以氧化石墨烯为碳源,硼酸为硼源,采用水热法一步制得硼掺杂还原氧化石墨烯(B-RGO),利用扫描电镜、X射线衍射和红外光谱表征其物理性能,并首次研究其对Cr(Ⅵ)的吸附动力学和热力学。结果表明,B-RGO中B含量为7.16at%,为纳米片状无序结构碳,表面存在含氧和含硼官能团,可以提供更多的活性吸附位点,因而其对 Cr(Ⅵ)的吸附性能优于RGO和GO。测试发现,其动力学符合准二级动力学模型,相关系数R2为0.992,化学吸附起主导作用;粒子内扩散模型表明,吸附的速率由膜扩散和内扩散共同控制。不同温度下的吸附等温线更符合Langmuir等温式,最大吸附量为119mg/g(318K),0<RL<1,说明B-RGO吸附Cr(Ⅵ)为有利吸附。热力学参数ΔG0<0,ΔH0>0,ΔS0>0,表明B-RGO吸附Cr(Ⅵ)的过程是自发的、吸热的熵增反应。
Boron-doped reduced graphene oxide (B-RGO) was prepared by one pot hydrothermal method using graphene oxide(GO) and boric acid as the carbon precursor and boron source.The physical properties of B-RGO were characterized by scanning electron microscopy (SEM),X-ray diffraction (XRD) and fourier transform infrared spectrum (FT-IR),and its adsorption kinetics and thermodynamics for Cr(Ⅵ) were also studied for the first time.The results showed that B-RGO was nanosheet-like disordered structure carbon,the content of B in B-RGO was 7.16 at%.The surface had oxygen-containing and boron-containing functional groups,which could provide more active adsorption sites.Thus,the adsorption performance of Cr(Ⅵ) by B-RGO was superior to that of RGO and GO.The adsorption kinetics fitted well to the pseudo-second-order model,and the correlation coefficients R2 was 0.992,suggesting that the adsorption of Cr(Ⅵ) by B-RGO was dominated by chemisorption.The intra-particle diffusion model showed that the rate-controlled step was governed by both film-diffusion and intra-particle diffusion.The adsorption isotherms at different temperatures were more consistent with the Langmuir isotherm,with a maximum adsorption quantity of 119mg/g (318K).Moreover,0<RL<1,indicating that the adsorption of Cr(Ⅵ) by B-RGO was a favorable process.The thermodynamic parameters ΔG0<0,ΔH0>0,ΔS0>0,manifesting that the adsorption process was spontaneous,endothermic and randomness.
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