Adsorption of nitrate an ion from aqueous solution by natural coal of dedo district, jimma zone, south west Ethiopia

Abstract

Nitrate anion is colorless, odorless and has no taste and is not detectable in drinkingwater without testing. Nitrate is one of the most important pollutants of urban and rural drinking water. Recently, the use of different technologies to remove these contaminants is investigated. In this study,the investigatedperformance of natural coal mineral originated from Jimma zone (Dedo district), as natural, low-cost, alternative and eco-friendly adsorbent forremoval of nitrates ions from aqueous solution within a batch process. The natural coal was characterized byFourier Transform Infrared (FTIR). The effects of variousexperimental parameters were examined such as contact time, pH, temperature, initial concentration of pollutant, andadsorbent mass. The removal of nitrate was 67.36% at natural coal pH 2 using1 g/l of adsorbent in 50 ml of nitrate solution having initial concentration of 1000 mg/L. Adsorption kinetic study revealed that the adsorption process followed second order kinetic. Theoretical correlation of the experimental equilibrium adsorption data for the Nitrate- natural coal system was properly explained by the Langmuir isotherm model. The pH heavily affected the adsorption capacity,and the percentage removal was found to decrease with increase in pH.The negative value of ΔHº and ΔGº indicates that the adsorption process is spontaneous and exothermic in nature. A decrease in randomness is indicated by negative values of entropy change.The obtained results indicated that this natural coal was very good adsorbent for nitrate ion, interesting alternative material with respect to more costly adsorbent used, and could be used as a highly efficient adsorbent for the separation of nitrate from drinking or waste water