Surface Area For Deposition Research Articles

Forest cover influences fish mercury concentrations in national parks of the western U.S.

The global prevalence of mercury (Hg) contamination and its complex biogeochemical cycling has resulted in elevated Hg concentrations in biota in remote and pristine environments. However, there is uncertainty in the relative importance of Hg deposition and landscape factors that control Hg cycling and bioaccumulation. To address this, we measured total mercury (THg) concentrations in 1344 fish across 60 subalpine lakes from 12 national parks (NPs). These parks represent three distinct high-elevation regions across the western U.S.: Cascades and Olympic Peninsula, Sierra Nevada and Great Basin, and Rocky Mountains. Within these regions, three NPs (Mount Rainier, Yosemite, and Rocky Mountain) were intensively studied representatives of each region. This study aimed to (1) assess the magnitude of mercury contamination in a collection of remote, small catchment lakes; (2) quantify the variability of fish THg concentrations among and within parks; and (3) test the relative importance of Hg inputs in comparison to landscape characteristics on lake-specific fish THg concentrations. The spatial variability in fish THg concentrations was 2.6-fold higher than variation in deposition to watersheds, suggesting that factors other than Hg delivery are important determinants of Hg accumulation in these environments. Spatially, fish THg concentrations (ng/g ww ± standard error) were lower in the Rockies (46.2 ± 5.0) and Sierra (56.5 ± 5.8) compared to the Cascades (67.8 ± 6.1). Additionally, fish THg concentrations increased with increasing conifer forest cover (Intensive parks: P < 0.0001, R2 = 0.43; All parks: P = 0.0001, R2 = 0.23) but were not correlated with wet Hg deposition across the catchment. These findings suggest that forest composition is likely an important aspect of Hg delivery to lake food webs, and although the mechanisms are unclear, could be tied to some combination of forest influences on catchment organic carbon and increased surface area for dry Hg deposition.

Laser-directed energy deposition to achieve high-aspect-ratio micropillar arrays for 3D interdigitated microsupercapacitors

Microsupercapacitors (MSCs) are promising micropower sources. High-performance active electrode materials have been extensively developed for them because MSC capacitances are critically determined by the electrochemical features of active materials. However, the limited two-dimensional spaces of conventional MSCs pose a substantial challenge in rational electrode design for fully exploiting the active material performances. Therefore, the development of three-dimensional (3D) MSCs has garnered considerable research interest. Herein, 3D interdigitated metal current collectors for 3D MSCs are successfully microfabricated using laser-directed energy deposition (LDED) of Inconel 625 powder. High-aspect-ratio (∼14) micropillars (diameter, 110 µm) are printed on a stainless-steel substrate, thus significantly increasing the surface area for active material deposition. Finally, reduced graphene oxide and polyaniline are electrodeposited as active materials on this 3D platform to boost MSC capacitance. The resulting 3D MSC exhibits substantially high electrochemical performance, with an energy and power densities of 18.76 μWh/cm2 and 0.395 mW/cm2, respectively, and high areal capacitances of 120.7–216.2 mF/cm2 at 1 mA/cm2 depending on the thickness of polyaniline. These inspiring results not only suggest a new route for using high-throughput LDED for high-performance MSCs but also suggest a new 3D fabrication strategy for next-generation micropower sources.

Experimental design using the Taguchi method for the development of conductive textiles used in flexible thermoelectric generators

This paper presents several aspects of the robust experimental design methodology using the Taguchi method to develop electrically conductive textiles. These conductive textiles will be used to make thermoelectric generators based on the Seebeck effect. Since the experimental development involves the use of the magnetron sputtering method with more than three variables, the Taguchi method was selected to observe how different parameters (5 independent variables such as argon flow, power, pressure, deposition surface area and metal type used for solid targets) influence the mean and variance of the process performance defined by the thickness of the metal film deposited (dependent variable). In the experimental design framework, the analysis using the Taguchi method, followed by optimisation, helped select the optimal experiments from the set of possible experiments. This methodology reduced the number of experiments by 21–42% and minimised resource consumption (e.g., metal targets, argon, energy).

