Reduction of COD in TNT red water through adsorption on macroporous polystyrene resin RS 50B

•Macroporous polystyrene resin RS 50B can be used to reduce COD in TNT red water.•The adsorption of COD onto resin RS 50B is endothermic and spontaneous.•120 g L−1 of resin can reduce 92.49% COD after 8 h of adsorption at 30 °C.

2,4,6-trinitrotoluene (TNT) is an important single compound explosive. During the purification stage of TNT production, a great amount of wastewater called red water is generated, which has an intense red color with high amount of chemical oxygen demand (COD). In this paper, macroporous polystyrene resin RS 50B was used to reduce COD in TNT red water. The effect of resin dosage, initial COD and temperature on COD removal was studied. The results showed that COD removal increased with increasing resin dosage and temperature. When the resin dosage was 120 g L−1, 92.49% COD can be removed after 8 h of adsorption at 30 °C. The adsorption of COD on resin was coincident with Langmuir isotherm. The change in Gibbs free energy ΔG was −4.843, −5.468 and −5.833 kJ mol−1, respectively, when the temperature was 30, 40 and 50 °C, indicating that the adsorption was spontaneous. The intraparticle diffusion of COD onto resin was identified to be the rate limiting step. Macroporous polystyrene resin RS 50B could be a potential adsorbent for treatment of TNT red water.