Adsorption of Sodium Diclofenac in Functionalized Palygoskite Clays

The effects of acid and organo-functionalizations on the surface of Brazilian palygorskite clay was investigated, evaluating its potential in the adsorptive capacity of the drug sodium diclofenac present in wastewaters. The modifications on the clay structure were investigated by X-ray diffraction, X-ray fluorescence, thermogravimetric, differential thermal analysis, Fourier transform infrared spectroscopy, surface area by N-2 adsorption (77.5 K) and Zeta potential. The experimental design was carried out to find the best conditions for the adsorption tests, in which concentration, mass and pH were significant. In the kinetic study, the pseudo-second-order model better described the adsorption process for acid and organo-functionalized samples. Such results indicate that the adsorption behavior probably occurs due to the phenomenon of chemisorption. Regarding the adsorption isotherms, the Langmuir model was the one that best adjusted both the experimental data of acid and the organo-functionalized samples, whose maximum adsorption capacity were 179.88 and 253.34 mg/g, respectively. This model also indicates that the sodium diclofenac is adsorbed to monolayers homogeneously through chemisorption. In general, the studied clays proved to be suitable adsorbents for the removal of sodium diclofenac.

Automated summary

The effects of acid and organo-functionalizations on the surface of Brazilian palygorskite clay and its potential for adsorbing the drug sodium diclofenac in wastewaters were investigated. The modifications on the clay structure were analyzed, and the best conditions for adsorption tests were determined. The results showed that the adsorption behavior was likely due to chemisorption, and the Langmuir model adequately described the adsorption isotherms for both acid and organo-functionalized samples. The study concluded that Brazilian palygorskite clay was a suitable adsorbent for removing sodium diclofenac.