To develop flexible adsorbents for compact volatile organic compound (VOC) air purifiers, flexible as-spun zeolite fibers are prepared by an electrospinning method, and then zeolite particles are exposed as active sites for VOC (toluene) adsorption on the surface of the fibers by a thermal surface partial etching process. The breakthrough curves for the adsorption and temperature programmed desorption (TPD) curves of toluene over the flexible zeolite fibers is investigated as a function of the thermal etching temperature by gas chromatography (GC), and the adsorption/desorption characteristics improves with an increase in the thermal surface etching temperature. The effect of acidity on the flexible zeolite fibers for the removal of toluene is investigated as a function of the SiO2/Al2O3 ratios of zeolites. The acidity of the flexible zeolite fibers with different SiO2/Al2O3 ratios is measured by ammonia-temperature-programmed desorption (NH3-TPD), and the adsorption/desorption characteristics are investigated by GC. The results of the toluene adsorption/desorption experiments confirm that a higher SiO2/ Al2O3 ratio of the flexible zeolite fibers creates a better toluene adsorption/desorption performance.

Carboxylated multi-wall carbon nanotubes (MWCNTs-COOH) was functionalized with 3-amino-5-phenylpyrazole (MWCNTs- f) and characterized by FTIR, EDX, SEM, XRD and TGA. The MWCNTs-COOH and MWCNTs-f were used for the adsorption of Cd(II), Hg(II), and As(III) ions from aqueous solutions. Additionally, to study the influence of pH, adsorbent dose, and initial ions concentration on the adsorption process, the central composite design (CCD) was applied. The quadratic model was used for analysis of variance and indicated that adsorption of metal ions strongly depends on pH. Timedependent adsorption can be described by the pseudo-second-order kinetic model, and adsorption process was modeled by Langmuir isotherm for the adsorbents. Thermodynamic analysis showed that the adsorption of Cd(II), Hg(II) and As(III) ions were spontaneous and endothermic. Moreover, the competitive adsorption capacities of the heavy metal ions were slightly lower than noncompetitive ones. The same affinity order was observed under noncompetitive and competitive adsorption: As(III) > Cd(II) > Hg(II) in the case of MWCNTs-f. Desorption study revealed the favorable regeneration ability of adsorbents powders, even after three adsorption–desorption cycles.

Nitrogen-doped carbons have attracted much attention due to their novel application in relation to gas storage. In this study, nitrogen-doped porous carbons were synthesized using SBA-15 as a template, polypyrrole as the carbon and nitrogen precursor, and KOH as an activating agent. The effect of the activation temperature (600–850°C) on the CO2 adsorption capacity of the obtained porous carbons was studied. Characterization of the resulting carbons showed that they were micro-/meso-porous carbon materials with a well-developed pore structure that varied with the activation temperature. The highest surface area of 1488 m2 g–1 was achieved at an activation temperature of 800°C (AC-800). The nitrogen content of the activated carbon decreased from 4.74 to 1.39 wt% with an increase in the activation temperature from 600 to 850°C. This shows that nitrogen is oxidized and more easily removed than carbon during the activation process, which indicates that C-N bonds are more easily ruptured at higher temperatures. Furthermore, CO2 adsorption isotherms showed that AC-800 exhibited the best CO2 adsorption capacity of 110 mg g–1 at 298 K and 1 bar.

Transition-metal-embedded carbon nanotubes (CNTs) have been accepted as a novel type of sensing material due to the combined advantage of the transition metal, which possesses good catalytic behavior for gas interaction, and CNTs, with large effective surface areas that present good adsorption ability towards gas molecules. In this work, we simulate the adsorption of O2 and O3 onto Rh-doped CNT in an effort to understand the adsorbing behavior of such a surface. Results indicate that the proposed material presents good adsorbing ability and capacities for these two gases, especially O3 molecules, as a result of the relatively large conductivity changes. The frontier molecular orbital theory reveals that the conductivity of Rh-CNT would undergo a decrease after the adsorption of two such oxidizing gases due to the lower electron activity and density of this media. Our calculations are meaningful as they can supply experimentalists with potential sensing material prospects with which to exploit chemical sensors.

