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A conceptual methodology for simultaneous optimization of water and heat with non-isothermal mixing
Yanlong Hou, Wanni Xie, Zhenya Duan, Jingtao Wang
Front. Chem. Sci. Eng.. 2017, 11 (2 ): 154-165.
https://doi.org/10.1007/s11705-016-1593-z
A new conceptual methodology is proposed to simultaneously integrate water allocation and energy networks with non-isothermal mixing. This method employs a simultaneous model and includes two design steps. In the first step, the water allocation network (WAN), which could achieve the targets of saving water and energy, is obtained by taking account the temperature factor into the design procedure. The optimized targets of both freshwater and energy are reached at this step which ensures this approach is a simultaneous one. In the second step, based on the obtained WAN, the whole water allocation and heat exchange network (WAHEN) is combined with the non-isothermal mixing to reduce the number of heat exchangers. The thus obtained WAHEN can achieve three optimization targets (minimization of water, energy and the number of heat exchangers). Furthermore, the effectivity of our method has been demonstrated by solving two literature examples.
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Environmental and economic assessment of vegetable oil production using membrane separation and vapor recompression
Weibin Kong, Qi Miao, Peiyong Qin, Jan Baeyens, Tianwei Tan
Front. Chem. Sci. Eng.. 2017, 11 (2 ): 166-176.
https://doi.org/10.1007/s11705-017-1616-4
Solvent extraction of crude oil from oilseeds is widely applied for its high production capacity and low cost. In this process, solvent recovery and tail gas treatment are usually performed by adsorption, paraffin scrubbing, or even cryogenics (at low tail gas flow rates). Membrane separation, which has a lower energy consumption than these techniques, spans a broad range of admissible concentrations and flow rates, and is moreover easily combined with other techniques. Vapor recompression has potentials to reduce the heat loss in association with distillation and evaporation. In this study, we proved the possibility of combining membrane separation and vapor recompression to improve the conventional vegetable oil production, by both experiments and process simulation. Nearly 73% of energy can be saved in the process of vegetable oil extraction by the novel processing approach. By further environmental assessment, several impact categories show that the optimized process is environmentally sustainable.
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Catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over the x Pd/OMS-2 catalysts: Effect of Pd loading
Zhidan Fu, Lisha Liu, Yong Song, Qing Ye, Shuiyuan Cheng, Tianfang Kang, Hongxing Dai
Front. Chem. Sci. Eng.. 2017, 11 (2 ): 185-196.
https://doi.org/10.1007/s11705-017-1631-5
The Pd catalyst supported on cryptomelane-type manganese oxide octahedral molecular sieve (OMS-2) were prepared. The effect of Pd loading on the catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over x Pd/OMS-2 has been investigated. The results show that the Pd loading plays an important role on the physicochemical properties of the x Pd/OMS-2 catalysts which outperform the Pd-free counterpart with the 0.5Pd/OMS-2 catalyst being the best. The temperature for 50% conversion was 25, 240 and 160 °C, and the temperature for 90% conversion was 55, 285 and 200 °C for oxidation of CO, toluene, and ethyl acetate, respectively. The low-temperature reducibility and high oxygen mobility of x Pd/OMS-2 are the factors contributable to the excellent catalytic performance of 0.5Pd/OMS-2.
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Metal salts with highly electronegative cations as efficient catalysts for the liquid-phase nitration of benzene by NO2 to nitrobenzene
Shenghui Zhou, Kuiyi You, Zhengming Yi, Pingle Liu, Hean Luo
Front. Chem. Sci. Eng.. 2017, 11 (2 ): 205-210.
https://doi.org/10.1007/s11705-017-1625-3
Metal salts with highly electronegative cations have been used to effectively catalyze the liquid-phase nitration of benzene by NO2 to nitrobenzene under solvent-free conditions. Several salts including FeCl3 , ZrCl4 , AlCl3 , CuCl2 , NiCl2 , ZnCl2 , MnCl2 , Fe(NO3 )3 ·9H2 O, Bi(NO3 )3 ·5H2 O, Zr(NO3 )4 ·5H2 O, Cu(NO3 )2 ·6H2 O, Ni(NO3 )2 ·6H2 O, Zn(NO3 )2 ·6H2 O, Fe2 (SO4 )3 , and CuSO4 were examined and anhydrous FeCl3 exhibited the best catalytic performance under the optimal reaction conditions. The benzene conversion and selectivity to nitrobenzene were both over 99%. In addition, it was determined that the metal counterion and the presence of water hydrates in the salt affects the catalytic activity. This method is simple and efficient and may have potential industrial application prospects.
