry and chilled air at 10°C) on the wear mechanisms of tungsten carbide cutting tools during drilling Aluminium alloy 7075 (Al 7075) at two different feed rates. Chilled or cold air was used as a cooling medium in drilling Al 7075 to promote green manufacturing. Drilling operations of Al 7075 were performed at a constant cutting speed of 123 m/min with feed rates of 0.01 and 0.1 mm/rev. The cutting tools’ flank wear were measured using an optical microscope with Dino-Capture software and further examination on the tool wear (e.g., built-up edge, built-up layer, and crack) were conducted using Scanning Electron Microscopy (SEM). The results of this study indicate that at higher feed rate of 0.1 mm/rev, adhesive wear is dominant due to the presence of evident material adhesion and fractures on the cutting edges. The use of chilled air was found to cause less material adhesion, however more edge fracture occurred which could be due to workpiece hardening. Therefore, it is inferred that drilling Al 7075 with chilled air requires harder and stronger cutting tool in order prolong the tool life.

Cerium metal oxidation studied by IR reflection-absorption and Raman scattering spectroscopies

Oxidation of cerium metal is a complex process which is strongly affected by the presence of water vapor in the oxidative atmosphere. Here, we explore, by means of infrared reflection-absorption spectroscopy (IRRAS) and Raman scattering spectroscopies, thin oxide films, formed on cerium metal during oxidation, under dry vs ambient (humid) air conditions (∼0.2% and ∼50% relative humidities, respectively) and compare them with a thin film of CeO2 deposited on a Si substrate. Complementary analysis of the thin films using x-ray diffraction and focused ion beam-scanning electron microscopy enables the correlation between their structure and spectroscopic characterizations. The initial oxidation of cerium metal results in the formation of highly sub-stoichiometric CeO2−x . Under dry air conditions, a major fraction of that oxide reacts with oxygen to form CeO∼2, which is spectroscopically detected by Raman scattering F 2g symmetry mode and by IRAAS F 1u symmetry mode, splitted into doubly-degenerate transverse optic and mono-degenerate longitudinally optic (LO) modes. In contrast, under ambient (humid) conditions, the oxide formed is more heterogenous, as the reaction of CeO2−x diverges towards the dominant formation of Ce(OH)3. Prior to the spectral emergence of Ce(OH)3, hydrogen ions incorporate into the highly sub-stoichiometric oxide, as manifested by Ce–H local vibrational mode detected in the Raman spectrum. The spectroscopic response of the thin oxide layer thus formed is more complex; particularly noted is the absence of the LO mode. It is attributed to the high density of microstructural and compositional defects in the oxide layer, which results in a heterogenous dielectric nature of the thin film, far from being representable by a single phase of CeO∼2.

Investigating the thermal oxidation behavior of Ti–6Al–7Nb alloy in dry air

AbstractThe thermal oxidation behavior of a forged Ti–6Al–7Nb (Ti67) alloy was investigated in dry air conditions. The alloy specimens were oxidized for 50 h at different temperatures (650°C, 750°C, and 850°C) and the oxidation kinetics were analyzed. The microstructure of Ti67 after oxidation and the different phases and compounds were identified. A parabolic equation based on weight gain was used to define the oxidation rate. The parabolic rate constant increased from 1.10 × 10−8at 650°C to 2.10 × 10−8and 1.53 × 10−7g2/(cm4·h) at 750°C and 850°C, respectively. At 650°C, the oxidation behavior resumed the parabolic behavior until 40 h, a breakaway phenomenon. At 750°C, a linear behavior was observed in the periods of 20–50 h. This linear trend appeared also after 35–50 h at 850°C. The activation energy was found to be 238.4 kJ/mole. At the lowest oxidation temperature (650°C), a disconnected oxide layer was observed. These variations in the response of Ti67 alloy to the different thermal oxidation conditions are worthy of consideration when modifying the surfaces for biomedical applications.

Microscopy of maize grains subjected to continuous and intermittent drying

Drying is an important step in the post-harvest processes as a way of product conservation and quality preservation. In this context, this study aimed to evaluate the effect of continuous and intermittent drying of maize grains with different rest periods on the integrity of their micro- and macroscopic structures. Maize grains were harvested with a moisture content of 0.3399 ± 0.001 dry basis (db) and subjected to continuous and intermittent drying with 4, 8, 12, and 16 hours of rest period. An experimental fixed-bed dryer, with controlled drying air conditions at a temperature of 100 °C and air flow of 1.5 m3 min.−1 m−2 (12 m3 min.−1 m−3), was used. Continuous drying was completed with a moisture content of 0.1628 ± 0.0003 db, whereas intermittent drying was interrupted with 0.2195 ± 0.0002 db and resumed after rest. The drying rate, integrity through grain images, the conformation of particles through scanning electron microscopy, and cell membrane integrity were evaluated. The drying rate increased with an increase in the rest period, the increase in rest period reduced the intensity of cracks, and the reduction in rest period led to higher dispersion and reduction in the size of starch granules and lower integrity of cell membranes.