본 연구에서는 Na형 Faujasite 제올라이트 분리막의 프로필렌/프로페인 분리 거동을 예측하기 위하여 제올라이트 13X 입자의 프로필렌 및 프로페인 단일기체에 대한 중량식흡착 거동을 관찰하고자 하였다. 제올라이트 13X 입자의 프로필렌 및 프로페인에 대한 중량식흡착 거동은 자성부유평형저울(MSB)을 이용하여 323, 343, 363 K의 온도와 0.02-1 bar의 압력 범위에서 0.1 bar씩 증가시키면서 측정되었다. 그 결과, 온도가 증가할수록 프로필렌 및 프로페인의 흡착량은 감소하였으며, 프로필렌/프로페인의 흡착 선택도는 증가하였다. 또한 흡착 온도가 증가함에 따라 프로필렌과 프로페인의 확산계수는 증가하여 아레니우스 식을 따랐고, 프로필렌/프로페인 확산 선택도는 323 K에서 0.9753으로 최대값을 가졌다. 흡착 특성을 통해 분리막의 투과선택도를 계산하였고, Na형 Faujasite 제올라이트 분리막의 단일 기체 투과 특성과 비교하였다. 그 결과 계산된 투과선택도와 측정된 투과선택도가 모두 323 K에서 최대값을 갖는 것을 확인하였다. 따라서 본 연구에서는 중량식 흡착법으로 예측된 분리막의 프로필렌/프로페인 분리거동 예측이 합리적이며 또한 표면확산에 기반한 프로필렌/프로페인 분리용 제올라이트 분리막의 분리성능예측에 적용될 수 있음을 알 수 있었다.

In this study, volatile organic compounds (VOCs) emitted from printing industries were analyzed, and an inorganic adsorbent, γ-alumina, was selected for the effective control of the VOC emissions. Printing processes commonly require inks, thinners, and cleaners, and they were mixed organic solvents containing aromatic compounds, ketones, and alcohols. Therefore, toluene, methyl ethyl ketone (MEK), and isopropyl alcohol (IPA) were selected as model compounds for this study. The adsorptive properties using γ-alumina were determined for the model compounds. Both batch isotherm and continuous flow column tests demonstrated that the adsorption capacity of MEK and IPA was 3~4 times higher than that of toluene. The column test performed at an inlet toluene concentration of 100 ppm showed that an 80% breakthrough for toluene was observed after 3 hours, but both MEK and IPA were continuously adsorbed during the same time period. A numerical model simulated that the γ-alumina could remove toluene at a loading rate of 0.4 mg/min only for a 4-hour period, which might be too short of a duration for real applications. Consequently, lifetime enhancement for γ-alumina must be implemented, and ozone oxidation and regeneration would be feasible options.

우드펠렛은 가정용, 상업용, 산업용 등으로 사용되며 특히 화력발전소에서 석탄 대용으로 수입량이 급증하여 연간 약 2,400만톤 가량 수입되고 있는 상황이다. 우드펠렛 검역훈증제로 기존에는 메틸브로마이드(이하 MB)가 최근까지 사용되어져 왔으나, MB의 높은 흡착률과 우드펠렛의 과도한 수용비로 인해 최종가스농도 기준에 미치지 못하여 재투약하는 사례가 빈번히 발생해 문제가 되어져왔다. 이를 해결하기 위해 농림축산검역본부에서는 올해 초 MB와 포스핀을 병행으로 처리하는 방식의 소독처리기준을 신설하였다. 새로운 소독처리기준이 설정됨에 따라 배기시 안전한 배기시간 수준을 설정하기 위해 병행처리 후 수착과 탈착되는 가스농도를 조사하였다. 실내 훈증상에 우드펠렛을 채우고 약제 처리한 결과 각 훈증제의 TLV(Threshold Limit Value)-TWA(Time Weighted Average) 기준이하로 농도가 감소되는 배기시간은 25℃일 때 MB는 120시간, 포스핀은 6시간으로 측정되었고 15℃일 때 MB는 186시간, 포스핀은 19시간으로 측정되었다.

