ADSORPTION OF MALACHITE GREEN FROM AQUEOUS DYE SOLUTION USING WATERLEAF AND AMARANTHUS LEAF DERIVED CARBON ADSORBENTS

Abstract

The derivation of activated carbon from calcium hydroxide (Ca(OH)2)treated and untreated waterleaf(Talinumtriangulare) and amaranthus(Amanranthushybridus)was carried out. The potential of these adsorbents in the removal of malachite green (MG) dye from aqueous solution was reported in this study. Untreated waterleaf carbon, treated waterleaf carbon, untreated amaranthus carbon, treated amaranthus carbon and commercial activated carbon (UWC, TWC, UAC, TAC and CAC) were characterized using Fourier transformed infrared (FTIR) and scanning electron microscopy (SEM) instrumental methods of analyses. The results showed changes in spectra peaks and microstructure images after adsorption. Various experimental variables such as adsorption dosage, contact time and temperature were studied using batch technique. Percentage MG dye removed from aqueous solution increased as time of adsorption increased from 15 to 90 minutes. Quantity of MG dye removed also increased as adsorbent dosage increased from 0.02 to 0.1 g. Increase in temperature enhanced the removal efficiency of the adsorbents. The adsorption isotherm models used were Langmuir, Freundlich and Elovich. Langmuir and Elovich model were found to have the correlation coefficient value in good agreement for all the adsorbents (UWC, UAC, TWC, TAC and CAC). Freundlich best describe TWC, TAC and CAC. The pseudo-first-order, pseudo-second-order, intra-particle diffusionand Elovichkinetic models were used as kinetic models to test the experimental data. The pseudo-second-order exhibited the best fit for the kinetic studies. Thermodynamic studies for the adsorption of MG on all the samples were found to be spontaneous and endothermic in nature.