Search

Showing total 228 results
Start Over Search Limiters Available in Library Collection Topic chemical bonding
228 results

224. Nuclear Quadrupole Resonance Studies on Inorganic Solids

Author

Sundara Ramaprabhu and K.V.S. Rama Rao

Subjects
CRYSTALLINE SUBSTANCES, Electron nuclear double resonance, Materials science, Nuclear magnetic resonance, CHEMICAL BONDING, NUCLEAR QUADRUPOLE RESONANCE, SOLIDS, RESONANT NUCLEUS, CRYSTALS - Physical Properties, INORGANIC SOLIDS, Condensed Matter Physics, Nuclear quadrupole resonance, Electronic, Optical and Magnetic Materials
Abstract

Since the first observation of nuclear quadrupole resonance (NQR) by Dehmelt and Kruger in 1950, there has been a continuous interest in this field and significant advances have been made in recent years. NQR frequency is regarded as a fingerprint of crystalline substances because it is characteristic not only of a molecule but also of a crystalline modification. From the standpoint of molecular structure, the NQR frequency reflects the electronic environment of the resonant nucleus and thereby provides useful information about chemical bonding. This paper mainly focusses on the experimental and theoretical investigations having come out during the period 1981 to 1983 on inorganic solids.

Published
1986

228. Synthesis, characterization, and debromination reactivity of cellulose-stabilized Pd/Fe nanoparticles for 2,2',4,4'-tretrabromodiphenyl ether.

Author

Huang, Guofu, Wang, Mianmian, Hu, Yongyou, Lv, Sihao, and Li, Changfang

Subjects
*DEBROMINATION, *CELLULOSE, *PALLADIUM, *IRON, *METAL nanoparticles, *SCANNING electron microscopes, *X-ray photoelectron spectroscopy, *X-ray diffractometers
Abstract

In this study, two kinds of cellulose derivatives (polyanionic cellulose (PAC) and hydroxypropylmethyl cellulose (HPMC)) were selected as stabilizers of Pd/Fe nanoparticles (NPs) to investigate their influences on the debromination performances of 2,2',4,4'-tretrabromodiphenyl ether (BDE47). Field emission scanning electron microscope (FE-SEM) images revealed that the cellulose-stabilized Pd/Fe NPs were smaller and more uniform than the bare-Pd/Fe NPs. X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) results suggested that cellulose coatings found on Pd/Fe NPs surfaces featured some antioxidation abilities, which followed the order of HPMC < PAC. Sedimentation tests demonstrated that the stabilizing power of PAC for Pd/Fe NPs was higher than that of HPMC. Fourier transfer infrared spectrometer (FTIR) results indicated that PAC molecules were bound to the Pd/Fe NPs surfaces by polar covalent bonds and hydrogen bonds, while HPMC molecules interacted with the nanoparticles by hydrogen bonds. Batch debromination test for BDE47 demonstrated that the catalytic debromination rate with cellulose-stabilized Pd/Fe NPs was higher than that with bare-Pd/Fe NPs during reaction period of 15 min. Overall, this study indicated that both celluloses are beneficial to forming smaller, more regular, stable and antioxidative Pd/Fe NPs, leading to higher debromination reactivity for BDE47 compared with the bare-Pd/Fe NPs. Therefore Pd/Fe NPs can be utilized as a promising remediation technology for the contaminated groundwater and soils. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF