• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.45-50
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• 2023

Microfluidic preconcentration technologies, which collect or extract low-abundance analytes in a specific location, have been spotlighted in various applications such as medical and bio-engineering. Here, we conducted extensive studies on the variables to be considered when concentrating target samples based on electrophoresis in an electromembrane system utilizing an ion exchange membrane. Using negatively charged Alexa Fluor 488 and positively charged Rhodamine 6G as fluorescent dyes, we examined the effects of flow velocity of the main channel, channel electrolyte concentration, and applied voltage on sample preconcentration. As a result, it was found that the preconcentration of the target sample occurs much better when the flow velocity is slow and the concentration of the main channel containing the sample is high, given that the channel concentration ratio (main and buffer) is constant. In addition, based on the experimental data acquired in this study, the electrophoretic mobility values of Alexa Fluor 488 and Rhodamine 6G were experimentally calculated and compared.

• Journal of Environmental Health Sciences
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• v.33 no.2 s.95
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• pp.150-157
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• 2007

The chemical and photochemical decolorization of Rhodamine B (RhB) in water has been carried out by Fenton, Fenton-like and photo-Fenton-like process. The effect of applied $H_2O_2,\;Fe^{2+}$ dosage (Fenton process), $H_2O_2,\;Fe^{\circ}$ dosage (Fenton-like and photo-Fenton-like process), UV light power (photo-Fenton-like process) pH (all processes) have been studied. The results obtained showed that more than 98% of color removal was obtained for the RhB solutions in every process. However, Fenton-like process was not suitable for the color removal of RhB because Fenton-like process was required much more reagents than Fenton and photo-Fenton-like process. The Fenton and photo-Fenton-like process showed similar reagents need. Optimum pH for three processes in this study is about pH 3. The relative order of sensitivity for pH of each process was: Fenton-like > photo-Fenton-like > Fenton.

• Korean Journal of Materials Research
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• v.30 no.6
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• pp.279-284
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• 2020

In this work, a carbon-doped carbon nitride photocatalyst is successfully synthesized through a simple centrifugal spinning method after heat treatment. The morphology and properties of the prepared photo catalyst are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectrophotometer (UV-vis), and specific surface area. The results show that the band gap of the prepared sample, g-CN-10 is 2.1 eV, is significantly lower than that of pure carbon nitride, 2.7 eV. As the amount of cotton candy increased, the absorption capacity of the prepared catalyst for visible light is significantly enhanced. In addition, the degradation efficiency of Rhodamine B (RhB) by sample g-CN-10 is 98.8 % over 2 h, which is twice that value of pure carbon nitride. The enhancement of photocatalytic ability is attributed to the increase of specific surface area after the carbon doping modifies carbon nitride. A possible photocatalytic degradation mechanism of carbon-doped carbon nitride is also suggested.

• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.195-199
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• 1993

The output energy of Rh-6G dye laser was enhanced by the energy transfer in the mixture of Rh-6G and C-545. The laser was pumped by coaxial flashlamp filled argon gas. The optimum concentration of Rh-6G was $10_-4mol/l$ without mixing. The output energy was enhanced about 70 % at 0.4 % C-545 mixture with respect to the concentration of Rh-6G. The peak output power and the output energy were 27 kW and 50 mJ at the pumping energy of 346 J.

• Journal of Korean Society on Water Environment
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• v.23 no.3
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• pp.377-384
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• 2007

This study has carried out a performance of dimensionally stable anode for the purpose of decolorization of Rhodamine B (RhB) in water. Seven kinds of 1, 2 and 3 component electrodes were prepared by plating and thermal deposition, which were coated by the oxides of Pt, Ru, Ir, Sn-Sb, Ir-Sn-Sb, Ru-Sn-Sb and Ru-Sn-Ti on Ti metal surface, respectively. Performance for RhB decolorization of the seven electrodes lay in: Ru-Sn-Ti/Ti ${\fallingdotseq}$ Ru-Sn-Sb/Ti > Ir-Sn-Sb/Ti > Sn-Sb/Ti > Ru/Ti > Ir/Ti > Pt/Ti. The effects of electrode area and distance, electrolyte type and concentration, current density and pH were investigated on the decolorization of RhB using Ru-Sn-Ti/Ti electrode. Decolorization of RhB was not influenced by electrode area and distance largely, however wattage was influenced by them. NaCl was superior to the decolorization of RhB than $Na_2SO_4$. Optimum NaCl dosage and current density were 0.5 g/L and $0.183A/cm^2$, respectively. The pH effect of decolorization of RhB was not significant within the range of 3-7.