Wood ash versus expanded clay aggregate as internal curing water reservoirs in high performance concrete

The performances of expanded clay aggregate and wood ash as internal curing water reservoirs were studied in the mortar phase of a hypothetical high performance concrete with a low water-to-binder ratio. The two materials substituted the 15 and 30% of the sand volume. Two different binders, Portland cement and high-volume fly ash blended cement, were used. The compressive strength and the volume stability of the mortars in sealed and air-drying conditions were studied. Furthermore, the desorption capacity of the internal curing water reservoirs and the internal humidity inside the mortars during the first days after casting were analysed. The results shown that the reduction in the self-desiccation shrinkage was higher when the expanded clay aggregate was used, even in air-drying curing conditions, due to its higher desorption capacity in low-relative-humidity environments in comparison to that of the wood ash. However, wood ash had a stronger beneficial effect on early age autogenous shrinkage without significantly increasing the drying shrinkage. The two alternative aggregates influenced the strength moderately. Considering the technical, economic, and environmental implications of using the two lightweight aggregates, wood ash is recommended.

Performance assessment of a flat-sheet membrane-based dehumidifier with serpentine flow channels: An experimental study

Membrane-based dehumidification system is an emerging technology which drives based on the renewable low-grade energy sources. Water vapor selective membrane is able to separate water vapor from the air which can be used to condition air in buildings, more efficiently than conventional air-conditioning equipment. Flow channel designs (especially serpentine-type) and their impacts on the thermal–hydraulic performance of membrane-based dehumidifiers are essential and not well-studied. In the present work, a novel flat-sheet membrane dehumidifier with serpentine flow channels is designed and evaluated experimentally. The serpentine flow channel offers a long flow path that the air in the wet and dry sides of the channel interacts with each other through the membrane, thereby improving the heat and water vapor transfer. The effect of inlet air flow rate, relative humidity, and temperature of both wet and dry sides on the dehumidification rate, approach temperature, pressure drop, and coefficient of performance of the dehumidifier is examined. Results show that passing the humid air with higher flow rate, humidity, and temperature through the wet side channel leads to the higher dehumidification rate, approach temperature, and pressure drop. Increase of wet side air temperature and flow rate enhances the coefficient of performance, and the effect of inlet air relative humidity on the coefficient of performance is observed negligible at high air flow rates. Parametric study of dry side air condition reveals that the air with lower humidity improves the dehumidification rate and coefficient of performance, while its effect on the approach temperature and pressure drop is observed negligible. Elevated air temperature of dry side has positive and negative impact on the approach temperature and coefficient of performance of the dehumidifier, respectively.

Deciphering the discoloration in the manufacturing of natural rubber

Many naturally occurring color components, especially non-rubber components, are present in natural rubber (NR) latex, limiting some NR applications, particularly for light-colored NR products in high demand. Non-rubber components, like lipids and proteins, can be removed from NR to reduce its yellow color. This study looked at the factors that influence the yellow index (YI) in NR and NR latex discoloration techniques. Proteins were a crucial factor directly determining the YI of NR. Thus, increasing the number of centrifugation washings, speed, and time was used to remove proteins to minimize the YI of NR. Percentage of total solid content (% TSC) of field NR latex, the blend ratio between cream rubber and skim latex, or bottom fraction from fresh-field NR latex collected from centrifugation process, were also important factors. The addition of sodium metabisulphites as a polyphenol oxidase (PPO)-reducing agent reduced the YI significantly. The oxidative breakdown of endogenous non-rubber components at high temperatures was also confirmed to serve the increase in YI value due to air-drying conditions of NR.

