Lodeiro P, Cordero B, Grille Z, Herrero R, Sastre de Vicente M E
Departamento de Química Física e Enxeñería Química I, Universidade da Coruña, Alejandro de la Sota 1, 15071 A Coruña, Spain.
Biotechnol Bioeng. 2004 Oct 20;88(2):237-47. doi: 10.1002/bit.20229.
In recent years, there has been a significant increase in the studies concerning brown seaweed as biosorbents for metal removal owing to their high binding ability and low cost. This work reports the results of a study regarding the cadmium binding equilibria of dead biomass from the seaweed Sargassum muticum; this alga is a pest fouling organism that competes with the local fucalean species and may also interfere with the "sea industry"; therefore, it would constitute an ideal material to be used as biosorbent. Seven different treatments were tested in order to obtain a stable biomass that could be suitable for industrial use under a broad range of operational conditions. The treatments employed were protonation, chemical cross-linking with formaldehyde, KOH, Ca(OH)(2) and CaCl(2) or physical treatments with acetone and methanol. The equilibrium adsorption isotherms of Langmuir, Freundlich, and Langmuir-Freundlich were obtained for the quantitative description of the cadmium uptake. The effect of pH on biosorption equilibrium was studied at values ranging from 1 to 6, demonstrating the importance of this parameter for an accurate evaluation of the biosorption process. Maximum biosorption was found pH higher than 4.5. The maximum biosorption uptake for the raw biomass was 65 mg g(-1), while for formaldehyde cross-linking biomass the uptake increases to 99 mg g(-1) and for protonated biomass to 95 mg g(-1). Potentiometric titrations were carried out to estimate the total number of weak acid groups and to obtain their apparent pK value, 3.85, using the Katchalsky model. Kinetic studies varying cadmium concentration, algal dose, and ionic strength were carried out. Over 95% of the maximum cadmium uptake was achieved within 45 min, so the process can be considered relatively fast. A pseudo-second-order model, for the kinetics of cadmium biosorption, was shown to be able to reproduce experimental data points with accuracy.
近年来，由于褐藻具有高结合能力和低成本，关于其作为金属去除生物吸附剂的研究显著增加。本研究报告了鼠尾藻死亡生物质对镉的结合平衡研究结果；这种藻类是一种有害污损生物，与当地的墨角藻科物种竞争，还可能干扰“海洋产业”；因此，它将成为用作生物吸附剂的理想材料。为了获得在广泛操作条件下适合工业使用的稳定生物质，测试了七种不同处理方法。所采用的处理方法有质子化、用甲醛、氢氧化钾、氢氧化钙和氯化钙进行化学交联，或用丙酮和甲醇进行物理处理。获得了朗缪尔、弗伦德里希和朗缪尔 - 弗伦德里希平衡吸附等温线，用于定量描述镉的吸附情况。研究了pH值在1至6范围内对生物吸附平衡的影响，证明了该参数对准确评估生物吸附过程的重要性。发现pH高于4.5时生物吸附量最大。未处理生物质的最大生物吸附量为65 mg g⁻¹，而甲醛交联生物质的吸附量增加到99 mg g⁻¹，质子化生物质的吸附量增加到95 mg g⁻¹。进行了电位滴定以估计弱酸基团的总数，并使用卡查尔斯基模型获得其表观pK值3.85。进行了镉浓度、藻类剂量和离子强度变化的动力学研究。在45分钟内实现了超过95%的最大镉吸附量，因此该过程可被认为相对较快。镉生物吸附动力学的准二级模型能够准确再现实验数据点。
