Hong Liu

Boron nitride nanosheets (BNN) were prepared by molten hydroxide-assisted liquid exfoliation from hexagonal boron nitride powder with an effectively high yield, and then modified with hexachlorocyclotriphosphazene (HCCP) to obtain HCCP-BNN. The series of samples were applied to prepare flame-retardant cotton fabrics with the impregnation-drying method, and successful treatment was confirmed by scanning electron microscopy. The combustion performance of the as-prepared cotton fabrics was tested and evaluated. After coating with HCCP-BNN, the combustion rate of the fabric is reduced in vertical and horizontal combustion conditions and the limiting oxygen-index value of cotton fabric increases to 24.1, becoming less flammable than the blank cotton. The fibrous structure of the BNN and HCCP-BNN coated fabrics is relatively complete after combustion, which indicates that BNN have a certain protective effect on the fabric. The results demonstrate HCCP-BNN as an effective flame-retardant for cotton fabrics.

Residual antibiotics in water have become a primary source of water pollution due to their misuse. Recently, membranes, produced by layered nanomaterials such as graphene oxide (GO), boron nitride (BN) and transition metal dichalcogenides, have been used in water purification, desalination and molecule separation as they are energy saving and simple to operate. The performance of membranes is closely related to their structure and the properties of the nanomaterials used. In this work, BN nanosheets (BNNSs) and GO were used to fabricate a two-dimensional nanocomposite membrane in order to improve the membrane’s permeance. It should be mentioned that the corresponding equal mass of the pure GO membrane was almost impermeable for the antibiotic solution. Multi-walled carbon nanotubes (MWCNTs) were inserted into the GO layers to increase the interlayer spacing and adsorb more antibiotics from the water. The resultant MWCNTs/BNNSs/GO membranes showed improved permeance and stable sieving capability for the antibiotic and small species. Specifically, permeance reached 30.2 L m−2 h−1 bar−1, which was much higher than pure GO membrane and the antibiotic rejection was 96.1%.

Coalbed methane (CBM), known as an unconventional gas resource, can be used as a high-energy fuel; however, the concentration of methane is critical to its utilization approach. This review focuses on the adsorbents and technologies that are used for adsorption and enrichment of methane from low concentration gas mixture. Some familiar porous materials are summarized, together with the industrialized technologies commonly used in gas adsorption field. Activated carbons are suggested to be the preferred adsorbent with high performance/cost ratio especially in pressure swing adsorption. Finally, an adsorption and enrichment system for low concentration CBM is proposed, indicating excellent application potential.

Spherical SBA-15-based metal–organic framework (MOF) composite materials were prepared, with nickel as the metal center of MOFs. The materials were characterized via scanning electron microscopy, X-ray fluorescence analysis, X-ray powder diffraction, Fourier-transform infrared spectroscopy, and nitrogen (N₂) adsorption–desorption. The methane (CH₄) or N₂ high-pressure adsorption isotherms of the samples were measured and compared. The specific surface area and adsorption capacity of the composite materials were generally higher than the pristine MOFs, but were much lower than the synthesized SBA-15. The selectivity of the samples toward a binary gas mixture was determined from the Langmuir adsorption equation. The results revealed that, of all the samples, the MOF-2/SBA-15 sample had the best CH₄/N₂ adsorption selectivity, with an adsorption selection parameter (S) of 11.1. However, the adsorption of MOF-2/SBA-15 was less than that of spherical SBA-15, due to partial plugging of the pores during the synthesis process. Further research is essential for improving the performance of spherical SBA-15-based MOF materials and (in turn) the enrichment of CH₄ from the CH₄/N₂ mixture.

Phosphorus- and nitrogen-doped graphene oxides are conveniently obtained by the modification of as-prepared graphene oxide and characterized by scanning electron microscopy, X-ray powder diffraction, Fourier-transform infrared, and ultraviolet–visible spectra. The combustion performances of pure cotton fabric, respectively, enriched with graphene oxide, phosphorus-doped graphene oxide, and nitrogen-doped graphene oxides, are tested and evaluated. The results show that phosphorus-doped graphene oxide acts as the most promising flame retardant, which can effectively reduce the burning rate and heat release rate of the combustion process, with excellent smoke suppression effect. Based on the relevant parameters obtained from the experimental results of phosphorus-doped graphene oxide, Simtec simulation is operated to demonstrate vertical combustion of thin fabric before and after flame-retardant treatment, and the results are consistent with the trend of the experimental results and suggest a magnifying effect of phosphorus-doped graphene oxide.

An efficient silicon dioxide (SiO₂) microcapsule was synthesized and used for flame-retardant polyurethane foams. The polyurethane/25 wt% SiO₂ microcapsule composites achieved a limiting oxygen index value of 34.8% and UL-94 V-0 rating, and SDR was significantly reduced. TG, Py-gas chromatography–mass spectrometry, energy dispersive X-ray, and Fourier Transform infrared spectroscopy (FTIP) results indicated that SiO₂ microcapsule could serve as an outstanding flame retardant that operates by both chemical (condensation) and physical (cooling and blocking) mechanisms. The compact and stable char layer formed at the inner layer of the residue during thermal decomposition, and this situation results in the excellent flame retardancy of polyurethane.