ZnCl2-activated carbon from soybean dregs as a high efficiency adsorbent for cationic dye removal: isotherm, kinetic, and thermodynamic studies.

Activated carbon was prepared from soybean dregs using chemical activation by zinc chloride. The influence of activation parameters such as impregnation ratio, activation temperature and carbonization time was investigated. The physicochemical properties of activated carbon were characterized using SEM, FTIR, BET and TGA, respectively. The effect factors including pH, contact time, temperature and dose on the adsorption properties of methylene blue onto activated carbon were studied. The adsorption equilibrium data of methylene blue onto activated carbon were well fitted to the Langmuir model, giving a maximum adsorption capacity of 255.10 mg/g. It indicates that activated carbon is a promising adsorbent for removing methylene blue from aqueous solution. The kinetic data were well described by the pseudo-second-order model. Thermodynamic parameters indicate that adsorption process is spontaneous and endothermic.The effect of temperature on MB adsorbed by AC shows that the equilibrium adsorption capacity increases with increasing temperature from 303 to 323 K. Increasing adsorption capacities with temperature indicate that the adsorption of MB onto AC is controlled by an endothermic reaction.

Adsorptive Removal of Cationic Dye from Aqueous Solution by Graphene Oxide/Cellulose Acetate Composite.

The application of graphene oxide in water treatment is facing a rigorous challenge of how to separate nanoadsorbents from aqueous solution using conventional methods after adsorption. Herein, a new type of easily separated composite was fabricated using cellulose acetate (CA) crosslinked with graphene oxide (CAGO) and a simple vacuum freeze-drying method. The CAGO composites were subject to SEM, FTIR, TGA, and BET characterizations. The adsorption performance of the adsorbent for the removal of methylene blue (MB) was evaluated through investigating the experimental parameters such as initial dye concentration, temperature, adsorbent dose, contact time, and solution pH. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of methylene blue onto the CAGO-4 composite was 374.53 mg/g at 323 K. The kinetic data showed a good determination with pseudo-second-order equation. Thermodynamic analysis indicated that the adsorption was an endothermic and spontaneous process.