Removal of pharmaceuticals and personal care products (PPCPs) from water by adsorption on aluminum pillared clay

The natural layered clay-based materials offer a sustainable approach for removal of emerging pollutants from the environment. Their low-capacity and poor-selectivity for pollutants often limit their uses. This limitation is addressed in this study with the help of Al-oxide pillaring approach. Here microporous aluminum-pillared clay (Al-PILC) was prepared from locally available Smectite clay (montmorillonite, MMT), by intercalation of Al-oxide pillars into the interlayer structure. The method increased the surface area of natural clay to 258 m 2 g −1 and its porosity to 0.16 cm 3 g −1 . The adsorptive removal properties of prepared Al-PILC was evaluated on two selected pharmaceuticals and personal care products (PPCPs) viz . amoxicillin (AMOX) and imipramine (IMP). The results of the removal of these PPCPs were compared as a function of contact time (0–180 min), solution pH (2–12), initial concentration (0–100 mg L −1 ), and temperature (298–318 K). The Al-PILC adsorbs 332% more IMP and 681% more AMOX as compared to natural clay, and the maximum adsorption amounts on Al-PILC follows the order IMP > AMOX with 59.8 and 7.7 mg g −1 , respectively. The kinetics of adsorption of both AMOX and IMP follow pseudo-second-order model, with intraparticle diffusion as rate-determining step. The incorporated acidic sites in clay (in form of Al 2 O 3 pillars) enhanced its adsorption properties. These sites interacted with protonated amine and –OH groups of AMOX and the tertiary amine group of IMP. The Al-PILC exhibit effective regeneration and was reused up to three consecutive adsorption/desorption cycles. All in all, this study is expected to expand the application of Al-PILC on the adsorptive removal of the emerging pollutant from contaminated water.