Abstract:
This study aimed to evaluate the efficiency of activated carbon (CAP), prepared from date palm
stem, in removing Congo red (CR) dye from aqueous solutions. To achieve this, a Box-Behnken
design (BBD) was applied to optimize operating conditions and study the effects of three key
factors: sorbent dosage (X1), initial dye concentration (X2), and solution pH (X3). The physicochemical properties of the activated carbon showed a zero-charge (pHPZC) value of
10, and Bohm analysis indicated that the activated carbon surface contained a basic group. Kinetic analysis showed that the pseudo-second-order (PSO) model was the most appropriate for
describing the adsorption process, with a high correlation coefficient (R2 = 0.99). The equilibrium data were applied to the Langmuir and Freundlich models, with the Langmuir
model showing the best fit (R2 > 0.98), indicating monolayer adsorption on a homogeneous
I
surface. The maximum adsorption capacity was found to be 142.85 mg/g. Thermodynamic
parameters indicated that the adsorption process was endothermic.
