Modeling and simulations of the removal of formaldehyde using silver nano-particles attached to granular activated carbon

Shin, SeungKyu,Song, JiHyeon Elsevier 2011 Journal of hazardous materials Vol.194 No.-

<P><B>Highlights</B></P><P>► Silver nano-particles were attached onto the surface of GAC for the simultaneous catalytic oxidation and adsorption reactions of formaldehyde. ► By the silver nano-particles, formaldehyde oxidation to carbon dioxide as expressed as pseudo-first-order. ► The nano-particle deposits reduced the available surface area of the GAC and blocked the openings of the micro-pores. ► The modified numerical model yielded an accurate prediction of the performance of the Ag-GAC. ► Depending on the surface coverage ratio, the factions of catalytic oxidation and the formaldehyde mass removed were proportionally changed.</P> <P><B>Abstract</B></P><P>A combined reaction, consisting of granular activated carbon (GAC) adsorption and catalytic oxidation, has been proposed to improve the removal efficiencies of formaldehyde, one of the major indoor air pollutants. In this study, silver nano-particles attached onto the surface of GAC (Ag-GAC) using the sputtering method were evaluated for the simultaneous catalytic oxidation and adsorption of formaldehyde. The evolution of CO<SUB>2</SUB> from the silver nano-particles indicated that formaldehyde was catalytically oxidized to its final product, with the oxidation kinetics expressed as pseudo-first order. In addition, a packed column test showed that the mass of formaldehyde removed by the Ag-GAC was 2.4 times higher than that by the virgin GAC at a gas retention time of 0.5s. However, a BET analysis showed that the available surface area and micro-pore volume of the Ag-GAC were substantially decreased due to the deposition of the silver nano-particles. To simulate the performance of the Ag-GAC, the homogeneous surface diffusion model (HSDM), developed for the prediction of the GAC column adsorption, was modified to incorporate the catalytic oxidation taking place on the Ag-GAC surface. The modified HSDM demonstrated that numerical simulations were consistent with the experimental data collected from the Ag-GAC column tests. The model predictions implied that the silver nano-particles deposited on the GAC reduced the adsorptive capacity due to decreasing the available surface for the diffusion of formaldehyde into the GAC, but the overall mass of formaldehyde removed by the Ag-GAC was increased due to catalytic oxidation as a function of the ratio of the surface coverage by the nano-particles.</P>

Oxidation of formaldehyde, carbon monoxide and methanol over manganese-cerium-aluminum oxides supported on cordierite monoliths

전수완,이정은,박정규,김상환 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.2

Catalytic oxidation of formaldehyde, carbon monoxide, and methanol over cordierite-supported manganese-cerium-aluminum mixed oxides was investigated in a laboratory reactor. The activities of base metal oxides (BMO)comprising 27% MnO2, 21% CeO2, and 52% Al2O3 supported on cordierite monoliths calcined at 1,000 oC for 3 h in airdropped very rapidly due to the migration of mobile silicon dioxide (SiO2) from the cordierite to the base metal oxidesto react with or physically block the active catalysts. To immobilize migrating SiO2, barrier coats composed of alkalimetal (Ba, Sr, Ca, Mg) oxides and alumina were applied to the cordierite prior to coating with active base metal oxides. The base metal oxides supported on cordierite monoliths pretreated with BaO-Al2O3 barrier coats and calcined at1,000 oC for 3 h in air, initiated the oxidation of HCHO, CO, and CH3OH at 150, 220, and 170 oC, respectively. Thesecatalysts turned out to be more effective for the formaldehyde oxidation than 0.5% Pt/Al2O3 precious metal catalysts. Carbon monoxide and methanol oxidation conversions were comparable. The incorporation of small amount of palladium(0.147 wt%) to base metal oxides supported on cordierite monoliths pretreated with BaO-Al2O3 barrier coats,showed the superiority for HCHO, CO, and CH3OH oxidation to 0.5% Pt/Al2O3 precious metal catalysts. The temperaturesof 50% conversion of formaldehyde, carbon monoxide and methanol were 70 oC lower over base metal oxidescatalysts than over precious metal catalysts.

