Sorption and thermodynamic study of nitrate removal by using Amberlite IRA 900 (AI900) resin

This paper presents the efficiency removal and thermodynamics studies of nitrates by using ion exchange resin, Amberlite IRA 900-Cl (AI900). The effect of experimental factors of contact time resin (1–6 h), resin dosage resin (1–6 g), initial concentration of nitrate influent in the range between 20 and 250 mg/L and temperature between 25 and 65 °C were studied by using a batch sorption method. From the overall study, the data clearly demonstrated that the optimum temperature for the nitrate ions were removed was at 25℃ as the sorption of nitrate decreased when the temperature increased. The sorption managed to obtain 85% removal of nitrates from bulk concentration by using 2 g of AI900 resin in 1-hour contact time. While increasing the contact time of resin until 6 h in 1 g resin and increasing the amount of resin to 6 g of AI900 resin in 1-hour contact time, the adsorption capacity managed to rise at 98 and 97%, respectively. AI900 resin demonstrated an exothermic and spontaneous process of nitrate removal at the varied temperatures as both enthalpy (ΔH°) and entropy (ΔS°) showed negative signs at −26.801 kJ/mol and −43 J/K∙mol respectively. The sorption was feasible and favored at low temperature as the Gibb energy (ΔG°) showed negative sign and decreased with the increasing temperature