Integration of oxalic acid chelation and Fenton process for synergistic relaxation-oxidation of persistent gel-like fouling of ceramic nanofiltration membranes

Elucidating carbon conversion and bacterial succession by amending Fenon-like systems during co-composting of pig manure and branch

The essential point of current study was to investigate the effect of a Fenton-like system established by oxalic acid and Fe(II) on gas emission, organic matter decomposition and humification during composting. Branches were pretreated with Fenton reagents (0.02 M FeCl2·4H2O + 1.5 M H2O2) and then adding 10 % oxalic acid (OA). The treatments were marked as B1 (control), B2 (Fenton reagent), B3 (10% OA) and B4 (Fenton-like reagent). The results collected from 80 d of composting showed that adding Fenton-like reagent benefited the degradation of organic substances, as reflected by the total organic carbon and dissolved organic carbon, and the maximum decomposition rate was observed in B4. In addition, the Fenton-like reagent could improve the synthesis of humus characterized by complex and stable compounds, which was consistent with the spectral parameters (SUVA254, SUVA280, E253/E203 and Fourier transform-infrared indicators) of DOC. Furthermore, the functional microbial succession performance and linear discriminant effect size analyses provided microbial evidence of humification improvement. Notably, compared with the control, the minimum value of CH4 cumulation was reported in B4, which decreased by 30.44 %. Concluded together, the addition of a Fenton-like reagent composed by OA and Fe(II) is a practical way to improve the humification. Furthermore, the mechanisms related to the promotion of humification should be investigated from free radicals, functional genes, and metabolic pathways.

Membrane-catalysis integrated system for contaminants degradation and membrane fouling mitigation: A review

The integration of catalytic degradation and membrane separation processes not only enables continuous degradation of contaminants but also effectively alleviates inevitable membrane fouling, demonstrating fascinating practical value for efficient water purification. Such membrane-catalysis integrated system (MCIS) has attracted tremendous research interest from scientists in chemical engineering and environmental science recently. In this review, the advantages of MCIS are discussed, including the membrane structure regulation, stable catalyst loading, nano-confinement effect, and efficient natural organic matter (NOM) exclusion, highlighting the synergistic effect between membrane separation and catalytic process. Subsequently, the design considerations for the fabrication of catalytic membranes, including substrate membrane, catalytic material, and fabrication method, are comprehensively summarized. Afterward, the mechanisms and performance of MCIS based on different catalytic types, including liquid-phase oxidants/reductants involved MCIS, gas involved MCIS, photocatalysis involved MCIS, and electrocatalysis involved MCIS are reviewed in detail. Finally, the research direction and future perspectives of catalytic membranes for water purification are proposed. The current review provides an in-depth understanding of the design of catalytic membranes and facilitates their further development for practical applications in efficient water purification.

A Brief Overview of the Microstructural Engineering of Inorganic-Organic Composite Membranes Derived from Organic Chelating Ligands

This review presents a concise conceptual overview of membranes derived from organic chelating ligands as studied in several works. The authors' approach is from the viewpoint of the classification of membranes by matrix composition. The first part presents composite matrix membranes as a key class of membranes and makes a case for the importance of organic chelating ligands in the formation of inorganic-organic composites. Organic chelating ligands, categorized into network-modifying and network-forming types, are explored in detail in the second part. Four key structural elements, of which organic chelating ligands (as organic modifiers) are one and which also include siloxane networks, transition-metal oxide networks and the polymerization/crosslinking of organic modifiers, form the building blocks of organic chelating ligand-derived inorganic-organic composites. Three and four parts explore microstructural engineering in membranes derived from network-modifying and network-forming ligands, respectively. The final part reviews robust carbon-ceramic composite membranes as important derivatives of inorganic-organic hybrid polymers for selective gas separation under hydrothermal conditions when the proper organic chelating ligand and crosslinking conditions are chosen. This review can serve as inspiration for taking advantage of the wide range of possibilities presented by organic chelating ligands.

Absolute film separation of dyes/salts and emulsions with a superhigh water permeance through graded nanofluidic channels

The development of multifunctional films with a high permeability has been of great concern for effective separation of complex aqueous contaminants, especially in the face of zero or near-zero release regulations. Inspired by the natural structure of sandy soils, polydopamine-wrapped/connected polypyrrole sub-micron spheres (PPSM) were closely packed onto a polypyrrole-coated bacterial cellulose (PBC) support, by which a new two-layered PBC/PPSM composite film formed with graded nanofluidic channels. Interestingly, after being soaked in complex water environments of ethanol, acids, bases, heat, cold and high salinity, or else bended/folded for more than 10 times, the structure and performance of this film still stayed the same, validating its high structural stability and flexibility. Even in a high salinity environment over seawater, this PBC/PPSM film exhibits a dye-separation capacity of almost 100% with a surprisingly superhigh water permeance over one thousand L h^-1 m^-2 bar^-1, one or two magnitudes higher than that of the related films reported in the literature. Meanwhile, the ability for effective oil-water-separation was also validated. Besides the superhydrophilicity and underwater superoleophobicity, the synapse-like-structure-induced graded nanofluidic channels are also proposed to play a key role for rendering such an outstandingly comprehensive performance of the film by greatly overcoming fluid resistance and reducing permeation viscosity.