Amination/oxidization dual-modification of waste ginkgo shells as bio-adsorbents for copper ion removal

Exploration of low-cost adsorbents from abundant biomass exhibits great potential for toxic heavy metal removal in water and wastewater treatment. In this work, we develop a facile and general method for dual-modification of biomaterials like waste ginkgo shell to prepare novel bio-adsorbents with enhanced activities for heavy metal ion removal. By combination of oxidation and amination, the bio-adsorbents can be functionalized with enriched carbonyl and amino multiple groups. The synergistic effect of amination and oxidization played an important role in the improvement of surface chemical properties and pore structure. Compared with traditionally carbonized shells, dual-functionalized bio-adsorbents held superior activity and much higher adsorptive capability toward Cu2+ removal. Moreover, the prepared ginkgo shell based bio-adsorbent possessed excellent chemical stability and reusability, which provided promising potential for further industrial applications. By calculation, it was found that the whole adsorption process was satisfactorily fitted to Pseudo-second-order kinetic model, indicating the chemisorptions of functional groups as rate limiting step. Thermo dynamical studies further showed that the adsorption process was endothermic in nature. The progress may not only provide the amination/oxidization modified ginkgo shell for effective copper ion adsorption, but also open a new dual modification approach applied more generally to different bio-materials from nature. (C) 2019 Elsevier Ltd. All rights reserved.