Rapid removal of ammonia nitrogen in low-concentration from wastewater by amorphous sodium titanate nano-particles

An amorphous sodium titanate (ST) nano-particle was prepared via the facile hydrolytic process with the addition of sodium hydroxide and firstly used for ammonia nitrogen (NH ₃ -N) removal from wastewater. ST exhibited satisfactory adsorption efficiency for NH ₃ -N simulative wastewater (20 mg·L ⁻¹ ) at a wide range of pH 3.0–9.0, within a minimum contact time of 10 min. The Langmuir isotherm showed that the maximum adsorption capacity (298 K) of the adsorbent was reach up to 44.54 mg·g ⁻¹ . Concentrated competing cations had some interferences with NH ₃ -N adsorption at the order of Ca ²⁺ > K ⁺ > Mg ²⁺ > Na ⁺ according to their competition on adsorption sites. During the adsorption process, cation exchange between Na ⁺ and NH ₄ ⁺ played a powerful role for the NH ₃ -N removal and the contribution of Ti-OH groups was also involved in the adsorption. The regeneration test showed that the saturated adsorbents could be conveniently regenerated just by NaOH or NaCl solution treatment and there was no obvious decline of the adsorption capacity after reused for five times. The facile method of fabrication and regeneration, the rapid adsorption process and the satisfactory adsorption efficiency make sodium titanate a promising adsorbent for low concentration NH ₃ -N minimization.