Analysis of Experimental Measurements of Particulate Matter (PM) and Lung Deposition Surface Area (LDSA) in Operational Faces of an Oil Shale Underground Mine

Particulate matter (PM) in the context of underground mining results from various operations such as rock drilling and blasting, ore loading, hauling, crushing, dumping, and from diesel exhaust gases as well. These operations result in the formation of fine particles that can accumulate in the lungs of mineworkers. The lung deposited surface area (LDSA) concentration is a variant solution to evaluate potential health impacts. The aim of this study is to analyse PM and LDSA concentrations in the operational workings of the oil shale underground mine. Experimental measurements were carried out by a direct-reading real-time PM monitor, Dusttrak DRX, and a multimetric fine particle detector, Naneous Partector 2, during the loading and dumping processes using the diesel engine loader. Consequently, the analysis was conducted on PM, LDSA, particle surface area concentration (SA), average particle diameter (d), particle number concentration (PNC), and particle mass (PM0.3), producing a few valuable correlation factors. Averaged LDSA was around 1433 μm2/cm3 and reached maximum peaks of 2140 μm2/cm3 during the loading, which was mostly related to diesel exhaust emissions, and within the dumping 730 μm2/cm3 and 1840 μm2/cm3, respectively. At the same time, average PM1 was about 300 μg/ m3 during the loading, but within the dumping peaks, it reached up to 10,900 μg/ m3. During the loading phase, particle diameter ranged from 30 to 90 nm, while during the dumping phase peaks, it varied from 90 to 160 nm. On this basis, a relationship between PNC and particle diameter has been produced to demonstrate an approximate split between diesel particulate matter (DPM) and oil shale dust diameters. This study offers important data on PM and LDSA concentration that can be used for estimating potential exposure to miners at various working operations in the oil shale underground mines, and will be used for air quality control in accordance with establishing toxic aerosol health effects.

Three-dimensional copper current collector as an anode for rechargeable anode-less lithium-ion batteries

The formation of dendrites presents a significant challenge that hampers the performance of lithium metal batteries, leading to rapid capacity degradation, low coulombic efficiency, and potential short circuits. In this regard we have engineered a rechargeable lithium metal battery without a conventional anode – lithium, employing commercially available LiNi1/3Co1/3Mn1/3O2 as a cathode and enhanced three-dimensional copper foam current collector as an anode. The modification of the three-dimensional copper foam current collector with gold effectively reduced the local current density while providing a substantial surface area for lithium deposition. Moreover, our approach incorporates a blend of salts, namely lithium bis(trifluoromethanesulfonyl)imide and lithium difluoro(oxalato)borat, resulting in an impressive reversible capacity of 100 mAh g−1 with an outstanding coulombic efficiency of 99.9% after 50 cycles. These discoveries hold particular significance in the advancement of next-generation energy storage systems characterized by high energy density and immunity to dendrite formation.

Photodeposition synthesis of hollow g-C3N4/Ag nanotubes with high oxidation properties to enhance visible-light photocatalytic performance

A hollow Ag-deposited g-C3N4 nanotube (CNNT/Ag) with high oxidation properties was synthesized using a simple photodeposition method. The g-C3N4 nanotubes provided abundant active sites and a large specific surface area for effective deposition of Ag nanoparticles. The Ag NPs expanded the light absorption range of g-C3N4 through surface plasmon resonance (SPR) effects and acted as an electron acceptor, effectively inhibiting the recombination of photogenerated carriers, thereby improving the charge separation efficiency. The CNNT/Ag composites exhibited excellent photocatalytic performance in the visible light degradation of rhodamine B and tetracycline, 6.42 and 2.16 times higher than pure g-C3N4, respectively. The increased photocatalytic activity of CNNT/Ag composites was attributed to the synergistic electron transfer interface between CNNT and Ag NPs, promoting the migration efficiency of photo-generated carriers. This work presented a promising strategy for constructing effective photocatalysts for degrading organic pollutants using morphology optimization and SPR effects on noble metal surfaces.

