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湖南農業大學資源環境學院劉孝利、杜輝輝團隊製備了矽酸鹽改性油茶殼生物炭，並對其Cd去除吸附能力進行了表徵。相關成果發表於Journal of Cleaner Production（IF=7.246）。
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Highlihgts
Na2SiO3 modification improves porosity and functional groups on biochar surface.
Na2SiO3 modification significantly enhances Cd removal than raw biochar.
Cd adsorption fits the Langmuir isotherm and pseudo-second-order kinetic model.
Ion exchange, surface precipitation and complexation dominant Cd adsorption.
Abstract
Oiltea camellia shells are a substantial agricultural waste in southern China, but their resource utilization has not been given due attention. In this study, we prepared oiltea camellia shell biochar by pyrolysis (500°C) in the presence of sodium silicate, and investigated its adsorption capacity for Cd removal. The SEM characterization shows that silicon (Si) is loaded on biochar surfaces as fine particles, and are identified as quartz (SiO2), silicate and C-Si mixture according to X-ray diffraction. Silicate-modification significantly increases (45112%) specific surface area (SSA) and slightly increases (512%) porosity of biochar. Batch results reveal that Si-modification significantly enhances Cd adsorption, and this increment is more pronounced at pH>5. Furthermore, silicate-modification promotes the internal diffusion of Cd on biochar. FTIR and XPS analyses suggest that ion exchange with Na+, surface precipitation (CdCO3, CdSiO3 or Cd2SiO4), coordination with π electrons (C=C) and complexation with carboxyl and CSiO groups are the predominant sorption mechanisms. This study puts a new perspective on the waste utilization of oiltea camellia shells for heavy metal removal from wastewaters or stabilization in contaminated soils.
油茶殼是我國南方一種常見的農業廢棄物，其資源化利用一直沒有得到應有的重視。本研究在矽酸鹽存在的條件下，採用500℃熱解法製備油茶殼生物炭，並考察其對Cd去除的吸附能力。SEM表徵表明，矽（Si）以細小顆粒的形式附著在生物炭表面，經X射線衍射鑑定為石英（SiO2）、矽酸鹽和C-Si的混合物。矽酸鹽改性顯著增加了生物炭的比表面積（約45%112%），並略微增加了生物炭的孔隙率（約5%12%）。批處理結果表明，矽改性顯著提高了對Cd的吸附效果，且在pH>5時，這種提高更為明顯。此外，矽改性促進了Cd在生物炭上的內部擴散。FTIR和XPS分析表明，其主要吸附機制是與Na+進行離子交換、表面析出（CdCO3、CdSiO3或Cd2SiO4）、與非晶體電子配位（C=C）、與羧基和與C-Si-O基團絡合。本研究為油茶殼在廢水中重金屬去除和土壤穩定方面的廢棄物利用研究提供了新的思路。
責任編輯：宋瀟
校對和審核：張陽 王農