[Reduction Cooperated Fenton Oxidation of Zero-valent Iron (ZVI) Immobilized in Alginate Microsphere for Degradation of Acid Red B].

The zero-valent iron (ZVI) immobilized in an alginate microsphere was prepared by using sodium alginate as a support material. The characteristics of the Fe0/alginate microsphere was characterized by FT-IR, SEM, BET, and XPS. The SEM and BET analyses showed that the Fe0/alginate microsphere had a multilevel porous structure and could adsorb ARB. Combined with Fe0 reduction and Fe3+/Fe2+ catalytic oxidation, the mineralization of ARB could be effectively realized. The ARB in the solution was discolored rapidly by the reduction of Fe0/alginate microsphere and then oxidized efficiently by the subsequent Fenton reaction. The discoloration rate of ARB in the reduction stage was 96.8%, with an Fe0/alginate microsphere dosage of 0.24g·L-1 and pH of 2.96 after reaction time of 180 min. ARB was reduced to organics of lower molecular weight due to the degradation of azo groups by Fe0. In the subsequent Fenton oxidation stage, the mineralization degree of ARB increased to 64.7% after the addition of 10.75 mmol·L-1 H2O2. The influence of the Fe0/alginate microsphere dosage, pH, reusability of the Fe0/alginate microsphere, and the stability of iron ions in the alginate microsphere were investigated. Due to the coordination of Fe3+/Fe2+ ions with -COO--in the alginate, the iron ion in the solution was 3.9% of the total iron content in the microsphere. Iron ions could be well immobilized in calcium alginate microspheres, so the iron hydroxides were generated in lower amounts. The Fenton reaction can be conducted in a wide range of pH. The Fe2+/Fe3+immobilized in the alginate microsphere demonstrated good catalytic performance after it was reused four times. Therefore, the synergy of reduction and Fenton oxidation by the Fe0/alginate microsphere was a better strategy for dye degradation.

New insight into the fouling behavior of hydrophobic and hydrophilic polypropylene membranes in integrated membrane bioreactors.

To investigate the effect of hydrophobic and hydrophilic polypropylene hollow fiber membranes (PPHFMs) applied in membrane bioreactors (MBR), the fouling behaviors of membrane surfaces and pores have been tested. The structural and morphological features on the membrane surface were characterized using attenuated total reflection-Fourier transform infrared spectroscopy, field emission scanning electron microscopy, atomic force microscope, energy dispersive X-ray spectroscopy and laser granularity distribution analysis. The results showed that significantly more polysaccharide, protein and inorganic ingredients were accumulated in the original membrane compared to the hydrophilic membrane. Furthermore, it was found that the pore size influenced the particle distribution and accumulation, such that smaller pore size membranes tended to contain fewer pollutants and a narrow size distribution. Under a constant flux of 11.5 L/m2 h, the transmembrane pressure (TMP) varied narrowly between 38 and 53 KPa. Alongside this, a relatively hydrophilic membrane (PP-g-AA) showed the characteristics of lower TMP in comparison to hydrophobic membranes (PP). Indeed, the flux recovery was 30% higher than those of the original PPHFM. This investigation broadens our understanding of membrane modifying and fouling behavior in integrated MBRs.

[Degradation of N-nitrosodimethylamine by Palladium/ Iron Bimetallic Composite Catalytic Fiber].

N-nitrosodimethylamine (NDMA) in the water environment is a carcinogenic organic contaminant, which can be converted to hypotoxic compounds by zero-valent iron degradation. For the removal of trace NDMA in water, the theory and efficiency of zero-valent iron degradation should be intensely researched. In this study, the polypropylene (PP) fibers were chosen as substrate materials and the composite catalyst fibers containing Pd/Fe0 bimetal were prepared by the UV irradiation-coordination method for the removal of trace NDMA. Pd/Fe0/PP-g-AA was characterized by scanning electron microscope, inductively coupled plasma atomic emission spectrometry, and X-ray photoelectron spectroscopy. The NDMA removal by Pd/Fe0/PP-g-AA under different conditions was investigated. The results indicated that when the acrylic acid monomer mass fraction was 20%, the composite catalytic fiber Pd/Fe0/PP-g-AA showed a better degradation effect on NDMA. The removal of NDMA followed the pseudo-first-order reaction kinetics model. The initial NDMA concentration and the pH of the solution could not greatly influence the catalytic degradation of trace amounts of NDMA. The presence of 3CO2- and NO3- significantly inhibited the degradation of NDMA. However, the NDMA degradation had been less affected by SO42-, HCO3-, and nature organic matter (NOM) existing in the solution.

Poly[diaqua-(µ(4)-3,5-dicarb-oxyl-ato-pyra-zol-1-ido-κN,O:N,O:O:O,O)lanthanum(III)].

In the title coordination polymer, [La(C(5)HN(2)O(4))(H(2)O)(2)](n), the lanthanum(III) metal centre is nine-coordinated, with a distorted tricapped trigonal prismatic geometry, by the O atoms of two water mol-ecules and by two N and five O atoms of two N,O-bidentate, one O,O'-bidentate and one O-mono-dentate 3,5-dicarb-oxyl-ato-pyra-zol-1-ide ligands. The polymeric three-dimensional structure is stabilized by inter-molecular O-H⋯O hydrogen bonds.