| Abstrakt: |
The aim of this work was to investigate the capacity of nitric acid modified-H3PO4-activated carbon produced from Gmelina arborea bark in the removal of metanil yellow from aqueous solution. The effects of initial dye concentration, C0, contact time, adsorbent dosage, and initial solution pH on the adsorption capacity qe were studied. Experimental data were analyzed with the Langmuir, Freundlich, Flory-Huggins and Temkin isotherm models. Results show low equilibrium adsorption capacities which decreased with increase in Co. The optimum experimental qe obtained was 2.35 mg/g by Co 25 mg/L. The optimum contact time of 300 min was obtained. Correlation coefficient R2, values (0.861-0.9781) obtained, show that the four applied isotherm models analyzed experimental data well. The optimum pH and adsorbent dosage were 2 and 0.01 g/25 mL solution, respectively. The ΔGads value of -11.248 kJ/mol based on the Flory-Huggins isotherm, and the separation factor, RL values 0.489, 0.332, and 0.199 for Co 25, 50, and 100 mg/L, respectively, show the adsorption to be spontaneous and favourable. The H3PO4-activated carbon was modified with nitric acid, to determine the effect of the modification on the surface area and adsorption capacity. Compared with a similar work with unmodified H3PO4-activated carbon (yet unpublished), there was a decrease in surface area, and qe by 109.59 m2/g and 12.363 mg/g, respectively. These results show that the modification of the activated carbon with nitric acid had a negative effect. [ABSTRACT FROM AUTHOR] |
