Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, USA.
J Hazard Mater. 2011 Jun 15;190(1-3):501-7. doi: 10.1016/j.jhazmat.2011.03.083. Epub 2011 Mar 29.
Biochar converted from agricultural residues or other carbon-rich wastes may provide new methods and materials for environmental management, particularly with respect to carbon sequestration and contaminant remediation. In this study, laboratory experiments were conducted to investigate the removal of phosphate from aqueous solution by biochar derived from anaerobically digested sugar beet tailings (DSTC). Batch adsorption kinetic and equilibrium isotherm experiments and post-adsorption characterizations using SEM-EDS, XRD, and FTIR suggested that colloidal and nano-sized MgO (periclase) particles on the biochar surface were the main adsorption sites for aqueous phosphate. Batch adsorption experiments also showed that both initial solution pH and coexisting anions could affect the adsorption of phosphate onto the DSTC biochar. Of the mathematical models used to describe the adsorption kinetics of phosphate removal by the biochar, the Ritchie N_th-order (N=1.14) model showed the best fit. Two heterogeneous isotherm models (Freundlich and Langmuir-Freundlich) fitted the experimental isotherm of phosphate adsorption onto the biochar better than the Langmuir adsorption model. Our results suggest that biochar converted from anaerobically digested sugar beet tailings is a promising alternative adsorbent, which can be used to reclaim phosphate from water or reduce phosphate leaching from fertilized soils. In addition, there is no need to regenerate the exhausted biochar because the phosphate-laden biochar contains abundance of valuable nutrients, which may be used as a slow-release fertilizer to enhance soil fertility and to sequester carbon.
由农业残余物或其他富碳废物转化而成的生物炭可为环境管理，特别是碳封存和污染物修复，提供新的方法和材料。本研究通过利用厌氧消化甜菜尾渣（DSTC）制备生物炭，进行了从水溶液中去除磷酸盐的实验室实验。批吸附动力学和平衡等温线实验以及使用 SEM-EDS、XRD 和 FTIR 进行的吸附后特征分析表明，生物炭表面的胶体和纳米级氧化镁（方镁石）颗粒是水溶液中磷酸盐的主要吸附位点。批吸附实验还表明，初始溶液 pH 值和共存阴离子都会影响 DSTC 生物炭对磷酸盐的吸附。在所使用的描述生物炭去除磷酸盐吸附动力学的数学模型中，Ritchie N_th 阶（N=1.14）模型拟合效果最佳。两种非均相等温线模型（Freundlich 和 Langmuir-Freundlich）比 Langmuir 吸附模型更能拟合磷酸盐吸附到生物炭上的实验等温线。研究结果表明，由厌氧消化甜菜尾渣转化而成的生物炭是一种很有前途的替代吸附剂，可用于从水中回收磷酸盐或减少施肥土壤中磷酸盐的淋失。此外，无需再生耗尽的生物炭，因为负载磷酸盐的生物炭含有丰富的有价值养分，可作为缓释肥料来提高土壤肥力并固碳。
