Tuning Pickering Emulsions for Optimal Reaction and Filtration Conditions

The use of Pickering emulsions has recently received increased attention in catalyzed multiphase reactions. Here, the ultrafiltration of Pickering emulsions is studied for product separation and to retain the catalyst in the reactor. To find the optimum between a high specific surface area for high reaction rates and a suited drop size distribution for high permeate fluxes, the preparation method of Pickering emulsion was investigated. It was found that the stability of the emulsion during filtration does not only depend on the solid particle content, but also on the drop size distribution.     

Highly Active,Entirely Biobased Antimicrobial Pickering Emulsions

We present the development of surfactant-free, silica-free and fully biobased oil-in-water antimicrobial Pickering emulsions, based on the self-assembly of β-cyclodextrin and phytoantimicrobial oils (terpinen-4-ol or carvacrol). Undecylenic acid (UA), derived from castor oil, can be used as bio-based drug to treat fungal infection, but is less effective than petroleum-based drugs as azole derivatives. To maximize its antifungal potential, we have incorporated UA in fully biobased Pickering emulsions. These emulsions are effective against fungi, Gram-positive and Gram-negative bacteria. The carvacrol emulsion charged with UA is +390 % and +165 % more potent against methicillin-resistant S. aureus (MRSA), compared to UA and azole-based commercial formulations. Moreover, this emulsion is up to +480 % more efficient that UA ointment against C. albicans. Finally, remarkable eradication of E. coli and MRSA biofilms was obtained with this environmental-friendly emulsion.     

Cryogenic 3D Printing of w/o Pickering Emulsions Containing Bifunctional Drugs for Producing Hierarchically Porous Bone Tissue Engineering Scaffolds with Antibacterial Capability

How to fabricate bone tissue engineering scaffolds with excellent antibacterial and bone regeneration ability has attracted increasing attention. Herein, we produced a hierarchical porous β-tricalcium phosphate (β-TCP)/poly(lactic-co-glycolic acid)-polycaprolactone composite bone tissue engineering scaffold containing tetracycline hydrochloride (TCH) through a micro-extrusion-based cryogenic 3D printing of Pickering emulsion inks, in which the hydrophobic silica (h-SiO₂) nanoparticles were used as emulsifiers to stabilize composite Pickering emulsion inks. Hierarchically porous scaffolds with desirable antibacterial properties and bone-forming ability were obtained. Grid scaffolds with a macroscopic pore size of 250.03 ± 75.88 μm and a large number of secondary micropores with a diameter of 24.70 ± 15.56 μm can be fabricated through cryogenic 3D printing, followed by freeze-drying treatment, whereas the grid structure of scaffolds printed or dried at room temperature was discontinuous, and fewer micropores could be observed on the strut surface. Moreover, the impartment of β-TCP in scaffolds changed the shape and density of the micropores but endowed the scaffold with better osteoconductivity. Scaffolds loaded with TCH had excellent antibacterial properties and could effectively promote the adhesion, expansion, proliferation, and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells afterward. The scaffolds loaded with TCH could realize the strategy to “kill bacteria first, then induce osteogenesis”. Such hierarchically porous scaffolds with abundant micropores, excellent antibacterial property, and improved bone-forming ability display great prospects in treating bone defects with infection.     

用于细菌生物膜感染治疗的Pickering乳液制备

人体常见的持续性感染疾病通常与细菌生物膜有关。使抗菌药物高效渗透到细菌生物膜内部并杀伤细菌是治疗细菌生物膜感染的关键。本研究构建了一种具有强渗透性和杀菌性的Pickering乳液。该Pickering乳液以天然抗菌剂丁香油为油相内核,以稳定吸附在油水界面的正电壳聚糖纳米颗粒(CS-NPs)为外壳,通过与负电胞外基质的静电相互作用,实现对细菌生物膜的强渗透。制备的壳聚糖纳米颗粒平均粒径为590.30±3.90 nm,多分散性指数PDI为0.125±0.003,平均电势为15.60±0.40 mV。Pickering乳液平均粒径为2312±53 nm,多分散性指数PDI为0.137±0.013,平均电势为26.45±0.55 mV。细菌生物膜渗透实验与杀菌性能实验表明,该Pickering乳液对细菌生物膜有较强的渗透能力,并能有效地杀伤细菌。该Pickering乳液有望用于治疗人体与细菌生物膜相关的持续性感染。     

活性染料皂煮剂HY应用初探

将特殊水溶性高分子与其他非离子、阴离子表面活性剂复配,得到活性染料皂煮剂HY,通过研究HY净洗能力和防沾色能力探讨了其用于活性染料染色后皂煮的性能。结果表明,HY具有较强的洗除浮色的能力和优异的防沾色能力,可将织物的摩擦牢度提高0.5~1.5级,从而满足客户对色牢度的要求。     

Synthesis of a Series of Anionic Surfactants Derived from NP and their Properties as Emulsifiers for Reducing Viscosity of Highly Viscous Oil via Formation of O/W Emulsions

