Removal of Tetracycline from Water by Palygorskite

The use of antibiotics and hormones in human and veterinary has resulted in frequent detection of these pharmaceuticals in ground water and waste water. Thus, it is of great interest to study the interaction between common pharmaceuticals and clay minerals and humic materials.
Palygorskite(PFL) is clay consisting of modulated 2:1 layers. The tetrahedral sheets of PFL are continuous, but every two tetrahedral ribbons along the b axis exhibit a reversal of the orientation of their apical O atoms. This reversal leads to the periodic interruption of the octahedral sheet, which, unlike that of smectite, becomes discontinuous (Chisholm 1992; Chiari et al. 2003; Giustetto et al. 2004). The sorption of tetracycline(TC) on PFL was studied as a function of pH, ionic strength, temperature, pH adsorption edge PFL contents and tetracycline concentrations under ambient conditions using a batch technique. The TC sorption capacity on PFL is as high as 90 mg/g at pH 8.7, and decreased to 35 mg/g at pH 11. Because PFL is a fiber structure, XRD analysis are not found any variation, thus the adsorption is on the surface of PFL.

The results from this study indicate that the palygorskite could be a good candidate as a sorbent to remove TC from water on one hand, and could be a great environmental sink for TC on the other hand. This dual property deems further study on interactions between a broad spectrum of antibiotics and different types of clays, for example, rectorite.