Experimental and theoretical studies of the schiff base (<i>Z</i>)-1-(thiophen-2-yl- methyleneamino) propane-2-ol

Berhanu, Asnake Lealem,Sharma, Neha,Mohiuddin, Irshad,Malik, Ashok Kumar,Aulakh, Jatinder Singh,Lee, Jechan,Kim, Ki-Hyun Elsevier 2020 Journal of molecular structure Vol.1200 No.-

<P><B>Abstract</B></P> <P>In this study, a quantum chemical model was developed to better account for the properties of a Schiff base, (<I>Z</I>)-1-(thiophen-2-yl-methyleneamino) propane-2-ol, which is derived from thiophene-2-carboxy aldehyde and 1-amino-2-propanol. To predict its molecular structure, the assignment of the vibrational wavelength (for FT-IR) and chemical shift (for <SUP>1</SUP>HNMR) of (<I>Z</I>)-1-(thiophen-2-yl-methyleneamino) propane-2-ol was performed experimentally and theoretically. All of the theoretical calculations were performed using the Gaussian 09 program package. The theoretically and experimentally obtained results were in good agreement (R<SUP>2</SUP> ≥ 0.99). The energies of the highest occupied and lowest unoccupied molecular orbitals were estimated using B3LYP (Becke three-parameter hybrid functional combined with Lee–Yang–Parr correlation functional)/6-311++G (d, p). Optimization of the structure of (<I>Z</I>)-1-(thiophen-2-yl-methyleneamino) propane-2-ol provided information concerning the stable form of the geometry of the molecule, stoichiometry of the complexes, and thermodynamic parameters (e.g., energy and entropy). The results indicate that the Schiff base formed stable complexes with Ni<SUP>2+</SUP>. The energy of the complex was much lower than that of the free Schiff base. The charge distribution values of each atom in the Schiff base were in agreement with the Pauling scale for electronegativity and vibrational wavelength.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Experimental and Theoretical study of (Z)-1-(thiophen-2-yl-methyleneamino) propane-2-ol was investigated. </LI> <LI> The vibrational FTIR wavelength and chemical shift (for <SUP>1</SUP>HNMR) were studied with DFT studies. </LI> <LI> (Z)-1-(thiophen-2-yl-methyleneamino) propane-2-ol formed a more stable complex with Ni<SUP>2+</SUP>. </LI> <LI> Bond lengths and bond angles were calculated to characterize its strength. </LI> <LI> HOMO -LUMO energy gap of the Schiff base was calculated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Energy density enhancement <i>via</i> pyrolysis of paper mill sludge using CO₂

Lee, Jechan,Tsang, Yiu Fai,Kim, Sungpyo,Ok, Yong Sik,Kwon, Eilhann E. Elsevier 2017 Journal of CO<SUB>2</SUB> utilization Vol.17 No.-

<P><B>Abstract</B></P> <P>Paper manufacture is a very energy-intensive industry and generates a large amount of waste such as paper mill sludge (PMS). Given that the current PMS disposal ways (<I>e.g.</I>, incineration and landfilling) are not eco-friendly and costly, establishing an appropriate PMS disposal platform including energy recovery is crucial to making more environmentally benign and economically viable industrial paper manufacturing process. In this respect, this study places a great emphasis on investigating the influence of CO<SUB>2</SUB> on pyrolysis of PMS by systematical analysis of major three-phase pyrolytic products, such as gases and tar, under N<SUB>2</SUB> and CO<SUB>2</SUB> atmospheres. It was validated that using CO<SUB>2</SUB> as a reaction medium in pyrolysis of PMS not only increased the production of CO (a major constituent of syngas) by ∼1000% but also decreased the amount of tar by 23%. The increase in CO production and decrease in tar formation likely resulted from reactions between CO<SUB>2</SUB> and volatile organic compounds (VOCs) generated from thermal decomposition of PMS, which could be expedited by catalytic effects of minerals contained in PMS. The results shown in this paper could be applied to design green paper manufacturing processes efficiently utilizing a potent greenhouse gas, CO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Paper mill sludge (PMS) disposal <I>via</I> the thermo-chemical process. </LI> <LI> Using CO<SUB>2</SUB> for the energy density enhancement. </LI> <LI> The influence of CO<SUB>2</SUB> was enhanced in the presence of minerals of PMS. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effects of carbon dioxide on pyrolysis of peat

Lee, Jechan,Yang, Xiao,Song, Hocheol,Ok, Yong Sik,Kwon, Eilhann E. Elsevier 2017 ENERGY Vol.120 No.-

