Removal of Reactive Red Dye from Aqueous Solution Using Locally Available Clay Soil As Low Cost Adsorbent
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Date
2015
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Addis Ababa University
Abstract
Textile industry is one of those industries that discharge great amounts of effluents with synthetic
dyes to the environment causing public concern. Reactive dyes are applied in textile industries
which causes severe problem of water pollution and treatment. This study investigates the
potential use of low cost clay soil for the removal of reactive red dye from aqueous solution.
The clay soil washed repeatedly until the dirt was eliminated. Then, it was heated at 105°C for
24hrs and activated with H2SO4 in order to increase adsorption sites. The clay soil was
characterized for its physicochemical properties. The effects of solution pH, adsorbent dose,
initial dye concentration and contact time at room temperature were studied in batch adsorption
experiment. Mechanism of adsorption was studied using isotherm and kinetic models .The
interaction effect of process parameters and optimization were studied using response surface
methodology.
Experimental results have shown that, adsorption capacity was found to increase with higher
initial dye concentration and lower solution pH. Maximum adsorption capacity of reactive red
dye was found at pH 1 and optimum time of 120min. Langmuir, Freundkich, D-R isotherm
models were investigated and the result showed that the adsorption process was most fitted to the
Langmuir isotherm model giving correlation coefficient of 0.985.The calculated adsorption free
energies from the D-R isotherm model 12.9kJ/mol indicated that the Adsorption process
proceeds via chemisorptions. The kinetic study showed that Pseudo second-order model best
described the kinetics of adsorption which confirmed the adsorption process was chemisorptions.
The optimum condition for reactive red dye removal was found at pH 1.5, 40 mg/L of initial dye
concentration 4 g/100 ml of adsorbent dose and contact time of 120 minutes. The results showed
that clay soil has the potential to be applied as adsorbent to remove textile dye from textile
wastewater.
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Keywords
Low Cost Adsorbent