• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.216-221
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• 2010

Polyvinyl acetate (PVAc) prepared by emulsion polymerization has broad applications for additive such as paint binder, adhesive for wood and paper due to its low glass transition temperature which help to plasticize substrate resins. Since emulsion polymerization has a disadvantage that surfactant and ionic initiator degrade properties of the product polymer, poly (vinyl acetate-eo-ethyl acrylate) (VAc-EA) was synthesized using potassium persulfate as catalyst and polyvinylalcohol (PVA) as protective colloid to prevent the degradation. The copolymer latex product was internally plasticized and has enhanced adhesion, water resistance during VAc-EA emulsion polymerization. No coagulation and complete conversion occur with the reactant mixture of 10 mmol/L potassium persulfate, 10 mmol/L poly ( vinyl alcohol) (PVA 17). As the concentrations of PVA increase, the viscosity becomes increase.

• Toxicological Research
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• v.25 no.3
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• pp.132-139
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• 2009

The toxicity test of ammonium persulfate was conducted to ensure of its potential toxic effects according to the single-dose acute oral toxicity study (OECD Guideline 423) and 90-day repeated dose sub-chronic oral toxicity study guideline (OECD Guideline 408) for establishing national chemical management system, and matching in the Globally Harmonized Classification System (GHS) category. In acute oral toxicity study, pasty stool, perineal contamination and temporary body weight decrease were observed after dosing 1st and 2nd challenge (300 mg/kg body weight). All test animals were dead within 6 hours after dosing at 3rd challenge (2000 mg/kg body weight). Therefore, the GHS class of test substance is considered class 4. In sub-chronic toxicity study, body weight changes, food consumptions, hematological, biochemical and pathological examination did not show any noticeable and significant differences between the administered (5, 20, 80 mg/kg body weight) and control (vehicle only) group animals. Based on these results, the no observed adverse effect level (NOAEL) is considered above 80 mg/kg body weight.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.963-972
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• 2014

In this study, ibuprofen(IBP) degradation by the photochemical ($UV/S_2O{_8}^{2-}$) and sonochemical ($US/S_2O{_8}^{2-}$) processes was examined under various parameters, such as UV ($10{\sim}40{\pm}5W/L$) and US ($50{\sim}90{\pm}5W/L$) power density, optimum dosage of persulfate ion ($S_2O{_8}^{2-}$), temperature ($20{\sim}60^{\circ}C$) and anions effect ($Cl^-$, $HCO_3{^-}$, $CO{_3}^{2-}$). The pseudo-first-order degradation rate constants were in the order of $10^{-1}$ to $10^{-5}min^{-1}$ depending on each processes. The synergistic effect of IBP degradation in $UV/S_2O{_8}^{2-}$ and $US/S_2O{_8}^{2-}$ processes could investigated, due to the generation of $SO_4{^-}$ radical. This result can confirm from the produced $H_2O_2$ and $SO{_4}^{2-}$ concentration in each processes. IBP degradation rate affected by the $S_2O{_8}^{2-}$ dosage, temperature, power and anion existence parameters. In particular, IBP degradation rate increased with the increase of the temperature ($60^{\circ}C$) and applied power density (UV:$40{\pm}5W/L$, US:$90{\pm}5W/L$). On the other hand, anions effect on the IBP degradation was negative, due to the anion play as a the scavenger of radical.

• Environmental Engineering Research
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• v.25 no.2
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• pp.178-185
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• 2020

The aim of this study is to investigate the degradation of ciprofloxacin (CIP) from its aqueous solutions via different advanced oxidation processes (AOP). The effects of persulfate (PS) concentration, pH, zinc oxide nanoparticles (ZnO-NPs) dose, initial CIP concentration, and reaction time on the degradation of CIP were studied. It was found that the sonochemical (US) degradation is a less efficient process (with removal efficiency of 36%) compared to the sono-nano-chemical (US/ZnO) process which resulted in removal efficiency of 70%. Maximum removal of 99% was obtained using the sono-nano-chemical/PS (US/ZnO/PS) process at a frequency of 60 kHz, time of 10 min, pH of 7, initial CIP concentration of 25 mg/L, and PS concentration of 476.06 mg/L. The addition of PS and ZnO-NPs to the process enhanced the rate of US degradation of CIP. In addition, the kinetic parameters for the US/ZnO/PS process were obtained by fitting the kinetic data into the pseudo-first-order and pseudo-second-order kinetic models. The kinetic data was found to fit into the pseudo-first-order kinetic model than the pseudo-second-order model. The results showed that the AOP using US/ZnO/PS is a promising technique for the treatment of ciprofloxacin containing solutions.

• Journal of Radiation Industry
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• v.5 no.3
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• pp.253-258
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• 2011

Acetylsalicylic acid (ASA) has been issued recently in contaminated water environments because of potential impacts on ecosystem and public health. This study was aimed at investigating the possibility of ASA degradation using gamma ray irradiation. In addition, the use of sodium persulfate, hydrogen peroxide, ferrous sulfate were tested in order to examine a synergistic effect with gamma ray. The absorbed dose was ranged from 0.2 to 10 kGy and the concentration of oxidants were from 0.1 to 10 mM in this study. The concentration of ASA was gradually decreased corresponding to the increase of the absorbed dose. When soudium persulfate was simultaneously applied, most of the parent compound was completely degraded even at a low dose of 0.8 kGy. The removal efficiency of total organic carbon was 90% even at the highest dose of 10 kGy without sodium persulfate. However, the efficiency was dramatically enhanced up to 98% at the same dose by adding 10 mM of oxidants. It was suggested that hydroxyl radical ($OH{\cdot}$) and sulfate radical ($SO{_4}^-{\cdot}$) were formed in the system and made roles in degrading ASA at the same time.

