Highly efficient and selective removal of anionic dyes from aqueous solutions using magneto-responsive Fe-aminoclay/Fe2O3/polyvinyl alcohol composite microgels.

[Display omitted] • Fe-AC/Fe 2 O 3 /PVA microgels were manufactured using a microfluidic approach. • The microgels were solidified via Schiff-base and acetalization reactions. • The microgels showed high adsorption selectivity and capacity for anionic dyes. • The microgels maintained a high reusability level of ∼ 85 % after five cycles. • The microgels can be easily recovered by an external magnetic field after adsorption. In this study, magneto-responsive iron-aminoclay/iron oxide/polyvinyl alcohol (Fe-AC/Fe 2 O 3 /PVA) composite microgels were successfully fabricated via a Schiff-base and acetalization reactions using a microfluidic approach. The as-prepared Fe-AC/Fe 2 O 3 /PVA composite microgels were used as adsorbents to remove organic dyes from aqueous solutions. The chemical cross-linking and morphology of the prepared microgel particles were evaluated using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, optical microscopy, Brunauer–Emmett–Teller surface area analysis, and scanning electron microscopy. The Fe-AC/Fe 2 O 3 /PVA microgels served as an effective adsorbent by exhibiting a remarkable adsorption capacity for anionic dyes such as methyl orange (MO), Congo red (CR), and methyl blue (MB) owing to their fast diffusion kinetics, porous structures, and numerous amino groups. The microgels had maximum adsorption capacities of 457.31 mg/g for MO, 352.88 mg/g for CR, and 566.98 mg/g for MB. The prepared microgels were systematically evaluated for their adsorption behavior toward the anionic dyes from aqueous solutions at various process parameters, such as pH, contact time, and dye concentration. The adsorption process for the anionic dyes fitted well with the pseudo-second-order kinetic model and Sips isotherm model, verifying that the sorption process was mainly governed by chemisorption. Furthermore, the Fe 2 O 3 magnetic nanoparticle incorporation made it simple to separate the microgels from the aqueous solutions and reuse them. The microgels maintained an adsorption efficiency of above 80 % even after five adsorption–desorption cycles. These results demonstrate that the magneto-responsive Fe-AC/Fe 2 O 3 /PVA hybrid microgels are an effective and sustainable adsorbent for treating wastewater contaminated with anionic dyes. [ABSTRACT FROM AUTHOR]