High internal phase emulsions (HIPEs) can be applied as templates for synthesis of porous polymers, which can be used in several industrial areas as catalyst supports and column fillers. For this reason, the present work evaluated the use of HIPEs for synthesis of porous poly(styrene‐co‐divinylbenzene) (P[S‐co‐DVB]) particles through suspension polymerizations. Firstly, the effects of HIPE preparation conditions (surfactant concentration, stirring speed and the duration of the stirring step) on the properties of the obtained particles are investigated. As observed experimentally, the increase of the stirring speed, of the duration of the stirring step and of the surfactant concentration led to reduction of primary cavity dimensions and to higher number of interconnecting pores. Then, the effects of reaction parameters (DVB content, presence of a porogenic agent and the holdup of the organic phase) on the properties of obtained particles are also evaluated. It is observed that the addition of heptane as porogenic agent and the increase of the organic holdup led to increase of the specific area and porosity of the produced spherical polyHIPEs beads, which can exhibit specific area of 33 m².g−1, specific volume of pores of 0.25 cm³.g−1 and large pore diameters (ranging from 100–1100 Å). Thus, it is shown that the proposed technique can be used for manufacturing of new supports for enzyme immobilization.
Copolymers based on glycidyl methacrylate (GMA) are considered attractive as sorbents because the epoxy groups can be easily converted into other groups. Studies involving the influence of the synthesis parameters on the morphological characteristics of these copolymers are scarce. This work investigates the synthesis of copolymers of poly(GMA-co-EGDMA) with different porosity degrees obtained by varying the synthesis parameters. GMA-EGDMA copolymers were synthesized by suspension polymerization employing varied conditions and characterized by measuring apparent density, surface area and pore volume distribution, optical and scanning electron microcopies, FT-IR, thermogravimetry and titration of epoxide rings. The copolymer with highest surface area and pore volume (260.4 m 2 /g and 0.5 cm 3 /g) was prepared employing cyclohexane as diluent, 80% EGDMA in monomeric composition and 100% of dilution degree. There was a relation between the epoxide content of the copolymers determined by titration and the residue content formed in the first decomposition stage.
Ammoniacal nitrogen is an environmental pollutant present in various effluents, such as landfill leachate. It is possible to use ion‐exchange resins in systems for tertiary treatment of effluents containing NH4+ ions and as support for NH3 recovery after treatment of these effluents by employing air stripping. This article presents an exploratory study of sorption of NH4+ ions by sulfonic resins prepared from styrene‐divinylbenzene (Sty‐DVB) copolymers with varied morphological structures: hypercrosslinked resin, a macroporous copolymer prepared by conventional aqueous suspension polymerization, and a polyHIPE copolymer. These three resins are sulfonated by employing concentrated sulfuric acid. The sulfonic resin derived from hypercrosslinked resin has the highest cation exchange capacity (5.06 meq g−1) and is selected for batch studies and column tests. The best result (removal rate of 87%) is achieved with 20 g of resin, time of 20 min, and concentration of 100 ppm. Kinetic behavior and sorption processes are best described by the pseudo‐second‐order, Weber–Morris intraparticle diffusion, and Langmuir models. The saturation point occurs when 900 mL of the NH4+ solution at 2500 ppm (15 mL min−1) is percolated through the column. The working capacity of this resin is 14.06 g cm−3. The resin can be reused during five cycles with removal efficiency between 71% and 82%.
This work reports the preparation of magnetic polymeric microspheres based on poly(methyl methacrylate) and the investigation of these materials as catalysts in heterogeneous Fenton processes for the decolorization of methyl orange (MO). The microspheres were prepared by polymerization of the magnetic material together with the monomers by aqueous suspension polymerization. The microspheres had specific surface area of 48.2 m 2 g -1 . Mossbauer data indicated that the magnetic material was a mixture of magnetite (31%), maghemite (21%), and goethite (48%). Fenton reactions were performed by varying the concentration of H 2 O 2 , pH, composite mass, and contact time. The highest color removal rates (around 80%) were reached at pH 3.0, 20% w/v of composite, 20 minutes contact time, and 10 ppm of H 2 O 2 . The composite could be reused during four cycles with removal efficiency above 50%. The results indicated that the adsorption and oxidation mechanisms act together determining the variation of the MO dye removal.
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