Preparation of PMMA Electrospun Fibers Bearing Porphyrin Pendants and Photocatalytic Degradation of Organic Dyes.

Porphyrins have a large π-π conjugation force between molecules, and they are easy to aggregate in solution, which affects the photoelectric properties of porphyrins. Connecting porphyrins to polymer links through covalent bonds not only retains the mechanical properties and thermal stability of polymer materials, but also has the photoelectric properties and catalytic properties of porphyrins, which improves the availability of materials. In this study, first, a porphyrin ligand with double bonds in the side chain was designed and the corresponding copper and zinc complexes were synthesized by adjusting the metal ions in the center of the pyrrole ring. Then, the metalloporphyrin complexes were copolymerized with methyl methacrylate (MMA), and two metalloporphyrin/PMMA copolymers were obtained: CPTPPCu/PMMA and CPTPPZn/PMMA. The structure of the compounds was characterized by IR, 1H NMR, MS, and UV-Vis spectra. Metalloporphyrin/PMMA copolymers were prepared into electrospun fiber materials by electrospinning. The morphology of the composites was studied by SEM, and the thermal stability and optical properties of electrospun fibers were studied by TGA and FL. The catalytic activity of electrospun fiber materials for the degradation of organic dyes was studied. The results showed that the efficiency of the metalloporphyrin/PMMA copolymer in photocatalytic degradation of methylene blue (MB) was better than that of the PMMA electrospun fiber blended with metalloporphyrin.

[Effect of activated sludge properties on short-term membrane fouling in submerged membrane bioreactor based on statistical analysis].

The influence of activated sludge properties on membrane fouling was investigated using statistical method. The results show that extracelluler polymeric substances (EPS), soluble microbial products (SMP), suspended solids in the supernatant (SSs), dynamic viscosity (micro), relative hydrophobicity (RH) and Zeta potential all have a significant influence on membrane permeability during microfiltration of activated sludge wastewater. The pearson's correlation coefficient (r(p)) for linear correlations between membrane fouling resistance and these sludge properties are 0.898, 0.712, 0.810, 0.691, 0.837, -0.881, respectively. The statistical results also show that SMP, micro, SSs, Zeta potential, and RH are mostly determined by EPS, indicating that EPS is the main and essential factor affecting membrane fouling in activated sludge properties. The pearson's correlation coefficient (r(p)) for linear correlations between total EPS and other sludge properties are 0.682, 0.633, 0.783, -0.953, 0.877, respectively. EPS should be controlled in the operation of membrane bioreactor to achieve a suitable permeation.