Search

Your search keyword '"Lam, Chun Ho"' showing total 113 results
Start Over Author "Lam, Chun Ho"
113 results on '"Lam, Chun Ho"'

8. Teaching Electrochemistry with Common Objects: Electrocatalytic Hydrogenation of Acetol with U.S. Coins

Author

Lam, Chun Ho and Jackson, James E.

Abstract

Electrocatalytic hydrogenation of acetol (IUPAC: 1-hydroxy-2-propanone), a species formed upon thermal liquefaction of biomass, can be achieved using inexpensive objects: filter paper, coins, batteries, salts, and water. This simple example demonstrates that "green" chemical transformations can be achieved with familiar items and helps students appreciate that chemistry is all around them. It also illustrates reactivity contrasts between nickel and copper as catalytic metals effecting hydrogenation. Reactions can be completed in 2 to 2.5 h and can be analyzed visually on the basis of a color change or more quantitatively with classic visible wavelength spectrophotometers that can be found in almost any high school or undergraduate institution. Reagents used in the experiment are nontoxic and can be easily disposed of safely.

Published
2020
Full Text
View/download PDF

13. Teaching Atom Economy and E-Factor Concepts through a Green Laboratory Experiment: Aerobic Oxidative Cleavage of Mesohydrobenzoin to Benzaldehyde Using a Heterogeneous Catalyst

Author

Lam, Chun Ho, Escande, Vincent, Mellor, Karolina E., Zimmerman, Julie B., and Anastas, Paul T.

Abstract

We herein report an efficient aerobic oxidative cleavage of meso-hydrobenzoin to benzaldehyde using a heterogeneous earth-abundant metal oxide catalyst. The reaction can be carried out at 70 °C in ethanol and uses a balloon filled with O2 as oxidant. Reagents are simple and have long shelf lives, and the whole laboratory exercise can be done in 120 min, which makes it highly implementable to standard undergraduate organic curriculum. meso-Hydrobenzoin cleaves exclusively to benzaldehyde, which gives off a nice almond smell, and generates water as the only byproduct. The exercise also compares the present methodology with two other conventional diol oxidative cleavage protocols to illustrate the use of atom economy and E-factor. This laboratory exercise is suitable for second-year undergraduates because it does not require any prerequisites while demonstrating the concepts of catalysis, ease of separation, atom economy, E-factor, earthabundant material utilization, and biomass transformation.

Published
2019
Full Text
View/download PDF

16. Fermentative bioconversion of food waste into biopolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) using Cupriavidus necator

Author

Hathi, Zubeen J., primary, Haque, Md Ariful, additional, Priya, Anshu, additional, Qin, Zi-hao, additional, Huang, Shuquan, additional, Lam, Chun Ho, additional, Ladakis, Dimitris, additional, Pateraki, Chrysanthi, additional, Mettu, Srinivas, additional, Koutinas, Apostolis, additional, Du, Chenyu, additional, and Lin, Carol Sze Ki, additional

Published
2022
Full Text
View/download PDF

27. Enhancing the Properties of Photocatalysts via Nonthermal Plasma Modification: Recent Advances, Treatment Variables, Mechanisms, and Perspectives

Author

Chen, Qianqian, Song, Bing, Li, Xiaochen, Wang, Renjie, Wang, Shun, Xu, Sankui, Reniers, François, Lam, Chun Ho, Chen, Qianqian, Song, Bing, Li, Xiaochen, Wang, Renjie, Wang, Shun, Xu, Sankui, Reniers, François, and Lam, Chun Ho

Abstract

Surface modification is crucial in improving catalyst activity, since all catalytic reactions occur on the surface of the catalyst. This review discusses the application of nonthermal plasmas (NTP) for surface modification and functionalization of heterogeneous photocatalysts. NTP pretreatment provides an environmentally friendly and effective means for functionalization, surface etching, and/or defect regulation on the surface of photocatalysts. The correlations between modification variables and the properties of catalysts are reviewed in depth. Moreover, insights into the modification mechanisms are reviewed to provide state-of-the-art understanding and suggest that more advanced modification can be achieved. Finally, challenges and perspectives for future studies are provided., SCOPUS: re.j, info:eu-repo/semantics/published

Published
2021

30. Polymerization During Low-Temperature Electrochemical Upgrading of Bio-Oil: Effects of Interactions Among Bio-Oil Fractions

Author

Deng, Wei, primary, Wang, Xuepeng, additional, Syed-Hassan, Syed Shatir A., additional, Lam, Chun Ho, additional, Hu, Xun, additional, Xiong, Zhe, additional, Han, Hengda, additional, Xu, Jun, additional, Jiang, Long, additional, Su, Sheng, additional, Hu, Song, additional, Wang, Yi, additional, and Xiang, Jun, additional

Published
2021
Full Text
View/download PDF

35. Aqueous SOA formation from the photo-oxidation of vanillin: Direct photosensitized reactions and nitrate-mediated reactions.