Treatment of paraffin deposition behavior in gas-condensate wells with chemical inhibitors

As deep gas-condensate reservoirs are explored, the problem of paraffin deposition is becoming more prominent. Therefore, this paper collects condensate samples from representative paraffin deposition gas-condensate wells and analyzes basic physical properties. The cold plate deposition device is employed to study paraffin deposition behavior under well conditions and to divide the critical regions for paraffin deposition in gas-condensate wells. The experimental apparatus, such as the crude oil dynamic paraffin deposition rate tester, is utilized to investigate the preventive effect of paraffin dispersants and paraffin crystal modifier. The results show that there is significant phase change behavior in gas-condensate wells and gas phase is dominant form, but there is also phase evolution. It can be identified from the experiments that paraffin deposition is mainly located in the 1000 ~ 1500 m region, and a paraffin deposition identification chart has been established. The maximum deposition rate could reach 15.50 mm/year, which matched the temperature and pressure conditions of 45 ℃ and 70 MPa. The preventive effect of paraffin crystal modifiers greatly exceeds that of paraffin dispersants, with paraffin prevention rates of 85–95% at the optimal concentrations of 0.25–0.50 wt.%. The dissolving paraffin rate can reach 0.0169 g/min. It decreases the paraffin appearance temperature approximately 40% and significantly changes the paraffin crystal morphology. Increased deposition surface area of the cold plate structural design describes the paraffin deposition. This diagram facilitates the reliable identification of paraffin deposition areas and the deposition rates in the wellbore during production. The optimum amounts of BZ and PI paraffin inhibitors are quantified. This study provides a comprehensive understanding of the paraffin deposition behavior, and scientific basis and guidance for the selection of paraffin inhibitors in gas-condensate wells.

Negatively Charged Hydrophobic Carbon Nano-Onion Interfacial Layer Enabling High-Rate and Ultralong-Life Zn-Based Energy Storage.

Zn-based electrochemical energy storage (EES) systems are attracting more attention, whereas their large-scale application is restricted by the dendrite and parasitic reaction-caused unstable Zn anodes. Herein, a negatively charged hydrophobic carbon nano-onion (CNO) interfacial layer is proposed to realize ultrastable and high-rate Zn anodes, enabling high-performance Zn-based EES. For the CNO interfacial layer, its hydrophobicity not only blocks active water but also reduces the Zn2+ desolvation barrier, and meanwhile, the negatively-charged CNO nanoparticles adsorb Zn2+ and repel SO4 2- to homogenize Zn2+ flux, accelerate Zn2+ desolvation and suppress the self-corrosion of Zn anodes. Besides, the conductive CNO interfacial layer increases the surface area for the Zn deposition to reduce local current density. Consequently, under the modulation of the CNO interfacial layer, Zn plating/stripping exhibits impressive reversibility with an average Coulombic efficiency of 99.4% over 800 cycles, and Zn anodes present significantly enhanced electrochemical stability and rate performance, whose operation lifetime exceeds 2000h at 1mAcm-2 and 350h even at 10mAcm-2 . Moreover, high-rate and ultralong-life Zn-ion hybrid supercapacitors are achieved with the CNO interfacial layer-modulated Zn anode and activated CNO cathode. This work provides new thinking in regulating the Zn deposition interface to realize high-performance Zn-based EES.

