Equilibrium and Kinetic Studies on the Biosorption of 2-chlorophenol and 4-chlorophenol by Live Aspergillus niger

Abstract

In this study the potential of the live fungus Aspergillus niger (A. niger) to remove 2-chlorophenol (2-CPh) and 4-chlorophenol (4-CPh) was evaluated. The biosorption properties are affected by the treatment conditions, such as initial pH, contact time, initial chlorophenol concentration, biomass concentration, and temperature. The optimal pH value for 2-CPh and 4-CPh biosorption by the live A. niger was found to be a natural pH of 5.1. The biosorption of 2-CPh reached equilibrium in 48 h, whereas, the equilibrium for 4-CPh was reached in 96 h. From the sorption studies it was observed that the uptake of 2-CPh was higher than 4-CPh. The sorption isotherms of 2-chlorophenol and 4-chlorophenol were modeled according to the Langmuir and Freundlich equations. The equilibrium data fit well with the Langmuir isotherm model for 2-CPh and 4-CPh. The rates of biosorption were found to obey the rules of the intra-particle diffusion model with good correlation for especially 4-CPh. When the initial 2-CPh concentration was increased from 50 mg/L to 690 mg/L, the biosorption capacity of A. niger increased from 4.81 mg/g to 38.80 mg/g. However, the maximum 4-CPh biosorption capacity was obtained as 12.26 mg/g for 260.8 mg/L initial 4-CPh concentrations at pH 5.1 and 28 degrees C. This research showed that fungal biosorption has a potential to be used in the removal of 2-CPh and 4-CPh from wastewaters.