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The feasibility of coating by cooling crystallization on ibuprofen naked tablets
Fatima Mameri, Ouahiba Koutchoukali, Mohamed Bouhelassa, Anne Hartwig, Leila Nemdili, Joachim Ulrich
Front. Chem. Sci. Eng.. 2017, 11 (2 ): 211-219.
https://doi.org/10.1007/s11705-017-1619-1
Sugar spray coating is a frequently used process in the pharmaceutical industry. However, this process presents the disadvantage to form an amorphous coating around the active ingredient. A crystalline coating formed on the surface of a tablet is highly desirable. Recently, a new process of coating by cooling crystallization has been developed and applied on bisacodyl pastilles obtained by melt crystallization. In this work, we investigated the feasibility of coating by cooling crystallization on ibuprofen “naked tablets” manufactured by compression. In the first part of this work, the solubility and the metastable zone width have been determined experimentally for the coating solution because they are essential factors for any crystallization process. In the second part, the coating process is investigated on the operating conditions that affect the surface morphology and the crystal growth rate. These experimental conditions include concentration of the coating solution, degree of sub-cooling, agitation speed, retention time, and surface properties of the naked ibuprofen tablets. The results show that naked tablet coating by cooling crystallization is feasible and can be applied in the pharmaceutical industry.
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Solvates and polymorphs of clindamycin phosphate: Structural, thermal stability and moisture stability studies
Junbo Gong, Dejiang Zhang, Yuanyuan Ran, Keke Zhang, Shichao Du
Front. Chem. Sci. Eng.. 2017, 11 (2 ): 220-230.
https://doi.org/10.1007/s11705-017-1624-4
Clindamycin phosphate (CP), an antibacterial agent, has been reported to form several solid-state forms. The crystal structures of two CP solvates, a dimethyl sulfoxide (DMSO) solvate and a methanol/water solvate (solvate V), have been determined by single crystal X-ray diffraction. The properties and transformations of these forms were characterized by powder X-ray diffraction, Single-crystal X-ray diffraction, differential scanning calorimetry, thermo gravimetric analysis, hot-stage microscopy, and dynamic vapor sorption. Very different hydrogen bonding networks exist among the host-host and host-solvent molecules in the two crystal structures, resulting in different moisture stabilities. The thermal stabilities of the two solvates upon heating and desolvation were also studied. When the temperature was above the boiling point of methanol, solvate V converted to a polymorphic phase after a one step desolvation process, whereas the desolvation temperature of the DMSO solvate was below the boiling point of DMSO. At the relative humidity above 43%, the DMSO solvate transformed to a hydrate at 25 °C. In contrast, solvate V did not transform at any of the humidities studied.
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Preparation and characterization of hydrothermally engineered TiO2 -fly ash composite membrane
Kanchapogu Suresh, G. Pugazhenthi, R. Uppaluri
Front. Chem. Sci. Eng.. 2017, 11 (2 ): 266-279.
https://doi.org/10.1007/s11705-017-1608-4
This work targets the preparation and characterization of an inexpensive TiO2 -fly ash composite membrane for oily wastewater treatment. The composite membrane was fabricated by depositing a hydrophilic TiO2 layer on a fly ash membrane via the hydrothermal method, and its structural, morphological and mechanical properties were evaluated. The separation potential of the composite membrane was evaluated for 100–200 mg·L–1 synthetic oily wastewater solutions. The results show that the composite membrane has excellent separation performance and can provide permeate stream with oil concentration of only 0.26–5.83 mg·L–1 . Compared with the fly ash membrane in the average permeate flux and performance index (49.97 × 10–4 m3 ·m–2 ·s–1 and 0.4620%, respectively), the composite membrane exhibits better performance (51.63 × 10−4 m3 ·m−2 ·s−1 and 0.4974%). For the composite ash membrane, the response surface methodology based analysis inferred that the optimum process parameters to achieve maximum membrane flux and rejection are 207 kPa, 200 mg·L–1 and 0.1769 m·s–1 for applied pressure, feed concentration and cross flow velocity, respectively. Under these conditions, predicted responses are 41.33 × 10–4 m3 ·m−2 ·s−1 permeate flux and 98.7% rejection, which are in good agreement with the values obtained from experimental investigations (42.84 × 10−4 m3 ·m−2 ·s−1 and 98.82%). Therefore, we have demonstrated that the TiO2 -fly ash composite membrane as value added product is an efficient way to recycle fly ash and thus mitigate environmental hazards associated with the disposal of oily wastewaters.
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