Inverse Pickering Emulsion Stabilized by Exfoliated Hexagonal-Boron Nitride (h-BN)

Nanotechnology-assisted treatment of pharmaceuticals contaminated water

The presence of pharmaceutical compounds in wastewater due to an increase in industrialization and urbanization is a serious health concern. The demand for diverse types of pharmaceutical compounds is expected to grow as there is continuous improvement in the global human health standards. Discharge of domestic pharmaceutical personal care products and hospital waste has aggravated the burden on wastewater management. Further, the pharmaceutical water is toxic not only to the aquatic organism but also to terrestrial animals coming in contact directly or indirectly. The pharmaceutical wastes can be removed by adsorption and/or degradation approach. Nanoparticles (NPs), such as 2D layers materials, metal-organic frameworks (MOFs), and carbonaceous nanomaterials are proven to be more efficient for adsorption and/or degradation of pharmaceutical waste. In addition, inclusion of NPs to form various composites leads to improvement in the waste treatment efficacy to a greater extent. Overall, carbonaceous nanocomposites have advantage in the form of being produced from renewable resources and the nanocomposite material is biodegradable either completely or to a great extent. A comprehensive literature survey on the recent advancement of pharmaceutical wastewater is the focus of the present article.

Boron nitride nanosheets decorated MIL-53(Fe) for efficient synergistic ibuprofen photocatalytic degradation by persulfate activation

In this study, based on one-step hydrothermal method, boron nitride nanosheets (BNNs) and MIL-53(Fe) composites (BNFe-X) were successfully prepared and the catalytic performance of BNFe-X on persulfate (PS) activation for ibuprofen (IBP) photodegradation was investigated. The introduction of BNNs changed the morphology of MIL-53(Fe) to be a unique prism-like structure and enhanced the degradation efficiency of IBP, which followed the pseudo-first-order rate kinetics. Among the prepared composites, BNFe-3 (3% BNNs) exhibited the highest IBP degradation activity and possessed strong stability after four cycles. Over 99% IBP removal was achieved at the irradiation time of 60 min. The promoted decomposition rate of IBP could be ascribed to be the activation of PS and the enhanced electrons transfer efficiency between BNNs and MIL-53(Fe). The scavenger studies and electron spin-resonance spectroscopy (ESR) demonstrated the generation of SO2-, OH and O2-, and all these radicals had the different contributions in IBP degradation. Based on the LC-MS-MS and TOC results, the possible decomposition pathways of IBP in BNFe-3/PS system were proposed. This work suggested that the BNNs/Fe-based MOFs composites and PS system had great potential in organic pollutants degradation in aqueous solution.

Porous Gelatin Membranes Obtained from Pickering Emulsions Stabilized with h-BNNS: Application for Polyelectrolyte-Enhanced Ultrafiltration

In recent years, numerous studies have been conducted to develop biopolymer-based membranes, highlighting the challenges to prepare porous structures with control porosity. In this paper an innovative method that relies on the generation of Pickering emulsions was developed to prepare porous membranes from gelatin for filtration purpose. Hexagonal boron nitride nanosheets (h-BNNS) were used to stabilize micro-droplets of castor oil in a continuous homogeneous gelatin solution. Two steps in the membrane preparation process strongly influenced the porous structure. Specifically, the duration of the drying time after emulsion casting and the duration of the cross-linking step affected membrane pore size, hydrophobicity, water swelling, and water permeability. By controlling these two steps, membranes could be designed with pore size between 0.39 and 1.60 μm and display pure water permeability between 150 and 506 L h⁻¹ m⁻² bar⁻¹. These membranes have been tested for complexation–ultrafiltration experiments in which iron ions were removed from aqueous solutions with/without poly (acrylic acid) (PAA). Without PAA, the removal of free iron (II) ions was low (not more than 14%). The addition of PAA (200 ppm) allowed obtaining high removal rates (97%) at pH ≥ 5 with 3 bars of transmembrane pressure.

Highly Thermally Conductive Polymer Composite Originated from Assembly of Boron Nitride at an Oil-Water Interface

Thermally conductive polymer packaging material is of great significance for the thermal management of electronics. Inorganic thermally conductive fillers have been demonstrated as a convenient approach to achieve this goal by sacrificing the lightweight and processability of the polymer. To address this problem, an effective 3D boron nitride (BN) network was constructed as a heat conduction pathway in a polystyrene (PS) matrix based on an oil-water interface assembly in this work. Styrene oil droplets were stabilized by BN sheets in the water phase to form Pickering emulsions, and then in situ polymerization was trigged to synthesize PS microspheres with ultrathin BN layer-covered surfaces (PS@BN microspheres). Composite substrates were fabricated through hot-compressing the PS@BN microspheres to form BN networks based on the original microsphere template. Benefited from the network structure, the maximum thermal conductivity of the composite substrate reached 0.94 W/mK at 33.3 wt % BN, which is 626% folds of that of pure PS. It was also demonstrated that the storage modulus and thermal stability of the composite substrate were dramatically improved by the BN network. The reported composite substrate and its fabrication strategy are promising in the development of thermal management of electronics.

