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Comparison study on strategies to prepare nanocrystalline Li2ZrO3-based absorbents for CO2 capture at high temperatures
Qiang XIAO, Xiaodan TANG, Yefeng LIU, Yijun ZHONG, Weidong ZHU
Front Chem Sci Eng. 2013, 7 (3): 297-302.
https://doi.org/10.1007/s11705-013-1346-1
A comparison study has been conducted on the strategies for synthesizing nanocrystalline Li2ZrO3 and K-doped Li2ZrO3 absorbents for CO2 capture at high temperatures, including solid-state and liquid-phase methods, citrate route, and starch-assisted sol-gel method combined with freeze-drying technique. The absorption properties, including uptake rate and absorption capacity, of synthesized absorbents were investigated by thermogravimetric analysis (TGA) at different CO2 partial pressures. The nanosized Li2ZrO3 crystals synthesized by the citrate route exhibit a faster uptake and a higher, nearly stoichiometric absorption capacity than those synthesized by the solid-state and liquid-phase methods. The doping of K into Li2ZrO3 can significantly improve the uptake rate of CO2, especially at low CO2 partial pressures. For the synthesis of K-doped Li2ZrO3, the citrate route has poor reproducibility and scalability, whereas the starch-assisted sol-gel method combined with freeze-drying technique is reproducible and easily scaled up, and the thus synthesized absorbents possess excellent CO2 capture properties.
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Investigation of hydrolysis conditions and properties on protein hydrolysates from flatfish skin
Hua ZHANG, Hongji ZHU, Shipeng WANG, Weihua WANG
Front Chem Sci Eng. 2013, 7 (3): 303-311.
https://doi.org/10.1007/s11705-013-1341-6
Response surface method (RSM), based on Box-Behnken design, was used to optimize the enzymatic hydrolysis conditions of flatfish skin protein hydrolysates (FSPH). Among the tested proteases, the combination of nutrase and trypsin was selected. The optimal hydrolysis conditions were as follows: pH 7.3, temperature 51.8°C, and the enzyme/substrate (E/S) ratio 2.5; under these conditions, the maximum peptide yield (PY) was 69.41±0.43%. The physiochemical analysis showed that the amino acids (His, Asp and Glu) of FSPH accounted for 18.15%, and FSPH was a mixture of polypeptides mostly distributed among 900–2000 Da. FSPH could exhibit a 93% chelating effect on ferrous ion at a concentration of 400 μg/mL, and also a notable reducing power. This study showed bioprocess for the production of FSPH for the first time, which had a good potential for valuable ingredients in the food, cosmetic and medicine industries.
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Anodic oxidation of azo dye C.I. Acid Red 73 by the yttrium-doped Ti/SnO2-Sb electrodes
Li XU, Zhi GUO, Lishun DU
Front Chem Sci Eng. 2013, 7 (3): 338-346.
https://doi.org/10.1007/s11705-013-1335-4
This work was conducted to study the ability of anodic oxidation of azo dye C.I. Acid Red 73 (AR73) using the yttrium-doped Ti/SnO2-Sb electrodes. The effects of Sb doping level, yttrium doping level, thermal decomposition temperature and cycle times of dip-coating thermal decomposition on the properties of the electrodes were investigated. The results showed that the excellent electrochemical activity of Ti/SnO2-Sb-Y electrode can be achieved at a 7∶1 molar ratio of Sn∶Sb and thermal decomposition temperature of 550°C. Moreover when the cycle times of dip-coating and thermal decomposition were up to 10 times, the performance of the electrode tends to be stable. The Ti/SnO2-Sb electrodes doped with yttrium (0.5 mol-%) showed the most excellent electrochemical activity. In addition, the influences of operating variables, including current density, initial pH, dye concentration and support electrolyte, on the colour removal, chemical oxygen demand (COD) removal and current efficiency were also investigated. Our results confirmed that the current efficiency increased with the concentrations of dye and sodium chloride. Moreover, increasing the current density and the initial pH would reduce the current efficiency.
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A logic-based controller for the mitigation of ventilation air methane in a catalytic flow reversal reactor
Zhikai LI, Zhangfeng QIN, Yagang ZHANG, Zhiwei WU, Hui WANG, Shuna LI, Mei DONG, Weibin FAN, Jianguo WANG
Front Chem Sci Eng. 2013, 7 (3): 347-356.
https://doi.org/10.1007/s11705-013-1347-0
The control system of a catalytic flow reversal reactor (CFRR) for the mitigation of ventilation air methane was investigated. A one-dimensional heterogeneous model with a logic-based controller was applied to simulate the CFRR. The simulation results indicated that the controller developed in this work performs well under normal conditions. Air dilution and auxiliary methane injection are effective to avoid the catalyst overheating and reaction extinction caused by prolonged rich and lean feed conditions, respectively. In contrast, the reactor is prone to lose control by adjusting the switching time solely. Air dilution exhibits the effects of two contradictory aspects on the operation of CFRR, i.e., cooling the bed and accumulating heat, though the former is in general more prominent. Lowering the reference temperature for flow reversal can decrease the bed temperature and benefit stable operation under rich methane feed condition.
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14 articles
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