Li, JianhongJianhongLiSHAN-LI WANGZheng, LirongLirongZhengChen, DongliangDongliangChenWu, ZhipengZhipengWuSun, ChenghuaChenghuaSunBolan, NanthiNanthiBolanZhao, HongtingHongtingZhaoPeng, An-AnAn-AnPengFang, ZhengZhengFangZhou, RongfuRongfuZhouLiu, GuobinGuobinLiuBhatnagar, AmitAmitBhatnagarQiu, YongYongQiuWang, HailongHailongWang2025-09-232025-09-232022-02-2415565068https://www.scopus.com/pages/publications/85179538166?inwardhttps://scholars.lib.ntu.edu.tw/handle/123456789/732265A better understanding of different retention mechanisms of potentially toxic elements (PTEs) by biochars during the remediation of contaminated sites is critically needed. In this study, several synchrotron-based spectroscopic techniques were used to investigate lead (Pb) and copper (Cu) retention mechanisms on silicon-rich coconut-fiber biochar (CFB) and ammonia, nitric acid and hydrogen peroxide modified CFB (i.e., ACFB, NCFB and HCFB). Results showed that binding-sites on ACFB and NCFB were more efficient compared to that on CFB and HCFB to bind Pb/Cu. The percentage of Pb species as Pb(C2H3O2)2 increased from 22.2% (Pb-loaded CFBs) to 47.4% and 41.9% on Pb-loaded NCFBs and HCFBs, while the percentage of Cu(OH)2 and Cu(C2H3O2)2 increased from 5.8% and 32.8% (Cu-loaded CFBs) to 41.5% and 43.4% (Cu-loaded NCFBs) and 27.1% and 35.1% (Cu-loaded HCFBs), respectively. Due to their similar atomic structures of Pb/Cu, Pb(C2H3O2)2/Pb-loaded montmorillonite and Cu(C2H3O2)2/Cu(OH)2 were identified as the predominant Pb/Cu species observed in Pb- and Cu-loaded MCFBs. Density functional theory calculations suggested that silicate and the synergistic effect of hydroxyl and carboxylic-groups on MCFBs were highly efficient in Pb retention, while azido-groups and/or carboxylic-groups played major roles in Cu retention. These results provide novel insights into the PTE retention mechanisms of MCFBs.Binding sitesMetal retentionModified biocharPotentially toxic elementsSynchrotron radiationpreprint10.2139/ssrn.40424582-s2.0-85179538166