<P><B>Abstract</B></P> <P>This study focuses on the mechanistic understanding of effects of CO<SUB>2</SUB> on pyrolysis of peat. To do this, three pyrolytic products (<I>i.e.</I>, syngas: H<SUB>2</SUB> and CO, pyrolytic oil (tar), and biochar) were characterized. Thermal cracking of volatile organic carbons (VOCs) generated from pyrolysis of peat was enhanced in the presence of CO<SUB>2</SUB>. Besides the enhanced thermal cracking of VOCs, unknown reaction between CO<SUB>2</SUB> and VOCs was also identified. Accordingly, CO<SUB>2</SUB> played a role in enhancing syngas production and in reducing tar formation in pyrolysis of peat. This study also reveals that peat-biochar produced in CO<SUB>2</SUB> exhibited a larger surface area than that produced in N<SUB>2</SUB>. The results shown in this paper would be used for various applications such as energy recovery from peat using a potent greenhouse gas (for example, CO<SUB>2</SUB>).</P> <P><B>Highlights</B></P> <P> <UL> <LI> More CO can be produced from pyrolysis of peat in CO<SUB>2</SUB> than in N<SUB>2</SUB>. </LI> <LI> Less amount of tar produced from pyrolysis of peat in CO<SUB>2</SUB> than in N<SUB>2</SUB>. </LI> <LI> Surface area of peat-biochar made in CO<SUB>2</SUB> is larger than that made in N<SUB>2</SUB>. </LI> <LI> CO<SUB>2</SUB> can modify the quantity/quality of pyrolytic products from peat. </LI> </UL> </P>

Establishing a green platform for biodiesel synthesis via strategic utilization of biochar and dimethyl carbonate

Lee, Jechan,Jung, Jong-Min,Oh, Jeong-Ik,Sik Ok, Yong,Kwon, Eilhann E. Elsevier Applied Science 2017 Bioresource technology Vol.241 No.-

<P><B>Abstract</B></P> <P>To establish a green platform for biodiesel production, this study mainly investigates pseudo-catalytic (non-catalytic) transesterification of olive oil. To this end, biochar from agricultural waste (maize residue) and dimethyl carbonate (DMC) as an acyl acceptor were used for pseudo-catalytic transesterification reaction. Reaction parameters (temperature and molar ratio of DMC to olive oil) were also optimized. The biodiesel yield reached up to 95.4% under the optimal operational conditions (380°C and molar ratio of DMC to olive oil (36:1)). The new sustainable environmentally benign biodiesel production introduced in this study is greener and faster than conventional transesterification reactions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sustainable production of biodiesel using biochar and dimethyl carbonate. </LI> <LI> A high biodiesel yield from vegetable oil by pseudo-catalytic transesterification. </LI> <LI> New application of biochar derived from waste biomass. </LI> </UL> </P>

Rapid biodiesel synthesis from waste pepper seeds without lipid isolation step

Lee, Jechan,Kim, Jieun,Ok, Yong Sik,Kwon, Eilhann E. Elsevier 2017 Bioresource technology Vol.239 No.-

<P><B>Abstract</B></P> <P> <I>In situ</I> transformation of lipid in waste pepper seeds into biodiesel (<I>i.e.</I>, fatty acid methyl esters: FAMEs) via thermally-induced transmethylation on silica was mainly investigated in this study. This study reported that waste pepper seeds contained 26.9wt% of lipid and that 94.1% of the total lipid in waste pepper seeds could be converted into biodiesel without lipid extraction step for only∼1min reaction time. This study also suggested that the optimal temperature for <I>in situ</I> transmethylation was identified as 390°C. Moreover, comparison of <I>in situ</I> process via the conventional transmethylation catalyzed by H<SUB>2</SUB>SO<SUB>4</SUB> showed that the introduced biodiesel conversion in this study had a higher tolerance against impurities, thereby being technically feasible. The <I>in situ</I> biodiesel production from other oil-bearing food wastes can be studied.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biodiesel production with high yield from waste pepper seeds without lipid isolation. </LI> <LI> Biodiesel synthesis with high tolerance against impurities contained in the seeds. </LI> <LI> Optimization of reaction temperature for thermally induced <I>in situ</I> transmethylation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Sustainable approach to biodiesel synthesis via thermally induced transesterification using biochar as surrogate porous media

