S1 File -

<div><p>To remove phosphate from water, a novel Fe-doped ZIF-8 was synthesized as a superior adsorbent. The Fe-doped ZIF-8 was fully characterized using different characterization techniques and it was found that the as-prepared Fe-doped ZIF-8 (denoted as ZIF-(2Zn:1Fe)) showed a polyhedral morphology with a large specific surface area of 157.64 m<sup>2</sup>/g and an average pore size of 3.055 nm. Analyses using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction showed that Fe atoms were successfully incorporated into the ZIF-8 skeleton. Batch experiments demonstrated that the molar ratio of Fe and Zn has effects on phosphate adsorption. The adsorption kinetics conformed to a pseudo-second-order model with a high correlation coefficient (<i>R</i><sup>2</sup> = 0.9983). The adsorption isotherm matched the Langmuir model (<i>R</i><sup>2</sup> = 0.9994) better than the Freundlich model (<i>R</i><sup>2</sup> = 0.7501), suggesting that the adsorption of phosphoric acid by ZIF-(2Zn:1Fe) can be classified as a chemisorption on a homogeneous surface. The adsorption amount was 38.60 mg/g. It was found that acidic environments favored the adsorption reaction and the best adsorption was achieved at an initial pH of 2. Inhibition of adsorption by common anions is NO<sub>3</sub><sup>-</sup>> CO<sub>3</sub><sup>2-</sup>> SO<sub>4</sub><sup>2-</sup>> Cl<sup>-</sup>. Characterization results indicate that the main mechanism of adsorption is surface complexation interactions.</p></div>