Abstract
Herein, we report the synthesis of magnetic nanoparticle (MNP)-reduced graphene oxide (rGO) and polymethylmethacrylate (PMMA) composite (MNPs/rGO/PMMA) as adsorbent via an in situ fabrication strategy and, in turn, the application for adsorptive removal and recovery of Cr(VI) from tannery wastewater. The composite material was characterized via XRD, FTIR and SEM analyses. Under batch mode experiments, the composite achieved maximum adsorption of the Cr(VI) ion (99.53 ± 1.4%, i.e., 1636.49 mg of Cr(VI)/150 mg of adsorbent) at pH 2, adsorbent dose of 150 mg/10 mL of solution and 30 min of contact time. The adsorption process was endothermic, feasible and spontaneous and followed a pseudo-2nd order kinetic model. The Cr ions were completely desorbed (99.32 ± 2%) from the composite using 30 mL of NaOH solution (2M); hence, the composite exhibited high efficiency for five consecutive cycles without prominent loss in activity. The adsorbent was washed with distilled water and diluted HCl (0.1M), then dried under vacuum at 60 °C for reuse. The XRD analysis confirmed the synthesis and incorporation of magnetic iron oxide at 2θ of 30.38°, 35.5°, 43.22° and 57.36°, respectively, and graphene oxide (GO) at 25.5°. The FTIR analysids revealed that the composite retained the configurations of the individual components, whereas the SEM analysis indicated that the magnetic Fe3O4–NPs (MNPs) dispersed on the surface of the PMMA/rGO sheets. To anticipate the behavior of breakthrough, the Thomas and Yoon–Nelson models were applied to fixed-bed column data, which indicated good agreement with the experimental data. This study evaluates useful reference information for designing a cost-effective and easy-to-use adsorbent for the efficient removal of Cr(VI) from wastewater. Therefore, it can be envisioned as an alternative approach for a variety of unexplored industrial-level operations.
Highlights
Over the years, enormous studies have been investigated for wastewater treatments with the breakthrough of research using value-added nanomaterials, including NPs and nanocomposites [1,2]
The tannery wastewater was characterized by determining various parameters such as pH, chemical oxygen demand (COD), biological oxygen demand (BOD)
The spectrum of the composite sample reflects the extra peak of Fe–O–Fe stretching at 537 cm−1 due to the magnetic reduced graphene oxide (rGO) (MNPs/rGO) incorporated to PMMA, which indicates that the polymer was successfully magnetized [38]
Summary
Enormous studies have been investigated for wastewater treatments with the breakthrough of research using value-added nanomaterials, including NPs and nanocomposites [1,2]. Tanning is one of the global water-and-soil polluting industries due to its high environmental risks [3]. The usage of chemicals during the tanning process produces a large amount of carcinogenic mobilization of toxic metals, which is the vital concern of the current era [4]. Chrome tanning relies on chromium salts and liquors to minimize hazardous environmental impacts. Vegetable tanning is a natural process of tree tannins and water [5]. Among these common tanning procedures, chrome tanning is highly favorable due to its low cost and high productivity [6]
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