Activation of peroxymonosulfate using carbon black nano-spheres/calcium alginate hydrogel matrix for degradation of acetaminophen: Fe3O4 co-immobilization and microbial community response

[Display omitted] •Integration of carbon black nano-spheres with calcium alginate hydrogel to activate PMS.•Hardness, alkalinity, nutrients and scavengers were considered during the process.•Enhanced efficiency via co-immobilization with nano-sized magnetite.•Evaluation of effluent bio-toxicity by microbial community response. Herein, we focused on the degradation of acetaminophen (ACT) drug in liquid phase by peroxymonosulfate (PMS) activated by carbon black nano-spheres (CBNS). The nanostructured activator was immobilized into calcium alginate hydrogel matrix (CAHM) to avoid the washout of the fine nanostructures. The Langmuir modeling showed an insignificant contribution to the adsorption process in the removal of ACT. The basic pH conditions favored the decomposition of ACT. Among nutrients, the presence of nitrogenous compounds including nitrite, nitrate and ammonium caused a little decrease in the reactor performance, while the addition of phosphate ion improved the efficiency from 76.8% to 81.9%. The results demonstrated the involvement of both SO4•− and •OH radicals in the degradation of ACT and domination of SO4•− radicals in the degradation process. Co-immobilization of the CBNS with electro-synthesized magnetite nanoparticles resulted in not only the enhanced reusability potential but also improved the efficiency of the treatment process to 95.6%. Mineralization efficiency of the process was not remarkable; however, the process produced an effluent with lower toxicity toward the microbial community of the activated sludge.