查看更多>>摘要：Pearls have been highly valued as gemstones for thousands of years because of their unique and fascinating colors. However, it was difficult to harvest pearls in large quantities in nature due to their scarcity. Thus, there has been a steady demand for the development of artificial pearlescent pigments, and substrate-based pigments composed of mica substrates with coated metal oxide layers were introduced in the 1960s. Although these pigments remain the most common pearlescent pigments up to date, they have no other functions except for the pearlescent effect. Herein, we present novel micron-sized particles which are layered platelets with a unique pseudotriangular shape (triangular with concave sides and a bifurcated vertex) and composed of antimicrobial reagents, silver cations, and 2-mercaptoethane sulfonate anions. These particles exhibit both pearlescent and antimicrobial properties owing to their structure (layered platelets) and constituents (antimicrobial reagents), respectively. An additional advantage of these particles is that they can be prepared in one-pot process through a precipitation reaction by simply mixing two aqueous solutions containing silver cations and sodium 2-mercaptoethane sulfonate anions. These particles can potentially be used as pigments requiring both pearlescent and antimicrobial properties in the pigment field.
查看更多>>摘要：In this current study, the electrophoretic deposition (EPD) process of polyaniline (PANI) is reported kinet-ically via the use of response surface methodology (RSM) with a focus on the three models of kinetics; Hamaker, Zhang, and Baldisseri using both statistical and quantitative techniques. The particles of formic acid and acetonitrile-based suspensions as a result of the electrostatic interaction were evaluated using particle size and zeta potential analyses. The fundamentals of PANI-EPD kinetics were used to demonstrate the influence of the EPD parameters on the properties of the deposited films over an interval of 180-600 s. The cathodic reduction during PANI-EPD simultaneously, the entanglement process and the control of the kinetics was once reported. Therefore, low voltages were used to avoid significant loss of PANI, which decreases during the EPD process, initiated by physicochemical characterization (SEM, FT-IR and XRD). The effect of deposition time and deposition voltage on PANI-EPD kinetics at intervals (180-600 s) was quantified by RSM. Accordingly, the result obtained obeyed a linear growth law consistent with Hamaker's' law. For comparison, optical absorbance and profilometry provide an approximation of PANI's deposition rate, extinction coefficient, and density. Again, the Baldisseri model was able to reproduce experimental data well alongside some other semi-empirical equations of kinetics. The study is very significant in terms of the process through which thermal degradation occurs and as a result used this to anticipate the thermal stability of a process, thereby avoiding thermal degradation of polymer products as an industrial application.
查看更多>>摘要：Transition metals were plasma-sprayed onto stainless-steel substrates and further oxidised to form a surface layer of the metal oxides. Catalytic wet oxidation of glucose, a model compound for organic waste was carried out at temperature range of 150-170 °C for 60 min. Rietveld patterns showed evidence of metal oxides in the oxidised coatings of M0O3, Co3O4, CuO and CuNiln oxide. The SEM cross-sections reveal two-layered coatings for MoO3, Co3O4 and CuO. Highest COD reduction was obtained by Co3O4 after 60 min at 160 °C for the low-oxygen screening trials. Initial screening trials detected a high concentration of metallic Mo, Co and Cu by ICP-MS. The re-oxidised MoO3 catalysts yielded the highest concentration of acetic acid (96 mg L~(-1)) post 60 min of CWO reaction at 170 °C using 40 bar O2. The leaching of Mo metal with spallation of the top oxide layer was confirmed with the reuse trials. On contrary, CuNiln oxide showed minimum amounts of leached Cu, Ni, and In metals into the reaction media, with the catalyst producing 67 mg L~(-1) of acetic acid at 170 °C using 40 bar O2. Therefore, CuNiln oxide was selected as the best oxidised transition metal catalyst for CWO of glucose.
