Gum karaya (Sterculia urens) stabilized zero-valent iron nanoparticles: characterization and applications for the removal of chromium and volatile organic pollutants from water

Abstract

This paper illustrates a method for the stabilization of nanoscale zerovalent iron (NZVI) suspensions with a "green" biopolymer, Gum Karaya (GK). The stability, sedimentation, aggregation behavior and reactivity towards Cr(VI) and volatile organic compounds using NZVI-GK (GK stabilized NZVI) and bare NZVI, were assessed. The stabilization mechanism of NZVI-GK was demonstrated using ATR-FTIR, XRD, XPS, TEM, SEM, TGA and particle size analysis. The NZVI-GK nanoparticle suspension was found to be stable for at least three months, suggesting a superior stability rendering property of GK which forms a scaffold to prevent NZVI from aggregating. Batch experiments, centred on Cr(VI) reduction and degradation of volatile organic compounds, confirmed that NZVI-GK was more reactive than bare NZVI. Furthermore, XPS and ICP-MS results revealed that Cr(VI) was reduced to Cr(III) by NZVI-GK and the remaining Cr(III) insolution was adsorbed onto GK, thereby completely removing chromium from the contaminated water.Our study suggests that an important role is played due to the attributes of GK (which include nontoxicity, biodegradability and cost-effectiveness) in conjunction with the ability of NZVI to remove all chromium viz. [Cr(VI) and Cr(III)] coupled with the total degradation and removal of VOCs (cis-1,2-dichloroethene, perchloroethene and trichloroethene) from water.

Sustainable Synthesis of Nanoscale Zerovalent Iron Particles for Environmental Remediation

“…The synthesized nanoparticles had a higher surface area than nZVI synthesized without stabilizer and also exhibited a much higher degradation efficiency. Gum Karaya ( Sterculia urens )‐stabilized nZVI particles were found to be better agents than bare nZVI for the removal of hexavalent chromium . Chitosan, a glucosamine biopolymer derived from crustaceans, is an important surface modifier because of its excellent film‐forming ability, cost‐effectiveness, hydrophilicity, biocompatibility, and biodegradability.…”

Major Advances and Challenges in Heterogeneous Catalysis for Environmental Applications: A Review

“…Heterogeneous catalytic removal of pollutants from water with the use of nano zero-valent iron (nZVI) was studied in detail by many authors [148][149][150][151][152][153]. nZVI has been applied at many contaminated sites (in situ) where it not only adsorbs and reduces contaminants but also enhances bioremediation [154,155].…”

The enhanced reduction of bromate by highly reactive and dispersive green nano-zerovalent iron (G-NZVI) synthesized with onion peel extract

“…Furthermore, the specific surface area of G-NZVI (59.7 m 2 g −1 ) was almost four times higher than that of bare NZVI (13.8 m 2 g −1 ), which could possibly lead to the higher reductive capacity of G-NZVI for bromate removal. 37 The addition of polyphenols from onion peel extract during the synthesis of G-NZVI may facilitate the nucleation of iron nanoparticles by avoiding their agglomeration due to magnetism and thereby increase the surface area of G-NZVI during its crystal growth. 38 …”