Synthesis and characterization of magnetic biochar adsorbents for the removal of Cr(VI) and Acid orange 7 dye from aqueous solution

Chella Santhosh,Amit Bhatnagar,Pranas Baltrėnas,Taeyoung Kim,Kumud Malika Tripathi,Edita Baltrėnaitė,Ehsan Daneshvar

doi:10.1007/s11356-020-09275-1

Abstract

In this study, different types of magnetic biochar nanocomposites were synthesized using the co-precipitation method. Two biochar materials, namely, sewage sludge biochar and woodchips biochar, were prepared at two different temperatures, viz., 450 and 700 °C. These biochars were further modified with magnetic nanoparticles (Fe3O4). The modified biochar nanocomposites were characterized using field emission–scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), SQUID analysis, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The potential of prepared adsorbents was examined for the removal of hexavalent chromium (Cr(VI)) and Acid orange 7 (AO7) dye from water as a function of various parameters, namely, contact time, pH of solution, amount of adsorbents, and initial concentrations of adsorbates. Various kinetic and isotherm models were tested to discuss and interpret the adsorption mechanisms. The maximum adsorption capacities of modified biochars were found as 80.96 and 110.27 mg g-1 for Cr(VI) and AO7, respectively. Magnetic biochars showed high pollutant removal efficiency after 5 cycles of adsorption/desorption. The results of this study revealed that the prepared adsorbents can be successfully used for multiple cycles to remove Cr(VI) and AO7 from water.Graphical

Highlights

IntroductionExposure to heavy metal ions, especially As(III)/(As(V)), Hg(II), Cd(II), Pb(II), and Cr(VI), even at lower concentrations, can have detrimental effects on human health, such as different types of cancers, and neurological and mental problems (Xu et al 2018)
Responsible Editor: Zhihong XuElectronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Presence of elevated concentrations of inorganic and organic contaminants in water bodies is considered a serious global issue
35.69°, 36.92°, 42.98°, 52.93°, 57.23°, and 62.91°, respectively, were matched with the standard JCPDS No 82-1533, which reveals that the biochar materials were modified successfully—coated with Fe3O4 nanoparticles without any other morphological impurities

Summary

Introduction

Exposure to heavy metal ions, especially As(III)/(As(V)), Hg(II), Cd(II), Pb(II), and Cr(VI), even at lower concentrations, can have detrimental effects on human health, such as different types of cancers, and neurological and mental problems (Xu et al 2018). Another important source of water contamination is synthetic dyes, which are classified as organic pollutants. Dyes are complex aromatic molecules that are highly water soluble and resistant for biodegradation. These organic colorants are the first visible pollutants in water.

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