• Journal of Environmental Science International
• /
• v.19 no.9
• /
• pp.1143-1152
• /
• 2010

The purpose of this study is to degradation of Rhodamine B (RhB, dye) and N, N-Dimethyl-4-nitrosoaniline (RNO, indicator of the electro-generation of OH radical) in solution using boron doped diamond (BDD) electrode. The effects of applied current (0.2~1.0 A), electrolyte type (NaCl, KCl, and $Na_2SO_4$) and electrolyte concentration (0.5~3.0 g/L), solution pH (3~11) and air flow rate (0~4 L/min) were evaluated. Experimental results showed that RhB and RNO removal tendencies appeared with the almost similar thing, except of current. Optimum current for RhB degradation was 0.6 A, however, RNO degradations was increased with increase of applied current. The RhB and RNO degradation of Cl type electrolyte were higher than that of the sulfate type. The RhB and RNO degradation were increased with increase of NaCl concentration and optimum NaCl dosage was 2.5 g/L. The RhB and RNO concentrations were not influenced by pH under pH 7. Optimum air flow rate for the oxidants generation and RhB and RNO degradation were 2 L/min. Initial removal rate of electrolysis process was expressed Langmuir - Hinshelwood equation, which is used to express the initial removal rate of UV/$TiO_$2 process.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.11 no.1
• /
• pp.107-112
• /
• 2011

In this study, photocatalytic degradation and mineralization of bisphenol A (BPA), which has been listed as one of endocrine disruptors, were carried out in the CPC system using $Tio_2$ slurry and UVA irradiation. The degradation efficiency has been investigated under the controlled parameters including initial concentration (5, 10, 20 mg/L), dosage of $Tio_2$ (0.1, 0.5, 1.0 g/L), UVA power (0, 80, 120 W) and temperature (0, 20, 30). At 10mg/L of initial concentration, BPA was degraded above 80% after 10min, BPA were degraded 97% and 49% at 20 mg/L and 30 mg/L, respectively. At $Tio_2$ dosage was 0.1 and 0.5 g/L, the degradations of BPA showed similar trend and were about 70% after 1 hr, and the degradation of BPA was above 80% after 30 min at 1 g/L of $Tio_2$ dosage. The increase of degradation seem to be due to the increase in the total surface area, namely number of active sites, available for the photocatalytic reaction as the dosage of photocatalyst increased. When the UVA power was 120 W, BPA was degraded rapidly above 60% after 10min of reaction time. To investigate the effect of temperature, carried out experiment controlled temperature, there were no significant differences depending on the temperature. After 1hr, the degradation of BPA were 46%, 67%, and 69% at 10, 20 and $30^{\circ}C$.

• Clean Technology
• /
• v.13 no.3
• /
• pp.222-227
• /
• 2007

The photocatalytic degradation of livestock wastewater has been investigated over $TiO_2$ photocatalysts irradiated with a ultraviolet (UV) light. The effect of operational parameters, i.e., distance, reaction area, concentration of suspended solids(SS), and column diameter on the degradation of livestock wastewater has been performed in lab-scale. The optimal conditions for livestock wastewater were determined: distance was 3 cm (less than 7 cm), reaction area was $3.6\;m^2$, SS concentration was 40 mg/L (less than 300 mg/L) and column diameter was 5 mm (less than 10 mm). Under the optimal conditions, COD, color and coliform removal efficiencies were approximately 49%, 53% and 100%, respectively. Non-biodegradable COD removal efficiency increased with 57% using by photocatalysis process. Therefore, it is shown that photocatalysis has an effect on degradation of non-biodegradable organic matter.

• Land and Housing Review
• /
• v.13 no.2
• /
• pp.117-123
• /
• 2022

In this study, titanium dioxide photocatalyst was applied to the ventilation system to reduce particulate matter and nitrogen oxides (NOx), which are representative indoor harmful substances. A reaction device capable of installing an ultraviolet lamp was designed and manufactured so that the pollutant decomposition effect of the titanium dioxide photocatalyst identified through previous studies could be applied indoors. The reaction device was used on the indoor ventilation system and applied to the Mock-Up test. As a result of the Mock-up test, the NOx reduction performance according to the change in air volume once per hour and five times per hour was confirmed. As a result, it was confirmed that as the number of ventilation increases, the NOx reduction time decreases proportionally, and the reduction performance increases.

• Economic and Environmental Geology
• /
• v.12 no.2
• /
• pp.79-93
• /
• 1979

Twenty five samples of the scheelite-powellite series from twelve Korean tungsten deposits of various geologic settings were studied mineralogically and geochemically. Variations in the trace-element contents of the scheelite minerals are considered in relation to geologic settings and mineralogic properties. Scheelites from ore deposits developed in similar geologic settings and under similar physicochemical conditions are characterized by specific combinations of trace elements.

• Current Photovoltaic Research
• /
• v.10 no.1
• /
• pp.16-22
• /
• 2022

The long-term stability of PSCs against visual and UV light, moisture, electrical bias and high temperature is an important issue for commercialization. In particular, since the operation temperature of solar cell can rise above 85℃, a study on thermal stability is required. In this study, the cause of thermal-induced degradation of PSCs was investigated using the SCAPS-1D simulation tool. First, PSCs of TiO₂/CH₃NH₃PbI₃/Spiro-OMeTAD/Au structure were exposed to a constant temperature of 85℃ to observe changes in conversion efficiency and quantum efficiency. Because the EQE reduction above 500 nm was remarkable, we simulated PSCs performance as a function of lifetime, doping density of perovskite and spiro-OMeTAD. Consequently, the main cause of thermal-induced degradation is considered to be the change in the perovskite doping concentration and lifetime due to ion migration of perovskite.

• Korean Journal of Environmental Agriculture
• /
• v.23 no.2
• /
• pp.85-91
• /
• 2004

The objective of this study is to determine the optimum conditions of operational parameters using factorial design for phenol degradation in photocatalytic oxidation reactors. Factorial design is widely used to select the dominant factors and their ranges in experiments involving several factors where it is necessary to study the effect of factors on a response. The effects of initial concentration of phenol, intensity of UV light and surface area of catalyst on phenol degradation were investigated. Two levels were considered in this study so that the experiment was a $2^3$ factorial design with three replicates. The experimental results show that an increase in initial concentration of phenol from 5 to 50 mg/L intensity of UV light from 5,000 to $20,000\;{\mu}W/cm^2$, and surface area of catalyst from 740 to $2,105\;cm^2$ enhanced the phenol degradation rate by an average of 1.86, 1.79, and 2.10 mg/L hr, respectively. Interaction effects do not appear to be as large on the phenol degradation rate as the main effects of single factors. The optimum working condition for photocatalytic oxidation reactors, despite the higher three factors the better removal rate, is the highest surface area or catalyst.