Strong adsorption of tetracycline on octahedral Cu2O nanocrystals exposed with {111} facets: Adsorption behavior and mechanism insight

The extensive use of tetracycline (TC) as veterinary therapeutics and animal growth promoters has caused human health problems. Some adsorbents have been developed to remove TC, but the adsorption capacity is still unsatisfactory. Here, we synthesized octahedral cuprous oxide nanocrystals (oct-Cu2O NCs) by a hydrothermal method at room temperature. Surprisingly, the maximum adsorption capacity of oct-Cu2O NCs reached an astonishing amount of 1112.6 mg/g. Adsorption kinetics and isotherm experiments for TC removal were carried out to evaluate its potential as an adsorbent. The key factors like pH and solution ions as well as the mechanism of TC adsorption on oct-Cu2O NCs were also studied. The main adsorption process may be that the hydroxyl group (-OH) on the {111} facets surface of oct-Cu2O NCs is replaced by the amino group (-NH2) of TC. The high adsorption capacity is generated by the abundant Cu atoms with dangling bonds on the {111} facets surface and the strong chemical coordination between the -NH2 of TC and Cu(I). This work provides an alternative with a promising application prospect for the treatment of TC in water. [Display omitted] •Oct-Cu2O NCs with {111} facets were prepared through a simple hydrothermal method.•Oct-Cu2O NCs possess excellent tetracycline adsorption performance.•A large number of adsorption active sites are on the {111} facets.•Strong adsorption is generated by the coordination between -NH2 of TC and Cu(I).