High-performance novel ZIF-67 and ZIF-67@MWNTs composite adsorbents for efficient removal of pharmaceutical contaminant from water: Exceptional capacity and excellent reusability

The removal of pharmaceutical waste products like ibuprofen (IBP) from water is very important for the environment and the health of human and aquatic organisms. In the present work, the adsorption of IBP from aqueous solution was investigated by synthesizing novel ZIF-67 and ZIF-67@MWNTs hybrid composite material by incorporating ZIF-67 particles with carboxyl functionalized multiwalled carbon nanotubes (COOH-MWNT). The synthesized ZIF-67 and ZIF-67@MWNTs adsorbents were characterized by the XPS, XRD, SEM, TEM, BET, FTIR, and TGA analysis to examine their physio-chemical properties. The synthesized novel ZIF-67 has a 1743 m2/g BET surface and 0.692 cm3/g total pore volume. The IBP adsorption process including isotherm and kinetic studies as well as the effect of different parameters i.e. pH, initial concentration, time, adsorbents, and their dosage were examined. Among all the synthesized composite materials, the ZIF-67@MWNT-50 mg material showed the highest IBP adsorption capacity of 841 +/- 5 mg/g, about 467 +/- 5 mg/g more than the ZIF-67 following the Langmuir and pseudo-second-order model. The enhancement in the IBP adsorption is because of the incorporation of COOH-MWNT and the presence of a large number of active binding sites which showed the van der Waal interactions, host-guest interactions, pi- pi interactions, and H-bonding between the adsorbate and adsorbent. For the detailed study of the IBP adsorption mechanism of ZIF-67, molecular dynamic (MD) simulations were performed. Additionally, the reusability of ZIF-67@MWNT-50 mg material via a simple regeneration method up to five cycles while maintaining about 96 % adsorption capacity of the pristine non-used ZIF67@MWNT-50 mg material revealed its importance as an effective adsorbent for the adsorptive elimination of different pharmaceutical hazardous materials from water.