AbstractA novel composite (nZVI@K-GCN) was firstly synthesized by liquid phase reducing nanoscale zero-valent iron (nZVI) on potassium-doped graphitic carbon nitride (K-GCN). The results of Fourier transform infrared (FTIR) spectrometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) suggested that nZVI@K-GCN possessed abundant active functional groups such as terminal amino-groups (-NH or -NH2 groups) and -OH, and the specific surface area and pore volume from BET of nZVI@K-GCN were 4.7 times and 3.7 times higher than that of graphitic carbon nitride (GCN), respectively. These properties showed that the composite was especially suitable for heavy metal treatment. The application of the composite in the removal of chromium(VI) from aqueous solution showed that the maximum adsorption capacity of nZVI@K-GCN towards Cr(VI) was 68.6 mg/g at 308 K when the initial concentration of Cr(VI) was 30 mg/L, and more than 99% removal was obtained at pH = 3. This adsorption was an endothermic and spontaneous process. XPS patterns and batch experiments proved that complexation, electrostatic attraction and reduction precipitation were the main adsorption mechanism for Cr(VI) on nZVI@K-GCN.

中文翻译：

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纳米零价铁改性钾掺杂石墨氮化碳的合成、去除Cr(VI)性能及机理

摘要首先通过液相还原纳米零价铁（nZVI）在钾掺杂石墨氮化碳（K-GCN）上合成了一种新型复合材料（nZVI@K-GCN）。傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）、扫描电子显微镜（SEM）和Brunauer-Emmett-Teller（BET）的结果表明nZVI@K-GCN具有丰富的活性官能团，例如末端氨基nZVI@K-GCN的-基团（-NH或-NH2基团）和-OH以及BET比表面积和孔体积分别是石墨氮化碳（GCN）的4.7倍和3.7倍。这些特性表明该复合材料特别适合重金属处理。将该复合材料应用于去除水溶液中的铬(VI)表明，当Cr(VI)初始浓度为308 K时，nZVI@K-GCN对Cr(VI)的最大吸附量为68.6 mg/g。为30 mg/L，在pH = 3时去除率超过99%。这种吸附是吸热的自发过程。XPS图谱和批量实验证明络合、静电吸引和还原沉淀是nZVI@K-GCN对Cr(VI)的主要吸附机制。