Author

Mabato, Beatrix Rosette Go, Lyu, Yan, Ji, Yan, Huang, Dan Dan, Li, Xue, Nah, Theodora, Lam, Chun Ho, and Chan, Chak K.

Abstract

Vanillin (VL), a phenolic aromatic carbonyl abundant in biomass burning emissions, forms triplet excited states (3VL*) under simulated sunlight leading to aqueous secondary organic aerosol (aqSOA) formation. This direct photosensitized oxidation of VL was compared with nitrate-mediated VL photo-oxidation under atmospherically relevant cloud and fog conditions, through examining the VL decay kinetics, product compositions, and light absorbance changes. The majority of the most abundant products from both VL photo-oxidation pathways were potential Brown carbon (BrC) chromophores. In addition, both pathways generated oligomers, functionalized monomers, and oxygenated ring-opening products, but nitrate promoted functionalization and nitration, which can be ascribed to its photolysis products (•OH, •NO2, and N(III), NO2- or HONO). Moreover, a potential imidazole derivative observed from nitrate-mediated VL photo-oxidation suggested that ammonium may be involved in the reactions. The effects of secondary oxidants from 3VL*, pH, the presence of volatile organic compounds (VOCs) and inorganic anions, and reactants concentration and molar ratios on VL photo-oxidation were also explored. Our findings show that the secondary oxidants (1O2, O2•-/•HO2, •OH) from the reactions of 3VL* and O2 play an essential role in VL photo-oxidation. Enhanced oligomer formation was noted at pH < 4 and in the presence of VOCs and inorganic anions, probably due to additional generation of radicals (•HO2 and CO3•-). Also, functionalization was dominant at low VL concentration, whereas oligomerization was favored at high VL concentration. Furthermore, guaiacol oxidation by photosensitized reactions of VL was observed to be more efficient relative to nitrate-mediated photo-oxidation. Lastly, potential VL photo-oxidation pathways under different reaction conditions were proposed. This study indicates that the direct photosensitized oxidation of VL, which nitrate photolysis products can further enhance, may be an important aqSOA source in areas influenced by biomass burning emissions. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

38. The Green ChemisTREE: 20 years after taking root with the 12 principles

Author

Erythropel, Hanno C., primary, Zimmerman, Julie B., additional, de Winter, Tamara M., additional, Petitjean, Laurène, additional, Melnikov, Fjodor, additional, Lam, Chun Ho, additional, Lounsbury, Amanda W., additional, Mellor, Karolina E., additional, Janković, Nina Z., additional, Tu, Qingshi, additional, Pincus, Lauren N., additional, Falinski, Mark M., additional, Shi, Wenbo, additional, Coish, Philip, additional, Plata, Desirée L., additional, and Anastas, Paul T., additional

Published
2018
Full Text
View/download PDF

44. Teaching Electrochemistry with Common Objects: Electrocatalytic Hydrogenation of Acetol with U.S. Coins

Author

Lam, Chun Ho and Jackson, James E.

Abstract

Electrocatalytic hydrogenation of acetol (IUPAC: 1-hydroxy-2-propanone), a species formed upon thermal liquefaction of biomass, can be achieved using inexpensive objects: filter paper, coins, batteries, salts, and water. This simple example demonstrates that “green” chemical transformations can be achieved with familiar items and helps students appreciate that chemistry is all around them. It also illustrates reactivity contrasts between nickel and copper as catalytic metals effecting hydrogenation. Reactions can be completed in 2 to 2.5 h and can be analyzed visually on the basis of a color change or more quantitatively with classic visible wavelength spectrophotometers that can be found in almost any high school or undergraduate institution. Reagents used in the experiment are nontoxic and can be easily disposed of safely.

Published
2020
Full Text
View/download PDF

47. A switchable route to valuable commodity chemicals from glycerol via electrocatalytic oxidation with an earth abundant metal oxidation catalyst.

Author

Lam, Chun Ho, Bloomfield, Aaron J., and Anastas, Paul T.

Subjects
*ELECTROCATALYSIS, *GLYCERIN
Abstract

Electrocatalytic upgrading of glycerol to value-added commodity is demonstrated using an ultralow loading of a cobalt-based oxidation catalyst at 16 μg cm−2. Reactions take place under ambient conditions in an aqueous environment, while generating H2 as a byproduct. Selectivity towards two major products, lactic acid and glyceric acid, can be controlled via simple variation of reaction conditions. The system is scalable and functions well even in the presence of methanol, an impurity commonly found in the industrial bio-diesel waste stream. Industrial glycerol waste from a local bio-diesel plant was also shown to be upgradable after a simple aqueous pretreatment. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results