Tetracycline antibiotics (TCs) are a group of the top selling and widely used antibiotics that have been frequently detected in various environments. The interaction between TCs and goethite (α-FeOOH), one of the most common crystalline oxide minerals in aqueous environment and soil, is unclear. Apart from adsorption, this study firstly demonstrated that transformation of tetracycline (TTC) occurred in the presence of goethite. The transformation kinetics and mechanism of TTC with goethite were investigated to gain a better understanding of the fate of TCs in the natural environment. The results showed that the transformation of TCs by goethite explicitly exhibited two-stage kinetics, wherein an initial period of fast transformation was followed by a continuous slow transformation. Hydroxyl groups on goethite were identified as major reactive sites, among which singly coordinated hydroxyls (FeOH) were more reactive than doubly coordinated hydroxyls (Fe₂OH) towards the transformation of TTC. On the basis of transformation rates, speciation of TTC and functional groups on goethite surface, a kinetic model was established successfully describing the transformation of TTC by goethite under conditions of varying reactant concentration and pH. The transformation of TTC by goethite mainly resulted in a N,N-dedimethylation product that did not show antimicrobial properties towards Escherichia coli. This study indicates that Fe(III)-(hydro)oxides in soils and sediments may play an important role in the natural attenuation of tetracycline antibiotics and their bioactivity.

四环素抗生素（TCs）是最畅销和使用最广泛的抗生素，在各种环境中经常被发现。TC和针铁矿（α-FeO​​OH）之间的相互作用尚不清楚，α-FeO​​OH是水性环境和土壤中最常见的结晶氧化物矿物之一。除了吸附之外，该研究首先证明在针铁矿存在下四环素（TTC）发生了转化。研究了针铁矿转化TC的动力学和机理，以更好地理解天然环境中TC的命运。结果表明，针铁矿对TCs的转化明确表现出两阶段动力学，其中快速转化的初始阶段之后是连续缓慢的转化。FeOH）对TTC的转化反应比双配位羟基（Fe ₂ OH）更具反应性。根据转化率，TTC的形态和针铁矿表面的官能团，建立了动力学模型，成功地描述了在反应物浓度和pH变化的条件下针铁矿转化TTC的动力学模型。针铁矿对TTC的转化主要导致N，N-去二甲基化产物，该产物对大肠杆菌没有抗药性。这项研究表明，土壤和沉积物中的Fe（III）-（氢）氧化物可能在四环素抗生素的自然衰减及其生物活性中起重要作用。