Browsing by Author "Zeng, Wanting"

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Adsorption/Desorption Behaviors of Acetone over Micro-/Mesoporous SBA-16 Silicas Prepared from Rice Husk Agricultural Waste
(2016-09)
Zeng, Wanting
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
The preparation of micro-/mesoporous SBA-16 adsorbent by rice husk derived sodium silicate as the silica source and its acetone adsorption/desorption behaviors were reported for the first time. The pore structural properties of waste-derived SBA-16 materials were controlled and optimized by adjusting the surfactant/silica molar ratios from 0.002 to 0.01 for achieving the best acetone adsorption performance. And the relationship between structural properties and acetone adsorption performances of SBA-16 adsorbents was investigated. The resultant waste-derived SBA-16 materials, denoted as RSBA-16, had specific surface areas of 575-1001 m(2) g(-1), pore sizes of 3.3-3.7 nm and pore volumes of 0.41-0.72 cm(3) g(-1). Among the studied adsorbents, RSBA-16(0.004) exhibited the highest saturated acetone adsorption capacity of 179 mg g(-1). It also showed excellent regeneration stability during 20 consecutive cycles. The results indicated that specific surface areas in both micro-and meso-pore ranges were the main factor that determined the superiority of acetone adsorption capacity of RSBA-16(0.004) over other adsorbents such as mesoporous RMCM-41 and micro-/mesoporous RSBA-15. The acetone adsorption experiments at 500-5000 ppmv demonstrated that the adsorption isotherm was well fitted with the Langmuir model, thus the adsorption of acetone on RSBA-16 might be a monolayer physisorption process. The results demonstrated the high adsorption capacity and cyclic stability of waste-derived RSBA-16(0.004) can be considered as a potential adsorbent for VOCs removals.
High-performance CO2 capture on amine-functionalized hierarchically porous silica nanoparticles prepared by a simple template-free method
(2016-02)
Zeng, Wanting
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
The adsorption of CO2 on polyethyleneimine (PEI)-functionalized hierarchically porous silica nanoparticles (PSNs), prepared by using rice husk as a silica source via a simple template-free method, was reported in this study. Compared with traditional alkaline fusion and surfactant-templating methods for preparing waste-derived porous silica materials as CO2 adsorbents, this method holds specific important advantages in being an inexpensive, and energy-saving process with faster production rate. The results revealed that the (NH4)(2)SiF6 salt formed during the synthetic process served as an effective porogen, which can be readily removed by washing with water. Additionally, the total pore volumes of PSNs materials were strongly correlated to the amount of (NH4)(2)SiF6. When evaluated as a support of PEI for CO2 adsorption, 55PEI/PSNs(12/14) could reach 159 mg/g at 75 degrees C under 15 % CO2, which was remarkably superior to those using waste silicate precursors reported in the previous literature. It was demonstrated that both PEI loading, and total pore volume of the PEI/silica composite sorbents, played key roles on CO2 adsorption. Besides, 55PEI/PSNs(12/14) also showed high stability during 20 cycles of adsorption-desorption operation, implying its high potential in post-combustion CO2 capture.
Swelling-agent-free synthesis of rice husk derived silica materials with large mesopores for efficient CO2 capture
(2014-09-01)
Zeng, Wanting
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
Swelling-agent-free synthesis of silica materials with large mesopores were developed using silicate from rice husk ash (RHA) as an alternative silica precursor in this study. Unlike the conventional methods for preparing large-pore silica materials in which toxic and expensive additives were employed as swelling agents, the obtained silica materials with large mesopores could be facilely prepared via a simple temperature-controlled approach without adding pore expanders. The fusion and hydrothermal temperature effects on the structural properties of obtained mesoporous silicas were investigated by the XRD, nitrogen adsorption-desorption, SEM and TEM analyses. The obtained mesoporous MS-400(25), which was fabricated using rice husk fused at 400 degrees C and treated with sodium hydroxide at 25 degrees C, exhibited bimodal meso-porosities (2.7 and 24 nm) and large pore volume (1.92 cm(3)/g). The bi-porosities mainly originated from the intra-particle mesostructure within silica particles and the inter-particle porosity between the aggregated nano-sized silica particles, respectively. The synthesized silicas were applied as the supports of adsorbents for CO2 capture. The adsorption tests clearly revealed that the tetraethylenepentamine (TEPA) impregnated MS-400(25) material could achieve CO2 adsorption capacity of 173 mg/g under 10% CO2 at 75 degrees C, which was the best sorbents among all samples due to its relatively large pore volume. (C) 2014 Elsevier B.V. All rights reserved.