Synthesis of gum tragacanth-grafted pentapolymer hydrogels for As(III) exclusion: Roles of microwaves, RSM optimization, and DFT studies

• Published in: International journal of biological macromolecules 2021-08, Vol.184, p.909-925
• Main Authors: Karmakar, Mrinmoy, Mondal, Himarati, Ghosh, Narendra Nath, Chattopadhyay, Pijush Kanti, Singha, Nayan Ranjan
• Format: Article
• Language: English
• Subjects: Computational studies on adsorption; DFT for hydrogel structures; In situ comonomers; Microwave assisted polymerization; Simulated UV–vis; Temperature-time-power optimization
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2021.06.070

Microwave assisted homogeneous heating, selectivity in radical formation, and the faster polymerization facilitate the synthesis, structures, properties, and the higher branching associated stability of multifunctional multipolymers. Thus, the optimum gum tragacanth (GMTR)-grafted pentapolymer hydrogel/ HG2 was synthesized from three monomers, i.e., cis-butenedioic acid (cBDA), N-hydroxymethylacryalamide (NHMAm), and 2-(methacryloyloxy)ethanol (MAOE), and in situ generated 2-(3-((hydroxymethyl)amino)-3-oxopropoxy)ethyl-2-methylbutanoate (CM1) and 2-hydroxyethyl 3-(N-(hydroxymethyl)-2-methylbutanamido)-2-methylpropanoate (CM2) comonomers through microwave assisted facile polymerization in aqueous medium. Here, twenty-one GMTR-grafted-[cBDA-co-CM1-co-NHMAm-co-CM2-co-MAOE/ HG1] hydrogels were prepared by using variable amounts of synthesis parameters, of which the optimum HG2 was chosen for the scale-up repetitive As(III)-exclusion. RSM was used to measure the optimum power-temperature-time of microwave irradiation. The structures of HG1, HG2, and As(III)-adsorbed HG2/ As(III)-HG2, in situ anchored comonomers, GMTR-grafting, reusability, thermostability, and surface phenomena were comprehended by XPS, NMR, UV–vis, FTIR, TG, XRD, DLS, and SEM analyses; pHPZC; network parameters; and thermodynamic variables. The geometries, electronic structures, and variable coordinations of As(III) with HG2 were investigated through DFT studies of HG2 and As(OH)3-HG2. The highest exclusion efficiency of 25 mg HG2 within 5–100 mg L−1 As(III) and at 298 K was 192.91 mg g−1, which was significantly higher than that of HG1. •Scalable semisynthetic superadsorbent by microwave assisted facile polymerization•In situ attached two multifunctional comonomers in reusable pentapolymer hydrogels•Optimization of synthesis parameters from twenty one gum tragacanth-g-pentapolymers•RSM-based power-temperature-time optimization of microwave for the maximum yield•DFT studies on mono-, bi-, and tri-dentate coordinations in As(III)-hydrogel