Mechanism of Removal of Hexavalent Chromium from Aqueous Solution by Fe-Modified Biochar and Its Application

Abstract

This study discussed the mechanism of Fe-modified biochar (FeBC) derived from rice straw biochar (BC) as an adsorbent for removing Cr(VI) from aqueous solution and assessed its applicability in actual industrial wastewater. The Cr(VI) removal percentage increased with the FeBC dose, which achieved a removal of 99.5% at 8.0 g/L FeBC. Increasing the solution pH from 2 to 10 slightly reduced Cr(VI) adsorption by 6.6%. Coexisting ions such as Ca2+, Na+ and Cl− inhibited the removal of Cr(VI); the removal rate decreased to 60% at their concentration of 0.25 mol/L. The adsorption isotherm and kinetics were better described by the Langmuir isotherm and pseudo-second-order kinetic models, respectively. Through scanning electron microscopy with energy dispersive X-ray, the Brunauer–Emmett–Teller method, Fourier transform infrared, X-ray diffraction and X-ray photoelectron spectroscopy, the analysis revealed that FeBC with iron oxides loaded onto its surface had more active sites than BC; the surface functional groups changed; the removal of Cr(VI) by FeBC was mainly attributed to electrostatic adsorption; the redox reaction of Cr, and Fe loaded onto BC enhanced Cr(VI) reduction process. FeBC showed a good removal performance on actual industrial wastewater with the concentration of both total Cr and Cr(VI) meeting the integrated wastewater discharge standard of China.

Fabrication of Iron-Containing Biochar by One-Step Ball Milling for Cr(VI) and Tetracycline Removal from Wastewater

“…It was worth noting that the removal efficiency of Fe@MBC for Cr(VI) and TC was greatly improved to 91.96% and 84.56%, which may be due to the further promotion of the adsorption effect by the introduction of FeCl 3 . 1 Compared to other adsorbents listed in Table S1, Fe@MBC exhibits a strong removal capacity for Cr(VI) and TC while having a simple preparation process.…”

“…The industrialization process in today's world is advancing by leaps and bounds, and the resulting waste containing heavy metals and antibiotics is discharged into the water environment, resulting in a sharp decline in water quality. 1,2 The presence of heavy metals and antibiotics in the environment is a major concern due to their potential toxicity and ability to accumulate in organisms. 3−5 This not only poses a threat to human health but also has a significant impact on the ecological balance of the environment.…”

“…52,53 However, so far, most studies have focused on loading Fe on the surface of biochar by impregnating biomass or raw biochar. 1,54,55 Few related studies have focused on the remediation of Cr(VI) and TC by surface Fe-loaded biochar through one-step ball milling of anhydrous FeCl 3 with biochar.…”

“…The industrialization process in today’s world is advancing by leaps and bounds, and the resulting waste containing heavy metals and antibiotics is discharged into the water environment, resulting in a sharp decline in water quality. , The presence of heavy metals and antibiotics in the environment is a major concern due to their potential toxicity and ability to accumulate in organisms. − This not only poses a threat to human health but also has a significant impact on the ecological balance of the environment. − Chromium (Cr) was a representative heavy metal that can be used in the printing and dyeing industry, so it was widely used in the printing and dyeing process. , Cr was typically found in water in two forms: Cr­(VI) and Cr­(III) (Qiu et al, 2020). Numerous studies have demonstrated that Cr­(VI) is significantly more toxic than Cr­(III). , Tetracycline (TC) was widely used in medical and agricultural pest control operations. − The water environment has shown high concentrations and frequencies of TC, which was one of the most prevalent antibiotics detected. , Tetracycline can also accumulate in the organism for a long time and cause the organism to develop resistance and drug resistance, causing great harm to human health. , Therefore, there is an urgent need for effective and practical measures to remove Cr and TC pollution in water.…”

Carbon-Oxalate (C-Ox) Practicum Waste as an Adsorbent Material Candidate in the Chemistry Laboratory

“…Various techniques have been applied to remove Cr(VI), such as chemical precipitation, ion exchange, and redox, (Mahmoud et al 2021;Pan et al 2022), electrolysis, phytoremediation, and adsorption (Qi et al, 2021). Among these techniques, the adsorption technique was considered the most effective, inexpensive, easy to operate, accessible, available, and profitable method (Dim et al, 2021).…”