Electroless Production of Fertilizer (Struvite) and Hydrogen from Synthetic Agricultural Wastewaters
Electroless Production of Fertilizer (Struvite) and Hydrogen from Synthetic Agricultural Wastewaters
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DOI：
10.1021/jacs.0c07916
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发表时间：
2020-11-04
影响因子：
15
通讯作者：
Greenlee, Lauren F.
中科院分区：
文献类型：
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作者：
Kekedy-Nagy, Laszlo;Abolhassani, Mojtaba;Greenlee, Lauren F.
从农业和城市污水流中实现可持续的磷(P)回收的努力已经加强。然而，将磷回收与节能结合起来可能是本世纪最大的挑战之一。在这项研究中，我们首次报道了在小型电化学反应器中，以纯镁(MG)或镁合金为阳极，以316不锈钢(SS)为阴极，从磷酸二氢铵(NH_4H_2PO_4)水溶液中同时化学生产鸟粪石和二氢。在化学镀过程中(即在没有外加电源的情况下)，监测了开路电位(OCP)、阳极上鸟粪石的形成和阴极上二氢的产生。结果表明，HnPO4n-3/NH4+溶液中有鸟粪石生成，溶液中HnPO4n-3/NH4+的浓度和阳极的组成都会影响鸟粪石的晶体结构/形貌和沉淀膜厚度。纯镁阳极的膜厚为0.6-4.1微米，而AZ31镁合金为1.7-9.9微米的鸟粪石膜。动力学分析表明，两种镁负极材料对镁离子的溶解大多遵循零级动力学规律，速率常数(K)依赖于鸟粪石层的形貌。傅立叶变换红外光谱、X-射线衍射仪和扫描电子显微镜表明合成的鸟粪石质量较好。用气相色谱-热导检测器和离子色谱仪分别测定溶液中的氢气和镁离子。此外，我们充分证明，该反应器能够去除天然禽类废水中73%的HnPO4n-3，主要是鸟粪石。这项研究强调了以绿色和可持续的方式从废水中同时生产鸟粪石和氢气的可行性，而不需要投入任何能源。
The drive toward sustainable phosphorus (P) recovery from agricultural and municipal wastewater streams has intensified. However, combining P recovery with energy conservation is perhaps one of the greatest challenges of this century. In this study, we report for the first time the simultaneous electroless production of struvite and dihydrogen from aqueous ammonium dihydrogen phosphate (NH4H2PO4) solutions in contact with either a pure magnesium (Mg) or a Mg alloy as the anode and 316 stainless steel (SS) as the cathode placed in a bench-scale electrochemical reactor. During the electroless process (i.e., in the absence of external electrical power), the open circuit potential (OCP), the formation of struvite on the anode, and the generation of dihydrogen at the cathode were monitored. We found that struvite is formed, and that struvite crystal structure/morphology and precipitate film thickness are affected by the concentration of the HnPO4n-3/NH4+ in solution and the composition of the anode. The pure Mg anode produced a porous 0.6-4.1 mu m thick film, while the AZ31 Mg alloy produced a more compact 1.7-9.9 mu m thick struvite film. Kinetic analyses revealed that Mg dissolution to Mg2+ followed mostly a zero-order kinetic rate law for both Mg anode materials, and the rate constants (k) depended upon the struvite layer morphology. Fourier-transform infrared spectrometry, X-ray diffraction, and scanning electron microscopy indicated that the synthesized struvite was of high quality. The dihydrogen and Mg2+ in solution were detected by a gas chromatography-thermal conductivity detector and ion chromatography, respectively. Furthermore, we fully demonstrate that the reactor was able to remove similar to 73% of the HnPO4n-3 present in a natural poultry wastewater as mainly struvite. This study highlights the feasibility of simultaneously producing struvite and dihydrogen from wastewater effluents with no energy input in a green and sustainable approach.