Synthesis of an Alginate-Based Fe₃O₄–MnO₂ Xerogel and Its Application for the Concurrent Elimination of Cr(VI) and Cd(II) from Aqueous Solution

Abstract

In this study, magnetite−manganese oxide (Fe 3 O 4 − MnO 2 ) nanoparticles were synthesized and immobilized on alginate, producing a magnetite−manganese oxide xerogel (mMOX). This eco-friendly xerogel was used as an adsorbent of Cr(VI) and Cd(II). It was mesoporous and thermally stable, as determined by Brunauer−Emmett−Teller and thermogravimetric analysis. A scanning electron microscope coupled with an energydispersive X-ray system, Zetasizer, and attenuated total reflectance−Fourier transform infrared were used for characterization of adsorbents. The performance of the mMOX was investigated for the simultaneous adsorption of Cr(VI) and Cd(II) at different temperatures, pH values, contact times, initial concentrations of the adsorbate, and adsorbent doses. The developed xerogel (mMOX) showed high adsorption capacities of 3.86 mg/g for Cr(VI) and 3.95 mg/g for Cd(II) on 120 min of contact time with 5 ppm Cr(VI) and Cd(II) solution. The kinetic data fitted well with the pseudo-second order, while the Freundlich isotherm model was found to be fit for adsorption data. Thermodynamic study revealed the adsorption to be spontaneous and exothermic. The adsorbent showed useful application for real water samples by more than 75% uptake of Cr and Cd with low adsorption of Na, K, and Mg. The regeneration study indicated that the mMOX could be reused up to six cycles with more than 50% removal of Cr(VI) and Cd(II) ions from aqueous solution with minimal leaching of metal ions (Fe, Ca, Na, K, and Mn) into the solution.

Valorization of Ginger Waste-Derived Biochar for Simultaneous Multiclass Antibiotics Remediation in Aqueous Medium

“…It is expressed as where q t is the measured and model-predicted quantity of antibiotics adsorbed at time t, K id is the intraparticle diffusion rate constant (mg/(gmin 0.5 ), C is the intercept that is evaluated from graph plotted between qt and t 0.5 , and t 0.5 is the adsorption half-life. 31 Kinetic studies were conducted between 10 and 210 min at 30 °C. The values for the kinetic constant k 2 of PSO were in good agreement between q e,exp and q e,cal , and high correlation coefficient R 2 for all tested antibiotics demonstrated the best fitting by pseudo-second order suggesting chemisorption mechanism of adsorptive removal aligning with the findings of the isotherm studies.…”

Green-synthesis of superparamagnetic Fe3O4/alginate bio-nanocomposites for heavy metal contamination removal from industrial wastewater

“…The bionanocomposite adsorption capacity was evaluated 88.49 mg g − 1 for copper and 86.95 mg g − 1 for nickel (Foroutan et In a study magnetite − manganese oxide nanoparticles immobilized by alginate. Optimum conditions for Cd 2+ removal were selected 6 for pH, 30°C for temperature, 120 min for contact time and 10 mg for the adsorbent amount (Kumar et al 2021).…”

“…and anthropogenically especially by the increasing the development of industry (metallurgy, mining operations, fertilizer, paint, and textile industries etc.) (Foroutan et al 2018;Briffa et al 2020; Kumar et al 2021). In addition to being toxic, these metals are not biodegradable and accumulate in the food chain.…”

An innovative hybrid biosorbent composed of nano ZnO and marine macro algaeJania rubensembedded in an alginate/PVA matrix: insights into Pb2+removal in water

“…20 Another work reported the preparation of alginate-based Fe 3 O 4 ÀMnO 2 xerogels for the removal of Cr 6+ and Cd 2+ . 21 However, no report has been found on the use of a metal oxide adsorbent combined with marine algae and embedded in an alginate and PVA matrix which is the focus of this present work.…”