Analysis of Hot-Air Supplemented Solar Drying Using Computational Fluid Dynamics Technique

Energy is a crucial input in the process of economic, social and industrial development of any nation. Fluctuating solar insolation and late sunrise hour has led to poor quality dried biological material production. A simulation of hot-air supplemented solar dryer (HSSD) designed for such purpose is presented for temperature distribution based on direct solar irradiation of 1423 W/m2 of Akure, Nigeria (5.304º Latitude 7.258º Longitude). The environmental conditions in the hybrid dryer were measured during a day of operation. The model of the dryer was created and a numerical model was established to allow replicating the internal environmental conditions of the dryer. The airflow, temperature, radiative heat flux and other parameters inside the HSSD system were simulated using computational fluid dynamics (CFD) approach. The simulated result was compared with the calculated and estimated parameter values for the HSSD. The simulated air-flow pattern and temperature distribution on the horizontal and vertical planes in the drying chamber were analyzed and the results revealed spatial homogeneity of drying air condition. However, there is higher velocity profile at the outlet vent due to buildup of hot air at outlet vent. There was relatively low interference of external temperature in the drying chamber.

Moisture sorption isotherms, drying behavior, and quality attributes of mango sheets dried using hot air combined with relative humidity control

The equilibrium moisture contents of mango sheets were determined at 40–60°C and 11%–82% relative humidity (RH). The effects of RH and temperature of the drying air were investigated. The main objectives were: (a) to determine the moisture sorption isotherms and (b) to investigate the effects of applying hot air combined with RH control on mango sheet drying to imitate heat pump drying. Peleg's model was the best-fitting model for the equilibrium moisture content. Controlling the RH at 15% clearly raised the drying rate after drying for 2 hr compared to drying without any RH control. Single-stage drying at 60°C and 15% RH and two-stage drying both required shorter drying times and provided superior mango color and textural qualities than the single-stage drying at 60°C without any RH control. These results implicitly indicated the potential of heat pump dryer in the mango sheet drying. Novelty impact statement The moisture sorption isotherms together with the equations developed in this study are beneficial for the operation of heat pump dryer in mango sheet drying. The hot air combined with relative humidity control was applied in mango sheet drying experiments in order to imitate the drying air conditions occurring in a heat pump dryer. This study revealed that the application of heat pump dryer in the commercial drying of mango sheet or other agricultural products is interesting because this drying technique has potential to obtain the uniformity of moisture content of products without the necessity of opening the drying chamber to switch the positions of either trays or trolleys inside the drying chamber along the whole drying process which is both time- and labor-consuming and increases the risk of contamination.

Investigation of Tribological Behaviour on DLC Coatings for AA5051 using DC Sputtering

DLC coatings are deposited on aluminium substrates to improve the wear resistance property of the substrates using sputtering deposition in this study. DLC coatings are deposited using the graphite target onto the Al5051 substrates using DC sputtering. The deposited coatings are then analyzed for their adhesion strength, hardness, coefficient of friction, and chemical compositions. The pin-on-disk method is conducted in vacuumed conditions, dry air conditions (0% RH), and ambient air conditions (40% RH). The different testing conditions have shown different results for the same testing sample. This indicates the nature of DLC film adsorption in ambient air conditions. The chemical composition study has further revealed the adsorbing compounds and the ability of hydrogen and water molecules to get adsorbed on the thin-film surface. This study gives insight into the effect of molecules present in the ambient air on the performance of DLC coatings. It investigates the effect of three DLC coatings deposited using the graphite target onto the Al5051 substrates using DC sputtering.

Effect of Post-Drying Tempering of Rice on Minimizing Kernel Fissuring and Maximizing Moisture Removal

HighlightsMore moisture can be removed in a single drying pass without severely fissuring kernels when samples are tempered than when immediately cooled without tempering.Tempering rice kernels immediately after drying can reduce the percentage of fissured kernels by up to half of that when kernels are immediately cooled without tempering.Abstract. Improper rice drying results in kernel fissuring, leading to head rice yield reduction due to breakage during milling. The objective of this study was to determine the percentage points (pp) of moisture content (MC) reduction that can be achieved in a single drying pass without significantly fissuring kernels. Long-grain rough rice of cultivars CL XL745 and Diamond at initial MCs of 18%, 17%, 16%, 15%, and 14% were dried using air at 45°C/20% relative humidity (RH), 50°C/15% RH, 55°C/12% RH, 60°C/10% RH, and 65°C/8% RH to MCs of 17%, 16%, 15%, 14%, 13%, or 12% with and without post-drying tempering. All temperature/RH combinations resulted in a humidity ratio of 0.012 kg water kg-1 dry air. Tempering was conducted at the drying air temperature for 4 h. The resulting samples achieved between 1 and 7 pp of MC reduction in a single drying pass. The pp of MC reduction that can be attained in a single drying pass without causing significant fissuring varied across the cultivars tested. Generally, ~2 pp of MC reduction was achieved in a single drying pass for CL XL745 and ~4 pp for Diamond without causing adverse fissuring when samples were not tempered after drying. However, with tempering, ~3.5 pp of MC reduction was achieved in a single drying pass for CL XL745 and ~5.5 pp for Diamond without causing significant fissuring. However, these amounts varied depending on the drying air conditions and initial MC. For both cultivars, tempering immediately after drying reduced the fissured kernel percentage by up to half of that when the kernels were not tempered. These findings quantify the importance of rice tempering and provide information on how much moisture can be safely removed in a single drying pass. Such findings may be applied to different dryer types to reduce fissuring due to drying, thereby minimizing head rice yield reductions. Keywords: Drying, Glass transition, Rice quality, Single-pass drying, X-ray imaging.

