Synthesis Of Metal-doped Few-layer Boron Nitride Nanocomposites For Adsorption Of Antibiotics In Water

In recent years,the pollution of pharmaceutical wastewater in the environment had caused widespread concerns in the society with the rapid development of the pharmaceutical industries.Different levels of antibiotic pollution can be detected in all river basins around the world and the constant accumulation of antibiotics from water bodies had caused great harm to human health and ecosystems.Compared with traditional water pollution treatment technologies such as degradation and oxidation,the adsorption method has become one of the most practical and feasible drug pollution treatment methods due to economic and environmental protection,simple operation and other advantages.In this paper,three kinds metal-doped boron nitride-based nanocomposites with high adsorption properties were constructed by adjusting the synthesis methods and conditions on the based of two-dimensional graphene-like thin-layer boron nitride（BN）nanomaterials,and their adsorption performances and mechanisms for antibiotics in water were studied.The adsorbents were analyzed by XRD,FT-IR and N₂ adsorption-desorption,TEM,XPS and other characterization methods,and studied the structure-performance relationships through changing the adsorption reaction conditions and analyzing adsorption kinetics,isotherms and thermodynamic.This research work further expanded the application of boron nitride-based nanomaterials in the field of adsorption and separation and provided references for the development of high-performance adsorbents for the advanced treatment of antibiotics in pharmaceutical wastewater.1.Metal zinc nanoparticles were introduced by in-situ synthesis method,and the calcination temperatures were adjusted to prepare metal zinc oxide-supported thin-layer boron nitride nanosheet（Zn O@BN）adsorbents.Metal zinc was uniformly doped and dispersed in the graphene-like boron nitride nanosheet structure in the form of zinc oxide nanoparticles（Zn ONPs）.The incorporated Zn ONPs significantly enriched the surface active centers of BN and enhanced the pi-pi interaction between Zn O@BN and the antibiotic chlortetracycline（CTC）by modulating the electron arrangement on the BN surface.Compared with pure BN,the adsorption capacity of Zn O@BN-800calcined at 800°C for CTC increased by 61.7%.After 5 hours,the adsorption equilibrium was reached and the equilibrium adsorption capacity reached 291 mg/g.The adsorption process conformed to the pseudo-second-order kinetic model and the Freundlich isotherm model,enhanced pi-pi interaction,electrostatic interaction,hydrophobic interaction and metal-pi complexation were the main adsorption forces.2.Graphene-like thin-layer molybdenum disulfide（Mo S₂）and BN nanocomposite（BN-Mo S₂）adsorbents were prepared efficiently in one step by using simple,green and low-cost ball milling technology.Mo S₂ was successfully loaded on the surface of BN stably through the physical and mechanical force of the ball mill.The optimal compound molar ratio of BN and Mo S₂ was 1:2,the removal rate of CTC by BN-Mo S₂was increased by 52.8%and 24.6%respectively and reached 94.6%compared with monomer BN and Mo S₂.After 14 hours,the adsorption equilibrium was reached and the equilibrium adsorption capacity was 381 mg/g.The adsorption process had strong chemical and physical force,belonged to multi-layer adsorption process on the non-uniform surface and the reaction of adsorption was spontaneous and endothermic.The synergistical enhanced pi-pi interaction,hydrophobic interaction and electrostatic interaction played important roles during the adsorption process.3.The bimetallic copper molybdenum sulfur doped BN nanocomposite（BN-Cu2Mo S4）adsorbents were synthesized by the hydrothermal co-growth method through introducing the two-dimensional ternary transition metal chalcogenide copper molybdenum sulfur（Cu₂Mo S₄）.The results of characterization showed that Cu₂Mo S₄was successfully loaded on BN,the metal Mo and monovalent copper on the surface of the material were partially oxidized.The BN-Cu₂Mo S₄ synthesized under the conditions of 170℃,Cu I as the copper source and 0.1 g of BN compound had the best adsorption effect on CTC,the adsorption capacity increased by 95%and 138%compared with BN and Cu₂Mo S₄ monomer respectively and the equilibrium adsorption capacity was up to 472 mg/g.The pseudo-second-order kinetic model and Freundlich isotherm model described the adsorption process better.The cycle stability of BN-Cu₂Mo S₄ was good and the CTC removal rate remained 84%after 5 cycles of regeneration.The adsorption mechanism was presumed to be synergistical enhanced pi-pi interaction,pi-metal complexation,electrostatic interaction and hydrophobic interaction.