Lee, Jechan,Jung, Jong-Min,Ok, Yong Sik,Kwon, Eilhann E. Elsevier 2017 Energy conversion and management Vol.151 No.-

<P><B>Abstract</B></P> <P>This study validates whether maize residue biochar could be used as surrogate porous media for thermally induced transesterification of waste cooking oil. The highest yield of fatty acid methyl esters (FAMEs) reached up to 91% at 300°C with the biochar while it reached at 380°C with silica. This suggests that energy saving can be expected using biochar in the biodiesel production process. Larger pore size and wider pore distribution of the biochar likely provides favorable conditions for the high biodiesel yield at lower temperature than silica. Based on similar FAME yields between refined soybean oil and waste cooking oil, the thermally induced transesterification with the biochar exhibited an extraordinary tolerance against impurities in waste cooking oil.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sustainable biodiesel production with carbon-neutral resources. </LI> <LI> Biochar acts asan excellent porous material for biodiesel synthesis. </LI> <LI> Enhanced production of biodiesel compared to commercial porous media. </LI> <LI> Lowering optimal temperature for thermally induced transesterification with biochar. </LI> </UL> </P>

Production of renewable C4–C6 monoalcohols from waste biomass-derived carbohydrate via aqueous-phase hydrodeoxygenation over Pt-ReO<i> _x </i>/Zr-P

Lee, Jechan,Ro, Insoo,Kim, Hyung Ju,Kim, Yong Tae,Kwon, Eilhann E.,Huber, George W. Elsevier 2018 Process safety and environmental protection Vol.115 No.-

<P><B>Abstract</B></P> <P>A bifunctional catalyst, Pt-ReO<I> <SUB>x</SUB> </I> supported on zirconium phosphate (Pt-ReO<I> <SUB>x</SUB> </I>/Zr-P), was prepared and tested for aqueous-phase hydrodeoxygenation (APHDO) of waste biomass-derived carbohydrate (<I>e.g.</I>, sorbitol) to produce C4–C6 monoalcohols such as butanol, pentanol, and hexanol in a high-pressure continuous flow reactor. For steady-state operation, the reaction parameters were optimized to achieve the highest yield of C4–C6 monoalcohols from APHDO of sorbitol. Approximately 30% yield of C4–C6 monoalcohols was reached at optimal reaction conditions (temperature: 453K, pressure: 6.21MPa, weight hourly space velocity (WHSV): 0.16h<SUP>−1</SUP>) for APHDO of sorbitol over the Pt-ReO<I> <SUB>x</SUB> </I>/Zr-P catalyst. The effect of catalyst support for monoalcohol production was also evaluated by comparison between the Pt-ReO<I> <SUB>x</SUB> </I>/Zr-P and carbon supported Pt-ReO<I> <SUB>x</SUB> </I> (Pt-ReO<I> <SUB>x</SUB> </I>/C) catalysts. The Zr-P supported catalyst exhibited a four times higher yield of C4–C6 monoalcohols than the carbon supported catalyst, suggesting that acid sites atomically separated from metal sites play a crucial role in producing monoalcohols via CO bond cleavage of chemical intermediates produced during APHDO of sorbitol.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Production of C4–C6 monoalcohols from sorbitol via hydrodeoxygenation. </LI> <LI> Pt-ReO<I> <SUB>x</SUB> </I>/Zr-P catalyst gave 30% C4–C6 monoalcohol yield for APHDO of sorbitol. </LI> <LI> Optimized APHDO conditions for C4–C6 monoalcohol production from sorbitol. </LI> </UL> </P>

Utilizing CO₂ to suppress the generation of harmful chemicals from thermal degradation of polyvinyl chloride

Lee, Taewoo,Lee, Jechan,Ok, Yong Sik,Oh, Jeong-Ik,Lee, Sang-Ryong,Rinklebe, Jö,rg,Kwon, Eilhann E. Elsevier 2017 Journal of cleaner production Vol.162 No.-

