Effectiveness and mechanisms of the adsorption of carbendazim from wastewater onto commercial activated carbon.

Abstract

The wide application of fungicides is becoming one of the main causes of water pollution. Activated carbon (AC) is a frequently-used adsorbent in water treatment. In this work, aiming to obtain a better understanding of fungicides on AC, carbendazim was selected as a model fungicide in water. The effects of AC dosage, adsorption temperature, adsorption time and pH value of solution on carbendazim adsorption by AC were investigated. When the initial concentration of carbendazim was 500mgL-1 and the volume of wastewater was 25mL, the optimum dosage of AC and reaction time was determined to be 0.3g and 150min, respectively. The pH ranging from 3.0 to 10.0 exhibited little effect on the adsorption capability of AC. The higher the adsorption temperature was, the better adsorption capacity was. Adsorption capacity could reach 32.31mgg-1 under the optimal adsorption conditions. The kinetics study reveals that the adsorption of carbendazim occurred on the surface of adsorbent during initial stage. The adsorption data was well fitted by Langmuir adsorption isotherm, indicating that the adsorption process was monolayer adsorption. The thermodynamic experiments confirmed that the adsorption of carbendazim was an endothermic process with the coexistence of physical and chemical adsorption. Because the main components of AC used in this research work is amorphous carbon with low impurity and its surface has not been modified with additional functional groups, the conclusion of the study was easy to be replicated by repeated experiments. Therefore, the findings of this study could guide the adsorption of carbendazim onto the other kinds of AC with high specific surface area, and provide useful information for application of commercial AC in treatment of fungicides wastewater.