Polydopamine layer-coated porous Ni foam host for Li metal batteries under lean electrolytic cell operations

Li metal batteries (LMBs) face challenges such as volume change, dendrite growth, electrolyte depletion, and safety concerns. To address these issues, employing three-dimensional (3D) porous substrates and artificial solid electrolyte interphase (SEI) layers has been proposed for uniform Li ion distribution and interfacial stability. Here, we present a dendrite-free Li metal anode for LMBs operating under lean electrolytic conditions. This is achieved by synergistically combining oxidized 3D Ni foam as a conductive substrate and polydopamine (PDA) coating as an artificial SEI layer. The oxidized 3D Ni foam provides abundant lithiophilic sites with a large surface area for Li-ion deposition, effectively mitigating volume expansion due to its high elastic modulus. The PDA artificial SEI layer acts as a protective barrier, enhancing electrolyte wettability and preventing direct contact with Li metal surface. The PDA-coated oxidized 3D Ni foam demonstrates stabilized operation in full cell even with a small amount of electrolyte, achieving a Coulombic efficiency of approximately 99 % over 150 cycles and an exceptionally low voltage hysteresis (∼10 mV) for over 400 h. Our approach utilizing the highly conductive 3D foam substrate and the passivating PDA SEI layer enables outstanding electrochemical performance, opening avenues for future research on commercially viable LMBs.

An insight into wax/asphaltene deposition behavior in the wellbore regions of gas condensate reservoirs

Wax/asphaltene deposition has been an important problem in the gas condensate reservoirs development. The cold plate device is designed to reveal the effect of operating conditions on the wax/asphaltene deposition behavior. The characteristic of wax/asphaltene deposition with well conditions is determined. The results show that when the temperature difference was considered, the growth rate of wax deposition thickness in the operation period was that stabilizing first, rising again, and then slowing down. However, the temperature and hydrogen bonding interaction significantly affects the asphaltene deposition process. The asphaltene deposition rate was stable at the beginning period of operation, then increased significantly, and decreased gradually after reaching the peak value of 21.61 g/cm2·h. An identification diagram of the wellbore deposition location is established. Increased deposition surface area of the cold plate structural design ensures qualitative and quantitative characterization of wax/asphaltene deposition traits. The real well fluids components were employed in the experiments to obtain critical conditions for wax/asphaltene deposition which approximated actual production conditions. This diagram facilitates the reliable identification of wax/asphaltene removal areas in the wellbore during production. This study provides a comprehensive understanding of the wax/asphaltene deposition behavior, which helps the gas condensate well operation safety and efficiency.

YSZ/Ni double‐shell powder via surface electroless deposition tuned by an active kinetic model

AbstractYttria‐stabilized zirconia (YSZ) powder with surface Ni plating has promising application in many fields due to its large surface area, low density and excellent high temperature performance. In this study, YSZ/Ni double‐shell powder was fabricated via electroless deposition method, and an active surface kinetic model was developed to tune the surface area and nuclei loading quantitatively. A novel concept, active surface ratio (ASR, the ratio of active deposition surface area to projected area of ceramic powder), is proposed to intrinsically correlate deposition rate with nuclei topology on ceramic surface. The intrinsic relationship between microstructure of metallized ceramic surface and deposition duration was clarified. The active surface kinetic model reveals the correlation between the ASR and instantaneous deposition rate and provides necessary theoretical basis for effective control of ceramic surface modification process by electroless deposition.

Au nanoparticle sensitized blue TiO2 nanorod arrays for efficient Gatifloxacin photodegradation.

TiO2 nanorod arrays have been widely used in photocatalytic processes, but their poor visible light absorption and rapid carrier recombination limit their application. Both introducing oxygen vacancies and using precious metals as surface plasmon resonance (SPR) stimulators are effective strategies to enhance their photocatalytic performance. Herein, Au nanoparticle sensitized blue TiO2 nanorod arrays (Au/B-TiO2) were successfully fabricated for efficient Gatifloxacin photodegradation. The degradation efficiency of Gatifloxacin was up to 95.0%. Moreover, the corresponding reaction rate constant (Ka) was up to 0.02007 min-1. Additionally, it was suggested that Gatifloxacin could be subject to three different degradation pathways. The superior catalytic activity of Au/B-TiO2 is a result of the combined effect of the two components. Firstly, TiO2 nanorod arrays provide a larger surface area for Au deposition and act as efficient transfer channels. Secondly, the presence of oxygen vacancies in blue TiO2 nanorod arrays enhances the catalytic activity. Thirdly, Au acts as a SPR activator, providing a large number of high-energy electrons in the photocatalysis process. Lastly, the improved light capture capabilities are essential for efficient removal of Gatifloxacin. This work provides a new approach for the construction of a high-performance heterojunction photocatalyst in advanced oxidation processes.

