Studies of kinectcis, balance and thermodynamics of diuron adsorption in aqueous solution using granulated Basassu coconout activated charcoal

Resumo

The babassu coconut granular activated charcoal (CAB) in natura was used as adsorbent material to investigate how efficient it was in the removal of the herbicide diuron in aqueous solution. The balance of data were represented by the isotherms, kinetic and thermodynamic parameters of adsorption in duplicate, considering the effect temperature on adsorption in 298, 308 and 318 ± 2 K. The CAB submitted specific area of 517.4 m²·g^-1, with predominantly microporous structure and surface with alkaline trend (pH of zero load of 7.8). The results indicated that the adsorption balance was reached in 300 minutes, getting 34.401 mg·g^-1 of amount adsorbed and removal efficiency of 62.3 %. Kinetic data were best described through pseudo first-order model. The retentions of diuron were favoured with increasing temperature, indicating that this parameter has great importance in adsorption. The balance data were well adjusted to the isothermal model of Langmuir, indicating that the surface of the CAB was completely covered by a monolayer of molecules of diuron in 318 K (56.5 mg·g^-1). The adsorption of diuron in CAB resulted in a spontaneous, endothermic process with increase in the disorder of the system and regulated by physisorption. Results showed efficiency of the CAB as adsorbent in diuron removal from aqueous solution.