• Journal of the Institute of Convergence Signal Processing
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• v.21 no.4
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• pp.177-182
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• 2020

Interest in heat pumps is increasing as an eco-friendly and energy-saving heating method. In particular, in order to develop a heat pump capable of heating in a low-temperature area, research to prevent frost on the surface of the outdoor unit is increasing. In other words, when heating through a heat pump in a low-temperature area, a frost layer is formed on the surface of the outdoor unit, which lowers the heat transfer performance, thereby reducing the heating capacity. Therefore, in this study, an adsorption-type dehumidification system is attached to remove the moisture vapor of the air into the outdoor unit of the heat pump. It is believed that this study can suggest the most effective dehumidification method in low temperature regions. In addition, it is expected that a heat pump with high energy efficiency can be developed by attaching an adsorption dehumidifying system to the front of the outdoor unit of the heat pump.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.91-96
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• 2021

This study was conducted to improve the operating conditions of an adsorption tower filled with potassium impregnated activated carbon for high hydrogen sulfide capture capacity. Heat treatment modified the surface properties of activated carbon, and ultimately determined its adsorption capacity. The activated carbon doped with potassium showed 57 times more adsorption at room temperature than that of using the raw adsorbent. It is believed that uniform pore formation and strong bonding of the potassium on the surface of carbon contributed to the chemical and physical absorption of hydrogen sulfide. The SEM analysis on the surface structure of various commercial carbons showed that the modification of surface properties through the heat treatment generated the destruction of pore structures resulted in the decrease of the absorption performance. The pressure drop across the activated carbon bed was closely related with the grain size and shape. The optimum size of irregularly shaped activated carbon granules was 2~4 mesh indicating economical feasibility.

• Analytical Science and Technology
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• v.35 no.2
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• pp.53-59
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• 2022

Mugwort (Artemisia montana), which is a perennial plant mainly distributed throughout Northeast Asian regions, has been used as a preferred source of various foods and traditional medicines in Korea. In particular, as essential oils extracted from mugwort were reported to be biologically active, its steam distillate has been widely used to treat various conditions, such as itching, hemorrhoids, and gynecological inflammation. Therefore, efforts have been devoted to develop effective methods for the collection of bioactive essential oils from mugwort. In this study, five mugwort extracts were obtained using different extraction conditions, namely, 6 % ethanol at room temperature and at 80 ℃, pure ethanol, n-hexane, and an adsorbent resin. To evaluate the five extracts of mugwort, area-under-the-curve values (AUCs), chemical profiles, and major bioactive essential oil contents were investigated using gas chromatography-mass spectrometry (GC-MS). An overall assessment of the volatile components, including essential oils, in the five extracts was conducted using AUCs, and the individual essential oil in each extract was identified. Furthermore, the four major essential oils (1,8-cineole, camphor, borneol, and α-terpineol), which are known to possess anti-microbial and anti-inflammatory activities, were quantified using authentic chemical standards. Based on the evaluation results, pure ethanol was the best extractant out of the five used in this study. This study provides evaluation results for the five different mugwort extracts and would be helpful for developing extraction methods to efficiently collect the bioactive oil components for medical purposes using chemical profiles of the extracts.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.367-376
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• 2022

One of biopolymer, β-glucan (BG) chains were crosslinked by citric acid under the heating condition for the adsorption of Pb and Cu ions in the aqueous solution. The variation of functional groups on BG itself and crosslinked β-glucan (CBG) with their surface adsorption characteristics were investigated by FTIR and SEM-EDX. Adsorption kinetic results showed that adsorption of Pb and Cu onto the CBG followed the pseudo-second-order kinetic model and intra-particle diffusion model. The Langmuir adsorption model was depicted better adsorption characteristics than the Freundlich model. The adsorption capacities of Pb and Cu onto the CBG estimated by the Langmuir model were 59.70 and 23.44 mg/g, respectively. This study suggested that CBG may act as an eco-friendly adsorbent for the adsorption of Pb and Cu in the aqueous solution.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.97-108
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• 2023

Two carbonaceous adsorbents CAT and CARBOPAL were tested for reducing the concentration of the three herbicides in water: 2,4-D (2,4-dichlorophenoxyacetic acid), TCP (2,4,6-trichlorophenol) and metolachlor. Textural and chemical characterization of the adsorbents include nitrogen isotherms, FTIR, titration and thermogravimetric analyses. Adsorption was studied in discontinuous adsorption experiments at different pH values. The experimental adsorption isotherms data were fitted to four theoretical models. Adsorbent characterization reveals that CAT has higher micropore area, lower pore diameter and lower acidity than CARBOPAL. The adsorption is a second-order process and the isotherms best fitted to Sips model. The efficiency of the process depends mainly on the charge of the adsorbate for TCP and 2,4-D, but it depends on the charge of the surface for metolachlor. Adsorption capacity is higher on CAT for 2,4-D and TCP (small molecules), and it is higher on CARBOPAL for metolachlor (large molecules). Theoretical calculations clearly support this assumption.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.109-115
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• 2023

