Abstract
Herein we demonstrate first report on fabrication, characterization, and adsorptive appraisal of graphene/cellulose nanofibers (GO/CNFs) monolith for methylene blue (MB) dye. Series of hybrid monolith (GO/CNFs) were assembled via urea assisted self-assembly method. Hybrid materials were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction patterns, Raman spectroscopy, elemental analysis, thermogravimetric curve analysis, specific surface area, surface charge density measurement, and compressional mechanical analysis. It was proposed that strong chemical interaction (mainly hydrogen bonding) was responsible for the formation of hybrid assembly. GO/CNFs monolith showed mechanically robust architecture with tunable pore structure and surface properties. GO/CNFs adsorbent could completely remove trace to moderate concentrations of MB dye and follow pseudo-second-order kinetics model. Adsorption isotherm behaviors were found in the following order: Langmuir isotherm > Freundlich isotherm > Temkin isotherm model. Maximum adsorption capacity of 227.27 mg g−1 was achieved which is much higher than reported graphene based monoliths and magnetic adsorbent. Incorporation of nanocellulose follows exponential relationship with dye uptake capacities. High surface charge density and specific surface area were main dye adsorptive mechanism. Regeneration and recycling efficiency was achieved up to four consecutive cycles with cost-effective recollection and zero recontamination of treated water.
Highlights
The development of competent and eco-friendly adsorbent material for water decontamination has been an ever-growing area for academia and industry, in particular aromatic organic dyes, which possess many hazards such as toxic [1], nonbiodegradable [2], aesthetically objectionable, and light restrictive nature in aqueous environment [1, 3]
We report on fabrication, characterization, and adsorptive evaluation of graphene/cellulose nanofibers (GO/CNFs) monolith for methylene blue (MB) dye
The successful oxidation of graphene oxide was confirmed by the presence of various kinds of oxygen functionality such as peak at 3422, 1715, 1628, 1385, and 1076 cm−1, which are mainly bloated from the starching vibration of hydroxyl group (-OH), carboxylic group (-C=O), aromatic skeleton of graphitic domains (C=C) [52], and alkoxy (C-O) and epoxy group (C-O), respectively
Summary
The development of competent and eco-friendly adsorbent material for water decontamination has been an ever-growing area for academia and industry, in particular aromatic organic dyes, which possess many hazards such as toxic [1], nonbiodegradable [2], aesthetically objectionable, and light restrictive nature in aqueous environment [1, 3]. By taking advantage of fundamental chemistry of graphene oxide a diverse range of functional adsorbents have been formulated, for instance, chemically reduced graphene [27], sponge [12, 31], hydrogels/aerogels [18, 33], and magnetically separable adsorbents [9, 19, 34,35,36,37] to improve its competency and recollection issues It suffers from low structural and adsorption capacities, while use of external magnate is practically not feasible as well. Most of the reported work is either selective for oil removal due to highly hydrophobic nature [49] or suffering from mechanically fragile three-dimensional structures and low adsorption capacity [12, 15, 18, 31, 33, 51] due to insufficient functional active sites and large pore size which considerably limit its easy regeneration-recycling properties, being not feasible for industrial applications. Comparison of MB adsorption capacity with previously reported works was discussed here
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