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Phase States of Polluted PM<SUB>2.5</SUB> at Seosan during a Winter Field Campaign in 2020
Sanjit Gaikwad,Dohyun Kim,Rani Jeong,Sangmin Oh,Kwangyul Lee,Minhye Jeong,Kyoung-Soon Jang,Changhyuk Kim,Mijung Song 한국대기환경학회 2021 한국대기환경학회 학술대회논문집 Vol.2021 No.10
PM2.5 pollutions have become a serious environmental issue in South Korea. However, still the physico-chemical properties of the polluted PM2.5 are not well-understood. In this study, a winter-field measurementwas conducted from 15 December 2020 to 15 January 2021 to investigate physico-chemical properties of PM2.5 using filter samples collected in a Seosan monitoring site. In addition, gaseous species, chemical compositions of PM2.5, and meteorological parameters were analyzed. Using all dataset, we investigated phases and phase states of the polluted PM2.5 showing that the aerosol particles were observed in liquid, and (semi) solid states over the atmospheric relative humidity. Moreover, these properties were linked with the aerosol pollutions observed in Seosan.
Sanjit Gaikwad,Seok-Jhin Kim,Sangil Han 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-
Three donor-acceptor type quinoxaline-based conjugated polymers, in which electron-donatingindacenodithiophene (IDT) and indacenodithieno[3,2-b]thiophene (IDTT) were connected to theelectron-accepting 2,3-diphenylquinoxaline (DPQ) derivatives, were synthesized using the Stillecoupling reaction. To investigate the effects of the strong electron-withdrawing cyano ( CN)substituent on the photovoltaic properties of polymers, it was selectively introduced in the DPQ uniton the polymer backbone. The combination of IDT and the standard DPQ produced the referencepolymer IDT-Qx, while the coupling of IDT and IDTT with mono-CN substituted DPQ provided thetarget polymers IDT-QxCN and IDTT-QxCN, respectively. Owing to the significant contributions of theCN substituent, IDT-QxCN and IDTT-QxCN exhibited better photovoltaic performances than IDT-Qxreference. Furthermore, the presence of more planar two thieno[3,2-b] thiophenes in IDTT than thetwo thiophenes in IDT allowed IDTT-QxCN to display the highest power conversion efficiency (5.47%)with an open circuit voltage of 0.95 V, short-circuit current density of 15.30 mA cm 2, andfill factorof 56.95%.
Ranjit Gaikwad,Sanjit Gaikwad,Sangil Han 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-
UTSA-16 (Zn) is the most promising adsorbent for CO2 capture because of its excellent CO2 capture performanceand low material cost. An eco-friendly synthesis method for UTSA-16 (Zn) was investigated bychanging the ratio of water to ethanol in solution (60:40 to 100:0) under microwave irradiation with differentwashing conditions: 1. diethyl ether and methanol washing (DEMW), 2. diethyl ether and waterwashing (DEWW), and 3. water washing (WW). Synthesis at an optimal ratio of water to ethanol(100:0) presented the best CO2 adsorption capacity of 5.08 mmol/g and CO2/N2 selectivity of 120. Theintegrity of the samples was investigated in terms of the particle morphology, crystallinity, porosity,and thermal stability using scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Telleranalysis, and thermogravimetric analysis. The stability of pelletized UTSA-16 (Zn) synthesized in awater-only solution was examined by exposing samples to humid air and acidic gases (NO2 and SO2);the pellets exhibited excellent stability to humid air and NO2 exposure. Additionally, the pellets exhibitedexcellent recyclability during the temperature swing adsorption–desorption process.
가이크와드란지트,Sanjit Gaikwad,Sangil Han 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.111 No.-
A series of bimetallic UTSA-16 (Zn, X; X = Mg, Mn, and Cu) metal organic frameworks (MOFs) with differentmetal ratios was synthesized using a microwave irradiation method. Synthesis at an optimalZn-to-metal ratio of 7:2 achieved a 9–18% increase in the CO2 adsorption capacity and an enhancedadsorption selectivity of CO2 over N2 compared to those of the parent UTSA-16 (Zn). Bimetallic UTSA-16 powders, with ratios of 7:2, were pelletized for a stability study that exposed the pellets to acid gases(NO2 and SO2) in a humid air condition; additionally, they underwent adsorption–desorption cyclicexperiments. The results showed that the CO2 capture performance was consistent after exposure toNO2 gas in humid air and adsorption–desorption cycling with temperature swing. The morphologicalproperties of the bimetallic MOFs were characterized using scanning electron microscopy,Brunauer Emmett Teller analysis, Fourier transform infrared spectroscopy, and X-ray diffraction. The characterization data showed that the bimetallic UTSA-16 (Zn, X) MOFs exhibited good crystallinityand morphology, similar to the original UTSA-16 (Zn) MOF.
Tentu Nageswara Rao,GAIKWAD SANJIT GULAB,Tentu Manohra Naidu,한상일 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.6
Multi-walled carbon nanotubes (MWCNT) were used as an adsorbent in a solid-phase extraction (SPE) process to detect pesticide residues in water. The MWCNT were prepared with polyvinyl pyrrolidone and polysilazane liquid by pyrolysis. The morphology and integrity of MWCNT were characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, X-ray diffractometer, and transmission electron microscope. Water samples including pesticides were passed through cartridges containing the MWCNT, where pesticides in the water were concentrated by adsorption. The analytical method for the detection of pesticides in dilute solution was proposed by using MWCNT as an adsorbent with gas chromatography/mass spectrometry for quantification of fenpropathrin, alphacypermethrin, and deltamethrin. The adsorption amounts of pesticides on the MWCNT were analyzed to identify the effects of temperature, flow rate, acidity, ionic strength, and analytes volume. The MWCNT-packed cartridges withstand a high load of water samples in the lowest concentration of 0.03 ng/L passing through for the extraction of pesticide residues at trace levels when compared with the commercial C18 cartridges, due to their large surface area and adsorption capacity.