Activated carbons were obtained from the peelings of cassava tubers (Manihot esculenta) by chemical activation using potassium hydroxide and phosphoric acid at impregnation ratios of 2 : 1 and 1 : 1, respectively, at 400°C for batch adsorption of nickel(II) ions from aqueous solution. Characterization of activated carbon samples was achieved via proximate analysis, Fourier-transform infrared spectroscopy, pH of zero-point charge, Boehm method, elemental analysis, scanning electron microscopy, and iodine number determination for each adsorbent. The effects of pH, contact time, initial adsorbate concentration, and adsorbent dose were studied at 27°C in order to optimize the conditions for maximum adsorption. Equilibrium was attained after 40 minutes of contact of both materials with activating solutions. Maximum adsorption capacities of 41.15 mg/g for ACPH, 47.39 mg/g for ACPA, 35.34 mg/g for NIC, and 34.48 mg/g for RM, respectively, were obtained at pH = 4. Equilibrium data showed that the Langmuir model best described the adsorption process with R² closed to unity, indicative of monolayer adsorption on a homogeneous surface. Kinetic studies showed that the adsorption process is controlled by the pseudo-second-order model. These results show that activated carbon prepared from cassava peelings constitutes an effective low-cost material for the treatment of wastewater containing nickel(II) ions.

中文翻译：

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来自木薯块茎 (Manihot esculenta) 皮的活性炭，用于去除水溶液中的镍 (II) 离子

从木薯块茎（Manihot esculenta) 通过化学活化使用氢氧化钾和磷酸分别以 2:1 和 1:1 的浸渍比，在 400°C 下从水溶液中批量吸附镍 (II) 离子。活性炭样品的表征是通过近似分析、傅里叶变换红外光谱、零点电荷的 pH 值、勃姆法、元素分析、扫描电子显微镜和每种吸附剂的碘值测定来实现的。在 27°C 下研究了 pH、接触时间、初始吸附物浓度和吸附剂剂量的影响，以优化最大吸附条件。两种材料与活化溶液接触 40 分钟后达到平衡。最大吸附容量分别为 ACPH 41.15 mg/g、ACPA 47.39 mg/g、NIC 35.34 mg/g 和 RM 34.48 mg/g，R ²接近统一，表明在均质表面上有单层吸附。动力学研究表明吸附过程受准二级模型控制。这些结果表明，由木薯皮制备的活性炭是一种有效的低成本材料，可用于处理含镍 (II) 离子的废水。