| 1. |
- Liu, Shuai, et al.
(author)
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Development of Pdn/g-C3N4 adsorbent for Hg0 removal – DFT study of influences of the support and Pd cluster size
- 2019
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In: Fuel. - : Elsevier BV. - 0016-2361. ; 254
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Journal article (peer-reviewed)abstract
- Elemental mercury in the flue gas is highly hazardous to the ecosystem. However, its removal from gas phase is of challenges as it is highly volatile, chemically very stable and insoluble in water. It is therefore imperative to develop novel adsorbents that are efficient in the removal of elemental mercury from gas mixtures. In this study, density functional theory (DFT) was adopted to assist the development of novel adsorbents for mercury removal based on the in-depth understanding of the adsorption of Hg0 on g-C3N4, single Pd atoms and Pdn(n=2–4) clusters as well as the influences of the support and the size of Pd clusters on Hg0 adsorption. It is found that Hg0 atoms are physically adsorbed on the pristine g-C3N4 and are chemisorbed on the pure Pdn clusters and the Pdn/g-C3N4. The strongest adsorption happens on the Pd2 cluster and the Pd3/g-C3N4, while single Pd atoms doped on the g-C3N4 do not adsorb Hg0 atoms effectively. For a Pd4 cluster, there are at least four adsorption sites for the adsorption of Hg0, while these sites become more active in the presence of the support and the number of active sites for Hg0 adsorption on a Pd4 cluster doped on the g-C3N4 becomes seven due to the enhanced charge transfer from Hg atoms to the Pd cluster and the g-C3N4 surface. The most charge transfers are found to take place in the case of Pd2, Pd2/g-C3N4 and Pd3/g-C3N4, indicating the most intensive interactions between Hg0 and these configurations. Moreover, the shortened Pd-Hg bonds in the Pd3/g-C3N4 and the Pd4/g-C3N4 also shows the enhanced mercury adsorption, while opposite phenomena were observed in the other two structures, i.e., the Pd/g-C3N4 and the Pd2/g-C3N4.
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| 2. |
- Wang, Ruifu, et al.
(author)
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Morphology and Flow Behavior of Cellulose Nanofibers Dispersed in Glycols
- 2019
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In: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 52:15, s. 5499-5509
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Journal article (peer-reviewed)abstract
- Understanding the morphology and flow behavior of cellulose nanofibers (CNFs) dispersed in organic solvents can improve the process of fabricating new cellulose-based nanocomposites. In this study, jute-based 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-oxidized CNFs with two different charge densities (0.64 and 1.03 mmol/g) were dispersed in ethylene glycol (EG) and propylene glycol (PG) using the solvent exchange method. The morphology and dimensions of CNFs in dry and suspension states were characterized using transmission electron microscopy, atomic force microscopy, and small-angle X-ray scattering techniques. The results showed that the cross-sectional dimensions remained the same in different solvents. Rheological measurements revealed that CNF suspensions in water or glycol (EG and PG) behaved similar to typical polymer solutions with a solvent-independent overlap concentration corresponding to the crowding factor of about 14. Furthermore, a thixotropic behavior was found in the concentrated CNF/glycol systems as observed in typical CNF aqueous suspensions. The fact that TEMPO-oxidized CNFs can be well dispersed in organic solvents opens up new possibilities to improve the CNF–polymer matrix blending, where the use of a viscous solvent can delay the transition to turbulence in processing and improve the control of fiber orientation because of a slower Brownian diffusive motion.
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