| 一步法La@MgFe2O4的制备及其吸附水中磷的性能 |
| 摘要点击 2459 全文点击 677 投稿时间：2020-08-08 修订日期：2020-09-02 |
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| 中文关键词 吸附 镧镁铁氧体 低温 市政污水 磷酸盐 |
| 英文关键词 adsorption lanthanum-magnesium ferrite low temperature municipal wastewater phosphate |
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| 中文摘要 |
| 由于磷矿资源紧张及磷污染引起的水体富营养化，迫切需要回收水体中的磷酸盐.利用铁氧体复合材料吸附回收水中的磷，由于吸附容量较大以及利用外加磁场易于从水中分离而日益得到重视.本研究利用一步共沉淀法直接制备尖晶石型La@MgFe2O4复合材料，将La3+固定在MgFe2O4缺陷位点上，考察La@MgFe2O4的吸磷尤其是低温时的吸磷能力，并采用XRD/FTIR/XPS/VSM等技术对La@MgFe2O4进行表征.结果表明，La3+离子以La（OH）3的形式负载在MgFe2O4晶界缺陷上，La3+的加入改变了MgFe2O4的结晶度和形貌，并大大提高了MgFe2O4的吸磷能力，其饱和磁化强度为14 emu·g-1，在外加磁场条件下可以从水中磁分离.当pH值为6时，温度降为10℃其最大吸附容量与25℃时相比几乎无降低，约为143.156 mg·g-1.动力学研究表明，La@MgFe2O4能在30 min内将低磷（10 mg·L-1）浓度转化为极低磷.吸附机制研究表明，磷通过配体交换形成内球络合物被去除.La@MgFe2O4对磷酸盐具有高度选择吸附性，吸附剂解吸后可多次重复使用.将其应用于中国北方低温市政污水，投加吸附剂的浓度为1 g·L-1，可在1 h内将磷酸盐浓度降低至0.5 mg·L-1以下，表明La@MgFe2O4在寒冷地区也具有良好应用前景. |
| 英文摘要 |
| Due to the shortage of phosphate and the eutrophication caused by phosphorus pollution, it is urgent to recover phosphate from wastewater. Given their high adsorption capacity and convenient separation from water to which a magnetic field is applied, ferrite composites have received increasing attention for phosphate recovery. In this study, Spinel La@MgFe2O4 was prepared using a one-step co-precipitation method. La3+ loading on grain boundary defects of MgFe2O4, and phosphorus absorption capacity were examined using X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The structure of La@MgFe2O4 involved La3+ loading on grain boundary defects of MgFe2O4 in the form of La(OH)3. The addition of La changed the crystallinity and morphology of MgFe2O4, which greatly improved the capacity of MgFe2O4 for phosphorus adsorption. Saturation magnetization remained at 14 emu·g-1, which was easily separated from water using an external magnetic field. The maximum adsorption capacity was 143.156 mg·g-1 at pH 6 and 10℃, which was comparable to that achieved at 25℃. Kinetic observations showed that a low phosphorus concentration (10 mg·L-1) could result in extremely low phosphorus adsorption by La@MgFe2O4 after 30 min. The adsorption mechanism shows that phosphorus is removed through ligand exchange and the formation of inner spherical complexes. La@MgFe2O4 has highly selective adsorption with respect to phosphate, and the adsorbent can be reused many times after desorption. Based on addition of 1 g·L-1 of La@MgFe2O4 in the treatment of low temperature municipal wastewater in Northern China, phosphate concentrations could be reduced to less than 0.5 mg·L-1 an hour, offering a promising means of phosphate adsorption even in cold regions. |
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