Chromium is an extremely toxic metal in the form of Cr(VI) that causes severe environmental and health problems. Therefore, the aim of this study was to remove chromium ions from wastewater by using cost effective and environmentally friendly bio-sorbents; Moringa stenopetala seed powder (MSSP), and banana peel powder (BPP) and to evaluate its adsorption capacities as bio-sorbents. FT-IR characterization of the adsorbents showed that there was a change in the functional groups of the structure of both adsorbents before and after the adsorption that might be due to the adsorption processes taken place on the surface of adsorbent. Adsorption experiments were carried out as batch studies with different contact times, pH, adsorbent dose, initial metal ion concentration, and temperature. Results showed maximum removal efficiency for Cr(VI) at 120 min contact time, adsorbent dose of 20 g/L and pH 2 by MSSP and pH 4 by BPP. The percentage removal of Cr(VI) increased with increasing adsorbent dose (from 5 to 20 g/L) and contact time (from 60 to 120 min). Freundlich isotherm model showed a better fit to the equilibrium data than the Langmuir model. The kinetics of adsorption for chromium was well represented by pseudo-second order kinetic model and the calculated equilibrium sorption capacity of the model showed good agreement with the sorption capacity obtained from experimental results.

中文翻译：

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使用辣木种子粉末（MSSP）和香蕉皮粉末（BPP）进行生物吸附以有效去除废水中的六价铬

铬是以Cr（VI）形式存在的剧毒金属，会引起严重的环境和健康问题。因此，本研究的目的是通过使用经济高效且环保的生物吸附剂去除废水中的铬离子。辣木种子粉末（MSSP）和香蕉皮粉末（BPP）并评估其作为生物吸附剂的吸附能力。吸附剂的FT-IR表征表明，吸附前后两种吸附剂结构的官能团都有变化，这可能是由于吸附剂表面发生了吸附过程所致。以不同的接触时间，pH，吸附剂剂量，初始金属离子浓度和温度为批次研究进行吸附实验。结果表明，在接触时间为120分钟时，Cr（VI）的去除效率最高，MSSP的吸附剂剂量为20 g / L，pH值为2，BPP的值为pH 4。Cr（VI）的去除百分率随着吸附剂量（从5到20 g / L）和接触时间（从60到120分钟）的增加而增加。与Langmuir模型相比，Freundlich等温模型显示出对平衡数据的更好拟合。假二阶动力学模型很好地表示了铬的吸附动力学，该模型的平衡吸附容量与实验结果得到的吸附容量吻合良好。与Langmuir模型相比，Freundlich等温模型显示出对平衡数据的更好拟合。假二阶动力学模型很好地表示了铬的吸附动力学，该模型的平衡吸附容量与实验结果得到的吸附容量吻合良好。与Langmuir模型相比，Freundlich等温模型显示出对平衡数据的更好拟合。假二阶动力学模型很好地表示了铬的吸附动力学，该模型的平衡吸附容量与实验结果得到的吸附容量吻合良好。