Chin-Hsiang Luo

Aerosol penetration properties of an electret filter with submicron aerosols with various operating factors.

This study was undertaken to determine the effects of using an electret filter on aerosol penetration. Various factors, including particle size (0.05 to 0.5 μ m), aerosol charge state (neutral and single charge), face velocity (0.1, 0.3, 0.5 and 1.0 m/s), and relative humidity (RH 30% and RH 70%), were examined to assess their effects on aerosol collection characteristics. The results presented here demonstrate that the electric fields of the electret and discharged filter were −1.53 × 104 and −1.3 × 102 (V/m). The penetration through the electret filter with singly charged aerosol and neutral aerosol ranged from 0.4% to 13% and 14% to 29%, respectively. According to these results, the coulombic capture force was dominant for the smaller aerosol and the dielectrophoretic capture mechanism was considered important for the larger aerosol. The level of penetration through the electret filter increased with increasing face velocity and relative humidity. The temperature did not affect the penetration through the electret. Furthermore, from the regression analysis conducted during the operating conditions of this work, the aerosol charge was shown to exert the greatest influence on aerosol penetration.

Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer

Diesel soot aggregates emitted from a model dynamometer and 11 on-road vehicles were segregated by a micro-orifice uniform deposit impactor (MOUDI). The elemental contents and morphological parameters of the aggregates were then examined by scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), and combined with a fractional Brownian motion (fBm) processor. Two mode-size distributions of aggregates collected from diesel vehicles were confirmed. Mean mass concentration of 339 mg/m3 (dC/dlogdp) existed in the dominant mode (180-320 nm). A relatively high proportion of these aggregates appeared in PM1, accentuating the relevance regarding adverse health effects. Furthermore, the fBm processor directly parameterized the SEM images of fractal like aggregates and successfully quantified surface texture to extract Hurst coefficients (H) of the aggregates. For aggregates from vehicles equipped with a universal cylinder number, the H value was independent of engine operational conditions. A small H value existed in emitted aggregates from vehicles with a large number of cylinders. This study found that aggregate fractal dimension related to H was in the range of 1.641-1.775, which is in agreement with values reported by previous TEM-based experiments. According to EDS analysis, carbon content ranged in a high level of 30%-50% by weight for diesel soot aggregates. The presence of Na and Mg elements in these sampled aggregates indicated the likelihood that some engine enhancers composed of biofuel or surfactants were commonly used in on-road vehicles in Taiwan. In particular, the morphological H combined with carbon content detection can be useful for characterizing chain-like or cluster diesel soot aggregates in the atmosphere.

Screen-Printed Carbon Electrodes Modified with Cobalt Phthalocyanine for Selective Sulfur Detection in Cosmetic Products

Cobalt phthalocyanine (CoPc) films were deposited on the surface of a screen-printed carbon electrode using a simple drop coating method. The cyclic voltammogram of the resulting CoPc modified screen-printed electrode (CoPc/SPE) prepared under optimum conditions shows a well-behaved redox couple due to the (CoI/CoII) system. The CoPc/SPE surface demonstrates excellent electrochemical activity towards the oxidation of sulfur in a 0.01 mol·L−1 NaOH. A linear calibration curve with the detection limit (DL, S/N = 3) of 0.325 mg·L−1 was achieved by CoPc/SPE coupled with flow injection analysis of the sulfur concentration ranging from 4 to 1120 mg·L−1. The precision of the system response was evaluated (3.60% and 3.52% RSD for 12 repeated injections), in the range of 64 and 480 mg·L−1 sulfur. The applicability of the method was successfully demonstrated in a real sample analysis of sulfur in anti-acne creams, and good recovery was obtained. The CoPc/SPE displayed several advantages in sulfur determination including easy fabrication, high stability, and low cost.

Photocatalytic Degradation Mechanism and Kinetics of Caffeine in Aqueous Suspension of Nano-TiO2

This study investigated TiO2 photocatalytic degradation of caffeine, a stimulating drug, in aqueous suspensions of titanium dioxide under a variety of conditions. Pure TiO2 powders were prepared using a modified homogeneous-precipitation process at low temperature (HPPLT) method. The degradation was studied by monitoring the intermediates employing high performance liquid chromatography (HPLC) separation coupled to an atmospheric pressure ionization mass spectrometry (API-MS) system operated under selected ion monitoring (SIM). These results indicate the original concentration of caffeine almost completely degraded within 360 min, and a degradation ratio of more than 50 % appearing within 120 min of irradiation in a pH range of 3—10. The reaction rates for the decomposition of caffeine in water are higher for runs at pH 3 (k = 0.013 min-1) and pH 11 (k = 0.012 min-1). The proposed conversion mechanism of caffeine was used. The caffeine was first oxidized to become dimethyl parabanic acid and further degraded to di(hydroxymethyl) parabanic acid. This study also detected the product from N-demthylation, theophyline.