UV-TiO2 광촉매 복합 흡착반응기에 의한 챔버 공기 중 포름알데히드 제거 특성

Jaemi Hendrix,최금찬 한국냄새환경학회 2015 실내환경 및 냄새 학회지 Vol.14 No.4

The potential use of UV-TiO2 photocatalytic oxidation absorbent reactor in the removal of gaseous formaldehyde was studied. This study was conducted inside a bench-type circulation reactor chamber at ambient air conditions. PCO (Photocatalytic Oxidaion) degradation test for formaldehyde was done repeatedly and the average was reported. It was evident that photocatalytic oxidation was proven to be an effective method to control indoor air pollutants, like formaldehyde in indoor air. However, by-products are produced in the case of formaldehyde degradation also CO2, CO, H2O and formic acid are produced. These by-products can inhibit the active site of the photocatalyst. Thus, addition of adsorbent succeeding the PCO-TiO2, acts as a secondary treatment wherein produced by-products from the degradation and unreacted HCHO will adhere to the surface of the adsorbent. In this study, synthetic zeolite and activated carbon pellets were used to control of by-products of formaldehyde. PCOTiO2 degradation alone achieves 86% for a period of 60 minutes. Addition of adsorbent improves the removal efficiency achieving 90% and 96% using activated carbon pellet and zeolite, respectively.

A review of the preparation and applications of MnO2 composites in formaldehyde oxidation

Shengnan Guan,Wenzhi Li,Jianru Ma,Yanyan Lei,Yuanshuai Zhu,Qifu Huang,Xiaomeng Dou 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-

This paper reviews several important preparation methods, and several kinds of MnO2 composites, which is efficient in formaldehyde catalytic oxidation. The preparation of MnO2 composites discussed in this article refer to sol–gel method, rheological phase reaction method, micro-emulsion method, chemical coprecipitation method, solid-phase synthesis and template method. After a presentation of methods for the preparation of MnO2, a review of the performance on formaldehyde catalytic oxidation over (I) manganese oxides; (II) metal–MnO2 oxide composites; (III) graphene–MnO2 composites is provided. The mechanisms for catalytic oxidation of HCHO over MnO2 composites, future directions and potential hotspots are also discussed to facilitate understanding.

SiO₂@V₂O₅@Al₂O₃ core–shell catalysts with high activity and stability for methane oxidation to formaldehyde

Yang, Euiseob,Lee, Jun Gyeong,Kim, Dong Hyeon,Jung, Yoon Seok,Kwak, Ja Hun,Park, Eun Duck,An, Kwangjin Elsevier 2018 Journal of catalysis Vol.368 No.-

<P><B>Abstract</B></P> <P>The stable tetrahedral geometry and high CH bond dissociation energy of methane complicate its direct catalytic conversion; for example, the selective oxidation of methane to formaldehyde, which avoids the production of carbon dioxide by full oxidation and is therefore important for the versatile utilization of natural gas, is still viewed as challenging. Here, we utilize hydrothermal synthesis followed by atomic layer deposition (ALD) to prepare an efficient and thermally stable catalyst based on novel SiO<SUB>2</SUB>@V<SUB>2</SUB>O<SUB>5</SUB>@Al<SUB>2</SUB>O<SUB>3</SUB> core@shell nanostructures, showing that the thickness of Al<SUB>2</SUB>O<SUB>3</SUB> shells over SiO<SUB>2</SUB>@V<SUB>2</SUB>O<SUB>5</SUB> cores can be tuned by controlling the number of ALD cycles. Catalytic methane oxidation experiments performed in a flow reactor at 600 °C demonstrate that SiO<SUB>2</SUB>@V<SUB>2</SUB>O<SUB>5</SUB>@Al<SUB>2</SUB>O<SUB>3</SUB> nanostructures obtained after 50 ALD cycles exhibit the best catalytic activity (methane conversion = 22.2%; formaldehyde selectivity = 57.8%) and outperform all previously reported vanadium-based catalysts at 600 °C. The prepared catalysts are subjected to in-depth characterization, which reveals that their Al<SUB>2</SUB>O<SUB>3</SUB> shell provides new surfaces for the generation of highly disperse T<SUB>d</SUB> monomeric species with a VOAl bond by promoting interactions between Al<SUB>2</SUB>O<SUB>3</SUB> and V<SUB>2</SUB>O<SUB>5</SUB> nanoparticles during ALD. Moreover, the surface Al<SUB>2</SUB>O<SUB>3</SUB> shell is found not only to protect V<SUB>2</SUB>O<SUB>5</SUB> nanoparticles against sintering at 600 °C, but also to anchor the produced T<SUB>d</SUB> monomeric vanadium species responsible for the high catalytic performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new core@shell catalyst is developed for partial methane oxidation. </LI> <LI> SiO<SUB>2</SUB>@V<SUB>2</SUB>O<SUB>5</SUB>@Al<SUB>2</SUB>O<SUB>3</SUB> nanostructure is an efficient and thermally stable catalyst. </LI> <LI> The thickness of Al<SUB>2</SUB>O<SUB>3</SUB> shells over SiO<SUB>2</SUB>@V<SUB>2</SUB>O<SUB>5</SUB> cores can be controlled. </LI> <LI> SiO<SUB>2</SUB>@V<SUB>2</SUB>O<SUB>5</SUB>@Al<SUB>2</SUB>O<SUB>3</SUB>-(50) nanostructures feature the best catalytic activity at 600 °C. </LI> <LI> A highly disperse vanadium species is formed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improvement in histology, enzymatic activity, and redox state of the liver following administration of Cinnamomum zeylanicum bark oil in rats with established hepatotoxicity

