Advances and applications of graphitic carbon nitride as sorbent in analytical chemistry for sample pretreatment: A review

As a green and efficient sorbent, graphitic carbon nitride (g-C3N4) with aromatic tri-s-triazine units has shown great potential for the enrichment or removal of metal ions and organic aromatic compounds, which makes it a promising candidate to complement graphenes in analytical chemistry. The in-built N-rich functional groups and electronic delocalization properties endow g-C3N4 with complex sorption mechanism, containing complexion, hydrogen bond, redox reaction, π – π conjugation, hydrophobic effect, acid-base reaction and electrostatic interaction. The structure and surface physicochemical properties related to the sorption behavior are mainly depended on the preparation and sorption conditions, such as polymerization temperature, polymerization precursors, the solution pH and ionic strength. As a new sorbent, g-C3N4 has been applied to the sample pretreatment in analytical chemistry with solid-phase extraction (SPE), magnetic solid-phase extraction (MSPE), and solid-phase microextraction (SPME) modes, recently. At the same time, a series of modification methods and technologies have been exploited to modify the structural and surface physicochemical properties of g-C3N4, facilitating more effective and selective sorption process. To raise awareness of the superior properties of g-C3N4 and facilitate its applications as a sorbent in analytical chemistry, the sorption properties (sorption mechanism, influence factors of sorption behavior), applications to the sample pretreatment and structural modifications of g-C3N4 are reviewed.