Adsorption of Zn, Cd and Mn Ions onto Purified and Functionalized CNTs from pharmaceutical wastewater

Abstract

The continuous discharge of industrial effluent 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 a 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 purified 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 Microscopy (HRSEM). Specific surface area obtained for P-CNTs and F-CNTs were 657.56 and 867.23 m-/g respectively. The HRSEM depicts the cluster nature of the produced CNTs while the HRTEM depicts the intermal and external diameter of 21.62 and 43.o0 nm respectively. The P-CNTs and F-CNTs adsorbents were used for the removal of heavy metals (Zn, Cd and Mn) from pharmaceutical wastewater. The influence of contact time, temperature and adsorbent dosage were investigated on the nano-adsorbents. F-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 oC with percentage removal 89.78, 94.65 and 93.32 % for Zn, Cd and Mn respectively on to F-CNIs. Freundlich 1sotherm 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 reaction process. The study shows that the functionalized carbon nanotubes produced has the affinity to remove Zn, Cd and Mn ions from pharmaceutical wastewater.