School of Civil Engineering, Liaoning Technical University, 88 Yulong Road, Xihe District, Fuxin, 123000, Liaoning Province, China.
School of Mining Engineering, China University of Mining and Technology, Xuzhou, 221000, China.
Environ Sci Pollut Res Int. 2024 Feb;31(6):8930-8951. doi: 10.1007/s11356-023-31697-w. Epub 2024 Jan 6.
A new adsorbent called iron-magnesium oxide coupled lignite (CIMBC) was developed to address the challenges of recovering high concentrations of ammonia nitrogen and phosphate in livestock farm wastewater and improving the inefficient use of lignite (BC) with low calorific value. CIMBC was synthesized using the modified ferromagnesium salt double-coating method. The experiments demonstrated that FeO and MgO could be effectively loaded onto the surface of BC at a Fe/Mg molar ratio of 1:2 and pyrolysis temperature of 500 °C. The optimal conditions for adsorption were determined to be an N/P concentration ratio of 2:1, adsorbent dosage of 1 g/L, and pH of 7. The presence of coexisting cations (Ca and Mg) inhibited the removal of ammonia nitrogen but enhanced the removal of phosphate. Likewise, the presence of coexisting anions (CO and SO) hindered the removal of both ammonia nitrogen and phosphate. The adsorption behavior followed the pseudo-second-order model and the Langmuir model, with a maximum adsorption capacity of 95.69 mg N/g for ammonia nitrogen and 101.32 mg P/g for phosphate. The adsorption process was a spontaneous endothermic process controlled by multiple levels. The main mechanisms of adsorption involved electrostatic attraction, intra-particle diffusion, ion exchange, chemical precipitation, and coordination exchange. After 5 times of adsorption-desorption, the recovery rate of CIMBC is less than 50%, and the removal rate of phosphate is less than 40%. Although the RCIMBC exhibited low reusability, but also it showed potential in removing heavy metals (Pb) from wastewater and for use as a slow-release fertilizer. CIMBC is a promising new adsorbent, which can realize resource utilization of lignite with low calorific value while removing nitrogen and phosphorus.
一种名为铁镁氧化物耦合褐煤（CIMBC）的新型吸附剂被开发出来，以解决从高浓度氨氮和磷酸盐的养殖废水中回收的挑战，并提高低热值褐煤（BC）的低效利用。CIMBC 是使用改良的铁镁盐双层包覆法合成的。实验表明，FeO 和 MgO 可以在 Fe/Mg 摩尔比为 1:2 和热解温度为 500°C 的条件下有效负载到 BC 的表面上。吸附的最佳条件确定为 N/P 浓度比为 2:1、吸附剂用量为 1g/L 和 pH 值为 7。共存阳离子（Ca 和 Mg）的存在抑制了氨氮的去除，但增强了磷酸盐的去除。同样，共存阴离子（CO 和 SO）的存在阻碍了氨氮和磷酸盐的去除。吸附行为遵循伪二级模型和 Langmuir 模型，对氨氮的最大吸附容量为 95.69mg N/g，对磷酸盐的最大吸附容量为 101.32mg P/g。吸附过程是一个自发的吸热过程，受多个层次控制。吸附的主要机制包括静电吸引、颗粒内扩散、离子交换、化学沉淀和配位交换。在 5 次吸附-解吸后，CIMBC 的回收率小于 50%，磷酸盐的去除率小于 40%。虽然 RCIMBC 表现出低的可重复使用性，但它也显示了从废水中去除重金属（Pb）并用作缓释肥料的潜力。CIMBC 是一种很有前途的新型吸附剂，可以实现低热值褐煤的资源利用，同时去除氮磷。
