Biochar-templated surface precipitation and inner-sphere complexation effectively removes arsenic from acid mine drainage
| Autor: | Jon Chorover, Robert A. Root, Dongmei Wang |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Goethite
010504 meteorology & atmospheric sciences Health Toxicology and Mutagenesis Inorganic chemistry chemistry.chemical_element Acidic mine drainage 010501 environmental sciences Ferric Compounds 01 natural sciences Mining Arsenic Arsenic sorption Ferrihydrite chemistry.chemical_compound Adsorption medicine Environmental Chemistry 0105 earth and related environmental sciences Mine tailings Schwertmannite Arsenate General Medicine Acid mine drainage Iron hydroxide activation Pollution Biochar chemistry Charcoal visual_art visual_art.visual_art_medium Ferric Research Article medicine.drug |
| Zdroj: | Environmental Science and Pollution Research International |
| ISSN: | 1614-7499 0944-1344 |
| DOI: | 10.1007/s11356-021-13869-8 |
| Popis: | Treatment of aqueous leachate from acid mine tailings with pristine biochar (BC) resulted in the removal of more than 90% of the dissolved arsenic with an attendant rapid and sustained pH buffering from 3 to 4. Pine forest waste BC was transformed to a highly effective adsorbent for arsenic remediation of acid mine drainage (AMD) because the dissolved iron induced “activation” of BC through accumulation of highly reactive ferric hydroxide surface sites. Physicochemical properties of the BC surface, and molecular mechanisms of Fe, S, and As phase transfer, were investigated using a multi-method, micro-scale approach (SEM, XRD, FTIR, XANES, EXAFS, and STXM). Co-located carbon and iron analysis with STXM indicated preferential iron neo-precipitates at carboxylic BC surface sites. Iron and arsenic X-ray spectroscopy showed an initial precipitation of ferrihydrite on BC, with concurrent adsorption/coprecipitation of arsenate. The molecular mechanism of arsenic removal involved bidentate, binuclear inner-sphere complexation of arsenate at the surfaces of pioneering ferric precipitates. Nucleation and crystal growth of ferrihydrite and goethite were observed after 1 h of reaction. The high sulfate activity in AMD promoted schwertmannite precipitation beginning at 6 h of reaction. At reaction times beyond 6 h, goethite and schwertmannite accumulated at the expense of ferrihydrite. Results indicate that the highly functionalized surface of BC acts as a scaffolding for the precipitation and activation of positively charged ferric hydroxy(sulf)oxide surface sites from iron-rich AMD, which then complex oxyanion arsenate, effectively removing it from porewaters. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s11356-021-13869-8. |
| Databáze: | OpenAIRE |
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