<P><B>Abstract</B></P> <P>This study put a great emphasis on the role of carbon dioxide (CO<SUB>2</SUB>) in thermal decomposition of polyvinyl chloride (PVC). To do this, systematic experimental works were carried out to explore the influence of CO<SUB>2</SUB> on pyrolysis of PVC by comparing with that in N<SUB>2</SUB>. First of all, a series of thermo-gravimetric analysis (TGA) of PVC in N<SUB>2</SUB> and CO<SUB>2</SUB> was performed to characterize the thermal deconstruction of PVC in N<SUB>2</SUB> and CO<SUB>2</SUB>, which confirmed that any physical aspect (<I>i.e.</I>, onset and end temperature of depolymerization of PVC) attributed by CO<SUB>2</SUB> was nearly negligible as compared to the case in N<SUB>2</SUB>. This phenomenon was also fully evidenced by differential thermogram (DTG) and differential scanning calorimeter (DSC) because both DTG and DSC curves in N<SUB>2</SUB> and CO<SUB>2</SUB> were identical. However, the concentration profiles of CO evolved from the thermal degradation of PVC in N<SUB>2</SUB> and CO<SUB>2</SUB> was significantly different: the enhanced generation of CO occurred in the presence of CO<SUB>2</SUB>. This observation suggested that the genuine role of CO<SUB>2</SUB> is to consume carbon source (<I>i.e.</I>, acting as a carbon scavenger) for pyrolysis of PVC. It also provided a favorable condition for suppressing the formation of harmful chemical compounds such as benzene derivatives and polycyclic aromatic hydrocarbons (PAHs). Therefore, the mass portion of the oil in pyrolytic products produced from pyrolysis of PVC in CO<SUB>2</SUB> was lower than that in N<SUB>2</SUB>. These particular thermal degradation behaviors may be explained by the genuine role of CO<SUB>2</SUB>: the enhanced thermal cracking of volatile organic carbons (VOCs) evolved from the pyrolysis of PVC. The findings of this study strongly suggest that CO<SUB>2</SUB> can be effectively applied to thermal disposal of recalcitrant wastes since employing CO<SUB>2</SUB> in thermal treatment provides a means for <I>in-situ</I> mitigation and/or reduction of harmful chemical species.</P>

Evaluating the effectiveness of various biochars as porous media for biodiesel synthesis via pseudo-catalytic transesterification

Lee, Jechan,Jung, Jong-Min,Oh, Jeong-Ik,Ok, Yong Sik,Lee, Sang-Ryong,Kwon, Eilhann E. Elsevier 2017 Bioresource technology Vol.231 No.-

<P><B>Abstract</B></P> <P>This study focuses on investigating the optimized chemical composition of biochar used as porous material for biodiesel synthesis via pseudo-catalytic transesterification. To this end, six biochars from different sources were prepared and biodiesel yield obtained from pseudo-catalytic transesterification of waste cooking oil using six biochars were measured. Biodiesel yield and optimal reaction temperature for pseudo-catalytic transesterification were strongly dependent on the raw material of biochar. For example, biochar generated from maize residue exhibited the best performance, which yield was reached ∼90% at 300°C; however, the maximum biodiesel yield with pine cone biochar was 43% at 380°C. The maximum achievable yield of biodiesel was sensitive to the lignin content of biomass source of biochar but not sensitive to the cellulose and hemicellulose content. This study provides an insight for screening the most effective biochar as pseudo-catalytic porous material, thereby helping develop more sustainable and economically viable biodiesel synthesis process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sustainable biodiesel production by using biochar with a high yield. </LI> <LI> Optimization of pseudo-catalytic transesterification temperature on biochar. </LI> <LI> Pseudo-catalytic biodiesel yield on biochar sensitive to lignin content of biomass. </LI> </UL> </P>

The role of algae and cyanobacteria in the production and release of odorants in water

Lee, Jechan,Rai, Prabhat Kumar,Jeon, Young Jae,Kim, Ki-Hyun,Kwon, Eilhann E. Elsevier 2017 Environmental pollution Vol.227 No.-

<P><B>Abstract</B></P> <P>This review covers literatures pertaining to algal and cyanobacterial odor problems that have been published over the last five decades. Proper evaluation of algal and cyanobacterial odors may help establish removal strategies for hazardous metabolites while enhancing the recyclability of water. A bloom of microalgae is a sign of an anthropogenic disturbance in aquatic systems and can lead to diverse changes in ecosystems along with increased production of odorants. In general, because algal and cyanobacterial odors vary in chemistry and intensity according to blooming pattern, it is necessary to learn more about the related factors and processes (<I>e.g.</I>, changes due to differences in taxa). This necessitates systematic and transdisciplinary approaches that require the cooperation of chemists, biologists, engineers, and policy makers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The type of odorants in water is highly dependent on algal or cyanobacterial species. </LI> <LI> Analytical techniques to trace the odorants in water are introduced. </LI> <LI> Factors affecting the production of odorants in water are discussed. </LI> <LI> Technical approaches for odorants treatment are also discussed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>