Abstract
This work investigated the potential of Jujube stone (JS) for the sorption of methylene blue (MB) dye from aqueous solution and examined the effects of the simultaneous association of ultrasound and stirring on the sorption process. Batch sorption studies were conducted to determine the effects of solution pH (3-11), initial dye concentration ( 50-200 mg L-1), sorbent dosage (0.2-0.8 g) and ultrasonic power (0, 30 or 60 W) on the MB uptake at 25 degrees C. The obtained results showed that the biosorption of MB increased with increasing dye concentration and was more favorable at basic pH. Both biosorption capacity and sorption rate were increased when coupling stirring with ultrasonic irradiation. The increase of sorption in the combined method is low for the higher biosorbent dosage, while the improvement is noteworthy for the lower sorbent mass. The biosorption was enhanced both with and without the assistance of ultrasound when the initial dye concentration augmented. The sorption of MB by the JS increased from 35.37 to 58.24 and 71.12 mg g(-1) when the ultrasonic power increased, respectively, from 0 W (stirring alone) to 30 and 60 W (ultrasound + stirring). The biosorption kinetics were analyzed using pseudo-first-order and pseudo-second-order model equations and the sorption data were very well described by the pseudo-second-order model with high determination coefficients and low average percentage errors for all experimented initial dye concentrations and biosorbent dosages. The biosorption capacities of JS were 82.64 and 104.17 mg g(-1) for the classical method and the simultaneous association of ultrasound and stirring, respectively. The results revealed that the JS has the potential to be used as a biosorbent for the removal of MB from aqueous solutions and the simultaneous association of ultrasound and stirring leads to an intensi.cation of the process.