We perform density functional theory calculations to study the CO and O2 adsorption chemistry of Pt@X core@shell bimetallic nanoparticles (X = Pd, Rh, Ru, Au, or Ag). To prevent CO-poisoning of Pt nanoparticles, we introduce a Pt@X core-shell nanoparticle model that is composed of exposed surface sites of Pt and facets of X alloying element. We find that Pt@Pd, Pt@Rh, Pt@Ru, and Pt@Ag nanoparticles spatially bind CO and O2, separately, on Pt and X, respectively. Particularly, Pt@Ag nanoparticles show the most well-balanced CO and O2 binding energy values, which are required for facile CO oxidation. On the other hand, the O2 binding energies of Pt@Pd, Pt@Ru, and Pt@Rh nanoparticles are too strong to catalyze further CO oxidation because of the strong oxygen affinity of Pd, Ru, and Rh. The Au shell of Pt@Au nanoparticles preferentially bond CO rather than O2. From a catalysis design perspective, we believe that Pt@Ag is a better-performing Ptbased CO-tolerant CO oxidation catalyst.

Cu(II) can cause health problem for human being and phosphate is a key pollutant induces eutrophication in rivers and ponds. To remove of Cu(II) and phosphate from solution, chitosan as adsorbent was chosen and used as a form of hydrogel bead. Due to the chemical instability of hydrogel chitosan bead (HCB), the crosslinked HCB by glutaraldehyde (GA) was prepared (HCB-G). HCB-G maintained the spherical bead type at 1% HCl without a loss of chitosan. A variety of batch experiment tests were carried out to determine the removal efficiency (%), maximum uptake (Q, mg/g), and reaction rate. In the single presence of Cu(II) or phosphate, the removal efficiency was obtained to 17 and 16%, respectively. However, the removal efficiency of Cu(II) and phosphate was increased to 50~55% at a mixed solution. The maximum uptake (Q) for Cu(II) and phosphate was enhanced from 11.3 to74.4 mg/g and from 3.34 to 36.6 mg/g, respectively. While the reaction rate of Cu(II) and phosphate was almost finished within 24 and 6 h at single solution, it was not changed for Cu(II) but was retarded for phosphate at mixed solution.

본 연구에서는 이온교환막을 결합한 막 결합형 축전식 탈염공정으로 적용하여 진행하였다. 막 결합형 축전식 탈염공정에서 흡착전압과 이온교환막의 두께가 흡착성능에 미치는 영향을 알아보았다. 흡착전압을 0.5, 1, 1.4 V로 달리하였고 흡착전압이 증가함에 따라 강한인력으로 인해 많은 이온들의 흡착으로 배출수 농도의 최소점이 낮아지고 전극이 포화상태가 되기까지의 운전시간이 증가하였다. 이온교환막의 두께를 1, 2, 3회로 코팅횟수를 달리하였고 막이 두꺼울수록 막 내에서 이온들의 움직임이 원활하지 않아 감소된 흡착성능을 확인하였다. 이온교환막의 적합한 두께는 1회 코팅했을 때 3.85 ㎛의 두께를 보였다.

현재 해수담수화 공정은 지속적인 연구를 통해 많은 개발이 이루어지고 있다. 그중 전기흡착탈이온(EAD) 공정은 이온교환막을 이용한 전기투석법과 이온교환수지를 이용한 이온교환수지법을 혼합하여 이루어지는 공정이다. 보다 효율적으로 이온교환이 이루어질 수 있는 공정이지만, 이온교환막 사이에 이온교환수지가 들어가기 때문에 사이즈가 비교적 크다. 또한, 이온교환수지의 크기 분포와 당량비가 모듈의 성능에 영향을 준다. 본 연구는 현재 상용화되고 있는 이온교환공정에서 쓰이고 있는 모듈의 문제해결과 성능 향상을 위해 보다 이온교환용량이 향상된 고분자와 현재 쓰이고 있는 일반적인 이온교환수지가 아닌 더 작고 균질한 이온교환능력을 가진 이온교환 나노입자를 제조하여 제막을 진행하였고, 다양한 특성평가가 이루어졌다.