Improved reproducibility of carbon-based cesium/formamidinium perovskite solar cells via double antisolvent drippings in adduct approach

High-quality perovskite materials are usually prepared in a non-reactive environment, which increases fabrication costs and poses difficulties in mass production. In this work, the deposition of cesium/formamidinium (CsFA) perovskite under low-cost dry-air conditions was modified to improve both material quality and photovoltaic performance. By using double chlorobenzene drippings in the adduct approach, pinhole-free and smooth CsFA films were achieved. The carbon-based perovskite solar cells (PSCs) using the obtained CsFA films provided an enhanced power conversion efficiency (PCE) with good reproducibility. The main reasons for this achievement are the suppression of charge recombination caused by traps in the perovskite films and the improvement of interface properties. In addition, our proposed method was found to be applicable for reproducible 1 cm × 1 cm solar modules. Our findings open up the possibility for low-cost, simple, and large-scale manufacturing of perovskite-based optoelectronic devices. • A modified CsFA deposition method for dry air conditions was proposed. • By using double antisolvent drippings in the adduct approach, the quality of CsFA films was improved. • The pinhole-free and flat CsFA device achieved an efficiency of 13.12% with good reproducibility. • The introduced method is also applicable for reproducible 1 cm 2 -area PSCs.

Evaluation of Drying Air Conditions for Antiozonant Wax Drying Process in the Spray Drying Tower

The drying technique of Antiozonant Wax (AOW) using drying air in the spray drying tower has a considerable effect on the produced AOW powder. In this study, the drying air flow rate was measured in such a way that AOW can transform into a powder with a size of 800 mesh. The diameter and height of the spray drying tower are 1 and 6 m, respectively. Meanwhile, the AOW flow rate to the spray drying tower varies from 100 kg/hour to 500 kg/hour. The intake AOW temperature was 70 °C and at the outlet was 40 °C, while the drying air temperatures in and out of the spray drying tower were 30 and 55 °C, respectively. From the calculation results, the flow rate of the drying air is directly proportional to the flow rate of the AOW into the spray drying tower but inversely proportional to the speed of the AOW powder down the spray drying tower. In the meantime, the drying period for AOW to become a powder is between 1.033 – 1.279 s, not significantly different. It gives insight into the need to dry air in the spray drying tower configuration so that the findings will conform to the predetermined requirements.

Role of brush-like additives in CO2 adsorbents for the enhancement of amine efficiency

Amine adsorbents have been widely investigated for direct CO2 capture from air. However, the low amine efficiency of the widely-studied amine sorbents is the critical factor to hinder the practical application under dry conditions. Herein, we developed the brush-like cetyltrimethylammonium chloride (CTAC) templating strategy to prepare micro-mesoporous silica nanoparticles (MMSN-X) and TEPA-functionalized adsorbents (MMSN-X/TEPA-Y). The character of samples was investigated by transmission electron microscopy, N2 adsorption-desorption, Fourier transform infrared spectroscopy, thermal gravimetric analyzer and X-ray photoelectron spectroscopy. The adsorbent (MMSN-30/TEPA-50) with appropriate amount of brush-like CTAC exhibited higher CO2 adsorption capacities (3.68 mmol/gadsorbent under simulated dry air conditions) than that of the adsorbents with none or less additives. The kinetic and thermodynamic model were applied to investigate the adsorption rate control factors and adsorption behavior of CO2 adsorbents with brush-like CTAC. Moreover, with the effect of brush-like CTAC, the significant variation of adsorption product (conversion from carbamate (CO2/N = 0.5) to carbamic acid (CO2/N = 1)) was detected by in situ Fourier transform infrared spectroscopy. These results demonstrated that the combination of CO2 and amine was altered in the presence of brush-like CTAC and thereby the amine efficiency was enhanced, which could be expected to be an efficient adsorbent for CO2 from air in practical applications.