(See Yong Zhu, Zhishan Bai, Bingjie Wang, Linlin Zhai, Wenqiang Luo, pp 238-251)
The novelty of this article is focusing on the synthesis method of microfluidic technology. Microfluidic technology occupies high position in product control for the controllable size, structure, component and morphology. The key part of microfluidic equipment is the chip. The continuous phase was pumped into microfluidic chip to sheer dispersed phase at the cross aisle. Dispersed phase nec [Detail] ...
Shape memory polymers (SMPs) are smart materials that can change their shape in a pre-defined manner under a stimulus. The shape memory functionality has gained considerable interest for biomedical applications, which require materials that are biocompatible and sometimes biodegradable. There is a need for SMPs that are prepared from renewable sources to be used as substitutes for conventional SMPs. In this paper, advances in SMPs based on synthetic monomers and bio-compounds are discussed. Materials designed for biomedical applications are highlighted.
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.
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.
The hydrogenation of 2-ethylanthraquinone (eAQ), 2-tert-amylanthraquinone (taAQ) and their mixtures with molar ratios of 1:1 and 1:2 to the corresponding hydroquinones (eAQH2 and taAQH2) were studied over a Pd/Al2O3 catalyst in a semi-batch slurry reactor at 60 °C and at 0.3 MPa. Compared to eAQ, TaAQ exhibited a significantly slower hydrogenation rate (about half) but had a higher maximum yield of H2O2 and a smaller amount of degradation products. This can be ascribed to the longer and branched side chain in taAQ, which limits its accessibility to the Pd surface and its diffusion through the pores of the catalyst. Density functional theory calculations showed that it is more difficult for taAQ to adsorb onto a Pd (111) surface than for eAQ. The hydrogenation of the eAQ/taAQ mixtures had the slowest rates, lowest H2O2yields and the highest amounts of degradation products.
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 xPd/OMS-2 has been investigated. The results show that the Pd loading plays an important role on the physicochemical properties of the xPd/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 xPd/OMS-2 are the factors contributable to the excellent catalytic performance of 0.5Pd/OMS-2.
ZnFe2O4-BiOCl composites were prepared by both hydrothermal and direct precipitation processes and the structures and properties of the samples were characterized by various instrumental techniques. The samples were then used as catalysts for the photocatalytic reduction of CO2 in cyclohexanol under ultraviolet irradiation to give cyclohexanone (CH) and cyclohexyl formate (CF). The photocatalytic CO2 reduction activities over the hydrothermally prepared ZnFe2O4-BiOCl composites were higher than those over the directly-precipitated composites. This is because compared to the direct-precipitation sample, the ZnFe2O4 nanoparticles in the hydrothermal sample were smaller and more uniformly distributed on the surface of BiOCl and so more heterojunctions were formed. Higher CF and CH yields were obtained for the pure BiOCl and BiOCl composite samples with more exposed (001) facets than for the samples with more exposed (010) facets. This is due to the higher density of oxygen atoms in the exposed (001) facets, which creates more oxygen vacancies, and thereby improves the separation efficiency of the electron-hole pairs. More importantly, irradiation of the (001) facets with ultraviolet light produces photo-generated electrons which is helpful for the reduction of CO2 to ·CO2–. The mechanism for the photocatalytic reduction of CO2 in cyclohexanol over ZnFe2O4-BiOCl composites with exposed (001) facets involves electron transfer and carbon radical formation.
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)3·9H2O, Bi(NO3)3·5H2O, Zr(NO3)4·5H2O, Cu(NO3)2·6H2O, Ni(NO3)2·6H2O, Zn(NO3)2·6H2O, 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.
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.
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.
A novel gelator that contained both Schiff base and L-lysine moieties was synthesized and its gelation behavior was tested. This gelator can form gels in various organic solvents. The resulting gel can be applied as a fascinating platform for visual recognition of enantiomeric 1-(2-hydroxynaphthalen-1-yl)naphthalen-2-ol (BINOL) through selective gel collapse. In addition, the mechanism for the reaction of the gel with chiral BINOL was investigated by scanning electron microscope and 1H nuclear magnetic resonance.
A microsphere biosorbent with uniform size (CV= 1.52%), controllable morphology and component, and high mechanical strength was synthesized from chitosan by microfluidic technology combining with chemical crosslinking and solvent extraction. This chitosan microsphere (CS-MS) was prepared with a two-step solidification process, which was acquired by drying for the enhancement of mechanical property in final. The adsorption behavior of CS-MS towards copper (II) and main influencing factors on adsorption performance were investigated by batch experiments. Kinetic data highlighted dominant chemical bonding along with electrons transferring in adsorption process. Isothermal analysis indicated that adsorption capacity was relevant to the number of active site. All these explorations provided a new direction for preparing highly comprehensive performance sorbent used in heavy metal treatment via microfluidic technology.
A new type of activated carbon (AC) was synthesized using broom sorghum stalk as a low cost carbon source through chemical activation with H3PO4 and KOH. The AC obtained by KOH had the largest BET surface area of 1619 m2·g−1 and the highest micropore volume of 0.671 cm3·g−1. CO2 adsorption was enhanced by functionalizing the AC with two different amines: triethylenetetramine (TETA) and urea. The structure of the prepared ACs was characterized by Brunauer-Emmett-Teller method, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and acid-base Boehm titration analyses. The adsorption behavior of CO2 onto raw and amine-functionalized ACs was investigated in the temperature range of 288–308 K and pressures up to 25 bar. The amount of CO2 uptake at 298 K and 1 bar achieved by AC-TETA and AC-urea was 3.22 and 2.33 mmol·g−1which shows a 92% and 40% improvement compared to pristine AC (1.66 mmol·g−1), respectively. Among different model isotherms used to describe the adsorption equilibria, Sips isotherm presented a perfect fit in all cases. Gas adsorption kinetic study revealed a fast kinetics of CO2adsorption onto the ACs. The evaluation of the isosteric heat of adsorption demonstrated the exothermic nature of the CO2 adsorption onto unmodified and modified samples.
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.
This article reports the different steps of the design, development and validation of a process for continuous production of carbon nanotubes (CNTs) via catalytic chemical vapor deposition from the laboratory scale to the industrial production. This process is based on a continuous inclined mobile-bed rotating reactor and very active catalysts using methane or ethylene as carbon source. The importance of modeling taking into account the hydrodynamic, physicochemical and physical phenomena that occur during CNT production in the process analysis is emphasized. The impact of this invention on the environment and human health is taken into consideration too.