Over the years, adsorption has proved to be an effectual technique in the recovery of a variety of substances from aqueous solution. In response to the call for environmental and economic sustainability, much attention has been placed on biosorbents. Persimmon tannin-based adsorbents (PTBAs), in particular, have shown promise in terms of recovering metals from wastewater. PTBAs are universally occurring, low-cost biological polymers that can be easily obtained and transformed into non-soluble tannin gels or immobilized onto various carriers. This study provides an overview of available literature (2002–2020) regarding the application of PTBA for remediating water containing heavy and precious metals. The adsorption capacity of several PTBAs (modified and unmodified) was summarized and this reflected the efficacy of PTBAs as a biosorbent. Gold was the most common target of PTBAs with the highest recorded maximum adsorption capacity of 15.36 mol/kg of Au³⁺. The uptake mechanisms of precious and heavy metals Au, Pd, Pt, V, and Cr(VI) unto PBTAs were also discussed. Furthermore, the factors influencing adsorption of metals by PTBAs, particularly pH, were identified. The effect of pH on metal adsorption onto PTBAs from previous studies is compiled and discussed.

中文翻译：

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柿鞣质作为废水中贵重金属吸附的生物吸附剂

多年来，吸附已被证明是从水溶液中回收多种物质的有效技术。为了响应环境和经济可持续性的呼吁，人们对生物吸附剂给予了极大关注。柿子基于单宁的吸附剂（PTBA）特别显示出从废水中回收金属的前景。PTBA是普遍存在的低成本生物聚合物，可以轻松获得并将其转化为不溶性单宁凝胶或固定在各种载体上。本研究概述了有关PTBA在修复重金属和贵金属水中的应用的现有文献（2002-2020年）。总结了几种PTBA（改性和未改性）的吸附能力，这反映了PTBA作为生物吸附剂的功效。³⁺。还讨论了贵金属和重金属Au，Pd，Pt，V和Cr（VI）对PBTA的吸收机理。此外，确定了影响金属被PTBA吸附的因素，特别是pH。汇总并讨论了pH对先前研究中金属吸附到PTBA上的影响。