Abstract
We prepared a novel adsorbent functionalized by bagasse magnetic biochar (BMBC). To study the removal behaviors and mechanisms of Cr(VI) by BMBC, batch adsorption experiments were conducted by modifying variables, such as pH, adsorption time, BMBC dosages, initial Cr concentration, co-existing ions, and ionic strength, and characterizing BMBC before and after Cr(VI) adsorption. BMBC was primarily composed of Fe2O3 and Fe3O4 on bagasse boichar with an amorphous structure. The specific surface area of BMBC was 81.94 m2 g−1, and the pHpzc of BMBC was 6.2. The fabricated BMBC showed high adsorption performance of Cr(VI) in aqueous solution. The maximum Cr(VI) adsorption capacity of BMBC was 29.08 mg g−1 at 25 ºC, which was much higher than that of conventional biochar sorbents. The adsorption process followed pseudo-second-order kinetics and could be explained by the involvement of the Langmuir isotherm in monolayer adsorption. The crystalline structure of Fe3O4 in the BMBC changed slightly during the adsorption process; Fe3O4 improved the adsorption of Cr(VI) on BMB. The desorption capacity of Cr(VI) was 8.21 mg g−1 when 0.2 mol L−1 NaOH was used as the desorption solution. After being reused three times, the removal efficiency is still as high as 80.36%.
Highlights
Chromium (Cr) is a well-known carcinogen that is ubiquitous in the environment
This study examined the removal of Cr(VI) from aqueous solutions by a novel bagasse magnetic biochar (BMBC) based on bagasse biochar with magnetic iron oxide
The highest percentage of Cr(VI) removal was observed at a pH of 2, with a dosage of 0.20 g of BMBC in a 50-mL solution
Summary
Langmuir isotherm parameters at 25, 35, and 45 °C showed that the adsorption process partially fitted the Langmuir isotherm model, with correlation coefficients (R2) of 0.9757, 0.9853, and 0.9935, respectively. This finding demonstrated that monolayer adsorption was the most common way by which Cr(VI) was adsorbed by BMBC. Comparison of the correlation coefficients between the two adsorption models revealed that the Langmuir adsorption isotherm model better fit the isotherm data for Cr(VI) adsorbed onto BMBC. Comparisons between adsorbents in their Cr(VI) removal capacities are potentially hampered by differences between the microenvironments of the different s olutions[41]
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