Adsorption of 4-chloro-2-nitrophenol from aqueous solutions by carbon nanofibers

Phenolic derivatives, such as a number of chloro- and nitrophenols, are toxic and carcinogenic [1]. Chronic toxic effects due to phenols reported in humans include vomiting, difficulty in swallowing, anorexia, liver and kidney damage, headache, fainting and other mental disturbances [2]. 4-Chloro-2-nitrophenol (4C2NP), which was chosen as the model compound in the present study, is recalcitrant and persistent towards biodegradation and is constituent intermediate of many industrial effluents [3]. Adsorption capacity of 4C2NP from aqueous solutions using carbon nanofibers (CNFs) was investigated in a batch system by considering the effects of various parameters like contact time, adsorbent dosage, pH and initial concentration. Optimum conditions for 4C2NP adsorption were found to be initial pH≈6.04, nanofiber CNFs dose≈ 0.01 g and equilibrium time≈ 20 min. Results showed that the removal efficiency of 4C2NP increased by increasing 4C2NP concentration and temperature and decreased by increasing the dosage of CNFs and pH. Based on correlation coefficients, Langmuir gave the poorest fit for 4C2NP adsorption onto CNFs. The kinetic studies indicate the adsorption of 4C2NP onto CNFs is followed a pseudo- second order kinetic model.