硼碳氮多孔材料的制备及其吸附再生性能研究

硼碳氮(BCN)多孔材料因其具有高的比表面积、优异的化学稳定性而被认为是一种优异的吸附材料。本文以废弃椰壳、硼酸(H₃BO₃)和尿素(CO(NH₂)₂)为原料,采用冷冻干燥法制备多孔生胚,并在NH₃气氛下通过高温固相反应法在不同的反应温度下合成BCN多孔材料。结果表明,随着反应温度的升高,BCN多孔材料孔径逐渐变大,当反应温度为950 ℃时平均孔径为2.1 nm。将BCN多孔材料用于吸附水中孔雀石绿(MG)有机染料,其最大吸附量可达1 239.8 mg·g^-1,5次循环再生后吸附量平均值仍高达1 138.6 mg·g^-1,说明BCN多孔材料具有优异的循环吸附性能。采用Langmuir和Freundlich等温吸附模型、准一级和准二级吸附动力学模型研究了浓度、吸附时间和平衡吸附量之间的关系。结果表明,BCN多孔材料的吸附与准二级吸附动力学模型吻合,其对MG的吸附属于均匀表面单层分子的Langmuir等温吸附。BCN多孔材料展现出优异的吸附能力,是一种非常有应用前景的新型吸附剂。

Preparation of Boron Carbonitride Porous Material and Its Adsorption and Regeneration Performance

Boron carbonitride (BCN)porous material is considered as an excellent adsorption material due to its high specific surface area and excellent chemical stability. In this paper, porous embryos were prepared by freeze-drying method and BCN porous material was synthesized by high-temperature solid-phase reaction method under NH₃ atmosphere at different reaction temperatures with waste coconut shells, boric acid (H₃BO₃) and urea (CO(NH₂)₂) as raw materials. The results show that with the increase of reaction temperature, the pore size of BCN porous material gradually increases, and the average pore size is 2.1 nm when the reaction temperature is 950 ℃. The as-prepared BCN porous material is applied to adsorb malachite green (MG), an organic dye pollution in water, and its maximum adsorption capacity can reach 1 239.8 mg·g^-1. After five cycles of regeneration, the average adsorption capacity is still as high as 1 138.6 mg·g^-1, indicating that BCN porous material has excellent cyclic adsorption performance. Langmuir and Freundlich isothermal adsorption models, pseudo-first-order and pseudo-second-order adsorption kinetic models were used to study the relationship among concentration, adsorption time and equilibrium adsorption capacity. The results show that the adsorption of BCN porous material is consistent with the pseudo-second-order adsorption kinetic model, and the adsorption on MG belongs to the Langmuir isotherm adsorption of uniform surface monolayer molecules. The as-prepared BCN porous material exhibits excellent adsorption capacity and is expected to be a very promising adsorbent.