This work focused on the use of low-cost magnetic biochar adsorbent prepared from Litchi chinensis peel for the Cr(VI) amelioration through the reduction-adsorption process. This magnetic biochar was prepared by the pyrolysis process, where the nano zerovalent iron (nZVIO) was decorated on the surface of Litchi peel biochar (LPBC). The XRD and TEM studies indicated that the nano-scale zerovalent iron nanoparticles were crystalline having a particle size of 5 ± 0.1 nm. The BET analysis showed the mesoporous nature of the material with good surface area (124 m²/g) and also material has a magnetic saturation value of 0.176 emu/g, where as surface area of LPBC were 325 m²/g and Ms valie 1.1 emu/g respectively. Three factorial Box–Behnken experimental design was simulated for Cr(VI) removal by taking key parameters initial concentration, adsorbent dose, and initial pH as independent factors. The optimum values obtained from desirability function and given by the model were initial Cr(VI) concentration of 5.87 mg/L, 3.14 for pH, and 0.195 g/L for adsorbent dose, which resulted in approximately 95.38% removal of Cr(VI) in these optimum conditions. Langmuir isotherm and pseudo-second-order kinetics data were explained in the adsorption studies. The adsorbent has an adsorption capacity of 98.36 mg/g at the obtained optimized conditions. The thermodynamics study specified a spontaneous process for Cr(VI) removal. The adsorption mechanism was detailed by XPS analysis which indicated a reduction of Cr(VI) to Cr(III) then adsorption of Cr(III) on the adsorbent surface.

这项工作的重点是使用由荔枝皮制备的低成本磁性生物炭吸附剂通过还原吸附过程改善 Cr(VI)。这种磁性生物炭是通过热解工艺制备的，其中纳米零价铁（nZVIO）装饰在荔枝皮生物炭（LPBC）的表面。XRD 和 TEM 研究表明，纳米级零价铁纳米粒子是晶体，粒径为 5 ± 0.1 nm。BET 分析表明材料的介孔性质具有良好的表面积（124 m ² /g），并且材料的磁饱和值为 0.176 emu/g，其中 LPBC 的表面积为 325 m ²/g 和 Ms valie 分别为 1.1 emu/g。通过将关键参数初始浓度、吸附剂剂量和初始 pH 值作为独立因素，模拟了三因子 Box-Behnken 实验设计以去除 Cr(VI)。从意愿函数获得并由模型给出的最佳值是初始 Cr(VI) 浓度为 5.87 mg/L，pH 为 3.14，吸附剂剂量为 0.195 g/L，这导致大约 95.38% 的 Cr(VI) 被去除在这些最佳条件下。在吸附研究中解释了 Langmuir 等温线和准二级动力学数据。在获得的优化条件下，吸附剂的吸附容量为 98.36 mg/g。热力学研究指定了去除 Cr(VI) 的自发过程。