查看更多>>摘要：Polyhedral oligomeric silsesquioxanes (POSSs) have received great attention owing to their structural stability and diverse external functional groups. The extensive development of synthetic strategies has yielded mono-and multi-functionalized POSSs. The synthesis of functionalized POSSs, however, generally requires complex reactions and tedious workup processes; therefore, it is difficult to meticulously control the structure of POSSs. To address this problem, we propose a novel straightforward and universal strategy to produce multifunctional POSSs with the desired number of vinyl groups. In brief, POSSs were built through cohydrolysis-cocondensation by employing methyltrimethoxysilane and vinyltrimethoxysilane (ViM-POSS) in a one-pot system. 1H NMR and X-ray photoelectron spectroscopy reveal that the stoichiometric ratio of the vinyl and methyl groups in ViM-POSSs is almost identical to the theoretical value. Moreover, all ViM-POSSs are synthesized as T-8 POSSs with rhombohedral structures in the R-3 space group and are stacked in the ABC sequence. Furthermore, as the portion of the vinyl group in ViM-POSSs increases from 0 to 100%, average molecular size, average molecular weight, and sublimation temperature of ViM-POSSs go up steadily. We therefore believe that this facile and effectual synthetic route will set a precedent for POSS synthesis in both academia and industry.
查看更多>>摘要：Atomizer flotation has the advantages of low cost, low energy consumption, adjustable, and long cycle life in industrial applications. The bubble diameter is an important parameter for floatation. The smaller the bubble diameter, the better the flotation effect. However, the bubble diameter produced by the atomizer during flotation separation is large at present. In this paper, a swirl effervescent atomizer is designed and experimental diagnosis through a spray measurement system and submerged spray visualization system. The diameter and size distribution of bubbles in 5 mm from the atomizer outlet to the jet cross-section spray were discussed. The results showed that the swirl effervescent atomizer obtained a fine Sauter mean diameter (SMD is 13-25 urn) compared with the traditional atomizer. Three flow patterns were observed at the submerged spray system: large bubbly flow, discrete bubbly flow, and slug flow. A statistical method of bubbles under high injection pressure was proposed. The effects of the operating conditions of the effervescent atomizer on the bubble diameter were investigated. The average bubble diameter decreased with the increase in injection pressure and gas-liquid mass flow ratios {GLR). However, with the GLR being increased to 0.15, the influence of injection pressure on bubble diameter was reduced. The backpressures (Liquid level heights) have less effect on bubbles compared with injection pressure and GLR. This paper has great significance for the sustainable development of the atomizer in the flotation separation application.
查看更多>>摘要：Since the global COVID-19 pandemic, the development of biocide-free antibacterial surfaces based on other sterilization mechanisms has gathered momentum. It however faces significant challenges. Photothermal sterilization based on photothermal agents (PTA), which can convert light energy to heat under near-infrared (NIR) irradiation, has been proposed as an attractive method to prevent bacterial infections and contamination. Gold nanoparticles (AuNPs) with localized surface plasmon resonance, which cause a photothermal effect via high photothermal conversion from light to heat energy, are generally used as PTA, and CuS as a p-type semiconductor with a narrow band gap is an emerging PTA. Therefore, in this study, an Au@CuS yolk-shell with inner gaps was prepared via the Kirkendall effect, and its photothermal performance was tested under NIR irradiation. Polydimethylsiloxane (PDMS) was used as the supporting substrate with low surface energy. Photothermal sterilization effect was explored by inactivating E. coli using Au@CuS/PDMS films. Effective inactivation of ￡ coli was observed in the 0.025 wt% Au@CuS/PDMS film within 10 s of NIR irradiation. The results show that the dramatic inactivation of E. coli is caused by the photothermal effect generated by the coupling of CuS and AuNPs.
查看更多>>摘要：Low water flux and poor chlorine resistance have become barriers to the applications of polyamide reverse osmosis (RO) membranes. Here, we design and develop a novel RO membrane with high permeability and self-healing chlorine resistance capability by doping alkaline-responsive polymer nanocon-tainers into the polyamide layer. The nanocontainer is prepared through chemical adsorption and electrostatic self-assembly with titanium dioxide (TiO2) as the core, calcium alginate (CA) and chitosan (CS) as the repair materials, and polyaspartic acid (PASP) as the responsive shell. In addition to increasing water transport through the channels, the PASP shell of the nanocontainer reacts with alkali during conventional alkaline cleaning and thereby the CA and CS are released to precisely repair the chlorinated polyamide and restore the NaCl rejection of the RO membrane. Upon release of the nanocontainer, TiO2 is also exposed to make the membrane antibacterial. The nanocontainer doping significantly enhances surface roughness of the RO membrane, and the water permeability of the thin-film nanocom-posite membrane doped with 0.005 wt% nanocontainers is increased by 43.71% to 5.03 L/m2 h bar compared with the blank membrane, while performing an excellent NaCl rejection of 98.02% and maintaining 95.95% after 8000 ppm h active chlorine treatment and alkaline cleaning process.
