Calligonum Crinitum as a Novel Sorbent for Sorption of Pb(Ⅱ) from Aqueous Solutions: Thermodynamics, Kinetics, and Isotherms

Safri A.; Fletcher A. J.; Abdel-Halim E.; Ismail M. A.; Hashem A.

摘要

Calligonum crinitum, a desert plant, was used as a natural adsorbent for the removal of Pb(II) ions from aqueous solutions. The sorption capacity of the sorbent was investigated through batch adsorption, as a function of contact time, metal ion concentration, and pH. The surface chemistry of the sorbent was probed using Fourier transform infrared spectroscopy, allowing an understanding of the key functionalities involved in binding the Pb(II) ions to the sorbent. Textural characteristics, including surface area and pore volume, showed higher surface areas relative to other natural adsorbents previously reported. Surface morphological analysis, observed via Scanning Electron Microscopy images and Energy-Dispersive X-Ray analysis, confirmed adsorption of Pb(II) ions, up to 71% on the surface of calligonum crinitum. Isothermal analysis, using Langmuir, Freundlich and Temkin models with nonlinear regression, showedthe Langmuir model to best represent adsorption within this system, yielding a maximum adsorption capacity of 337 mg g(-1) (pH 5.5, 30 degrees C). The optimum conditions of adsorption was pH, 5.5; adsorbent concentration, 0.3 g/l, contact time, 20 min at 30 degrees C. The Freundlich constant of 10 indicates that adsorption of Pb(II) ions is favourable onto calligonum crinitum. Adsorption kinetics were modelled using pseudo-first-order, pseudo-second-order and intra-particle diffusion models; the results indicate that the kinetics are pseudo-second-order, suggesting a degree of chemical influence in the adsorption process. While thermodynamic analysis shows the process to be exothermic in nature with an ordering of solute within the adsorption process. Calligonum crinitum has, therefore, been proven as an effective sorbent for the removal of Pb(II) ions from aqueous solutions, with potential in water remediation processes.

机译：Belligonum Crinitum，一棵沙漠植物，用作从水溶液中除去Pb（II）离子的天然吸附剂。通过批量吸附研究吸附剂的吸附能力，作为接触时间，金属离子浓度和pH的函数。使用傅里叶变换红外光谱法探测吸附剂的表面化学，允许了解参与将Pb（II）离子与吸附剂结合的关键功能。纹理特征，包括表面积和孔体积，显示出先前报道的其他天然吸附剂的表面积较高。表面形态分析，通过扫描电子显微镜图像观察和能量分散X射线分析，证实了Pb（II）离子的吸附，在Keligonum Crinitum的表面上高达71％。等温分析，使用Langmuir，Freundlich和Temkin模型具有非线性回归，显示Langmuir模型在该系统内最佳代表吸附，产生337mg g（-1）（pH 5.5,30℃）的最大吸附容量。吸附的最佳条件是pH值，5.5;吸附剂浓度，0.3g / L，接触时间，20分钟，30℃。<10的Freundlich常数表明Pb（II）离子的吸附有利于Keligonum crinitum。吸附动力学使用伪一阶，伪二阶和粒子扩散模型进行建模;结果表明动力学是伪二阶，表明吸附过程中的化学影响程度。虽然热力学分析显示了在吸附过程中溶质的顺序放热的过程。因此，Belligonum Crinitum已被证明是一种有效的吸附剂，用于从水溶液中除去Pb（II）离子，具有水修复方法的潜力。

Calligonum Crinitum as a Novel Sorbent for Sorption of Pb(Ⅱ) from Aqueous Solutions: Thermodynamics, Kinetics, and Isotherms

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