Use of calcined Mg–Al layered double hydroxides to regulate endocrine disruptor methylparaben in excess as adsorbent and as control releasing agent in normal situations

Abstract

Calcined Mg–Al layered double hydroxides (CLDH) were studied as potential adsorbents of the methylparaben (MPB), as a function of pH, contact time, temperature, adsorbent dosage and initial concentration, with the objective to reduce the hazardous effects that it can cause to human and its environment. The native layered double hydroxides (LDH) with carbonate as interlayer anion were prepared by a co–precipitation method and calcined at 450 °C for 1 h. The adsorption results showed that the adsorption capacity in removing MPB by CLDH (20.99 mg g−1) was greater than that of the precursor LDH (3.29 mg g−1). As seen from the XRD patterns of CLDH before and after the adsorption, MPB was intercalated into LDH interlayer by reconstruction of the original layered structure through so called “memory effect”. The adsorption isotherm and kinetic studies showed well fitting of experimental data to Langmuir and pseudo–second–order kinetic model, respectively, with a correlation coefficient more than 0.99. In addition, CLDH used as support for MPB displayed its controlled release properties in phosphate buffer solution at pH 7.4. Therefore, we can conclude that the calcined LDH employed in this study can be used not only as adsorbent to remove paraben from aqueous solutions, but also when required as support for the slow release of this endocrine disrupting compound, thus controlling its well and ill effects in different situations.