• Journal of Environmental Health Sciences
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• v.30 no.5 s.81
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• pp.358-365
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• 2004

The photocatalytic oxidation of Rhodamine B(RhB) was studied using photocatalytic reactor filled with module of quartz tube. Module of quartz tube consisted of small quartz tube (inner diameter, 1.5 mm; outer diameter, 3 mm) bundle coated with powder $TiO_2$ and uncoated large quartz tube (inner diameter, 20 mm; outer diameter, 22 mm). Two 30 W germicidal lamp was used as the light source and the reactor volume was 0.5 l. The effects of parameters such as the coating materials and numbers, initial concentration, $H_{2}O_2$ dose and metal deposition (Ag, Pt and Fe) and simultaneous application of $H_{2}O_2$ and metal deposition. The results showed that the initial reaction constant of quartz module coated with powder $TiO_2$ was higher 1.4 time than that of the $TiO_2$ sol and optimum coating number is twice. In order to increase reaction rate, simultaneous application of photocatalytic and photo-fenton reaction using Fe coating and dose $H_{2}O_2$ dose increased reaction rate largely.

• Journal of Environmental Science International
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• v.18 no.6
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• pp.667-674
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• 2009

This study has carried out to evaluate the effect of NaCI as electrolyte of single (electrolysis and UV process) and complex (electrolysis/UV) processes for the purpose of removal and mineralization of Rhodamine B (RhB) dye in water. It also evaluated the synergetic effect on the combination of electrolysis and UV process. The experimental results showed that RhB removal of UV process was decreased with increase of NaCl, while RhB removal of electrolysis and electrolysis/UV process was increased with increase of NaCI. The decolorization rate of the RhB solution in every process was more rapid than the mineralization rate identified by COD removal. The latter took longer time for further oxidation. Absorption spectra of an aqueous solution containing RhB showed a continued diminution of the RhB concentration in the bulk solution: concomitantly, no new absorption peaks appeared. This confirmed the decolorization of RhB, i.e., the breakup of the chromophores. It was observed that RhB removal in electrolysis/UV process is similar to the sum of the UV and electrolysis. However, it was found that the COD of RhB could be degraded more efficiently by the electrolysis/UV process than the sum of the two individual process. A synergetic effect was demonstrated in electrolysis/UV process.

• Environmental Engineering Research
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• v.20 no.4
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• pp.329-335
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• 2015

The effects of ion-doping on $TiO_2$ nanotubes were investigated to obtain the optimal catalyst for the effective decomposition of Rhodamine B (RB) through UV photocatalytic oxidation process. Changing the calcination temperature, which changed the weight fractions of the anatase phase, the average crystallite sizes, the BET surface area, and the energy band gap of the catalyst, affected the photocatalytic activity of the catalyst. The ionic radius, valence state, and configuration of the dopant also affected the photocatalytic activity. The photocatalytic activities of the catalysts on RB removal increased when $Ag^+$, $Al^{3+}$ and $Zn^{2+}$ were doped into the $TiO_2$ nanotubes, whereas such activities decreased as a result of $Mn^{2+}$ or $Ni^{2+}$ doping. In the presence of $Zn^{2+}$-doped $TiO_2$ nanotubes calcined at $550^{\circ}C$, the removal efficiency of RB within 50 min was 98.7%.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3400-3404
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• 2011

A new rhodamine B-coumarin conjugate (1) capable of recognizing both $Cu^{2+}$ and $Fe^{3+}$ using two different detection modes have been designed and synthesized. The metal ion induced optical changes of 1 were investigated in $CH_3CN-H_2O$ (1:1, v/v, HEPES 50 mM, pH = 7.0) solution. Sensor 1 exhibits selective colorimetric recognition of $Cu^{2+}$ and fluorescent recognition of $Fe^{3+}$ with UV-vis and fluorescence spectroscopy, respectively. Moreover, both of the $Cu^{2+}$ and $Fe^{3+}$ recognition processes are observed to be barely interfered by other coexisting metal ions.

• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1252-1256
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• 2009

A simple, selective and sensitive fluorescence quenching method was developed to the determination Cr(VI). The method is based on the oxidation of $I^-\;to\;{{I_3}^-}$ by Cr(VI) in sulfuric acid solution followed by immediate formation of ion association compound between I3 − and rhodamine 6G in Tween-80 micellar media at room temperature. The influence of several surfactants on rhodamine 6G fluorescence signal was studied; particular attention was paid in the aggregation behavior of rhodamine 6G–Tween-80 system. The experimental parameters (e.g., type of surfactant, reagent concentration) were studied and the optimal conditions were established. The linear calibration graph was obtained in the range 2.0 - 100.0 ng m$L^{-1}$ Cr(VI). The detection limit of the method was 0.37 ng m$L^{-1}$. The relative standard deviation (R.S.D.) is less than 5% (n = 5). The efficiency of the method for the determination of Cr(VI) in the presence of Cr(III) in the sample was investigated. The method was applied successfully to the determination of Cr(VI) and total Cr in water, and liver tissue samples.