Adsorption of nitroimidazole antibiotics (NIABs, such as dimetridazole, metronidazole, or menidazole) over metal-organic frameworks (MOFs, in this case, MIL-101(Cr)) was studied in order to examine the possible applications of MOFs in the purification of water contaminated with NIABs. The MOFs, especially after grafting with urea or melamine, effectively adsorbed the NIABs. For example, urea-MIL-101, compared with any reported result, showed the highest adsorption capacity for metronidazole. Based on the adsorption results over a wide range of conditions, a plausible adsorption mechanism could be suggested for the improved performance: H-bonding between -NO2 of the NIABs and -NH2 of the MOF (introduced via grafting with urea or melamine). The MOFs were shown as a promising adsorbent of NIABs because of their high adsorption capability and reusability (which was confirmed with recyclability testing and FTIR). (C) 2017 Elsevier B.V. All rights reserved.