Study of efficacy of date kernel ash on removal of nitrate from aqueous solutions (isothermic and kinetic study)

In recent decades, the presence of high concentrations of nitrate in drinking water has become a serious concern, which causes some disorders in human health, especially children. Nitrate can be removed by physical-chemical and biological methods. In this study, removal rate of nitrate from aqueous solutions was investigated by date kernel ash. In this experimental study which was conducted in vitro, the effect of initial nitrate concentration (50, 100, and 150 mg/L), initial pH (3, 5, 7, and 9), time (15, 30, 60, 120, and 180 minutes), and weight of adsorbent (0.4, 0.6, and 0.8 g) was investigated. The nitrate concentration was measured using spectrophotometer at two wavelengths 220 and 275 nm. All tests and samples analysis was done per textbooks on standard methods of sewage. The adsorbent dose increase from 0.4 g to 0.8 g in 100 mL nitrate solution with concentrations of 50 and 100 mg/L caused increase in absorption efficiency respectively from 75% to 91% and from 53% to 65%. Increase in solution’s initial pH from 3 to 9 caused decrease in the absorption efficiency from 52% to 8%. The results obtained in this study obey Freundlich isotherm (R2=0.98) and nitrate absorption obeys the pseudo-second order kinetic model (R2=0.999). The palm kernel ash is a natural and inexpensive absorbent that can be used to remove environmental pollutants.