The influence of crystal structure and formation path of precursor on phosphate adsorption during oxidation-hydrolysis phase transition of siderite

Effect of a Permanganate-Bearing Reactive Oxidant on Flocs in Electrocoagulation: Transformations and Interfacial Interactions

“…Furthermore, the generated Mn impurity and MnO 2 during the PEC process led to the stabilization of Fh by separating the LMCT process between absorbed Fe­(II) and 2-Fh . The above-stated reasons indicated that the transformation pathways of Fh to γ-FeOOH were blocked . In summary, various characterization studies of the floc structure provided additional support for our previous speculation that the enhancement of the EC process by PM relied heavily on the crystallization mechanism, and transformation from γ-FeOOH to Fh-based species.…”

“…Although the use of an iron anode further reduces the cost of the EC unit, Fe­(II) generated from the anode is an inefficient coagulant due to the prolonged hydrolysis process occurring in the presence of organic matter (OM) . The flocs with high crystallinity and a limited number of active sites are generated in this process, which exhibit difficulty in enlarging their sizes to achieve a satisfactory coagulation effect. , Furthermore, the high formation tendency of Fe­(II)–OM complexes in the EC unit may lead to the leakage of residual coagulant ions if the coagulation time is insufficient . Beyond that, compact integrated systems mean that reaction time should be sacrificed to minimize reactor volume.…”

“…Our previous study has shortened the start-up time of the coagulation process by introducing a reactive oxidant (permanganate, PM), which could react rapidly with Fe­(II) derived from the iron anode. In fact, it is common practice to enhance Fe-based coagulation by introducing PM, which is roughly attributed to the production of flocculation nuclei (manganese dioxide, MnO 2 ). − Moreover, during the complex redox reactions between the in situ formed Fe/Mn-based intermediates, inorganic- or organic-contaminants are removed through multiple pathways, such as adsorption, oxidation, co-precipitation, and so forth. ,− Despite this, the in-depth mechanism by which PM optimizes Fe-based coagulation or even EC has rarely been explored till date. Returning to the ECUF process, it is reported that the compact ECUF process outperformed the split EC-UF process in terms of membrane fouling control. , This was ascribed to the fact that from the macroscopic perspective, both the EC process and the electric field modulated the polarity and porosity of the cake layer, respectively. , Based on the ECUF process, the upgraded permanganate-bearing ECUF (PECUF) process was subsequently proposed due to its lower membrane fouling tendency, and higher working capacities, such as higher permeate flux, more effective contaminant removal, minimal secondary pollution, , and so forth.…”

“…12 The flocs with high crystallinity and a limited number of active sites are generated in this process, which exhibit difficulty in enlarging their sizes to achieve a satisfactory coagulation effect. 13,14 Furthermore, the high formation tendency of Fe(II)−OM complexes in the EC unit may lead to the leakage of residual coagulant ions if the coagulation time is insufficient. 15 Beyond that, compact integrated systems mean that reaction time should be sacrificed to minimize reactor volume.…”

Goethite Formed in the Periplasmic Space of Pseudomonas sp. JM-7 during Fe Cycling Enhances Its Denitrification in Water

“…These minerals bear a positive charge at neutral pH, which makes them prone to adhering to negatively charged bacteria and promoting microbial film adherence during the denitrification process. , The iron minerals created through the denitrification of iron­(II)-oxidizing microorganisms can display different types and degrees of crystallinity depending on the nutrient solution’s C/N ratios . Previous research indicates that chemical compounds within the solution, mineral additives, and organic compounds secreted by microorganisms significantly impact iron mineralization. − Furthermore, these minerals cause varying effects on the migration, metabolism, and electron transport mechanisms of different microorganisms. , …”