Low cost red mud modified graphitic carbon nitride for the removal of organic pollutants in wastewater by the synergistic effect of adsorption and photocatalysis

•RM-CN composite was directly prepared via one-step thermal polymerization method.•RM-CN has good catalytic activity under the synergistic effect of adsorption and photocatalysis.•The specific surface area of CN has been significantly enhanced with the introduction of RM.•The degradation mechanism of RM-CN was proposed based on capturing experiments and ESR technique. The red mud/g-C3N4 (RM-CN) composite was directly prepared via one-step thermal polymerization method using melamine and industrial waste residue (red mud) as raw materials. Under the synergistic effect of adsorption and photocatalysis, RM-CN composites have a significant effect for the removal of organic pollutants from wastewater. Compared with pure CN, the specific surface area of RM-CN has been significantly enhanced with the introduction of RM. Additionality, the optical absorption and photocurrent response exhibit obvious enhancement with respect to RM-CN as compared with that of pristine CN photocatalyst. The optimized 0.8% RM-CN product (with the RM mass content of 0.8 wt% in precursor) displayed referable photocatalytic degradation efficiency for antibiotics and dyes under visible light, as well as excellent recycle performance. This work poses a great potential in the actual wastewater treatment, and it is of great significance to the resource utilization and the cost saving of the raw material.