Lignosulfonate-controlled BiOBr/C hollow microsphere photocatalyst for efficient removal of tetracycline and Cr(VI) under visible light

•BiOBr/C hollow microspheres were prepared by a one-step hydrothermal method.•SLS enhanced the visible-light photocatalytic performance of BiOBr.•The effect of adding SLS on the morphology of BiOBr/C was studied in detail.•Possible degradation pathways and photocatalytic mechanisms were illustrated.