Abstract
Guava leaf, a waste material, was treated and activated to prepare adsorbent. The adsorbent was characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infra Red (FTIR) and Energy-Dispersive X-ray (EDX) techniques. The carbonaceous adsorbent prepared from guava leaf had appreciable carbon content (86.84 %). The adsorption of Congo red dye onto guava leaf-based activated carbon (GLAC) was studied in this research. Experimental data were analyzed by four different model equations: Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms and it was found to fit Freundlich equation most. Adsorption rate constants were determined using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion model equations. The results clearly showed that the adsorption of CR dye onto GLAC followed pseudo-second-order kinetic model. Intraparticle diffusion was involved in the adsorption process. The mean energy of adsorption calculated from D-R isotherm confirmed the involvement of physical adsorption. Thermodynamic parameters were obtained and it was found that the adsorption of CR dye onto GLAC was an exothermic and spontaneous process at the temperatures under investigation. The maximum adsorption of CR dye by GLAC was found to be 47.62 mg/g. The study shows that GLAC is an effective adsorbent for the adsorption of CR dye from aqueous solution.
Highlights
Color is one of the characteristics of an effluent
The results clearly showed that the adsorption of Congo red (CR) dye onto guava leaf-based activated carbon (GLAC) followed pseudo-second-order kinetic model
Thermodynamic parameters were obtained and it was found that the adsorption of CR dye onto GLAC was an exothermic and spontaneous process at the temperatures under investigation
Summary
Wastewater colored with dyes emanating from the production of the dye and its use in the textile and other industries (Allen and Koumanova 2005). Congo red is the sodium salt of benzidinediazobis-1-naphthylamine-4-sulfonic acid It was selected in this study as a model anionic dye due to its high solubility in aqueous solution and its persistence once it is discharged into natural environment. It mainly occurs in the effluents discharged from textile, paper, printing, leather industries, etc. Existing techniques which had been used for removing dyes from wastewater polluted with dyes are disadvantageous due to high cost, the formation of harmful products and consumption of high
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