Pantharee KongsatEdgar A. O'RearThirawudh Pongprayoon
13页
查看更多>>摘要：Polypyrrole (PPy) was used to obtain a coating on magnetite (Fe3O4) and hematite (Fe2O3) iron oxide nanoparticles (IONPs). PPy was synthesized on the surface of lONPs by admicellar polymerization for enhancement of electrical conductivity. Low surfactant and monomer levels enabled formation of films on the order of 1 nm thickness. The hydrophobic tendency of the modified IONPs was observed by aggregation in water and exclusion of water molecules. Coated IONPs were characterized by Fourier transform infrared spectroscopic techniques (FT-IR) and scanning electron microscopy (SEM) with particle size distribution analyzed by dynamic light scattering (DLS). Thermal stability of PPy-coated IONPs was investigated by thermogravimetric analysis (TGA). Lastly the magneticity and electrical conductivity of the modified IONPs were analyzed by VSM and multimeter measurements of packed IONPs in a circuit, respectively. Modified IONPs significantly enhanced electrical conductivity with greater effect related to the amount of PPy film coated on the IONP surface. Particle sizes of magnetite and hematite were found within the range between 50 and 2000 nm, depending upon PPy coating. The electrical property was successfully improved, but magnetic properties were not statistically different from the bare IONPs. The concentration of Py monomer at 30 mM shown as the critical concentration of both magnetite and hematite had the achievement of the high electrical conductivity.
查看更多>>摘要：In biphasic flow reactor, interphase mass transfer and associated chemical reaction is often enhanced by tuning the phase distribution to promote segmented flow. Since miniaturisation favours segmented flow, several studies are reported in reduced dimensions mostly in microchannels. Biphasic flow in millichan-nels is relatively less explored. Further, almost nothing is known about the influence of reaction on the flow physics. In the present study, extensive experiments are performed for reacting as well as non-reacting flow systems in a millichannel. Experiments reveal a higher conversion for vertical upflow primarily due to an enhanced range of segmented flow. Conversion is found to depend on flow morphology with segmented flow giving the maximum conversion followed by other flow patterns. The overall reaction rate constant is influenced by mixture velocity as larger values are obtained at higher velocities irrespective of the prevailing flow pattern. We observe reaction to induce phase inversion as well as transition between flow patterns along the conduit length. The phase properties are also observed to alter with reaction progress. The interplay of flow dynamics and reaction discussed in the paper is expected to aid design of milliscale flow reactors.
查看更多>>摘要：Coal gangue has the dual attributes of hazard and resource. With the increasing awareness of resources conservation and ecological sustainability, the high-value utilization of coal gangue has attracted active attention. In this research, thermal activation followed by HNO3 leaching were performed to extract valuable components from coal gangue. Firstly, the activation behavior and phase transformation mechanism during thermal activation were revealed through the Gibbs free energy calculation and experimental research. After activation, inert kaolinite was converted to active metakaolinite. Subsequently, the potential-pH diagrams analyses confirmed that the strategy of extracting Al, Ga, and Li into the leach liquor while precipitating Fe into the leach residue was feasible. Meanwhile, systematic leaching experiments showed that 95.2% of Al, 56.4% of Ga, and 80.5% of Li were extracted, while only 2.1% of Fe was dissolved at the optimal conditions. The leaching behavior of each component agreed well with the thermodynamic analysis. Finally, the raw ore, activated product, and leach residue were analyzed via a suite of characterization techniques. In contrast to the raw ore and activated product, the leach residue had large BET surface area and high available Si content, and was a promising Si fertilizer source. This study provides a useful reference for the high-value utilization of coal gangue.
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