Adsorption and catalytic degradation of sulfamethazine by mesoporous carbon loaded nano zero valent iron

In this work, a composite material of mesoporous carbon loaded nano zero valent iron (nZVI/MC) was prepared and used as an activator of persulfate (PS) to degrade sulfamethazine (SMZ). Scanning electron microscopy (SEM) images showed nano zero valent iron (nZVI) was dispersed on the surface or in the mesopores of mesoporous carbon (MC) without aggregation. nZVI/MC has less surface area (175.63 m2 g−1) than MC (240.83 m2 g−1). The adsorption efficiency of SMZ increased as the MC and nZVI/MC dosages increased. However, its adsorption efficiency decreased as its initial concentration and pH value increased for both the MC and nZVI/MC. nZVI/MC+PS process showed the most effective removal for SMZ, its removal rate reached 69.5%. Catalytic degradation results indicated that material dosage and temperature enhanced SMZ degradation in the nZVI/MC+PS process, while SMZ initial concentration had the opposite effect. For the effect of PS concentration, the SMZ removal efficiency increased in the beginning and then decreased. Quenching experiments indicated that SO4- was relatively more dominant that OH in the process of SMZ degradation, which could also be confirmed by EPR analysis. The main degradation pathways of SMZ were the Smiles-type rearrangement and the nitration of aniline moiety.