• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.104-109
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• 2004

Removal of nutrients from domestic sewage or industrial wastewater is needed to protect surface waters from eutrophication. This research was carried out to remove the nitrogen (N) and phosphorus (P) from the wastewater using the iron oxide obtained from the steel industry and the natural zeolite, respectively. This research was conducted in both batch and continuous systems. The removal efficiency of the nutrients was evaluated in the batch system using the varying concentrations of zeolite and iron oxide added. The removal efficiency of N was 60% at the 8g of zeolite added. In the same condition, the removal efficiencies of N were 76% and 82% at 12g and 16g of zeolite added, respectively. Removal efficiency of P was 80% as 8g of iron oxide was added. The removal efficiency of P was correspondingly increased as the concentration of iron oxide was increased. Continuous column system was also used to evaluate the removal efficiency of N and P by the addition of zeolite and ferric oxide, respectively. Removal efficiencies of N were compared in the mixed packing, two stage, and four stage columns, respectively. The removal efficiencies (80%) of N in the separate packed columns (two and four stages) were higher than the mixed packing column (400%) after 90 hr. Whereas, the removal efficiencies of P were similar to each other in the three columns.

• Carbon letters
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• v.11 no.2
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• pp.117-121
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• 2010

The composites of alginate, carbon nanotube, and iron(III) oxide were prepared for the removal of heavy metal in aqueous pollutant. Both alginate and carbon nanotube were used as an adsorbent material and iron oxide was introduced for the easy recovery after removal of heavy metal to eliminate the secondary pollution. The morphology of composites was investigated by FE-SEM showing the carbon nanotubes coated with alginate and the iron oxide dispersed in the alginate matrix. The ferromagnetic properties of composites were shown by including iron(III) oxide additive. The copper ion removal was investigated with ICP AES. The copper ion removal efficiency increased greatly over 60% by using alginate-carbon nanotube composites.

• Transactions on Electrical and Electronic Materials
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• v.2 no.3
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• pp.24-27
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• 2001

The end point of oxide chemical mechanical polishing (CMP) have determined by polishing time calculated from removal rate and target thickness of oxide. This study is about control of oxide removal amounts on the shallow trench isolation (STI) patterned wafers using removal rate and thickness of blanket (non-patterned) wafers. At first, it was investigated the removal properties of PETEOS blanket wafers, and then it was compared with the removal properties and the planarization (step height) as a function of polishing time of the specific STI patterned wafers. We found that there is a relationship between the oxide removal amounts of blanket and patterned wafers. We analyzed this relationship, and the post CMP thickness of patterned wafers could be controlled by removal rate and removal target thickness of blanket wafers. As the result of correlation analysis, we confirmed that there was the strong correlation between patterned and blanket wafer (correlation factor: 0.7109). So, we could confirm the repeatability as applying for STI CMP process from the obtained linear formula. As the result of repeatability test, the differences of calculated polishing time and actual polishing time was about 3.48 seconds. If this time is converted into the thickness, then it is from 104 $\AA$ to 167 $\AA$. It is possible to be ignored because process margin is about 1800 $\AA$.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.6
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• pp.813-822
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• 2006

Soluble manganese removal was analyzed as a function of filter media, filter depth, presence or absence of chlorination, and surface manganese oxide concentration in water treatment processes. Sand, manganese oxide coated sand (MOCS), sand+MOCS, and granular activated carbon(GAC) were used as filter media. Manganese removal, surface manganese oxide concentration, turbidity removal, and regeneration of MOCS in various filter media were investigated. Results indicated that soluble manganese removal in MOCS was rapid and efficient, and most of the removal happened at the top of the filter. When filter influent (residual chlorine 1.0mg/L) with an average manganese concentration of 0.204mg/L was fed through a filter column, the sand+MOCS and MOCS columns can remove 98.9% and 99.2% of manganese respectively on an annual basis. On the other hand, manganese removal in sand and the GAC column was minimal during the initial stage of filtration, but after 8 months of filter run they removed 99% and 35% of manganese, respectively. Sand turned into MOCS after a certain period of filtration, while GAC did not. In MOCS, the manganese adsorption rate on the filter media was inversely proportional to the filter depth, while the density of media was proportional to the filter depth.

• Analytical Science and Technology
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• v.37 no.1
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• pp.39-46
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• 2024

Alizarin dye, a persistent and hazardous contaminant in aquatic environments, presents a pressing environmental concern. In the quest for efficient removal methods, adsorption has emerged as a versatile and sustainable approach. This study focuses on the development and application of Zinc Oxide/Nickel Oxide (ZnO/NiO) nano-composites as adsorbents for alizarin dye removal. These semiconducting metal oxide nano-composites exhibit synergistic properties, offering enhanced adsorption capabilities. Key parameters affecting alizarin removal, such as contact time, adsorbent dosage, pH, and temperature, were systematically investigated. Notably, the ZnO/NiO nano-composite demonstrated superior performance, with a maximum alizarin removal percentage of 76.9 % at pH 6. The adsorption process followed a monolayer pattern, as suggested by the Langmuir model. The pseudo-second-order kinetics model provided a good fit to the experimental data. Thermodynamic analysis indicated that the process is endothermic and thermodynamically favorable. These findings underscore the potential of ZnO/NiO nano-composites as effective and sustainable adsorbents for alizarin dye removal, with promising applications in wastewater treatment and environmental remediation.

