Rey-Castro Carlos, Lodeiro Pablo, Herrero Roberto, Sastre de Vicente Manuel E
Departamento de Química Física e Enxeñería Química I, Universidade da Coruña, 15071 A Coruña, Spain.
Environ Sci Technol. 2003 Nov 15;37(22):5159-67. doi: 10.1021/es0343353.
Brown seaweeds are interesting materials to be used as biosorbents for heavy metals due to their high binding ability and low cost. The study of the passive biosorption of protons on this kind of materials and its dependency on pH, ionic strength, and medium composition is essential for the practical application of brown algae in wastewater treatment. This work reports the results of the study of the proton binding equilibria of dead biomass from the seaweeds Sargassum muticum, Cystoseira baccata, and Saccorhiza polyschides by potentiometric titration with a glass electrode in the pH range between 2 and 8. Two different salts, NaCl and KNO3, in concentrations ranging from 0.05 to 2 mol x L(-1), were used as background electrolytes. The influence of the ionic strength was accounted for by means of the Donnan model in combination with the master curve approach. Different empirical expressions to describe the swelling behavior of the biosorbent were tested. On the basis of the intrinsic affinity distribution analysis a unimodal Langmuir-Freundlich isotherm was selected to describe the proton binding properties. The results show very little influence of the type of salt. The ionic strength dependency of the proton binding is very similar for the three species, and average empirical expressions of the Donnan volume are proposed. The maximum proton binding capacities obtained ranged between 2.4 and 2.9 mol x kg(-1), with average intrinsic proton affinity constants between 3.1 and 3.3, and heterogeneity parameters of ca. 0.5 for S. muticum and C. baccata, and slightly higher (ca. 0.7) for S. polyschides. The combined Langmuir-Freundlich equation and Donnan model allowed a good description of the experimental charge vs pH curves obtained.
褐藻是一种很有意思的材料，由于其具有高结合能力和低成本，可作为重金属的生物吸附剂。研究这类材料对质子的被动生物吸附及其对pH值、离子强度和介质组成的依赖性，对于褐藻在废水处理中的实际应用至关重要。本文报道了通过玻璃电极电位滴定法，在2至8的pH范围内，对鼠尾藻、囊链藻和多管藻这三种海藻的死生物质的质子结合平衡进行研究的结果。两种不同的盐，即浓度范围为0.05至2 mol·L⁻¹的NaCl和KNO₃，被用作背景电解质。离子强度的影响通过唐南模型结合主曲线方法来考虑。测试了不同的经验表达式来描述生物吸附剂的膨胀行为。基于本征亲和力分布分析，选择了单峰朗缪尔 - 弗伦德利希等温线来描述质子结合特性。结果表明盐的种类影响很小。三种海藻的质子结合对离子强度的依赖性非常相似，并提出了唐南体积的平均经验表达式。获得的最大质子结合容量在2.4至2.9 mol·kg⁻¹之间，本征质子亲和常数的平均值在3.1至3.3之间，鼠尾藻和囊链藻的非均质性参数约为0.5，多管藻的略高（约0.7）。朗缪尔 - 弗伦德利希方程和唐南模型的结合能够很好地描述所获得的实验电荷与pH曲线。
