Kinetic evaluation of naphthalene onto acid -modified and unmodified bentonite clay mineral was investigated by means of the effects of concentration, contact time and pH. The amount of naphthalene adsorbed was determined spectrophotometrically. The optimum pH value and equilibrium contact time for the adsorption of naphthalene onto acidmodified and unmodified samples were found to be 6.0 and 30 minutes, respectively. The maximum adsorption capacity (q m ) for acid -modified and unmodified

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... bents was found to be 10.52 mg/g and 5.56 mg/g. These values were close with the experimental data (q e ) obtained from the adsorption of naphthalene onto acid -modified (9.0 mg/g) and unmodified (4.0 mg/g) adsorbents. The adsorption isotherm fitted well with Langmuir equation model for the acid -modified than the unmodified adsorbent. Kinetic evaluations of the adsorption showed that the process followed the pseudo -second -order equation model. The results obtained showed that modified bentonite clay mineral was reasonably effective adsorbent for the removal of naphthalene (organic contaminant), which is an important source for environmental pollutant. ©JASEM