• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.190-196
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• 2007

This study examined the nitrate removal efficiency which uses an electrowinning, and also analyzed the nitrate removal efficiency under a variety of operating conditions such as nitrate concentrations, pH, current densities, electrodes, reducing agents in order to determine optimal conditions. In addition, the multi-step electro-chemical process test has been also analyzed. During the electrowinning, the identical Zn-Zn and Pt-Ti electrodes in the insoluble oxidation electrode(Pt) has shown the highest nitrate removal efficiency in the 100 mg $NO_3^{-}$ -N/L concentration. In the concentration of 150 mg $NO_3^{-}$ -N/L, the efficiency of the Zn-Zn electrode were 70~85%, and that of Pt-Ti electrode were 40~50% without any change of pH. In the high concentration of 500 and 1,000 mg $NO_3^{-}$ -N/L, the higher the concentration, the more decrease of its nitrate removal efficiency decreased. However, the energy consumed for nitrogen removal increased when the nitrate concentration was high. As a result of the multi-step electro-chemical process test, We chose the Test 4. Because the first, most of the zinc consumed from 1 step was recovered from over the 2 step. The second, amount of consumption anode decreased with insoluble anode Pt from over the 2 step. And the third, Zn cathode increased the possibility of reusing Zn deposited. In view of the results so far achieved, the multi-step electro-chemical process would be applied to treat nitrogen involved in metal finishing wastewater.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.117-121
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• 2018

A stainless steel mesh was applied to the cathode of an electro-Fenton system. Methylene blue (MB) solution was chosen as the model waste water with non-biodegradable pollutants. For the model waste water, the degradation efficiency was compared among various SUS mesh cathodes with different surface treatments and magnetite coatings on them. With increasing amount of the magnetite coating on SUS mesh, the degradation efficiency also increased. The improved electro-catalytic characteristic was explained by the increased amount of in situ generated hydrogen peroxide near the cathode surface. Cyclic voltammetry data also showed improved electro-catalytic performance for SUS mesh with more magnetite coatings on them.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1130-1134
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• 2008

Acetic acid has been used as a solvent in the process of manufacturing terephthalic acid. Although the used acetic acid has been mainly separated and recovered through the distillation process, adsorption process can be applied to recover a small amount of acetic acid remaining in the stream after the distillation process. In this study, activated carbon was selected as an adsorbent for acetic acid and the effects of temperature and acid treatment on adsorption capacity were investigated. The adsorption capacities of activated carbon for acetic acid were 0.176 mmol/g at 303 K and 0.118 mmol/g at 343 K, respectively. Adsorption capacity decreased with increasing temperature. The acid treatment of the activated carbon induced the increase in adsorption capacity, which was ascribed to increase in surface functional groups such as phenolic hydroxyl groups and carboxilic acid groups on the carbon surface. In the results of acetic acid desorption, 89% of adsorbed acetic acid was desorbed from activated carbon.

• Membrane Journal
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• v.28 no.4
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• pp.252-259
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• 2018

An acidic, real metal-plating wastewater was treated by a fluidized bed membrane reactor introduced with granular activated carbon (GAC) as fluidized media. With GAC fluidization, there was no increase in suction pressure with time at each flux set-point applied. At neutral solution pH, much less fouling rate was observed than acidic pH under GAC fluidization. Higher solution pH resulted in the increase in particle size in metal-finishing wastewater, thus producing a less dense cake structure on membrane. More than 95% of chemical oxygen demand was observed from the fluidized bed membrane reactor under GAC fluidization. Total suspended solid concentration in membrane permeate was near zero. At the raw wastewater pH, no removal of copper and chromium by the fluidized bed membrane reactor was observed. As the pH was increased to 7.0, removal efficiency of copper and chromium was increased considerably to 99 and 94%, respectively. Regardless of solution pH tested, more than 95% of cyanide was removed possibly due to the strong adsorption of organic-cyanide complex on GAC in fluidized bed membrane reactor.

• Journal of the Korean Applied Science and Technology
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• v.38 no.5
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• pp.1241-1248
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• 2021

In order to figure out various environmental problems, various governments and companies are investigating more environmentally policies and technologies. In other words, activated carbon is widely used for the adsorption of different harmful gases and waste liquid treatment. However since the required surface properties are different in various industry, depending on the adsorption properties, the development of activated carbon demand in different ways. In this work, we have investigated and developed the activated carbon surface to improve the hydrophilic properties by nitric acid treatment through reforming of activated carbon.

• Membrane Journal
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• v.29 no.3
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• pp.123-129
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• 2019

Environmental pollution caused by the presence of heavy metal ion from growing industrialization or from leaching is increasing area of concern. There are several area of water purifications but among them adsorption on the functionalized polymer fibers is efficient and cost-effective method. Polyacrylonitrile (PAN) is exciting polymer due to the presence of excessive functional group which can be easily transformed for metal ion adsorption. PAN can be easily electrospun to prepare nanofiber that have higher surface area leading to better metal ion removal. Composite PAN fiber is yet another type of polymer covered in this review for waste water treatment.

