Sandwich-like, potassium(I) doped g-C3N4 with tunable interlayer distance as a high selective extractant for the determination of Ba(II).

Element doping is considered as an effective strategy to adjust the interlayer distance of graphitic carbon nitride (g-C3N4) and the element doped g-C3N4 can be applied in metal extraction. Here, a series of potassium(I) doped graphitic carbon nitride (g-C3N4-K) materials with modulated interlayer distance ranging from 3.257 Å to 3.198 Å were successfully synthesized by calcining the different doped ratios mixture of melamine and KOH. Interestingly, g-C3N4-K (Q(melamine):Q(KOH) = 7:1) composite achieves the optimal properties and displays excellent extraction capacity and selectivity for barium [Ba(II)]. It is attributed to the correlation between K dopants and interlayer distance of g-C3N4-K, which highlighted the effect of doped K on the decreasing interlayer. Furthermore, an original extraction method coupled with ICP-OES based on g-C3N4-K was established for Ba(II) and successfully applied in detection of trace Ba(II) in water sample from Yellow River and sample of sea fish.