硅铝铵离子筛的制备及其对污水中氨氮的脱除性能

通过常温搅拌制备了对污水中NH₄⁺具有高选择性去除的硅铝型弱晶态铵离子筛，其平均孔径介于2倍水合Ca²⁺直径和2倍水合Na⁺直径之间。结果表明，铵离子筛对NH₄⁺具有优良的吸附选择性和可再生性，吸附容量可达到25 mg·g⁻¹。受Na(AlO₄)双位点吸附规则制约，铵离子筛对Ca²⁺、Mg²⁺具有优良的筛截效果，市政污水中质量浓度为70 mg·L⁻¹的Ca²⁺ 不影响铵离子筛对NH₄⁺的吸附性能Na(AlO)。吸附饱和的铵离子筛经0.5 mol·L⁻¹ NaCl溶液多次洗脱和再生之后，仍能将污水中的氨氮质量浓度由40 mg·L⁻¹快速降至1 mg·L⁻¹以下。本研究可为高效去除污水中的氨氮提供一种简单、高效的方法。

Preparation of silicon-aluminum ammonium ion sieve and its performance on ammonia nitrogen removal from domestic wastewater

A silicon-aluminium weakly crystalline ammonium ion sieve was prepared through stirring at normal atmospheric temperature for highly selective extraction of ammonium ions from sewage. The average pore size of the sieve is 1.64 nm diameter, which is between 2 times the diameter of hydrated calcium ion (1.648 nm) and 2 times the diameter of hydrated sodium ion (1.432 nm). The results of simulated and real sewage treatment show that the prepared ammonium ion sieve had an excellent retention of NH4+ against Ca2+, Mg2+, Na+ and K+ ions. The adsorption capacity of NH4+ could reach 25 mg·g−1 and was not affected by Ca2+ up to 70 mg·L−1, which was likely due to the effect of dual-site adsorption of the Na(AlO4) domains. After the used ammonium ion sieve was eluted and regenerated for several times with 0.5 mol·L−1 NaCl solution, it still could lead to the rapid decrease of NH4+ concentration in sewage from 40 mg·L−1 to below 1 mg·L−1 by the regenerated sieves. This study provides a simple and efficient method for separating and extracting green ammonia from sewage.