Integrated ferrate and calcium sulfite to treat algae-laden water for controlling ultrafiltration membrane fouling: High-efficiency oxidation and simultaneous cell integrity maintaining

Spatial Confinement of Co Nanoparticles in N-Doped Carbon Nanorods for Wastewater Purification via CaSO3 Activation

“…•− and • OH under the high concentration of sulfite ions. 45−49 In this direction, a large number of heterogeneous catalysts, such as Fe−Cu, 50 FeS, 51 Fe-g-C 3 N 4 , 52 ferrate, 53 and siderite, 54 have been designed and developed for activating CaSO 3 on wastewater treatment. However, the inherent defect of the heterogeneous Fenton-like oxidation process is the limitation of mass transfer, which is often overlooked in sulfate radical-based advanced oxidation processes.…”

“…The Fenton-like oxidation process, in which peroxysulfates were used as the oxidants to generate reactive oxygen species (ROS) (e.g., SO 4 •– and • OH), − had been deemed as a green and promising technology for the degradation of organic pollution. − However, excessive use of peroxysulfates could cause potentially biotoxicity, thus leading to secondary pollution. − Recently, sulfite has been deemed as a promising potential substitute to peroxysulfate for generating SO 4 •– in wastewater treatment due to its inexpensiveness and low toxicity. − Among these sulfites, CaSO 3 is regarded to be most suitable for wastewater treatment because CaSO 3 could slowly and persistently discharge SO 3 2– due to its low solubility (compared to Na 2 SO 3 and NaHSO 3 ), thus avoiding the depletion of the generated SO 4 •– and • OH under the high concentration of sulfite ions. − In this direction, a large number of heterogeneous catalysts, such as Fe–Cu, FeS, Fe- g -C 3 N 4 , ferrate, and siderite, have been designed and developed for activating CaSO 3 on wastewater treatment. However, the inherent defect of the heterogeneous Fenton-like oxidation process is the limitation of mass transfer, which is often overlooked in sulfate radical-based advanced oxidation processes. − The mass transfer of ROS (e.g., SO 4 •– and • OH) from its generation sites on the surface of heterogeneous catalysts into chemical pollutants in wastewater is severely restricted by its supershort lifetime (1 ns to 1 μs), greatly impeding their practical applications. − Moreover, these ROS are often quenched by natural organic matter and background inorganic anions in real wastewater .…”

Carbon nanotubes as a nanocatalyst and nanoreactor for the efficient treatment of pharmaceutical wastewater via CaSO3 activation

“…38 This suggests that CaSO 3 could slowly discharge SO 3 2− , and it could be used as a sustained-release SO 3 2− source, which could effectively solve the quenching issue of SO 4 • − at a high concentration of SO 3 2− . 39 Hence, a wide variety of transition metal catalysts such as Fe, 40,41 Cu, 42 Mn, 43 and Co (ref. 44) have been developed for water decontamination via CaSO 3 activation.…”