Activated carbon from Cyclamen Persicum Tubers for Diclofenac removal from aqueous solution

The aim of this work was to evaluate the antibacterial activity of the crude methanolic extract obtaining from cyclamen persicum tubers and to re-use the remaining tissues after extraction process to prepare activated carbon by different methods then to set up a thermodynamic and kinetic study of diclofenac sodium (DCF) pharmaceutical adsorption from aqueous solution onto this activated carbon from cyclamen persicum tubers. The prepared activated carbon samples were compared using Surface area determined by iodine number method, scanning electron microphages (SEM) and FTIR analysis. DCF adsorption onto activated carbon was studied by batch experiments. The adsorptive properties of cyclamen tubers activated carbon (CTAC) was investigated and compared with Eucarbon® ; the available charcoal in the market, DCF concentration, pH, temperature and contact time parameters were studied . To investigate the nature of the surface and adsorption capacity of CTAC, Freundlich and Langmuir models were used to study adsorption isotherm at equilibrium. In order to determine whether the adsorption process is chemical or physical, three kinetics models were used. Thermodynamic study was carried out to determine if adsorption of DCF onto CTAC was exothermic or endothermic reaction. Results indicated antibacterial activity of the crude methanolic extract against staphylococcus. aureis gram positive bacterial strain; using (MHA) plate that showed zone of inhibition after overnight incubation at 37 °C, the yield of this extract was 9%(w/w). Results also showed that the activated carbon produced from cyclamen tubers gives highest percentage yield which reaches up to 51.8%, using phosphoric acid as activating agent, while largest Surface area determined by iodine number was 606.78 mg/g using zinc chloride as activating agent, SEM analysis showed that KOH produced the most porous structure in CTAC. Optimum percent of DCF removal was 72% when CTAC dosage was 0.25g and DCF concentration 50mg/L. Percentage removal of DCF increases when the concentration of DCF increases as the maximum percentage removal reached 81% when DCF concentration was 70mg/L and 0.7g CTAC and pH ranging from 6 to 2. The effect of temperature on adsorption by CTAC and Eucarbon® has also been investigated in the range of 15-45 °C. The results indicated that the temperature significantly affected DCF adsorption on both adsorbents. The equilibrium time for DCF adsorption was 120 min for CTAC and 150 min for Eucarbon®, but most of the adsorption attained within the first 15 min using CTAC while 30 min was needed for Eucarbon®. Frenundlich model describe adsorption isotherm of DCF more efficiently onto CTAC with n equal to 1.398 that indicated favorable adsorption. This finding validated the assumption of multilayer physical adsorption process of DCF. Pseudo-second order reaction model is the best for describing adsorption of DCF with correlation coefficient closes to unity, this validated that the adsorption process was physical one, adsorption process was exothermic as ΔS° had negative charge, and also as ΔH° was less than 40 Kj/ mol lthis suggesting a physisorption process. Concerning the change in free energy, the adsorption process of the DCF onto CTAC was spontaneous, depending on temperature.