• Advances in environmental research
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• v.3 no.3
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• pp.185-197
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• 2014

Efficient defluorination of perfluorooctanoic acid (PFOA) was achieved by integrating UV irradiation and $Fe^{2+}$ activation of persulfate ($S_2O{_8}^{2-}$). It was found that the UV-$Fe^{2+}$, $Fe^{2+}-S_2O{_8}^{2-}$, and UV-$S_2O{_8}^{2-}$ processes caused defluorination efficiency of 6.4%, 1.6% and 23.2% for PFOA at pH 5.0 within 5 h, respectively, but a combined system of UV-$Fe^{2+}-S_2O{_8}^{2-}$ dramatically promoted the defluorination efficiency up to 63.3%. The beneficial synergistic behavior between $Fe^{2+}-S_2O{_8}^{2-}$ and UV-$S_2O{_8}^{2-}$ was demonstrated to be dependent on $Fe^{2+}$ dosage, initial $S_2O{_8}^{2-}$ concentration, and solution pH. The decomposition of PFOA resulted in generation of shorter-chain perfluorinated carboxylic acids (PFCAs), formic acid and fluoride ions. The generated PFCAs intermediates could be further defluorinated by adding supplementary $Fe^{2+}$ and, $S_2O{_8}^{2-}$ and re-adjusting solution pH in later reaction stage. The much enhanced PFOA defluorination in the UV-$Fe^{2+}-S_2O{_8}^{2-}$ system was attributed to the fact that the simultaneous employment of UV light and $Fe^{2+}$ not only greatly enhanced the activation of $S_2O{_8}^{2-}$ to form strong oxidizing sulfate radicals ($SO{_4}^{\cdot-}$), but also provided an additional decarboxylation pathway caused by electron transfer from PFOA to in situ generated $Fe^{3+}$.

• Journal of Soil and Groundwater Environment
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• v.23 no.6
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• pp.104-113
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• 2018

A three-dimensional electrochemical process using nanosized zero-valent iron (NZVI)/activated carbon (AC) particle electrode and persulfate (PS) was developed for oxidizing pollutants. X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and Brunauer-Emmett-Teller (BET) surface area analysis were performed to characterize particle electrode. XRD and SEM-EDS analysis confirmed that NZVI was impregnated on the surface of AC. Compared with the conventional two-dimensional electrochemical process, the three-dimensional particle electrode process achieved three times higher efficiency in phenol removal. The system with current density of $5mA/cm^2$ exhibited the highest phenol removal efficiency among the systems employing 1, 5, and $10mA/cm^2$. The removal efficiency of phenol increased as the Fe contents in the particle electrode increased. The particle electrode achieved more than 70% of phenol removal until it was reused for three times. The sulfate radical played a predominant role in phenol removal according to the radical scavenging test.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.301-311
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• 2018

In this study, the ion-gelation method was applied to fabricate novel Fe-carbon-bentonite-alginate beads ($Fe^0$/C-BABs). $Fe^0$/C-BABs could effectively control Fe release during persulfate (PS) activation in N-acetyl-p-aminophenol (APAP) oxidation. A novel two-stage approach that combined $Fe^0$/C-BABs and an oyster-shell-filled bed (OSFB) column was developed to address the low pH and high Fe concentration of the effluent of the traditional PS process. The application of the $Fe^0$/C-BABs and OSFB column regulated pH levels and Fe release during the advanced oxidation of APAP. The characteristics of $Fe^0$/C-BABs were also investigated through scanning electron microscopy, energy dispersive spectrometry, and Fourier transform infrared spectroscopy. The long-term operation performance of $Fe^0$/C-BABs in a continuous fixed-bed reactor under simultaneous PS and APAP feeding was also evaluated. The effects of initial PS concentration, pH, fixed-bed weight, in-flow rate, and dissolved oxygen (DO) were investigated. Under selected conditions, 86.3% efficiency was achieved during the first stage of APAP degradation (effluent pH of 3.05, Fe contents: $106.25mgL^{-1}$). Water quality improved after the effluent was passed through the OSFB column (effluent pH of 6.32, Fe contents: $21.43mgL^{-1}$). Moreover, this study analyzed the free radicals and intermediates produced during APAP degradation to identify the possible routes of APAP degradation.

• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.322-328
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• 2014

In this study, revelation performance of concrete at early age according to types of cement, water reducing ratio of high performance superplasticizer and mixing of accelerator for early hydration was examined aiming for reduction of construction period of framework through securing strength at early age of concrete. It was observed that strength at early age, 5MPa in 12hours, 14MPa in 18hours, is secured by early strength improvement type cement and using promotion admixture for early hydration which are Sodium persulfate, Potassium hydroxide. Therefore cost reduction is expected to be possible in construction site by reducing construction period of frame work.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.19-24
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• 2005

In this paper, the fabrication process of Si pressure sensors utilizing piezoresistive effect was optimized. The efficiency(yield) of the fabrication process for Si piezoresistive pressure sensors was improved by conducting Si anisotrophic etching process after processes of piezoresistors and AI circuit patterns. The position and process parameters for piezoresistors were determined by ANSYS and SUPREM simulators, respectively. The measured thickness of p-type Si piezoresistors from the boron depth-profile measurement was in good agreement with the simulated one from SUPREM simulation. The Si anisotrohic etching process for diaphragm was optimized by adding ammonium persulfate(AP) to tetramethyl ammonium hydroxide (TMAH) solution.