Quaternization reaction of 2-vinylpyridine and 4-vinylpyridine network copolymers for 4-nitrophenol adsorption

Abstract

Este artigo avalia o emprego de copolímeros porosos (a base de estireno-STY e vinilpiridina-VP, reticulados com divinilbenzeno-DVB) como adsorventes de 4-nitrofenol de soluções aquosas. Os copolímeros foram sintetizados através de polimerização em suspensão aquosa via radical livre na presença de heptano (HEP) e tolueno (TOL) em diferentes proporções como agentes porogênicos. As unidades de VP nos copolímeros foram modificadas quimicamente pela adição eletrofílica de monômeros vinílicos funcionalizados (acrilonitrila). Os copolímeros quaternizados foram caracterizados por espectrofotometria na região do infravermelho (FTIR), análise elementar (CHN), microscopia ótica (OM) e microscopia eletrônica de varredura (SEM).This article aims to evaluate porous copolymers (based on styrene-STY and vinylpyridine-VP, cross-linked with divinylbenzene-DVB) as adsorbents for 4-nitrophenol from aqueous solution. These copolymers were synthesized by suspension polymerizations in the presence of heptane (HEP) and toluene (TOL) in different proportions as porogenic agents. The VP units of the copolymers were chemically modified by the addition of the electrophilic ethylenic compound (acrylonitrile). The quaternized copolymers were characterized by infrared spectrometry (FTIR), elemental analysis (CHN), optical microscopy (OM) and scanning electron microscopy (SEM).

Porous Cellulose Acetate/Block Copolymer Membranes for the Recovery of Polyphenolic Compounds from Aquatic Environments

“…37,38 However, DiBCP had characteristic bands corresponding to (1) the hydrogen bending of the pyridine ring at 1595 cm −1 and (2) the C−H out-of-plane bending of the pyridine ring at 818 cm −1 . 39,40 In addition, the presence of TMPES was confirmed by the band at 697 cm −1 in the fingerprint area that accounts to the Si− CH 2 stretching bonds. 41 Additionally, the mechanical properties of the membranes were examined in order to evaluate the good stability in water conferred by the TMPES treatment; the obtained values are summarized in Table S1.…”

“…Bands commonly assigned to the phenyl group stretching of the silane (around 1450 cm –1 ) and the C–H symmetric and asymmetric stretching (around 3000 cm –1 ) were not identified in the composite membrane because of the low PEO- b -P4VP and TMPES volumes added to the activated solutions. Also, the characteristic Si–O–Si bond stretching peak of TMPES (between 1000 and 1200 cm –1 ) was overlapped by the CA’s C–O stretching at 1100 cm –1 . , However, DiBCP had characteristic bands corresponding to (1) the hydrogen bending of the pyridine ring at 1595 cm –1 and (2) the C–H out-of-plane bending of the pyridine ring at 818 cm –1 . , In addition, the presence of TMPES was confirmed by the band at 697 cm –1 in the fingerprint area that accounts to the Si–CH 2 stretching bonds …”

Synthesis of novel methacrylate based adsorbents and their sorptive properties towards p-nitrophenol from aqueous solutions

“…However the removal of phenols reduced sharply in acidic solutions and there were almost no removals in solution at pH 5.0 or lower. Rodrigues et al [14] investigated the p-nitrophenol adsorption capacity of poly (2-and 4-vinylpyridine) crosslinked polymers and their quaternized analogues. The quaternized adsorbents showed much higher p-nitrophenol adsorption capacity than the unmodified polymers.…”

Cooperative coadsorption of 4-nitrophenol and basic yellow 28 dye onto an iron organo–inorgano pillared montmorillonite clay

“…An increase of pH leads to the formation of an anionic phenolate adsorbed by electrostatic interactions. Some explanations could be suggested to explain the adsorption of BY28: (a) donor-acceptor interactions between the free electrons pairs of the nontetracoordinated nitrogen (N) and the positive surface charge of the Fe-SMPM (empty cases) [25], (b) the formation of electronic donor acceptor interactions between the aromatic group(s) and the modified pillared clay [15], and (c) BY28 could be adsorbed onto pillared clay by hydrophobic interaction, i.e., nonpolar interactions between alkyl groups of pillared clay with the dyes molecules [26].…”