Secondary effluents are regarded as both sources and sinks of emerging contaminants. Adsorption by activated coke (ACO) is successfully being applied in the advanced treatment of secondary effluent from the wastewater treatment plant of China. However, ACO proved ineffective in removing the sweetener acesulfame (ACE). Herein, both mesoporous ACO and microporous activated carbon (AC) were comparatively used for the innovative confinement of Mn oxides within their porous structures by impregnation/calcination to enhance ACE adsorption. The optimal synthesis conditions were determined to be a MnSO 4 ·H 2 O/ACO mass ratio of 1.0% and a calcination temperature of 600°C (Mn-ACO600). Mn-ACO600 exhibited superior ACE adsorption compared to Mn-modified AC. Stable adsorption performance was observed within the neutral pH range, which favors practical applications. The pseudo-second-order model best described the adsorption kinetics, indicating a possible chemisorption mechanism. Both the Langmuir and Freundlich isotherm models could effectively simulate ACE adsorption, with a q max of 299.6 mg/g at 298 K. Thermodynamic analysis indicated a spontaneous and exothermic process (Δ H 0 = −68.51 kJ/mol) with entropy reduction (Δ S 0 = −218.56 J mol −1 ·K −1 ). Both coexisting inorganic anions and natural organic matter had insignificant influences. Furthermore, the recycled Mn-ACO600 retained an acceptable adsorption capability. Three-dimensional fluorescence excitation-emission matrix analysis demonstrated that Mn-ACO600 adsorption effectively removed organic matter from real secondary effluent.
The removal of dissolved organic matter from secondary effluent in sewage treatment is a significant challenge, necessitating the development of green and efficient composite magnetic materials for coagulation. In this study, activated carbon-modified magnetite nanoparticles (AC@MNPs) were synthesized via one-step activation pyrolysis using iron sludge as a precursor. The ballast coagulation process employed AC@MNPs as both magnetic species and adsorbent, with polymeric aluminum chloride (PACl) as a coagulant, for advanced treatment of secondary effluent. A response surface methodology identified optimal pyrolysis conditions: an activation ratio (KOH/ST) of 1.2, a pyrolysis time of 1 h, and a temperature of 640 °C. The influence of pyrolysis temperature (600 ∼ 700 °C) on the morphology and pore characteristics of AC@MNPs was investigated, highlighting its significance in coagulation performance. Characterization through XRD, VSM, and FTIR confirmed the favorable settling properties of the composite magnetic flocs and recyclability of AC@MNPs. Coagulation experiments revealed a synergistic effect of AC@MNPs and PACl, enhancing the removal of UV 254 and COD from 33.4 % and 36.2 % (with PACl alone) to 74.02 % and 76.53 %, respectively. The overall performance of the ballast coagulation process was evaluated, demonstrating effective removal of organics of various molecular weights. Finally, the coagulation mechanism was systematically discussed. Overall, this research offers insights into the application of magnetic coagulation technology for wastewater treatment advancements.
危险品化学品经营许可证（带存储）