Recent advances in adsorptive removal and photocatalytic reduction of Cr(VI) by porous organic polymers (POPs)

•Three distinct synthetic strategies for porous organic polymers (POPs) and related functional derivatives are presented.•Various types of POP-based materials, each possessing unique functional groups, and their applications in the adsorptive removal of Cr(VI) are summarized.•Two specific classes of POP-based materials, showcasing their significance in the field of photocatalytic reduction of Cr(VI), are highlighted.•A thorough analysis and discussion of the different photocatalytic mechanisms utilized in the reduction of Cr(VI) is discussed.