Davis Thomas A, Volesky Bohumil, Mucci Alfonso
Department of Chemical Engineering, McGill University, 3610 University Street, Que. H3A 2B2, Montreal, Canada.
Water Res. 2003 Nov;37(18):4311-30. doi: 10.1016/S0043-1354(03)00293-8.
The passive removal of toxic heavy metals such as Cd(2+), Cu(2+), Zn(2+), Pb(2+), Cr(3+), and Hg(2+) by inexpensive biomaterials, termed biosorption, requires that the substrate displays high metal uptake and selectivity, as well as suitable mechanical properties for applied remediation scenarios. In recent years, many low-cost sorbents have been investigated, but the brown algae have since proven to be the most effective and promising substrates. It is their basic biochemical constitution that is responsible for this enhanced performance among biomaterials. More specifically, it is the properties of cell wall constituents, such as alginate and fucoidan, which are chiefly responsible for heavy metal chelation. In this comprehensive review, the emphasis is on outlining the biochemical properties of the brown algae that set them apart from other algal biosorbents. A detailed description of the macromolecular conformation of the alginate biopolymer is offered in order to explain the heavy metal selectivity displayed by the brown algae. The role of cellular structure, storage polysaccharides, cell wall and extracellular polysaccharides is evaluated in terms of their potential for metal sequestration. Binding mechanisms are discussed, including the key functional groups involved and the ion-exchange process. Quantification of metal-biomass interactions is fundamental to the evaluation of potential implementation strategies, hence sorption isotherms, ion-exchange constants, as well as models used to characterize algal biosorption are reviewed. The sorption behavior (i.e., capacity, affinity) of brown algae with various heavy metals is summarized and their relative performance is evaluated.
通过廉价生物材料被动去除镉（Cd(2+)）、铜（Cu(2+)）、锌（Zn(2+)）、铅（Pb(2+)）、铬（Cr(3+)）和汞（Hg(2+)）等有毒重金属，即生物吸附，要求底物具有高金属吸收量和选择性，以及适用于应用修复场景的机械性能。近年来，人们研究了许多低成本吸附剂，但事实证明褐藻是最有效且最有前景的底物。正是它们的基本生化组成导致了在生物材料中这种增强的性能。更具体地说，是细胞壁成分如藻酸盐和岩藻依聚糖的特性主要负责重金属螯合。在这篇综述中，重点是概述褐藻与其他藻类生物吸附剂不同的生化特性。提供了藻酸盐生物聚合物大分子构象的详细描述，以解释褐藻表现出的重金属选择性。从其金属螯合潜力的角度评估了细胞结构、储存多糖、细胞壁和细胞外多糖的作用。讨论了结合机制，包括涉及的关键官能团和离子交换过程。金属与生物质相互作用的量化对于评估潜在实施策略至关重要，因此综述了吸附等温线、离子交换常数以及用于表征藻类生物吸附的模型。总结了褐藻对各种重金属的吸附行为（即容量、亲和力）并评估了它们的相对性能。
