Adsorption of Zn, Cd, and Mn ions onto Purified and Functionalized CNTs from Pharmaceutical Wastewater.

Abstract

The continuous discharge of industrial influent into the environment causes harmful effects in the surrounding ecosystem due to the inherent chemicals. This study is focused on the removal of heavy metals from pharmaceutical wastewater using carbon nanotube adsorbent (CNTs). Carbon nanotubes were produced using bimetallic Fe-Co catalyst supported on Kaolin via wet impregnation technique. Carbon nanotubes were synthesized through catalytic chemical vapour deposition and purified with acid treatment to give P-CNTs. The P-CNTs were functionalized with polyethylene glycol to give F-CNTs. The catalyst, P-CNTs and F-CNTs were characterized by Brunner Emmett-Teller (BET), High Resolution Transmission Electron Microscope (HRTEM), and High Resolution Scanning Electron Microscope (HRSEM). Specific Surface area obtained for P-CNTs and F-CNTs were 657.56 and 867.23 m2/g respectively. The HRSEM depicts the cluster nature of the produced CNTs while the HRTEM depicts the internal and external diameter of 21.62 and 43.60 nm respectively. The P-CNTs and F-CNTs adsorbents were used for the removal of heavy metals (Zn, Cd and Mn) from pharmaceuticals wastewater. The influence of contact time, temperature and adsorbent dosage were estimated on the nano-adsorbents. P-CNTs exhibited the most suitable results compared to P-CNTs with optimum conditions of 60 minutes contact time, 0.3 g adsorbent dosage and temperature of 60°Cwith percentage removal of 89.78, 94.65 and 93.32% for Zn, Cd and Mn respectively onto F-CNTs. Freundlich isotherm was more fitted to the adsorption data than the Langmuir isotherm. Pseudo-second order kinetic model best describes the adsorption behavior, and the thermodynamic studies showed the spontaneity and endothermic nature of the process. The stud\ show s that the functionalized carbon nanotubes produced has the affinity to remove Zn, Cd and Mn ions from pharmaceutical wastewater.