Comparative performance between rice husk and granular activated carbon for the removal of azo tartrazine dye from aqueous solution

In this study, the batch adsorption process was adopted to remediate azo tartrazine dye from an aqueous solution. The commercial granular activated carbon (GAC) adsorbent and rice husk (RH) as natural adsorbents were employed. The effect of the parameters such as pH (2-12), initial dye concentration (5-50 mg L-1), and contact time (10-180 min) was investigated with both adsorbents dose (0.05-0.2 g) of GAC and (0.1-1 g) of RH. The results indicated that the higher removal efficiency was achieved for both adsorbents GAC and RH such as 99.81% with adsorption capacity 3.32 mg g(-1) and 90.45% with an adsorption capacity of 1.24 mg g(-1), respectively. The optimum parameters were obtained for both adsorbents such as pH 2, initial tartrazine concentration 5 mg L-1, contact time 60 min of GAC and 120 min of rice husk, and adsorbent dose 0.1 g of GAC and 0.2 g of RH. The comparison between Langmuir and Freundlich isotherm adsorption models were checked and the data displays that Langmuir isotherm shows a higher correlation coefficient, R-2 (0.99 and 0.98) of RH and GAC respectively. The adsorption kinetics were investigated with pseudo-first-order and pseudo-second-order models and the rates of adsorption were found to confirm the pseudo-second-order kinetics with good correlation R-2 (0.97) of both adsorbents. Thermodynamic results indicating that the adsorption process was an endothermic, spontaneous, and favorable process in nature. The results appeared the removal efficiency of dye by RH was less than those of GAC at the same operating condition.

Automated summary

The study found that both GAC and RH demonstrated high dye removal efficiency and adsorption capacity. The Langmuir isotherm model showed better correlation with the adsorption data, and the pseudo-second-order adsorption kinetics model was confirmed for both adsorbents.