A series of alkyl phenol polyoxyethylene glycidyl ether (NP-n-O) and alkyl phenol polyoxyethylene ether hydroxypropyl sulfonate (NP-n-S) surfactants was synthesized to explore emulsification viscosity reduction. The optimum sulfonation conditions were obtained through orthogonal experiments, the ratio of alkyl phenol polyoxyethylene glycidyl ether and sodium bisulfite 1:1.5, 100 °C, and 6 h. The effects of concentrations of the synthesized surfactants, pH values, emulsifying temperature (40 and 60 °C) and water content on emulsification viscosity reduction and the stability of the emulsion to Venezuela’s Orinoco heavy oil were investigated. The water diversion ratio of emulsion at the reservoir temperature (55 °C) in 30 days was taken as an index, the results show that under the conditions of a temperature of 40 °C, an oil/water ratio of 7:3 and a surfactant NP-4-S concentration of 0.5 %, emulsions can be formed with a viscosity reduction rate reaching up to 99.69 % and with a water diversion ratio in 30 days reaching 9.38 %; while at 60 °C and an oil/water ratio of 7:3, at an NP-4-S concentration of 1 %, the viscosity reduction rate can reach 99.55 % and water diversion ratio is merely 4.23 % in 30 days. The mixture of NP-n-S, xanthan gum and cocamidopropyl dimethylamine oxide (CAO-30) at suitable concentration can greatly improve the emulsification viscosity reduction and emulsion stability, which gives an emulsion viscosity rate of over 98 %. Moreover, the emulsion can be stable for at least 30 days without water emerging.     

Molecularly imprinted polymer prepared by Pickering emulsion polymerization for removal of acephate residues from contaminated waters

A molecularly imprinted polymer (MIP) prepared with Pickering emulsion polymerization was designed by a computational approach for removal of acephate from aqueous solution. Methacrylic acid, ethylene glycol dimethacrylate, and chloroform were screened as the optimal functional monomer, crosslinker, and porogen by the Gaussian 03 package using the density functional theory method. The polymerization was carried out in an oil‐in‐water emulsion using nano‐SiO₂ particles as stabilizer instead of a toxic surfactant. The characterization results indicated that the prepared MIP had a porous and hollow core, and the particle size was approximately 20 μm. The binding and recognition abilities of MIP for acephate were studied through equilibrium adsorption analysis and selectivity analysis. The results showed that the MIP had high binding capacity and excellent selectivity for acephate. The saturated binding amount could reach 6.59 × 10³ μg/g. The Langmuir isotherm model gave a good fit to the experimental data. Moreover, the results of a reusability analysis and practical application suggested that the prepared MIP provides the potential for removal of acephate residues from aqueous solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43126.     

A New Series of Double-Chain Single-Head Sulfobetaine Surfactants Derived from 1,3-Dialkyl Glyceryl Ether for Reducing Crude Oil/Water Interfacial Tension

A new series of sulfobetaine surfactants with double-chain single-head structure were derived from 1,3-dialkyl glyceryl ethers and their performances in reducing Daqing crude oil/connate water interfacial tension (IFT) in the absence of alkali were studied. With a large hydrophilic head group and double hydrophobic chains, these surfactants are efficient at reducing crude oil/connate water IFT. Those with didecyl and dioctyl are good hydrophobic surfactants that can reduce Daqing crude oil/connate water to ultra-low IFT by mixing with a small molar fraction of various conventional single-chain hydrophilic surfactants, such as α-olefin sulfonates, dodecyl polyoxyethylene (10) ether, and cetyl dimethyl hydroxypropyl sulfobetaine. The asymmetric double-chain sulfobetaine derived from 1-decyl-3-hexyl glyceryl ether can reduce Daqing crude oil/connate water IFT to ultra-low solely over a wide concentration range (0.03–10 mM or 0.0017–0.58 wt.%), which allows for use of an individual surfactant instead of mixed surfactants to avoid chromatographic separation in the reservoir. In addition, formulations rich in sulfobetaine surfactants show low adsorption on sandstone, keeping the negatively charged solid surface water-wet, and forming crude oil-in-water emulsions. These new sulfobetaine surfactants are, therefore, good candidates for surfactant-polymer flooding free of alkali.     

Hierarchical N‐doped carbons from designed N‐rich polymer: Adsorbents with a record‐high capacity for desulfurization

The removal of 4,6‐dimethyldibenzothiophene is quite challenging in petroleum refining process. Adsorptive desulfurization is an efficient technique but the capacities and/or poor stability of current adsorbents need to be improved. Here, the fabrication of hierarchical N‐doped carbons (NCs) derived from carbonizing the polymerization of 2,4,6‐tris(chloromethyl)mesitylene and p‐phenylenediamine is reported. The results show that the NCs have developed micropores (0.34–0.93 cm³ g^?1) and mesopores (0.15–0.47 cm³ g^?1), and their surfaces have abundant pyrrole‐like/graphitic N and topological defects and vacancies, and high cycle stability (6 cycles). The typical adsorbent NC‐700 shows a record‐high capacity of 2.91 mmol g^?1 under ambient conditions. The computational results show that the doped N is capable of promoting adsorptive strength by 0.055–0.178 eV. In conclusion, the obtained materials exhibit excellent performance for deep desulfurization, and this work may open up new avenues for the development of efficient adsorbents. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3786–3793, 2018