Mercury adsorption kinetics on sulfurized biochar and solid-phase digestion using aqua regia: A synchrotron-based study

Various studies have focused on the performance and removal mechanism of aqueous Hg using biochars, but specific process has not been fully elucidated. Aqua regia digestion is considered a common extraction method from solid samples, uncertainties exist regarding biochars. Aqueous kinetic experiments followed by aqua procedures solid-phase analyses were conducted to investigate diffusion transformation processes oak biochar (BC) evaluate efficiency as well stability adsorbed Kinetic indicated adsorption capacity increased rate decreased pretreated with calcium polysulfide (CP-BC) relative unmodified BC. Confocal micro-X-ray fluorescence imaging illustrated penetration into interior BC accumulation CP-BC surface. extended X-ray absorption fine structure spectra modeling was first Hg(II)–O transformed Hg(II)–S forms CP-BC, whereas only Hg(II)–Cl observed The results suggest that cannot be completely extracted These provide information biochars incomplete regia, which critical for optimizing modification methods evaluating long-term in environments.