Fatemeh Niknezhad,Sara Sayad-Fathi,Arezoo Karimzadeh,Marjan Ghorbani-Anarkooli,Fatemeh Yousefbeyk,Ebrahim Nasiri 대한해부학회 2019 Anatomy & Cell Biology Vol.52 No.3

Formaldehyde (FA) is an environmentally-available pollutant. Since the liver acts as a detoxifier in the human body, it is the first and most affected organ in individuals exposed to higher-than-normal amounts of FA. FA mainly alters oxidant/ antioxidant status and initiates oxidative stress, and by means, causes functional damage to the liver. Thus, it is important to identify natural bioactive compounds with antioxidant properties in order to be used as food additives. Cinnamon (Cinnamomum zeylanicum) is a popular flavor and also a medicinal plant with a variety of beneficial effects. In the present original study, cinnamon essential oil (CEO) has been administrated at doses of 10, 20, and 100 mg/kg, orally, to hepatotoxicity rat models caused by FA (10 mg/kg, intraperitoneally). Liver enzymes and its histology were assessed and oxidative stress biomarkers in the liver tissue were also examined. CEO administration caused a significant increase in superoxide dismutase, glutathione peroxidase, and catalase and a prominent decrease in nitric oxide levels in the liver tissue. Also, in serum samples, CEO significantly reduced the elevated amounts of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase. When assessed histologically, portal area and central vein fibrosis alongside with the hepatocytes’ hypereosinophilia and swelling, focal inflammation, and necrotic areas were found to be prominently decreased in the CEO group. In conclusion, our study suggested that the CEO may have the potential for being used against FA-induced hepatotoxicity.

Graphene oxide/polymer composite for room temperature formaldehyde gas sensor

송민규,심상은 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Graphene has been considered as a promising candidate for vapor sensor since its high surface area, conductivity and sensitivity to its surroundings which are attributed to its unique 2D structure, functionalities on the graphene surface, conjugated carbon system and porosity. However, graphene should be functionalized by heteroatoms to assign selectivity and higher response compared to bare graphene itself. we introduce polyethyleneimine which contains abundant amount of nitrogen atoms via one step reaction. The as prepared sample is named as PEI-GO. The sample was characterized by IR, XPS, SEM. The sensing performance of the sample toward toxic gases was measured by our customized gas sensor system. It responded to formaldehyde gas most strongly among ammonia, trimethylamine, formaldehyde gas.

