Towards advanced removal of organics in persulfate solution by heterogeneous iron-based catalyst: A review

Construction of biomass-derived magnetic-recyclable FeNi-LDO@CS to activate persulfate for simultaneous degradation of cationic and anionic dyes: Discrepancy, mechanism and toxicity analysis

In this study, layered chitosan-based magnetic nickel ferrite NiFe2O4/chitosan (CS-LDO) composites were synthesized. The results show that under optimal conditions, 98 % of methylene blue (MB) and 92 % of xylenol orange (XO) can be simultaneously degraded within 120 min in the CS-LDO/persulfate (PS) system, and the removal rates of total organic carbon (TOC) and chemical oxygen demand (COD) can reach 67.32 % and 74.23 %, respectively. In addition, the strong magnetism of the material itself and multiple cycle experiments indicate that CS-LDO has good recyclability and reusability. The results of quenching experiments, electron paramagnetic resonance (EPR) and electrochemical characterization tests demonstrate that the degradation occurred via both radical and non-radical mechanisms. The differing types of reactive oxygen species (ROS) acting and the different electrostatic attraction between the materials and the two dyes lead to a significant difference in the removal effect of two dyes. The degradation mechanism is the redox reaction between Ni2+/Ni3+, Fe2+/Fe3+ and the synergistic effect of Ni3+/Fe2+. Finally, the biotoxicity assessment demonstrated that both the degradation intermediates of mixed dyes and the material itself exhibited low biotoxicity.

An insight into the role of experimental parameters in advanced oxidation process applied for pharmaceutical degradation

The advanced oxidation process (AOP) is an efficient method to treat recalcitrance pollutants such as pharmaceutical compounds. The essential physicochemical factors in AOP experiments significantly influence the efficiency, speed, cost, and safety of byproducts of the treatment process. In this review, we collected recent articles that investigated the elimination of pharmaceutical compounds by various AOP systems in a water medium, and then we provide an overview of AOP systems, the formation mechanisms of active radicals or reactive oxygen species (ROS), and their detection methods. Then, we discussed the role of the main physicochemical parameters (pH, chemical interference, temperature, catalyst, pollutant concentration, and oxidant concentration) in a critical way. We gained insight into the most frequent scenarios for the proper and improper physicochemical parameters for the degradation of pharmaceutical compounds. Also, we mentioned the main factors that restrict the application of AOP systems in a commercial way. We demonstrated that a proper adjustment of AOP experimental parameters resulted in promoting the treatment performance, decreasing the treatment cost and the treatment operation time, increasing the safeness of the system products, and improving the reaction stoichiometric efficiency. The outcomes of this review will be beneficial for future AOP applicants to improve the pharmaceutical compound treatment by providing a deeper understanding of the role of the parameters. In addition, the proper application of physicochemical parameters in AOP systems acts to track the sustainable development goals (SDGs).