The extraction and adsorption characteristics for three phenolic ketones with high physicochemical similarity among phenolic compounds, which are alcohol fermentation inhibitors in lignocellulosic biomass hydrolysates, were investigated. The most suitable basic extractant for selectively separating acetosyringone from three phenol ketones by reactive extraction was found to be trioctylphosphine oxide. In addition, it was found that adsorption using XAD16, a polymer neutral resin adsorbent, or physical extraction using hexane, was a suitable separation method for separation of 4'-hydroxyacetophenone (HAP) and acetovanillone (AVO). A five-step fractionation process including extraction and adsorption mentioned above has been first proposed to separate and concentrate the three phenol ketones present at equal mass percentages. When physical extraction with n-hexane and re-extraction with an aqueous NaOH solution were used as the steps 4 and 5 in the fractionation process respectively, it was possible to obtain almost 70% or more of the purity of three phenolic ketones.

• Membrane Journal
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• v.32 no.1
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• pp.13-22
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• 2022

Ever increasing global energy demand gives rise to uncontrollable environmental pollution. Demand on fossil fuel and consequent carbon emission leads to global warming and climate change. Nuclear energy is an alternative source to generate clean energy but mining of nuclear fuel is associated with harmful chemicals. Mining of valuable minerals from sea water by membrane separation process is a cost effective along with environmental friendly process. Separation and adsorption based mining of valuable minerals from sea water are another efficient process. Recovery of actinides from rare earth elements are very challenging and expensive process. Pressure driven membrane separation process is economically more viable along with environmental process. In this review membrane separation process are based on polyether sulfone, polyamide, polyimide, polyamidoxine and hybrid membranes. In case of adsorption process, mainly amidoxime kind of adsorbent are discussed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.175-176
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• 2022

By studying the characteristics of matrix insulated through heat generated through oxidation of iron powder, the basic research results on the possibility of buffering and applicability of Cold weather concrete as a curing method are presented. In order to prevent freezing due to a sharp decrease in temperature in the initial stage of curing, iron powder (Fe), powder activated carbon, which is a small amount of porous carbonaceous adsorbent, and salt (NaCl) as an oxidizing agent are replaced with iron powder admixture. As the curing temperature increases, the strength tends to increase, and when replacing the admixture at the same curing temperature, the strength slightly decreases. This is determined as a result of generating iron oxide through an oxidation reaction of iron powder, activated carbon, and NaCl generating a large amount of pores in the matrix. In addition, the internal temperature tends to increase as the mixing substitution rate increases, and it is judged that the oxidation heat of the iron powder mixture affects the increase of the internal temperature during curing. The higher the replacement rate of the iron powder mixture, the slightly lower the strength, but it is determined that freezing and melting that may occur in the early stage of curing can be prevented due to an increase in the initial internal temperature.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.134-140
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• 2023

Activated carbon is a carbonaceous material mainly used as a gaseous or liquid adsorbent. As fire-related accidents occur consistently due to the accumulation of heat of adsorption and oxidation of volatile organic compounds, the explosive characteristics and thermal stability of powdered and granular activated carbon made from coal and coconut shells were evaluated. As a result of the particle size analysis, the powdered activated carbon was in the particle size range (0.4~3) ㎛, and thermal properties such as exothermic onset temperature and decomposition behavior were analyzed using a differential scanning calorimetry and a thermogravimetric analysis. As a result of the evaluation of the explosion hazards for dust, both coal-based and coconut-based powdered activated carbon are classified as St1 class with weak explosion, but this is a relative and does not mean that the explosion hazards is absolutely low. Therefore, it is necessary to establish countermeasures for reducing the damage.

• Korean Chemical Engineering Research
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• v.62 no.2
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• pp.181-190
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• 2024

Here, we develop a centrifugal microfluidic reactor with simple, fast, and high-throughput manner for the generation of magnetic Janus micro-adsorbents (MAs). By using the multi-micronozzle consisting of two separate aligned needles and centrifugal tubes, we have synthesized highly monodispersed Prussian blue- and magnetic nanoparticle-laden micro-adsorbents (PB-MNP-MAs). The enhanced cesium (Cs⁺) adsorption was demonstrated by conducting the adsorption isotherm and kinetics experiment which can be contributed to the porous nature of the Ca-alginate networks with a high surface area of embedded PB nanoparticles, resulting to perform rapid adsorption activity within 10 min. After Cs⁺ adsorption process, the as-synthesized PB-MNP-MAs were successfully harvested by introducing the external magnetic fields. Therefore, we believe that our findings can be provided new direction towards the development of advanced functional adsorbents in biological and environmental fields.