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Background Phosphate (PO 4 3−) is the main etiological factor of eutrophication in surface waters. Metal organic frameworks (MOFs) are novel hybrid materials with amazing structural properties that make them a prominent material for adsorption. Methods Zeolitic imidazolate framework 67 (ZIF-67), a water stable member of MOFs, with a truncated rhombic dodecahedron crystalline structure was synthesized in aqueous environment at room temperature and then characterized using XRD and SEM. PO 4 3− adsorption from synthetic solutions using ZIF-67 in batch mode were evaluated and a polynomial model (R 2 : 0.99, R 2 adj : 0.98, LOF: 0.1433) developed using response surface methodology (RSM). Results The highest PO 4 3− removal (99.2%) after model optimization obtained when ZIF-67 dose, pH and mixing time adjusted to 6.82, 832.4 mg/L and 39.95 min, respectively. The optimum PO 4 3− concentration in which highest PO 4 3− removal and lowest adsorbent utilization occurs, observed at 30 mg/L. PO 4 3− removal eclipsed significantly in the presence of carbonate. The equilibrium and kinetic models showed that PO 4 3− adsorbed in monolayer (q max : 92.43 mg/g) and the sorption process controlled in the sorption stage. Adsorption was also more favorable at higher PO 4 3− concentration, according to the separation factor (K R) graph. Thermodynamic parameters (minus signs of ΔG°, ΔH°of 0.179 KJ/mol and ΔS°of 44.91 KJ/mol.K) demonstrate the spontaneous, endothermic and physisorption nature of the process. Conclusion High adsorption capacity and adsorption rates, make ZIF-67 a promising adsorbent for PO 4 3− removal from aqueous environment.

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