• Korean Journal of Environmental Agriculture
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• v.28 no.1
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• pp.69-74
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• 2009

In Korea, large amounts of chestnut shell as by-products are produced from food industries. However, most of the by-products exist with no disposal options. Biosorption uses biomass that are either abundant or wastes from industrial operations to remove toxic metals from water. Objective of this research was to evaluate the feasibility of using chestnut shell as by-products for removal of metal ions(Pb, Cu and Cd) from aqueous solution. The chestnut shell was tested for its efficiency for metal removal by adopting batch-type adsorption experiments. The adsorption selectivity of chestnut shell for metals was Pb > Cu > Cd at solution pH 5.5. The Langmuir isotherm adequately described the adsorption of chestnut shell for each metal. Using The maximum adsorption capacity predicted using Langmuir equation was 31.25 mg $g^{-1}$ 7.87 mg $g^{-1}$ and 6.85 mg $g^{-1}$ for Pb, Cu and Cd, respectively. Surface morphology, functional group and existence of metals on chestnut shell surface was confirmed by FT-IR, SEM and EDX analysis. The chestnut shell showed an outstanding removal capability for Pb compared to various adsorbents reported in the literatures. The overall results suggested that chestnut shell might can be used for biosorption of Pb from industrial wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.927-932
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• 2009

Toxic and recalcitrant organic pollutants in wastewaters can be effectively treated when advanced oxidation and biodegradation are combined, ideally with intimate coupling, in which both processes occur simultaneously in the same system. One means to achieve intimate coupling is to coat nanoscale $TiO_2$ on the outside of macroporous biofilm carriers. This study investigated the kinetics of photocatalysis with $TiO_2$-coated porous carriers. The carriers were made of polyvinyl alcohol (PVA) and coated with $TiO_2$ using a low-temperature sol-gel process. The $TiO_2$-coated carriers catalyzed the oxidation of methylene blue (MB) effectively under irradiation of UV light. The overall reaction rate with adsorption and photolysis saturated at high MB concentration, and approached the adsorption rate, which was first order for all MB concent rations. This result indicates that adsorbed MB may have slowed photocatalysis by blocking active sites for photocatalysis. The overall kinetics could be described by a quasi-Langmuir model. The estimated maximum specific (per unit mass of $TiO_2$) transformation rate of MB by the $TiO_2$-coated carriers was four times larger than that obtained from slurry-$TiO_2$ reactors. This observation demonstrated that the $TiO_2$ present as a coating on the carriers maintained high efficiency for transforming recalcitrant organic matter via photocatalysis. These findings serve as a foundation for advancement of an intimate coupling of photocatalysis to biodegradation.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.997-1002
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• 2007

The objectives of this research are to remove dissolved organic matter and nitrogen compounds by using aerated submerged bio-film(ASBF) reactors in batch systems and improve understanding of dissolved organic matter and nitrogen compounds removal rates with dynamic relationships between heterotrophic and autotrophic bacteria in the fixed-film reactor. This research explores the possibility of enhancing the performance of shallow wastewater treatment lagoons through the addition of specially designed structures. These structures are designed to encourage the growth of a nitrifying bacterial bio-film on a submerged surface. Specially, the effects of cold temperatures on the dissolved organic matter and ammonia nitrogen performance of the ASBF pilot plant was investigated for the batch system. It is anticipated thai the ASBF would be used for a design of biological treatment for removing of dissolved organic matter and nitrogen compounds in new wastewater treatment plants as well as existing wastewater treatment plants.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.88-88
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• 2011

최근 소비자의 생활수준이 향상되면서 섬유제품에 대한 기술적인 요구가 증가하고 있는데 그 중에서도 기모제품을 응용한 원단에 대한 요구가 급격히 증가하고 있다. 특히 기모원단은 기모공정 후 원단에 존재하는 기모유연제를 처리하기 위해 정련공정을 거쳐야 하는데 대부분의 염색공장에서는 이를 무시한 채 염색을 하고 있다. 이 때문에 잔존하는 기모유연제에 의해 염색 불량을 발생하게 된다. 기모원단에서 정련공정을 생략할 수 있다면, 공정의 단축으로 인한 Cost 절감 효과뿐만 아니라 폐수 부하량도 감소하는 등 시장 및 환경적인 측면에서 동시에 경쟁력을 가질 수 있게 된다. 본 연구에서는 (주)한송인더스트리에서 생분해성을 가지는 환경친화형 기모유연제를 개발하여 이를 염색공정 중 함께 처리함으로써 전체 공정을 단축하고, 개발한 친환경 기모유연제가 염색성에 영향을 미치지 않는 것을 확인하였다. 또한 기존 유연제와 개발된 유연제를 염색공정에서 동일한 조건으로 처리 하였을 때, 기존 유연제 처리 시료는 표면의 불순물과 Oil의 잔존으로 흡습성이 떨어져 균염성 떨어졌고, 염색된 원단에서도 염색불량을 확인할 수 있었다.