Bai Run-Ying, Song Bo-Wen, Zhang Yu, Hao Jun-Feng, Liu Jian-Ming, Liu Yu-Hong
School of Civil Engineering, Inner Mongolia University of Technology, Hohhot 010000, China.
Huan Jing Ke Xue. 2021 Mar 8;42(3):1461-1468. doi: 10.13227/j.hjkx.202008084.
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@MgFeO was prepared using a one-step co-precipitation method. La loading on grain boundary defects of MgFeO, 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@MgFeO involved La loading on grain boundary defects of MgFeO in the form of La(OH). The addition of La changed the crystallinity and morphology of MgFeO, which greatly improved the capacity of MgFeO for phosphorus adsorption. Saturation magnetization remained at 14 emu·g, which was easily separated from water using an external magnetic field. The maximum adsorption capacity was 143.156 mg·g at pH 6 and 10℃, which was comparable to that achieved at 25℃. Kinetic observations showed that a low phosphorus concentration (10 mg·L) could result in extremely low phosphorus adsorption by La@MgFeO after 30 min. The adsorption mechanism shows that phosphorus is removed through ligand exchange and the formation of inner spherical complexes. La@MgFeO 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 of La@MgFeO in the treatment of low temperature municipal wastewater in Northern China, phosphate concentrations could be reduced to less than 0.5 mg·L an hour, offering a promising means of phosphate adsorption even in cold regions.
由于磷短缺以及磷污染导致的富营养化问题，从废水中回收磷迫在眉睫。铁氧体复合材料因其高吸附容量以及在施加磁场时便于与水分离，在磷回收方面受到越来越多的关注。在本研究中，采用一步共沉淀法制备了尖晶石La@MgFeO。使用X射线衍射（XRD）、傅里叶变换红外光谱法（FTIR）、X射线光电子能谱（XPS）和振动样品磁强计（VSM）研究了La在MgFeO晶界缺陷上的负载情况以及磷吸附容量。La@MgFeO的结构涉及以La(OH)形式负载在MgFeO晶界缺陷上的La。La的添加改变了MgFeO的结晶度和形态，极大地提高了MgFeO对磷的吸附能力。饱和磁化强度保持在14 emu·g，使用外部磁场可轻松将其与水分离。在pH为6和10℃时，最大吸附容量为143.156 mg·g，与25℃时的吸附容量相当。动力学观察表明，低磷浓度（10 mg·L）在30分钟后会导致La@MgFeO对磷的吸附极低。吸附机制表明，磷通过配体交换和内球络合物的形成被去除。La@MgFeO对磷酸盐具有高度选择性吸附，吸附剂在解吸后可多次重复使用。基于在中国北方低温城市污水治理中添加1 g·L的La@MgFeO，一小时内磷酸盐浓度可降至0.5 mg·L以下，即使在寒冷地区也提供了一种有前景的磷吸附方法。