Ionic Liquid-Containing Pickering Emulsions Stabilized by Graphene Oxide-Based Surfactants

Emulsions stabilized by particles (i.e., Pickering emulsions) are complementary to those stabilized by small molecules or polymers and most commonly consist of oil droplets dispersed in a continuous water phase, with particles assembled at the fluid-fluid interface. New particle surfactants and different fluid-fluid interfaces are critical for developing next-generation systems for a number of advanced applications. Herein we report the preparation of IL-containing emulsions stabilized by graphene oxide (GO)-based nanoparticles using the IL [Bmim][PF₆]: GO nanosheets stabilize IL-in-water emulsions, and alkylated GO nanosheets (C₁₈-GO) stabilize IL-in-oil emulsions. The impact of particle concentration, fluid-fluid ratio, and addition of acid or base on emulsion formation and stability is studied, with distinct effects for the water and oil systems observed. We then illustrate the broad applicability of GO-based particle surfactants by preparing emulsions with different ILs and preparing inverted emulsions (water-in-IL and oil-in-IL emulsions). The latter systems were accessed by tuning the polarity of GO nanosheets by functionalization with a perfluorinated alkyl chain such that they were dispersible in IL. This work provides insight into the preparation of different IL-containing emulsions and lays a foundation for the architecture of dissimilar materials into composite systems.

2D Particles at Fluid-Fluid Interfaces: Assembly and Templating of Hybrid Structures for Advanced Applications

Fluid-fluid interfaces have widespread applications in personal care products, the food industry, oil recovery, mineral processes, etc. and are also important and versatile platforms for generating advanced materials. In Pickering emulsions, particles stabilize the fluid-fluid interface, and their presence reduces the interfacial energy between the two fluids. To date, most Pickering emulsions stabilized by 2D particles make use of clay platelets or GO nanosheets. These systems have been used to template higher order hybrid, functional materials, most commonly, armored polymer particles, capsules, and Janus nanosheets. This review discusses the experimental and computational study of the assembly of sheet-like 2D particles at fluid-fluid interfaces, with an emphasis on the impact of chemical composition, and the use of these assemblies to prepare composite structures of dissimilar materials. The review culminates in a perspective on the future of Pickering emulsions using 2D particle surfactants, including new chemical modification and types of particles as well as the realization of properties and applications not possible with currently accessible systems, such as lubricants, porous structures, delivery, coatings, etc.

Sample cell for studying liquid interfaces with an in situ electric field using X-ray reflectivity and application to clay particles at oil-oil interfaces

Commissioning results of a liquid sample cell for X-ray reflectivity studies with an in situ applied electrical field are presented. The cell consists of a Plexiglas container with lateral Kapton windows for air-liquid and liquid-liquid interface studies, and was constructed with grooves to accept plate electrodes on the walls parallel to the direction of the beam. Both copper and ITO plate electrodes have been used, the latter being useful for simultaneous optical studies. Commissioning tests were made at the I07 beamline of the Diamond Light Source.

Self-Assembly of Porous Boron Nitride Microfibers into Ultralight Multifunctional Foams of Large Sizes

As a kind of macroscopic boron nitride (BN) architectures, ultralight BN cellular materials with high porosity and great resilience would have a broad range of applications in energy and environment areas. However, creating such BN cellular materials in large sizes has still been proven challenging. Here, we report on the unique self-assembly of one-dimensional porous BN microfibers into an integral three-dimensional BN foam with open-cell cellular architectures. An ultrasonic-assisted self-assembly, freeze-drying, and high-temperature pyrolysis process has been developed for the preparation of cellular BN foam with a large size and desired shape. The developed BN foam has low density, high porosity (∼99.3%), great resilience, and excellent hydrophobic-lipophilic nature. The foam also exhibits excellent absorption capacities for a wide range of organic solvents and oils (wt % of ∼5130-7820%), as well as a high recovery efficiency (∼94%). Moreover, the unique hierarchical porous structure enables the foam to demonstrate a very low thermal conductivity (∼0.035 W/K/m). The excellent thermal insulation performance, superior mechanical property, and superb chemical and thermal stability enable the developed BN foam as an integrating multifunctional material in a broad range of high-end applications.