(Keynote) Understanding How Porous Transport Layer Properties and Electrode Structure Affect the OER Electrode in an Anion Exchange Membrane Electrolyzer

Water electrolysis to produce hydrogen is gaining significant attention due to a significant decrease in the cost of renewable energy sources such as solar, wind, and tidal etc. Among the existing water electrolysis technologies, anion exchange membrane water electrolysis has recently emerged due to its potential advantages over proton exchange membrane electrolysis and traditional alkaline electrolysis. Anion exchange membrane electrolyzers (AEMELs) can allow for the use of PGM-free electrocatalysts and low-cost component materials due to its less corrosive alkaline environment while also enabling electrochemical H2 compression.In an operating AEMEL, the anode electrode – where the oxygen evolution reaction (OER) occurs – controls a majority of the cell’s behavior. Recent work has shown that the most statistically relevant variables controlling the cell behavior are the catalyst choice, electrode structure and the properties of the porous transport layer (PTL). While the catalyst has been widely studied in the literature, significantly less attention has been paid to the catalyst layer design and the role of the PTL in dictating performance. The PTL is one of the most important components in AEM electrolyzer as it facilitates (i) water transport from the pores of the PTL through catalyst layer to the membrane towards hydrogen evolution reaction (HER) electrode, (ii) electron transport from the grains of the PTL through the catalyst material to the reaction sites in the catalyst layer, (iii) hydroxide transport from membrane to the reaction sites in the catalyst layer, and (iv) oxygen bubble removal from the reaction sites in the catalyst layer to the pores of the PTL.In this study, various PTLs with different properties (e.g. material, fabrication methods, features size and thickness) were used to support the catalyst layer in operating AEMELs. It was found that higher porosity facilitates multiphase (O2, H2O, OH-) transport, however, catalyst layer adhesion deceases, resulting in higher contact resistance increasing cell overpotentials. It was also found that nickel based PTLs perform relatively better than stainless steel. Moreover, fiber felts offer slightly lower overpotentials compared to sintered structures likely offering enhanced surface area for catalyst deposition and access to the active sites. Furthermore, an increase in thickness did not affect transient voltage response, though it had a negative effect on durability – likely due to low permeability, O2 blocking the pathways while increasing overall cell resistance. The experimental findings presented here would provide important insights for development of PTL materials and structures for efficient and low-cost water electrolysis.

A novel fluorescent sensor based on a magnetic covalent organic framework-supported, carbon dot-embedded molecularly imprinted composite for the specific optosensing of bisphenol A in foods

An efficient one-pot strategy for the synthesis of a bisphenol A (BPA) fluorescent sensor based on a magnetic covalent organic framework-supported, carbon dot-embedded molecularly imprinted composite (named MCOF@CD@MIP) is reported for the first time in this work. Herein, MCOFs were prepared via the simple in-situ growth of COF crystals on Fe3O4 nanoparticles and acted as supports to provide a large surface area for CD-embedded MIP layer deposition through a room temperature sol-gel molecular imprinting process. The fabricated MCOF@CD@MIP integrated the useful magnetic properties of Fe3O4, the signal transduction function of CDs, the signal amplification effect derived from the COFs and MIP, and the specific recognition behavior of MIP toward template molecule BPA. Based on the fluorescence quenching behavior of BPA for the MCOF@CD@MIP, a highly sensitive and selective fluorescent MCOF@CD@MIP sensor was developed over the concentration range of 25–3000 μg L-1 with a low detection limit (12 μg L-1). Furthermore, the MCOF@CD@MIP sensor was employed to detect BPA in canned goods and boxed drinks with satisfactory results, which agreed well with those obtained by the traditional high performance liquid chromatography (HPLC) method, demonstrating the good reliability, accuracy and practicality of our constructed sensor.

