Preparation Of Boron-nitride-carbon Nanosheets With High Specific Surface Area For Adsorption

In order to remove antibiotic pollutants and salt ions in water,boron-nitride-carbon nanosheets with high specific surface area were synthesized by high-temperature solid-state method,which have outstanding electrochemical and thermal stability,high specific surface area and positive surface charge.After configuring with activated carbon,the asymmetric CDI cell exhibits excellent desalination capacity and good cycling stability,and successfully inhibited the phenomenon of anodic oxidation in the process of electro-adsorption.In addition,this material also shows outstanding adsorption performance for antibiotic pollutants in water,and successfully solves the problem that traditional powder adsorbents are not easy to recover.The specific works are as follows:In the first part of the work,high-temperature solid-state method was used to synthesize MBCN suggesting the mesoporosity and BCN suggesting the microporosity.The specific methods are as follows:1.2.Commercial activated carbon?AC,HD2000?or OMC was mixed with boric acid and urea in deionized water.After drying,BCN or MBCN nanosheets were obtained by high temperature reaction and ammonia atmosphere doping.The successful preparation of boron-nitride-carbon materials was confirmed by X-ray photoelectron spectroscopy?XPS?,X-ray diffraction?XRD?,thermogravimetric?TG?and Fourier infrared?FTIR?analysis.The results show that BCN and MBCN have pore structure dominated by micropore and mesoporous respectively.At last,the Zeta potential and zero charge potential were used to test the BCN and MBCN nanosheets.An asymmetric CDI cells?BCN//AC,MBCN//AC?was constructed with the two boron-carbon-nitrogen nanosheets as the positive electrode and the commercial activated carbon as the negative electrode for the electro-adsorption of salt ions in water.The electric adsorption capacities of BCN//AC and MBCN//AC were 17.46 mg g^-1 and 14.49 mg g^-1,respectively,and both adsorbents showed good adsorption performance for salt ions in water.At the same time,the recycling performance of two asymmetric CDI cells was also investigated.After 50 cycles of test,the adsorption capacity still maintains more than 81%.In the second part of the work,we still take the two kinds of boron-nitride-carbon nanosheets synthesized in the first part as adsorbents and apply them to the physical adsorption experiments of roxithromycin and chloramphenicol.It was found that the adsorption capacity of chloramphenicol on BCN was higher,reaching 546.15 mg g^-1,while that of MBCN was only420.54 mg g^-1.The adsorption capacity of MBCN to roxithromycin was higher,reaching575.68 mg g^-1,while that of BCN was only 460.09 mg g^-1.At the same time,both adsorbents showed good adsorption kinetics,and the adsorption equilibrium could be reached with in 1hour.In addition,in order to explore the adsorption mechanism,this experiment also investigated the influence of NaCl salt ions and solution pH value on the adsorption process in detail.Finally,in order to investigate the recycling performance of the two adsorbents,we compared the recycling effects of air burning regeneration and acid and alkali hydrolysis regeneration adsorbents.After six cycles of tests,the final adsorption capacity remained above92%.