Altenor Sandro, Carene Betty, Emmanuel Evens, Lambert Jacques, Ehrhardt Jean-Jacques, Gaspard Sarra
COVACHIMM, EA 3592 Université des Antilles et de la Guyane, Pointe à Pitre Cedex, Guadeloupe.
J Hazard Mater. 2009 Jun 15;165(1-3):1029-39. doi: 10.1016/j.jhazmat.2008.10.133. Epub 2008 Nov 18.
Vetiver roots have been utilized for the preparation of activated carbon (AC) by chemical activation with different impregnation ratios of phosphoric acid, X(P) (gH(3)PO(4)/g precursor): 0.5:1; 1:1 and 1.5:1. Textural characterization, determined by nitrogen adsorption at 77K shows that mixed microporous and mesoporous structures activated carbons (ACs) with high surface area (>1000 m(2)/g) and high pore volume (up to 1.19 cm(3)/g) can be obtained. The surface chemical properties of these ACs were investigated by X-ray photoelectron spectroscopy (XPS) and Boehm titration. Their textural and chemical characteristics were compared to those of an AC sample obtained by steam activation of vetiver roots. Classical molecules used for characterizing liquid phase adsorption, phenol and methylene blue (MB), were used. Adsorption kinetics of MB and phenol have been studied using commonly used kinetic models, i.e., the pseudo-first-order model, the pseudo-second-order model, the intraparticle diffusion model and as well the fractal, BWS (Brouers, Weron and Sotolongo) kinetic equation. The correlation coefficients (R(2)) and the normalized standard deviation Deltaq (%) were determined showing globally, that the recently derived fractal kinetic equation could best describe the adsorption kinetics for the adsorbates tested here, indicating a complex adsorption mechanism. The experimental adsorption isotherms of these molecules on the activated carbon were as well analysed using four isotherms: the classical Freundlich, Langmuir, Redlich-Peterson equations, but as well the newly published deformed Weibull Brouers-Sotolongo isotherm. The results obtained from the application of the equations show that the best fits were achieved with the Brouers-Sotolongo equation and with the Redlich-Peterson equation. Influence of surface functional groups towards MB adsorption is as well studied using various ACs prepared from vetiver roots and sugar cane bagasse. Opposite effects governing MB and phenol adsorption mechanism on ACs are demonstrated. The various effects involved in adsorption mechanisms of each molecule are demonstrated.
香根草的根已被用于通过用不同浸渍比的磷酸（X(P)（gH₃PO₄/g前驱体）：0.5:1；1:1和1.5:1）进行化学活化来制备活性炭（AC）。通过在77K下的氮气吸附测定的结构表征表明，可以获得具有高表面积（>1000 m²/g）和高孔体积（高达1.19 cm³/g）的混合微孔和介孔结构的活性炭（ACs）。通过X射线光电子能谱（XPS）和 Boehm滴定法研究了这些ACs的表面化学性质。将它们的结构和化学特性与通过香根草根的蒸汽活化获得的AC样品的结构和化学特性进行了比较。使用用于表征液相吸附的经典分子苯酚和亚甲基蓝（MB）。使用常用的动力学模型，即伪一级模型、伪二级模型、颗粒内扩散模型以及分形的BWS（Brouers、Weron和Sotolongo）动力学方程研究了MB和苯酚的吸附动力学。确定了相关系数（R²）和归一化标准差Δq（%），总体结果表明，最近推导的分形动力学方程可以最好地描述此处测试的吸附质的吸附动力学，表明吸附机制复杂。还使用四种等温线分析了这些分子在活性炭上的实验吸附等温线：经典的Freundlich、Langmuir、Redlich-Peterson方程，以及新发表的变形Weibull Brouers-Sotolongo等温线。应用这些方程获得的结果表明，Brouers-Sotolongo方程和Redlich-Peterson方程的拟合效果最佳。还使用从香根草根和甘蔗渣制备的各种ACs研究了表面官能团对MB吸附的影响。证明了控制ACs上MB和苯酚吸附机制的相反效应。展示了每个分子吸附机制中涉及的各种效应。
