Development of MWCNTs/TiO2 nanoadsorbent for simultaneous removal of phenol and cyanide from refinery wastewater

Abstract

The continuous discharge of untreated refinery wastewater containing pollutants into the water bodies have raised enormous concern on the safety of human, aquatic species and therefore calls for concerted efforts towards developing effective and sustainable treatment method. This study focused on the development of MWCNTs/TiO2 nanoadsorbent for the removal of phenol and cyanide from refinery wastewater. MWCNTs was prepared via cracking of acetylene gas on nickel ferrites nanoparticles in a long tubular reactor. The MWCNTs and MWCNTs/TiO2 nanoadsorbent were characterized for surface properties. HR-SEM and HR-TEM results revealed successive dispersion of TiO2 on the pores of MWCNTs with average crystallite size of 37.32 nm and surface area of 360.66 m2/g. The batch adsorption process revealed maximum removal of cyanide and phenol onto MWCNTs/TiO2 adsorbent at 70 min, 0.3 g and 40 °C contact time, adsorbent dosage and temperature respectively. The experimental data were better described by Freundlich Isotherm and Pseudo second order kinetic model, an indication of multilayer adsorption. The values of the free energy change, (ΔG) were negatives which suggested the existence of strong bond formation between the adsorbates and the adsorbents. The study demonstrated that the developed MWCNTs/TiO2nanoadsorbent is an excellent material for the sequestration of phenol and cyanide from refinery wastewater.