This work investigated the interaction of phosphate (P) with three typical GRs (i.e., GR(Cl), GR(SO₄), and GR(CO₃)) that can be present in natural anoxic sediments. Our results show that GRs can rapidly adsorb P within 20 min and have a P adsorption capacity ranging from 24 to 76.5 mg/g at pH 7.5 under anoxic conditions. The adsorption of P by GR(Cl) and GR(SO₄) is favorable under acidic to neutral pH conditions, while the adsorption of P by GR(CO₃) is pH-independent. Competitive adsorption of coexisting ions such as SO₄^2-, bicarbonate/carbonate, and natural organic matter have also been observed for the adsorption of P by GR(Cl) and GR(SO₄). The addition of a small portion (1%) of GRs into sediment significantly enhanced the P sequestration under anoxic conditions, and the P adsorption capacity of GRs-amended sediment is 1-2 orders of magnitude higher than the pristine sediment. GRs adsorb P through ion-exchange with anions located on basal plane and lateral faces of GRs since the intercalation of P anions into the interlayer of GRs is not observed. P-bound GRs are stable in anoxic sediment compared with other Fe(III) hydroxides, which suffer from reductive dissolution and the release of P into pore waters. This work demonstrates the key role of GRs in P sequestration in lake sediments and their high potential for eutrophication control under anoxic conditions.

这项工作研究了磷酸盐（P）与天然缺氧沉积物中可能存在的三种典型GRs（即GR（Cl），GR（SO ₄）和GR（CO ₃））的相互作用。我们的结果表明，GRs在缺氧条件下，在20分钟内可以快速吸附P，并且在pH 7.5时具有24至76.5 mg / g的P吸附容量。GR（Cl）和GR（SO ₄）对P的吸附在酸性至中性pH条件下均有利，而GR（CO ₃）对P的吸附与pH无关。GR（Cl）和GR（SO ₄）吸附P的同时存在SO ₄ ^2-，碳酸氢根/碳酸根和天然有机物等共存离子的竞争性吸附。）。在缺氧条件下，向沉积物中添加一小部分（1％）GRs可以显着提高磷的固存，且GRs改良后的沉积物对P的吸附能力比原始沉积物高1-2个数量级。GRs通过与位于GRs基面和侧面的阴离子进行离子交换来吸附P，因为未观察到P阴离子嵌入GRs的中间层。与其他Fe（III）氢氧化物相比，P结合的GRs在缺氧沉积物中是稳定的，而Fe（III）的氢氧化物具有还原溶解作用，且P释放到孔隙水中。这项工作证明了GRs在湖泊沉积物中的P固存中的关键作用及其在缺氧条件下富营养化控制的高潜力。