Photocatalytic degradation of parabens in aquatic environment: Kinetics and degradation pathway

Parabens are p-hydroxybenzoic acid ester compounds widely used as preservatives in foods, cosmetics, toiletries and pharmaceuticals. These compounds exert a weak estrogenic activity as determined by in vitro estrogen receptor assay and in vivo uterotrophic assay. The photocatalytic degradation of parabens (butylparaben and ethylparaben), as a function of pH and initial concentration of parabens, was investigated in the presence of TiO2 photocatalyst (P-25, “Degussa”). Experiments conducted at pH 4 with O2-sparged concentration of 15 mg/L showed that in terms of the photocatalytic efficiency the catalysts were slightly superior to those tested at pH 6-11. The intrinsic reaction rates of 2.08 × 102 and 1.81 × 102 μmol L−1min−1 were estimated, and Langmuir-Hinshelwood model adsorption constants K were calculated as 0.05 and 0.06 L/μmol for butylparaben and ethylparaben, respectively. Ten organic intermediates appeared during the photocatalytic degradation of parabens, and were identified by LC/MS/MS. In addition, a tentative reaction pathway was proposed.

Inactivation efficiency to Bacillus subtilis and Escherichia coli bacterial aerosols of spraying neutral electrolyzed water.

The main objective of this study is to apply neutral electrolyzed water (NEW) spraying to inactivate bioaerosols. We evaluated the inactivation efficiency of NEW applied to inactivate two airborne bacterial Escherichia coli and Bacillus subtilis aerosols inside an environmental-controlled chamber in the study. Generated with electrolyzing 6.15 M sodium chloride brine, the NEW with free available chlorine (FAC) concentration 50, 100, and 200 ppm was pumped with an air pressure of 70 kg/cm2 through nozzle into the chamber to inactive E. coli and B. subtilis aerosols precontaminated air (initial counts of 3 × 104 colony-forming units [CFU]/m3). Bacterial aerosols were collected and cultured from chamber before and after NEW spray. The air exchange rate (ACH, hr−1) of the chamber was set to simulate fresh air ventilating dilution of indoor environment. First-order concentration decaying coefficients (Ka, min−1) of both bacterial aerosols were measured as an index of NEW inactivation efficiency. The result shows that higher FAC concentration of NEW spray caused better inactivation efficiency. The Ka values under ACH 1.0 hr−1 were 0.537 and 0.598 for E. coli of FAC 50 and 100 ppm spraying, respectively. The Ka values of FAC 100 ppm and 200 ppm spraying for B. subtilis were 0.063 and 0.085 under ACH 1.0 hr−1, respectively. The results indicated that NEW spray is likely to be effective in inactivation of bacterial airborne contamination. Moreover, it is observed in the study that the increase of ventilation rate and the use of a larger orifice-size nozzle may facilitate the inactivation efficiency. Implications: Bacterial aerosols have been implicated in deterioration of air quality and occupational health. Effective, safe, and economic control technology is highly demanded, especially for agricultural and food industries. In the study, NEW mist spraying performed effectively in controlling E. coli and B. subtilis modeling bioaerosols contamination. The NEW revealed its potential as an alternative airborne disinfectant worth being discovered for improving the environmental quality in the future.

