Molecular imprinted polymer to remove tetracycline from aqueous solutions

• A molecularly imprinted polymer (MIP) for tetracycline (TC) was synthesized.
• The porosity of the MIP is more homogeneous than its corresponding non-imprinted polymer.
• The polymers do not differ in their chemical properties.
• The electrostatic interactions play an important role in the adsorption of TC on MIP.
• The MIP footprints demonstrate a memory effect and high selectivity for TC.

The objective of this study was to synthesize a molecularly imprinted polymer (MIP) for tetracycline (TC), prepared in the form of well-defined polymer microspheres, and its corresponding non-imprinted polymer (NIP). TC adsorption on these polymers was investigated, determining: (i) the interactions responsible for the adsorption, (ii) the chemical and textural characteristics of the polymers, and (iii) the role of the solvent in the process. The two polymers were characterized texturally by different techniques: (i) the surface area was larger for the MIP than for the NIP, whereas the micropore volume was considerably lower for the MIP; (ii) XPS analysis showed very high and similar surface oxygen percentages in both materials. The adsorbent properties of the materials were assessed by determining the TC adsorption isotherms: the Freundlich model indicates the high homogeneity of the MIP and Shimizu model shows the total number of binding sites was 8.7 μmol g−1 for the MIP vs. 0.17 μmol g−1 for the NIP. Analysis of the influence of pH and ionic strength revealed that adsorbent–adsorbate electrostatic interactions play a key role in TC adsorption on the MIP. The adsorption capacity of the MIP was also found to decrease with temperature, showing it to be an exothermic process.

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