Deployment of a mobile platform to characterize spatial and temporal variation of on-road fine particles in an urban area

Traffic-related air pollutants (TRAPs) pose a serious health hazard for residents and commuters in urban areas. In this study, a real-time mobile monitoring system was deployed in Taipei, a typical East Asian city with an overlap of high population density, traffic, and special structures (e.g., viaducts), to capture the on-road TRAPs at different times of the day. In general, black carbon, ultrafine particles (UFPs), CO concentrations, and lung deposition surface area (LDSA) were positively correlated with traffic flow, and for PM2.5, a more independent fluctuating concentration was observed. During rush-hour periods, the mean concentrations of UFPs, PM2.5, and LDSA were 6.12 × 104 ± 3.83 × 104 cm−3, 23 ± 8 μg/m3, and 2.29 × 102 ± 1.20 × 102 μm2/cm3, respectively. Additionally, the UFP number concentration and LDSA were two times higher along the high-traffic commuting route than along the lower traffic route. Pollutants tended to accumulate at sites near viaducts and high buildings and were significantly influenced by vehicle composition. In this study, the ratio of LDSA to total particle surface area concentration was used as an indicator of the degree of particle irregularity, which was directly related to aging during transport.

Ligand removal of Au25 nanoclusters by thermal and electrochemical treatments for selective CO2 electroreduction to CO.

Undercoordinated metal nanoclusters have shown great promise for various catalytic applications. However, their activity is often limited by the covalently bonded ligands, which could block the active surface sites. Here, we investigate the ligand removal process for Au25 nanoclusters using both thermal and electrochemical treatments, as well as its impact on the electroreduction of CO2 to CO. The Au25 nanoclusters are synthesized with 2-phenylethanethiol as the capping agent and anchored on sulfur-doped graphene. The thiolate ligands can be readily removed under either thermal annealing at ≥180°C or electrochemical biasing at ≤-0.5V vs reversible hydrogen electrode, as evidenced by the Cu underpotential deposition surface area measurement, x-ray photoelectron spectroscopy, and extended x-ray absorption fine structure spectroscopy. However, these ligand-removing treatments also trigger the structural evolution of Au25 nanoclusters concomitantly. The thermally and electrochemically treated Au25 nanoclusters show enhanced activity and selectivity for the electrochemical CO2-to-CO conversion than their pristine counterpart, which is attributed to the exposure of undercoordinated Au sites on the surface after ligand removal. This work provides facile strategies to strip away the staple ligands from metal nanoclusters and highlights its importance in promoting the catalytic performances.

Nanoporous Gold‐Based Materials for Electrochemical Energy Storage and Conversion

Herein, the promising world of nanoporous gold (NPG) as an electrode material for energy storage and conversion is reviewed. NPG has excellent conductivity and a porous structure, providing a huge active surface area for deposition of transition metal atoms and electrochemically active materials. Moreover, NPG materials display high intrinsic activity because of their crystallographic structural defects to catalyze hosts of electrochemical reactions, considered pertinent in clean energy technologies. Therefore, taking into account their superior specific and mass activity, they provide a versatile platform for developing high‐performance catalysts for oxidation and reduction reactions, supercapacitors, and battery‐type electrode materials for the assembly of high density electric energy storage devices. Initially, a full overview of the strategies used to build NPG structures and incorporate other metallic elements in the pore walls is presented. Afterward, the water‐splitting parameters and performance of NPG catalysts for hydrogen generation are reviewed. Next, the possibility of using such porous materials as fuel cell electrodes is discussed. In short, the most recent advancements in the field paving the way for the preparation of advanced electrode materials meeting the most stringent requirements are reviewed, demonstrating the bright perspectives for innovation in the key area of energy conversion and storage.