Quantification of ellagic acid in cosmetic products by using a partially preanodized screen-printed carbon electrode coupled with flow injection analysis

A partially preanodized screen-printed carbon electrode (PSPCE*) coupled with flow injection analysis (FIA) was developed to raise the selectivity of ellagic acid (EA). To confirm the effectiveness of partial preanodization, two pretreated screen-printed carbon electrodes were electrochemically compared. One was a PSPCE* fabricated by potential cycling (-1.0 - +1.0 V vs. Ag/AgCl) to make the electrode surface partially preanodized and the other was a SPCE* fabricated by a high treatment potential (+2.0 V vs. Ag/AgCl). Cyclic voltammograms showed that the catalytic current of EA was observed at both the PSPCE* and SPCE*. No catalytic current of ascorbic acid 2-glucoside (AA2G) and magnesium ascorbyl phosphate (MAP) was observed at the PSPCE*. The PSPCE* selectively detected EA. The factors, which influence the EA response current, have previously been discussed. At the detection limit (0.012 ppm, S/N = 3), the linear calibration plot (R2 = 0.998) was attained for 0.1-50 ppm of EA solutions. A relative standard deviation of 4.37 and 3.90% was conducted for consecutive injections (n = 10) of 1 and 50 ppm EA, respectively. Finally, a practical application of the proposed method was demonstrated by the quantitative analysis of EA in skin whitening creams, and good recovery was obtained.

Nanomechanical Properties of Prepared-TiO2 Films Using Nanoindentation Technique

Nanoindentation was used to measure the hardness and Young’s modulus of prepared-TiO2 films. The thickness and refractive index of the TiO2 films were measured using ellipsometry with a monochromator. Scanning electron microscopy was used to determine the micrography of the TiO2 films. Pure TiO2 films were prepared from sols made by 3 % (w/w) of prepared-TiO2 suspension solution coated onto silicon wafers. After the dip-coating was completed, the coatings were further treated by various procedures, natural air-drying, water-vapor exposure, and calcinations. The prepared-TiO2 films were smooth and free of macro cracking. The grain sizes of these films were uniform and in the range of 50–100 nm and the films were of rutile structure. The prepared-TiO2 coatings exhibited more favorable porosity in water-vapor exposure than those under other conditions. The T-H2SO4 coatings exhibited higher hardness and modulus than those with T-H2O and T-NH4OH coatings after high temperature calcination. The values of hardness and modulus for T-H2SO4 coatings were 11.93 GPa and 226.25 GPa, respectively. Curves of hardness and modulus as a function of depth (0–2200 nm) of the coatings under calcination conditions show a peak at shallow contact depth within 100 nm and then demonstrate being rather constant. The hardness and modulus curve obtained from T-H2SO4 coatings in water-vapor exposure are rather constant.

Degradation of Butylparaben by Ozonation and UV/TiO2 Processes

Butylparaben is widely used as a bactericide and as an antimicrobial agent in the formation of personal care products (PCPs). Owing to a certain estrogenic activity, a possible relationship with breast cancer has been proved by many researchers. The removal efficiency of butylparaben in aqueous solutions was studied using advanced oxidation processes (AOPs). These results indicate that the reaction rates for the ozonation of butylparaben in water are higher under the concentration of ozone 5 mg/L in alkaline condition. The original concentration of butylparaben almost degraded within 50, 30, and 20 min at ozone concentrations of 1, 3, and 5 mg/L, respectively at pH 11 runs. The ozonation imposed butylparaben with a time dependence that appeared to follow pseudo first-order kinetics. The original butylparaben was degraded 50 %, 40%, 35%, and 32% within 24 hr at pH 3, 6, 9, and 11 respectively by UV/TiO2 process in the O2-sparged concentration of 30 mg/L. The rate constants are 0.045, 0.043, 0.025, and 0.020 hr-1 at the butylparaben concentrations of 10.30, 20.60, 30.90, and 41.20 μM, respectively.

Suburban atmospheric visibility sensing by an image degradation processor: model development and field test

This study describes some preliminary results of a new approach which seeks to develop a method by which uneven decay of atmosphere can be described by the fluctuation of a degradation parameter, k, extracted from online recorded images. The proposed processor is a combination of the empirical model for atmospheric non-homogeneity and an image degradation method. Estimation of the other parameter, C ave, derived from k values was an attempt to quantify the blurred level of atmospheric visibility according to the full-scale image computation. The C ave of code A–E images ranged from 0.437 to 0.831, and the related visual range observed by investigators was from 14.1 to 3.0 km, respectively. The standard deviation of C ave reveals that non-homogeneous degradation of blurring atmosphere happens. Low visibility related with a small visual range and a degraded image is companied by a large C ave and inherits high variation from heaving k values. Because of fluctuation and full-scale image representation, C ave is more meaningful and sensitive for atmospheric decay measurement than the prevailing visibility equal to the distance at which the farthest target can be recognized. Finally, a field test was applied to confirm a good correlation between observed visual range and two parameters (k and C ave).