Insights into Starch Coated Nanozero Valent Iron-Graphene Composite for Cr(VI) Removal from Aqueous Medium

Abstract

Embedding nanoparticles into an inert material like graphene is a viable option since hybrid materials are more capable than those based on pure nanoparticulates for the removal of toxic pollutants. This study reports for the first time on Cr(VI) removal capacity of novel starch stabilized nanozero valent iron-graphene composite (NZVI-Gn) under different pHs, contact time, and initial concentrations. Starch coated NZVI-Gn composite was developed through borohydrate reduction method. The structure and surface of the composite were characterized by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), and point of zero charge (pHpzc). The surface area and pHpzc of NZVI-Gn composite were reported as 525 m2 g−1 and 8.5, respectively. Highest Cr(VI) removal was achieved at pH 3, whereas 67.3% was removed within first few minutes and reached its equilibrium within 20 min obeying pseudo-second-order kinetic model, suggesting chemisorption as the rate limiting process. The partitioning of Cr(VI) at equilibrium is perfectly matched with Langmuir isotherm and maximum adsorption capacity of the NZVI-Gn composite is 143.28 mg g−1. Overall, these findings indicated that NZVI-Gn composite could be utilized as an efficient and magnetically separable adsorbent for removal of Cr(VI).

Removal of Chromium(VI) by Nanoscale Zero-Valent Iron Supported on Melamine Carbon Foam

“…Based on the above analysis, the Cr(VI) removal mechanism by Fe@MF-12.5-800 could be schematically described in Figure 5 e. The production of Cr(III), Fe(II) and Fe(III) made the entire process environmentally friendly [ 5 ].…”

“…These discharged Cr heavy metals exist dominantly in trivalent (Cr(III)) and hexavalent (Cr(VI)) forms, with the latter being more hazardous due to their strong toxicity and mobility [ 3 ], causing severe health problems such as multiorgan failure, renal necrosis and pulmonary fibrosis [ 4 ]. Hence, Cr(VI) standards for industrial effluents (0.1–0.5 mg/L) and drinking water (<50 µg/L) have been stipulated by the U.S. Environmental Protection Agency (USEPA) to curb water contamination [ 5 ]. Till date, broad categories of techniques were developed for Cr(VI) removal, including electrocoagulation [ 6 ], adsorption [ 7 ], bioremediation [ 8 ] and chemical reduction [ 9 ], of which adsorption (and/or subsequent reduction) is much preferred as it is easily designed, effective, tractable, economically feasible and no secondary contamination [ 10 ].…”

Thermodynamic, kinetic, and isotherm studies of Direct Blue 86 dye absorption by cellulose hydrogel

“…The LIM proposed that solute sorption from water solution occurs as monolayer absorption on specific homogenous sites with a finite number of identical sites. This LIM also assumes uniform absorption energies www.nature.com/scientificreports/ on the surface, no sorbate transmigration in the surface plane, and no interaction between adsorbed species [60][61][62] . Therefore, this data predicted the maximal absorption capacity of DB86, which corresponds to full monolayer coverage on the CAH sorbent surface.…”

Composite fabrication and characterization of crosslinked polyaniline/Pterocladia capillacea-activated carbon for adsorption of direct blue-86 dye from water

“…15 and Table 6 illustrate each linearized isotherm model's plots and related parameters. However, the arrangement of adsorptive removal of DB-86 dye by According to the Langmuir model, DB-86 dye adsorption occurs on a homogenous surface via monolayer adsorption, without interaction between adsorbed species [98][99][100]. The maximum monolayer capacity (Q m ) was 163.93 mg/g at dose 0.5 g/L.…”