Laboratoire de Chimie Analytique, Faculté des Sciences, Université de Yaoundé I, B.P. 812 Yaoundé, Cameroon.
J Hazard Mater. 2010 Jul 15;179(1-3):63-71. doi: 10.1016/j.jhazmat.2010.02.058. Epub 2010 Feb 25.
This study concerns the batch biosorption of paraquat on Ayous (Triplochiton schleroxylon) sawdust; the study centers on the evolution of biosorption parameters during the process. It appears that paraquat forms a monolayer on the sawdust surface as evidenced by the good correlation between the experimental data and the Langmuir model. The biosorption which is rather fast (the equilibrium was reached after ten minutes) follows a pseudo-second-order kinetic model and does not obey to the intra-particle diffusion model. According to the mathematical kinetic modeling, pore and surface mass transfer well describe the phenomenon. NaCl reduces the adsorption capacity of the material but has no significant effect on the kinetics. Alkaline solutions enhance the accumulation of the pollutant, the reverse being observed for acidic media. According to the thermodynamic data, this biosorption is a spontaneous and exothermic process. From these results we concluded that the adsorption of the pollutant is mainly due to cation exchange as indicated by the adsorption energy determined by the Dubinin-Radushkevich model (E=12.0736 kJ mol(-1)); some other interactions resulting from the affinity through organophilic interactions between paraquat and sawdust have also been pointed out. Desorption experiments conducted in HCl and HNO(3) solutions confirmed the proposed mechanism.
本研究关注的是百草枯在奥优斯（Triplochiton schleroxylon）木屑上的批量生物吸附；研究集中在生物吸附过程中参数的演变。百草枯似乎在木屑表面形成单层，这可以通过实验数据与朗缪尔模型之间的良好相关性得到证明。生物吸附速度相当快（十分钟后达到平衡），符合拟二级动力学模型，不遵循内扩散模型。根据数学动力学模型，孔和表面传质很好地描述了这一现象。NaCl 降低了材料的吸附能力，但对动力学没有显著影响。碱性溶液促进了污染物的积累，而在酸性介质中则相反。根据热力学数据，这种生物吸附是自发和放热的过程。从这些结果中我们得出结论，吸附污染物主要是由于阳离子交换，正如由 Dubinin-Radushkevich 模型确定的吸附能（E=12.0736 kJ mol(-1)）所表明的那样；通过百草枯和木屑之间的亲脂相互作用的亲和力，还指出了一些其他相互作用。在 HCl 和 HNO(3)溶液中进行的解吸实验证实了所提出的机制。