Evaluation of air quality with simple and easy chemical sensors: development of porous glass-based elements

Katsuyuki Izumi,Masahiro Utiyama,Yasuko Y. Maruo 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

The authors are tackling the development of novel chemical sensor elements for detecting air pollutants. The base material of the sensor elements is porous glass, which has favorable features such as transparency and porosity. The sensor elements were prepared by impregnating reagents in a sheet of porous glass. The reagents were the Saltzman reagent for the detection of nitrogen dioxide, β-diketones for formaldehyde and potassium iodide for oxidant. The resultant elements were colorless. The first element was highly sensitive and changed to clear wine red upon exposures to nitrogen dioxide. The second element for formaldehyde developed yellow and was detectable as low as a few tens ppb for an exposure time of 8 h. The third element for oxidant also showed high sensitivity. Evaluation of the effects of various gases on these elements, which are indispensable in applying them to the real atmosphere, is underway except for the NO2 elements. The concept leading to the present study is briefly explained.

연구보문 : 환경독성 ; 폐 대식세포주에서 포름알데히드에 의한 세포 사멸 효과에 대한 산화성 스트레스 관련성

박수현 ( Soo Hyun Park ) 韓國環境農學會 2009 한국환경농학회지 Vol.28 No.3

포름알데히드는 농약 노출 시에 나타나는 중요한 물질로 천식 및 알러지등의 호흡 질환을 일으키는 물질로 알려져 있으며, 폐에서 대식세포는 면역 반응에 있어서 방어 기능을 담당하는 세포로 알려져 있다. 그러나 대식세포에서 포름알데히드에 대한 효과는 알려져 있지 않고 있어서 대식 세포주인 Raw 264.7 세포를 이용하여 실험하였다. 실험 결과 포름알데히드는 세포 생존율을 감소 시켰으며, 이러한 반응은 항산화제인 vitamin C, NAC, 및 catalase 처리 시 차단되었다. 실제로 포름알데히드 처리시산화성 스트레스 지표인 lipid peroxide 형성이 증가하였으며 이들 반응 역시 항산화제들에 의해 차단되었다. 한편 포름알데히드 처리시 세포 사멸 촉진 단백질인 Bax 발현은 증가하였으며 세포 사멸 억제 단백질인 Bcl-2의 발현은 억제 되었으며 이러한 반응은 항산화제 처리시 차단되었다. 세포사멸 실행 단백질인 casapse-3의 활성형 역시 증가하였으며, 항산화제 처리시 차단되었다. 결론적으로 포름알데히드는 폐 대식세포에서 산화성 스트레스 증가를 통해 세포 사멸을 일으키는 것으로 나타났다. Formaldehyde (FA) is an important irritant compound in pesticide to induce asthma and allergy in respiratory system. Alveolar macrophage is also an pivotal cell in the immune response of respiratory system. However, the effect of FA in macrophage cell viability has not been elucidated. Thus, this study was conducted to investigate the effect of FA on apoptosis in Raw 264.7 cells, alveolar macrophage cell line. In this study, FA decreased cell viability of lung alveolar macrophage cells in a dose-dependent manner (>100 μM). FA-induced decrease of cell viability was blocked by the treatment of antioxidants (vitamin C, NAC, and catalase). Indeed, FA induced lipid peroxide formation in Raw 264.7 cells. FA decreased Bcl-2 expression but increased Bax expression in lung alveloar macrophage cells. In addition, FA also increased the cleaved form of caspase-3. In conclusion, FA induced apoptosis via oxidative stress in cultured Raw 264.7 cells.

실내 대기질 진단을 위한 금속산화물 기반 폼알데하이드 가스센서 연구 동향

김윤화,김일두,구원태,장지수 한국센서학회 2019 센서학회지 Vol.28 No.6

People currently spend more than 80% of their time indoors; therefore, the management of indoor air quality has become an important issue. The contamination of indoor air can cause sick house syndrome and various environmental diseases such as atopy and nephropathy. Formaldehyde gas, which is the main contaminant of indoor air, is lethal even with microscopic exposure; however, it is commonly used as an adhesive and waterproofing agent for indoor building materials. Therefore, there is a need for a gas sensor capable of detecting trace amounts of formaldehyde gas. In this review, we summarize recent studies on metal oxide-based semiconductor gas sensors for formaldehyde gas detection, methods to improve the gas-sensing properties of metal oxides of various dimensions, and the effects of catalysts for the detection of parts-per-billion level gases. Through this, we discuss the necessary characteristics of the metal oxidebased semiconductors for gas sensors for the development of next-generation sensors.