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The availability and accessibility of clean and secure water supplies are pressing technological and scientific issues worldwide. As a result of global water constraints, wastewater treatment and reuse are being evaluated as feasible alternatives to fresh water for agricultural irrigation and domestic and industrial purposes. Boron carbon nitride (BCN) nanosheets have been studied intensively in the last decade in batteries, biosensors, and capacitors, and for use as catalysts, and they have recently been used in wastewater treatment. BCN materials, along with their synthesis processes, characteristics, and application areas in water and wastewater treatment, are discussed thoroughly in this paper. Additionally, synthesis processes for ternary BCN compounds, including chemical vapor deposition, ion beam-aided deposition, magnetron sputtering, and pulsed laser deposition, are described. BCN materials have also been explored because of their flexible electrical features, excellent mechanical strength, outstanding unreactivity, and significant stability, which make them appropriate for a range of severe environment applications. Thus, the use of BCN materials as photocatalysts and adsorbents and in electrochemical reduction and capacitive deionization are also discussed thoroughly. The highest ammonia production of 172,226.5 μg/h.mg.cat and faradic efficiency of 95.3% have been obtained using the BCN@Cu/CNT catalyst, whereas the ammonia production and FE values for metal-free BCN are 7.75 μg/h.mg.cat and 13.8%. Moreover, the maximum attained adsorption capacities of BCN nanosheets for Pb2+ and Hg2+ are 210 and 625 mg/g, respectively. Overall, this review indicates that essential work on BCN nanosheets is still needed. Future research should focus on the development of BCN nanostructures to encourage multidisciplinary research. [Display omitted] • BCN nanosheets improved performance for water treatment is summarized. • Synthesis methods for ternary BCN nanosheets are explored. • BCN as photocatalysts, adsorbents, and in electrochemical reduction are discussed. • Metal-loaded BCN nanosheets were elaborated as effective water treatment strategy. • Metal and ammonia production potential of BCN increased with metal modification. [ABSTRACT FROM AUTHOR]

In this study, the effects of different operating conditions on the salt removal from brackish water by dry and fresh Scenedesmus obliquus (S. obliquus) were investigated to explore the mechanisms of algae biological desalination process. It was identified that, within only 30 min contact time, the salt removal increased with the increasing salinity, which was probably due to the higher NaCl concentration gradient from the bulk solution to the algae surface. Compared to other study with a longer algae cultivation period (16 days), this study demonstrated that both adsorption and absorption contributed to the NaCl removal, but adsorption played a more significant role (two thirds of the NaCl removal). The full adsorption can be reached within a relatively short period (1–30 min), and the salts removed by absorption is negligible when the contact time was short. The Langmuir isotherm adsorption model can accurately predict the NaCl adsorption, which indicated the formation of a single molecular layer on the algae surface. The FT-IR analysis further demonstrated different functional groups on the cell wall of S. obliquus can effectively combine the Na+ and Cl−. Overall, the fresh algae showed much faster adsorption kinetics. The results of this study showed promise for the search of alternative desalination technology with an environmentally friendly algae-based biological system. • Systematic study of mechanisms of algae biological desalination process • Salt removal by adsorption process rather than absorption process • Performance comparison between dry and fresh algae • Adsorption mechanism analyzed by isotherm adsorption models and FT-IR analysis [ABSTRACT FROM AUTHOR]