Leucaena leucocephala is a potential source of polyphenols widely available in southern Mexico. This work highlights the extraction of polyphenols from Leucaena leucocephala leaves waste (LLEPs) and the evaluation of their efficiency to remove the single and multicomponent Pb(II) and Cd(II) metal ions from aqueous solutions. Batch test conditions were carried out to examine the effects of contact time, initial metal ion concentration, and adsorbent dosage on the biosorption process. The surface textures and the composition of the LLEP biosorbent was characterized using pH of point of zero charge (pH_PZC), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry, respectively. Further analysis using ATR-FTIR after adsorption contact of biosorbent was also investigated. The highest Langmuir saturation monolayer adsorption capacity, q_m, for the removal of Pb(II) by LLEPs was obtained as 25.51 and 21.55 mg/g in mono- and bimetal solutions, respectively. The pseudo-second-order model provided the best fit for the kinetic data obtained for the removal of Pb(II), Cd(II), and their mixture, and the k₂ values depend on the adsorbent mass. This implied that the chemisorption process might be the mechanism of the solute ions-LLEPs interaction in this study. Furthermore, nearly 100% removal of lead and cadmium individually and 95% of their mixture was found using 0.9 g of LLEPs.

中文翻译：

---

基于白花蛇菊残留物的生态高效生物吸附剂，用于同时去除水系统中的Pb（II）和Cd（II）离子：吸附和机理。

银合欢是墨西哥南部广泛可用的多酚的潜在来源。这项工作亮点从多酚的提取银合欢叶子废物（LLEPs）和它们的效率评价从水溶液中除去单和多组分的Pb（II），镉（II）的金属离子。进行批量测试条件以检查接触时间，初始金属离子浓度和吸附剂剂量对生物吸附过程的影响。使用零电荷点的pH值（pH _PZC）表征LLEP生物吸附剂的表面质地和组成），衰减全反射傅立叶变换红外光谱（ATR-FTIR）和基质辅助激光解吸/电离飞行时间（MALDI-TOF）质谱。还研究了生物吸附剂吸附接触后使用ATR-FTIR进行的进一步分析。在单金属和双金属溶液中，通过LLEP去除Pb（II）的最高Langmuir饱和单层吸附容量q _m分别为25.51和21.55 mg / g。伪二级模型最适合于去除Pb（II），Cd（II）及其混合物和k ₂的动力学数据。值取决于吸附剂质量。这暗示在本研究中化学吸附过程可能是溶质离子-LLEPs相互作用的机制。此外，使用0.9克LLEP可以分别去除近100％的铅和镉，以及95％的混合物。