Application of carbon nitride nanosheets for adsorption of various humic substances from aqueous solutions

•The adsorption of LHA by CN-Ns reached 95.17 mg C·g−1 after the thermal oxidation.•The maximum amount of CN-N-575 for LHA was 143.11 mg C·g−1, 11.86 L·cm−1·g−1.•CN-N-575 exhibited high adsorptive removal of about 90% for both LHA and ESHA.•HSs adsorption on CN-Ns was mediated by the interactions and conformation effect.