Adsorptive Removal of Methylene Blue onto ZnCl2 Activated Carbon from Wood Apple Outer Shell: Kinetics and Equilibrium Studies

Methylene blue dye removal from aqueous solution was investigated using ZnCl2 activated carbon prepared from wood apple outer shell (Limonia acidissima, biomass waste). Influence of agitation time, adsorbent dose, dye concentration, pH and temperature were explored. Two theoretical adsorption isotherms namely Langmuir and Freundlich were used to describe the experimental results. The Langmuir adsorption capacity (Qo) was found to be 35.1 mg/g and the equilibrium parameter (RL) values indicate favourable adsorption. The experimental data were well fitted with Langmuir isotherm model and pseudo second order kinetic model. Desorption studies showed that ion exchange mechanism might be involved in the adsorption process

Kinetic modeling of liquid-phase adsorption of Congo red dyeusing guava leaf-based activated carbon

Guava leaf, a waste material, was treated andactivated to prepare adsorbent. The adsorbent was char-acterized using Scanning Electron Microscopy (SEM),Fourier Transform Infra Red (FTIR) and Energy-Disper-sive X-ray (EDX) techniques. The carbonaceous adsorbentprepared from guava leaf had appreciable carbon content(86.84 %). The adsorption of Congo red dye onto guavaleaf-based activated carbon (GLAC) was studied in thisresearch. Experimental data were analyzed by four differ-ent model equations: Langmuir, Freundlich, Temkin andDubinin–Radushkevich isotherms and it was found to fitFreundlich equation most. Adsorption rate constants weredetermined using pseudo-first-order, pseudo-second-order,Elovich and intraparticle diffusion model equations. Theresults clearly showed that the adsorption of CR dye ontoGLAC followed pseudo-second-order kinetic model.Intraparticle diffusion was involved in the adsorption pro-cess. The mean energy of adsorption calculated from D-Risotherm confirmed the involvement of physical adsorp-tion. Thermodynamic parameters were obtained and it wasfound that the adsorption of CR dye onto GLAC was anexothermic and spontaneous process at the temperaturesunder investigation. The maximum adsorption of CR dyeby GLAC was found to be 47.62 mg/g. The study showsthat GLAC is an effective adsorbent for the adsorption ofCR dye from aqueous solution