The purpose of this study is to produce an adsorbent material with biomass by-product that are readily visible in daily life. The biomass by-product used in the study are coffee grounds, oak leaves and chestnut peels. These biomass by-products were produced with dry, carbonization and activation treatments. The equipment for the evaluation of adsorption capacity was the batch type system to measure the concentration of test gases with the odor sensor device. Biomass by-products have been shown to improve the absorption characteristics of adsorbent through carbonization and activation. The adsorbent made with coffee grounds and chestnut peels had superior adsorption capacity to hydrogen sulfide (H2S) and complex odor (H2S & NH3) in a comparison with regular activated carbon. The odor sensor device could be used to evaluate the device of adsorption capacity of the adsorbent.

점토를 이용하여 세 종류의 새로운 형태의 변형된 유기물점토를 제조하였다. Cetylpyridinium chloride (CPC)를 점토에 층간 삽입시켜 OC-CPC를 합성하였고, Aluminium 축을 갖는 Al-PILC 만든 후, cetylpyridinium chloride를 Al-PILC에 삽입시켜 IOC-CPC 화합물을 합성하였다. IR과 TGA를 이용하여 이들 구조를 분석한 결과 층간 삽입반응이 성공적으로 이루어졌음을 확인할 수 있었다. X-ray 회절을 이용하여 층간 거리를 조사하였는데 OC-CPC가 제일 큰 값을 보여 주었다. 층간 구조를 갖는 화합물들은 삽입반응을 이용하여 구조를 변형시킬 수 있으며 이를 통해 층간거리, 표면적, 공간 크기, 화학적 친화성 같은 여러 물리적 성질들을 바꿀 수 있으므로, 본 논문에서는 자연점토를 이용하여 층간 반응을 통해 휘발성 유기화합물의 흡착에 쓰일 수 있는 유용한 유기점토 화합물을 합성하고 이들의 구조를 확인코자 하였다. 벤젠과 톨루엔의 흡착은 IOC-CPC나 Al-PILC에서 보다 OC-CPC에서 더 잘 이루어졌으며, 자연점토에서는 거의 흡착이 일어나지 않았다. OC-CPC 화합물에서는 친 소수성 성질이 크고 층간 거리도 증가했기 때문에 흡착이 잘 일어났다고 볼 수 있으며, 반면에 친수성이 큰 Al-PILC 에서는 벤젠과 톨루엔 같은 휘발성 유기물에 대한 흡착이 상대적으로 적게 일어났다.

Phosphorus is one of the limiting nutrients for the growth of phytoplankton and algae and is therefore one of leading causes of eutrophication. Most phosphorous in water is present in the form of phosphates. Different technologies have been applied for phosphate removal from wastewater, such as physical, chemical precipitation by using ferric, calcium or aluminum salts, biological, and adsorption. Adsorption is one of efficient method to remove phosphates in wastewater. To find the optimal media for phosphate removal, physical characteristics of media was analysed, and the phosphate removal efficiency of media (silica sand, slag, zeolite, activated carbon) was also investigated in this study. Silica sand showed highest relative density and wear rate, and phosphate removal efficiency. Silica sand removed about 36% of phosphate. To improve the phosphate removal efficiency of silica sand, Fe coating was conducted. Fe coated silica sand showed 3 times higher removal efficiency than non-coated one.

Transition-metal oxide semiconductors have various band gaps. Therefore, many studies have been conducted in various application fields. Among these, methods for the adsorption of organic dyes and utilization of photocatalytic properties have been developed using various metal oxides. In this study, the adsorption and photocatalytic effects of WO3 nanomaterials prepared by hydrothermal synthesis are investigated, with citric acid added in the hydrothermal process as a structure-directing agent. The nanostructures of WO3 are studied using transmission electron microscopy and scanning electron microscopy images. The crystal structure is investigated using X-ray diffraction patterns, and the changes in the dye concentrations adsorbed on WO3 nanorods are measured with a UV-visible absorption spectrophotometer based on Beer-Lambert’s law. The methylene blue (MB) dye solution is subjected to acid or base conditions to monitor the change in the maximum adsorption amount in relation to the pH. The maximum adsorption capacity is observed at pH 3. In addition to the dye adsorption, UV irradiation is carried out to investigate the decomposition of the MB dye as a result of photocatalytic effects. Significant photocatalytic properties are observed and compared with the adsorption effects for dye removal.