Abstract
Water hyacinth is an abundant bio-resource considered by many to be an environmental nuisance. It is found in almost all the creeks and waterways in the Niger Delta region of Nigeria known for its oil exploration activities and also in many other parts of the country. This work examines the preparation of activated carbon from water hyacinth by chemical activation using ammonium chloride at 400 o C at a heating rate of 10 o C /minute and a dwell time of 1hour thereby giving the plant an economic value. The adsorption equilibrium and kinetics of 2-nitrophenol on the water hyacinth activated carbon prepared was then carried out at 28 o C under varying experimental conditions of contact time, concentration and adsorbent dosage. The equilibrium data were fitted into the Freundlich and Langmuir adsorption isotherm model and two simplified kinetic models pseudo first order and pseudo –second order equations were applied to examine the kinetics of adsorption. The results showed that the equilibrium data fitted well into the Langmuir adsorption isotherm and the kinetics data fitted more into the pseudo –second order kinetic model. The equilibrium data were also examined using intra-particle diffusion model and it was observed that the rate of adsorption of 2-nitrophenol unto WHAC from aqueous solution is particle diffusion controlled, its diffusivity is independent of the extent of diffusion and the rate of adsorption is a function of initial concentration.
Highlights
Nitrophenols are important and versatile organic compounds in industrial, agricultural and defense applications
The equilibrium data were examined using intra-particle diffusion model and it was observed that the rate of adsorption of 2-nitrophenol unto water hyacinth activated carbon (WHAC) from aqueous solution is particle diffusion controlled, its diffusivity is independent of the extent of diffusion and the rate of adsorption is a function of initial concentration
This study investigated the adsorption of 2-nitrophenol in aqueous solution onto water hyacinth activated carbon
Summary
Nitrophenols are important and versatile organic compounds in industrial, agricultural and defense applications. They are frequently used as intermediates in the manufacture of explosives, pharmaceuticals, pesticides, pigments, dyes, rubber chemicals and so on (Uberoi & Bhattacharya, 1997). They are produced by microbial hydrolysis of several organophosphorous pesticides, such as parathion (Sethunathan, 1973; Nelson, 1982) or by photodegradation of pesticides that contain the nitrophenol moiety (Haghighi-Podeh, Bhattacharya & Qu 1995; USEPA, 1980). Nitrophenol has been detected in effluents from photographic and electronics industries (Bursey & Pellizzari, 1982) and effluents from other chemical plants, both 2-nitrophenol and 4-nitrophenol were detected in the final effluent from the wastewater of a petroleum refining industry (Snider and Manning, 1982)
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