Preparation and performance evaluation of novel magnetic porous carriers in fluidized bed bioreactor for wastewater treatment

Biofilm process is a promising wastewater treatment technology and biofilm carrier (biocarrier) is regarded as the core of this process. However, the traditional commercial biocarriers have their inherent drawbacks, therefore, the development of new-type biocarrier to enhance wastewater treatment efficiency is significantly important to biofilm-based reactors. In this study, based on radical suspension polymerization, a novel kind of magnetic porous carriers (PMCs) was prepared by modifying the porous polymer carriers (PPCs) with inorganic particles, and then applied in a fluidized bed bioreactor (FBBR) with a low packing ratio of 10 % (v/v) to synthetic wastewater treatment. The results showed that this novel biocarrier possesses paramagnetism with saturation magnetization of 1.01emu/g, low density (1.26 g/cm³), excellent hydrophilicity (surface water contact angle approaching zero) and rough surface. Besides, compared with the PPCs, the developed PMCs have larger pores (up to 50 μm or more), in which the larger-sized microbes are able to colonize. Moreover, as compared to the PPCs-based FBBR, the PMCs-based reactor achieved shorter time (7 days) for biofilm formaiton and significantly enhanced NH₃-N removal efficiency ( nearly 20 % increase at the level of influent NH₃-N concentration about 100 mg/L). High-throughput sequencing (HTS) results indicated that this new biocarrier could promote biodiversity and improve the abundance of Nitrosomonadales (the functional bacteria for ammonia removal in the bio-system), thus enhancing the ammonification process. Therefore, the developed PMCs could be preferable biocarriers for biofilm formation and provide an alternative to the traditional suspended biocarrier, demonstrating a promising potential, even at a lower filling ratio, to enhance the pollutants removal performance.

Mesoporous Palladium N,N'-Bis(3-Allylsalicylidene)o-Phenylenediamine-Methyl Acrylate Resins as Heterogeneous Catalysts for the Heck Coupling Reaction

Palladium N,N'-bis(3-allylsalicylidene)o-phenylenediamine complex (PdAS) immobilized onto mesoporous polymeric methyl acrylate (MA) based resins (PdAS(x)-MA, x = 1, 2, 5, or 10 wt.%) were successfully prepared as heterogeneous catalysts for the Heck reaction. The catalysts were synthesized via radical suspension polymerization using PdAS as a metal chelate monomer, divinylbenzene and MA as co-monomers. The effect of the PdAS(x) content on the physicochemical properties of the resins is also reported. The catalysts were characterized by using a range of analytical techniques. The large surface area (>580 m²·g^-1) and thermal stability (up to 250 °C) of the PdAS(x)-MA materials allows their application as catalysts in the C-C coupling reaction between iodobenzene and MA in the presence of trimethylamine at 120 °C using DMF as the solvent. The PdAS(10)-MA catalyst exhibited the highest catalytic performance with no significant catalytic loss being observed after five reuses, thereby indicating excellent catalyst stability in the reaction medium.

Heterogeneous palladium SALOPHEN onto porous polymeric microspheres as catalysts for heck reaction

Catalysts based on porous polymeric microspheres were prepared from N,N′-Bis(3,3′-allyl-salicylidene)-o-phenylenediamine Pd(II) (PdAS) metallo-monomer, styrene (STY), and divinylbenzene (DVB) as co-monomers. The effects of the STY/PdAS mass ratio of co-monomers were investigated to synthesize the optimal catalyst. All the prepared materials were characterized by scanning electron microscopy (SEM), N2 adsorption-desorption isotherms, inductively coupled plasma optical emission spectroscopy (ICP-OES), thermogravimetric analysis (TGA), solid-state diffuse-reflectance UV Vis (DRS UV-Vis) spectrometry, and X-ray photoelectron spectroscopy (XPS). Increasing the PdAS content from 1 to 5 wt%, based on the mass feed of monomers, produced well-defined spherical polymer resins with particle diameters of ~200 μm and high surface areas (>500 m2/g). XPS spectra shown a unique Pd2+ signal associated with the PdAS complex immobilized on a porous resin matrix. The catalytic performances of porous polymer microspheres were evaluated for Heck reaction between iodobenzene and methyl acrylate to produce methyl cinnamate, giving up to 100 % selectivity for the trans-isomer. The resin with 5 wt% PdAS showed the best catalytic activity in methyl cinnamate synthesis. Finally, the best catalytic system was evaluated in octinoxate production producing the target product with the same levels of conversion and selectivity for trans-isomer as was detected for methyl cinnamate synthesis.

Rhodium(i) diphenylphosphine complexes supported on porous organic polymers as efficient and recyclable catalysts for alkene hydrogenation

Highly stable, chemoselective and recyclable immobilized Rh(i) homogeneous catalysts for alkene hydrogenation.