Layer‐by‐Layer Assembly Fabrication of Porous Boron Nitride Coated Multifunctional Materials for Water Cleaning

Abstract

Cleanup of oil spills and industrial discharge of organic solvents is a global challenge. However, development of the ideal materials for water remediation with a high separation efficiency and low risk of fire is still rather sparse because the material needs to be superhydrophobic/superoleophilic and also flame‐retardant. Here, a novel coating material of porous boron nitride nanosheets (BNNSs) and a layer‐by‐layer assembly technology for tailoring inexpensive cotton fabric and melamine sponge with these desired properties are reported. The BNNS‐coated cotton fabric and melamine sponge exhibit high oil/water separation efficiency, selective absorption capacity of oil and organic solvents, and excellent recyclability. Furthermore, the coated materials show an efficient flame‐retardant effect which completely stops melamine sponge melt dripping upon exposure to the direct flame from a butane blowtorch within 52 s. The integrated advantages of the high porosity, low water adhesion, compressibility, strong fire‐resistance, simple operation, and commercial availability enable the porous BNNS‐coated cotton fabric and melamine sponge to satisfy various practical oil/water separation requirements.

Boron nitride aerogels consisting of varied superstructures

“…Despite active endeavors, it is still challenging to realize different wettability on BNrelated materials. 22,[38][39][40][41][42] Also, there is a possibility that the asobtained wetting states could only sustain for a short time. 22 Compared with the previous efforts, our work demonstrated not only the effective fabrication of the BN aerogel with varied microstructures but the tuning of wetting behavior without involving any special treatment, which are widely employed in wettability modulation, such as irradiation, etching, or coating.…”

Flame-Retardant Silanized Boron Nitride Nanosheet-Infused Superhydrophobic Sponges for Oil/Water Separation

“…Therefore, excellent flame-retardant property and thermal stability of the sponge were necessary for practical application. 14 The combustion behavior of the sponge was evaluated by measuring the oxygen index (OI) (expressed as a percentage). The as-fabricated sponges were cut into certain size (100 × 10 × 10 mm), and the mixed gas of oxygen and nitrogen was introduced before ignited.…”

“…12,13 Meanwhile, the flame retardant property of the sponge is also crucial, as the sponge is inevitably exposed to the risk of fire and explosion when absorbing flammable crude oil and organic solvents. 14,15 In addition, most of the sponges with flexible segments are unstable in harsh environments, which could limit their large-scale application. 16 Therefore, there is an urgent demand for the development of an ideal sponge with robust superhydrophobicity, superior flame retardancy, and excellent chemical stability.…”

“…Accordingly, seeking a technology that can separate oil/water mixtures effectively is urgently required. − Tremendous efforts have been devoted to develop green and safe oil/water separation materials (eg., fiber, copper mesh, molecular sieve, sponge, woven, etc.). Among them, three-dimensional (3D) porous commercial melamine sponge with the merits of low cost, lightweight, environment friendly, and intrinsic microlevel porous structure is promising for large scale oily wastewater treatment. , However, the melamine sponge with instinct hydrophilicity and lipophilicity always absorbs the water and oil simultaneously, which could reduce the separation efficiency and the sponge could become a flammable secondary pollutant. − Hence, the prerequisite to improve the oil/water mixtures separation efficiency of a sponge is to enhance its selectivity, for example, developing a superhydrophobic/superlipophilic sponge. , Meanwhile, the flame retardant property of the sponge is also crucial, as the sponge is inevitably exposed to the risk of fire and explosion when absorbing flammable crude oil and organic solvents. , In addition, most of the sponges with flexible segments are unstable in harsh environments, which could limit their large-scale application . Therefore, there is an urgent demand for the development of an ideal sponge with robust superhydrophobicity, superior flame retardancy, and excellent chemical stability.…”

Layer-by-Layer Deposition: A Promising Environmentally Benign Flame-Retardant Treatment for Cotton, Polyester, Polyamide and Blended Textiles

“…This fabric exhibited excellent FR (the sample passed VFTs; pHRR and THR values were reduced by 86% and 39%), hydrophobic, self-cleaning, selfhealing and antifouling properties with acid/alkali resistance [119]. The same properties could be achieved by coating cotton fabric with 16 BLs of cationic poly (dimethyldiallyl) ammonium chloride (PDDA) and anionic boron nitride nanosheets (BNNS) [120]. To obtain FR, wrinkle-resistant, antibacterial and UV-protective properties of cotton fabric, Safi et al dipped fabrics first into a cationic solution consisting of 1 wt% CH, 5 wt% citric acid and 2 wt% sodium hypophosphite (SHP), followed by drying at 110 • C; then, they dipped them into a solution of 5 wt% sodium lignin sulphonate (SLS) and 4 wt% boric acid (BA), followed by drying at 80 • C for each dip.…”