Response of the Cardiac Autonomic Control to Exposure to Nanoparticles and Noise: A Cross-Sectional Study of Airport Ground Staff.

Airport activity causes the emission of particulate matter and noise, two environmental contaminants and potential health hazards, particularly for the personnel operating nearby taxiways. We explored the association between exposure to fine/ultrafine particles (UFPs) and noise with heart rate variability (HRV), an early indicator of cardiovascular autonomic response, among a sample of airport ground staff. Between May and June 2018, thirty-four male operators (mean age = 43 years and SD = 6.7) underwent personal monitoring of exposure to nanoparticles and noise, and HRV during their work activity. We conducted univariate and multivariate analysis to test the effect of UFP and noise exposure HRV. Total Lung Deposition Surface Area (LDSA) was significantly associated with a decrease in HRV Total Power and Triangular index (β = −0.038 p = 0.016 and β = −7.8 × 10−5, p = 0.042, respectively). Noise peak level showed an opposite effect, which was significant for Total Power (β = 153.03, p = 0.027), and for Triangular index (β = 0.362, p = 0.035). Further investigation is warranted to clarify the effect of the concurrent exposure to UFPs and noise on early changes of cardiac autonomic regulation.

Photocatalytic degradation of methylene blue dye on reticulated vitreous carbon decorated with electrophoretically deposited TiO2 nanotubes

Titanate nanotubes (TiNT) were deposited over the surface of 100 pores per inch (ppi) reticulated vitreous carbon (RVC) by anodic electrophoresis at a cell voltage of 15 V, in an undivided cell, from an ethanol/water suspension containing TiNT coated with tetrabutylammonium hydroxide (TBAOH) surfactant. Scanning electron microscopy showed the open cell porous structure of TiNT/RVC coated by a uniform ca. 30 μm thick layer of TiNT. Calcination at 450 °C for 2 h in air improved the photocatalytic properties. The material was used as photocatalyst for the decolourisation of methylene blue (MB) dye. The 98% volumetric porosity of the RVC substrate provided good reactant access and large surface area for deposition of TiNT. The calcined TiNT/RVC substrate achieved a 91% dye degradation after 20 min, which was higher than uncoated, acid treated RVC and non-calcined TiNT/RVC substrate. The MB decolourisation improved at an increased thickness of 3D TiNT/RVC catalyst although the improvement was limited to 4 mm on 100 ppi RVC due to limited UV penetration.

Effect of water microdroplet size on the removal of indoor particulate matter

The effective removal of indoor particulate matter (PM) has received considerable attention due to the harmful effects of airborne PM on human health. Although various techniques have been introduced to remove indoor PM, no impeccable method has been established. In this study, we proposed the use of microscale water droplets produced by the ultrasonic module of a commercial household ultrasonic humidifier (UH) for effective PM removal. Water droplet size was regulated using micropinholes. The effect of water microdroplet size on the removal of indoor PM was experimentally investigated. Normalized PM concentration, PM removal efficiency and PM deposition constant were assessed by analyzing the measured temporal variations in PM concentration inside a test chamber. The PM deposition constants measured in this study were compared with those of other previous studies. Deposition events were quantitatively visualized by using a high-speed camera attached with a long-distance microscope. The increase in the deposition rate of surface area and the PM collection ratio were analyzed using digital image processing to examine the interactions between PM particles and water microdroplets with different droplet sizes. As a result, the removal efficiency of PM2.5 particles reaches up to 56.2% when water droplets of d = 2 μm are used. The PM10 removal efficiency is also increased by 73.9% within the initial 30 min. The deposition constant for the smallest water droplets of d = 2 μm is drastically increased. In addition, the increasing rate of the deposition surface area is exponentially increased, as the size of water droplets decreases. The small microscale water droplets generated by a commercial UH attached with a micropinhole are found to be effective for the removal of indoor PM.