Adsorption kinetics of reactive dyes removal from simulated wastewater using sawdust

Abstract

Environmental pollution with associated health problems poses great risks. Effluent with colour are among pollutants which can be removed by adsorption unto natural/synthetic adsorbents. This research studied Adsorption kinetics of reactive dyes removal from simulated wastewater by sawdust. The characterization of the sawdust was done using Fourier Transformed Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD) as well as Scanning Electron Microscopy (SEM). Concentration effect, time and temperature of adsorption were also studied and experimental data subjected to Sorption Kinetics. The FTIR results of unloaded activated and unactivated sawdust showed similar spectra. The XRD results had similar diffraction pattern; however, activated had higher angled diffraction. The SEM of both adsorbents showed rough and vertical groove structure; unactivated had rougher surface, while activated showed more vertical grooves. The concentrations result showed increase in amount of dyes adsorbed as concentration increased for both adsorbents. Increased time increased amount of dyes adsorbed for activated and decreased for unactivated sawdust. The amounts adsorbed were decreased for both as temperature increased. Activation of adsorbent enhanced adsorption of Dylon madona 18 blue and Windsor 15 purple with maximum uptake of 49.85 and 49.7 mg/L respectively, with 49.95 and 49. 94 mg/L for blue and purple respectively. Kinetic models revealed that Pseudo-second order gave better fit for both adsorbents. External diffusion was rate determining step as intraparticle study showed R2values that ranged from 0.617 to 0.703 for blue and purple dyes and 0.797 to 0.004 for blue and purple. The study proved that sawdust was good for reactive dyes removal from wastewater.