• Korean Journal of Materials Research
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• v.26 no.3
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• pp.109-116
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• 2016

To achieve the fabrication of high-quality Ag-coated Cu particles through a wet chemical process, we reported herein pretreatment conditions using an ammonium-based mixed solvent for the removal of a $Cu_2O$ layer on Cu particles that were oxidized in air for 1 hr at $200^{\circ}C$ or for 3 days at room temperature. Furthermore, we discussed the results of post-Ag plating with respect to removal level of the oxide layer. X-ray diffraction results revealed that the removal rate of the oxide layer is directly proportional to the concentration of the pretreatment solvent. With the results of Auger electron spectroscopy using oxidized Cu plates, the concentrations required to completely remove 50-nm-thick and 2-nm-thick oxides within 5 min were determined to be X2.5 and X0.13. However, the optimal concentrations in an actual Ag plating process using Cu powder increased to X0.4 and X0.5, respectively, because the oxidation in powder may be accelerated and the complete removal of oxide should be tuned to the thickest oxide layer among all the particles. Back-scattered electron images showed the formation of pure fine Ag particles instead of a uniform and smooth Ag coating in the Ag plating performed after incomplete removal of the oxide layer, indicating that the remaining oxide layer obstructs heterogeneous nucleation and plating by reduced Ag atoms.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.93-98
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• 2008

We investigated the effect of process temperature on removal rate and non-uniformity based on single head kinematics in oxide CMP. Generally, it has been known that the temperature profile directly transfers to the non~uniformity of removal rate on the wafer, which has similar tendency with the sliding distance of wafer. Experimental results show that platen velocity is a dominant factor in removal rate as well as average temperature. However, the non-uniformity does not coincide between process temperature and removal rate, due to slurry accumulation and low deviation of temperature. Resultantly, the removal rate is strongly dependent on the rotational speed of platen, and its non -uniformity is controlled by the rotational speed of polishing head. It means lower WIWNU (With-in-wafer-non-uniformity) can be achieved in the region of higher head speed.

• Journal of the Korean Society of Safety
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• v.6 no.4
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• pp.26-33
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• 1991

To remove SO$_2$ from flus gas, cupric oxide, manganese oxide and iron oxide were studied with varying loading value. The experiment was carried out in a flow reactor and the reactants were prepared by impregnation method using alumina. The reaction temperature was varied from 30$0^{\circ}C$ to 45$0^{\circ}C$. Experimental results showed that all of these metal oxides were effective on SO$_2$ removal reaction and cupric oxide was the best reactant. The sample with 10wt％ loading value was better reactant than with 20wt％ because in case of 20wt％ loading, metal dispersion on the alumina surface was not uniform. And the SO$_2$ removal efficiency was increased with the reaction temperature.

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.620-626
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• 2014

The main focus of this study was the evaluation of arsenic concentration in the ground water of Lahore at different depth and application of different mitigation techniques for arsenic removal. Twenty four hours of solar oxidation gives 90% of arsenic removal as compared to 8 hr. or 16 hr. Among oxides, calcium oxide gives 96% of As removal as compared to 93% by lanthanum oxide. Arsenic removal efficiency was up to 97% by ferric chloride, whereas 95% by alum. Activated alumina showed 99% removal as compared to 97% and 95% removal with bauxite and charcoal, respectively. Elemental analysis of adsorbents showed that the presence of phosphate and silica can cause a reduction of arsenic removal efficiency by activated alumina, bauxite and charcoal. This study has laid a foundation for further research on arsenic in the city of Lahore and has also provided suitable techniques for arsenic removal.

• Transactions on Electrical and Electronic Materials
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• v.7 no.4
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• pp.167-172
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• 2006

Submicron colloidal silica coated with ceria were prepared by mixing of silica and nano ceria particles and modified by hydrothermal reaction. The polishing efficiency of the ceria coated silica slurry was tested over oxide film on silicon wafer. By changing the polishing pressure in the range of $140{\sim}420g/cm^2$ with the ceria coated silica slurries in $100{\sim}300nm$, rates, WIWNU and friction force were measured. The removal rate was in the order of 200, 100, and 300 nm size silica coated with ceria. It was known that the smaller particle size gives the higher removal rate with higher contact area in Cu slurry. In the case of oxide film, the indentation volume as well as contact area gives effect on the removal rate depending on the size of abrasives. The indentation volume increase with the size of abrasive particles, which results to higher removal rate. The highest removal rate in 200 nm silica core coated with ceria is discussed as proper combination of indentation and contact area effect.