Synthesis Of Porous Boron Nitride Loaded Metal Oxide Nanoparticles Composites And Application In Water Treatment

China is a country with a shortage of freshwater resources.The increasingly serious problem of water resources pollution has further aggravated the contradiction of water shortages,and it also seriously threatens the ecological environment and human health.Therefore,the problem of wastewater treatment is a matter of no delay.Porous boron nitride?p-BN?features a large specific surface area,a rich pore structure,and good stability,making it ideal for use as an adsorbent in wastewater treatment applications.However,the surface hydrophobic structure,micron-sized particles,and high band gap of p-BN have limited their dispersion,recovery,and photocatalytic properties during wastewater treatment.In order to solve the above problems,p-BN with a high specific surface area and a developed pore structure was selected as the substrate in this thesis.By coating Fe₃O₄magnetic nanoparticles and TiO₂ semiconductor nanocrystals,p-BN-based composite materials with hydrophilic surface were prepared.The adsorption,degradation and recycling efficiency of the as-prepared p-BN-based composite materials for heavy metal ions and antibiotics in water were studied.The main contents of this thesis are as follows:?1?We prepared p-BN@Fe₃O₄ nanocomposites by in-situ growth of Fe₃O₄ magnetic nanoparticles on the surface of p-BN by solvothermal method.The structural characterization results show that the Fe₃O₄ nanoparticles with an average particle size of 7 nm are uniformly and densely coated on the surface of p-BN and exhibit superparamagnetism.Then the p-BN@Fe₃O₄ nanocomposites were used for the adsorption of heavy metal Pb?II?ions in water.The results showed when the initial concentration of Pb?II?was 180 mg/L and solution pH was 5.5,the maximum adsorption capacity of p-BN@Fe₃O₄ nanocomposites for Pb?II?is as high as 249.5 mg/g.In addition,the superparamagnetism of the p-BN@Fe₃O₄nanocomposites also enabled the rapid separation at low magnetic fields.Therefore,the p-BN@Fe₃O₄ nanocomposites have great potential in the treatment of heavy metal ions in wastewater.?2?The solvothermal method was used to prepare p-BN@TiO₂ composites successfully.The as-prepared nanocomposites with high crystallinity,good hydrophilicity,and strong photocatalytic activity for quinolone antibiotics in water.We studied the effects of the amount of H₂O₂ on the morphologies of TiO₂ nanocrystals in the reaction system.The photocatalytic degradation of quinolone antibiotics and the cycling performance of p-BN@TiO₂ composites were studied.The results showed that the degradation of ofloxacin and norfloxacin by the nanocomposites reached 100%and 76%,respectively,after irradiation with a 300 W xenon lamp for 120 min.After 4 cycles,the removal was still 92%and 73%respectively.Therefore,p-BN@TiO₂ composites is a kind of photocatalyst with high practical value.