天然沸石吸附氨氮的影响因素

Factors influencing ammonium removal by natural zeolite as adsorbent

对比研究了沸石对生活污水和人工配制氯化铵溶液中氨氮的吸附特性,考察了沸石投加量、反应时间、悬浮物、阳离子和阴离子对沸石吸附氨氮的影响。结果表明,沸石对生活污水中氨氮的吸附能力明显低于人工配制氯化铵溶液,氨氮去除率随着沸石投加量的增加而增加,但单位质量沸石的氨氮吸附量却随之减小,吸附过程呈现快速吸附,缓慢平衡的特点。生活污水中悬浮物的存在,会削减沸石对氨氮的吸附能力。不同类型的阳离子和阴离子的加入都能导致人工配制氯化铵溶液中氨氮在沸石上的吸附量存在差异。阳离子的影响趋势主要为价态的影响,即价态越高,对氨氮吸附阻碍作用越显著,当阳离子当量浓度>2 meq/L时,影响吸附强弱的顺序为Ca2+>Mg2+>Na+;阴离子影响沸石吸附强弱的顺序受初始氨氮的浓度影响较大。Langmuir等温方程式较Freundich、Dubinin Radushkevich、Koble Corrigan和Temkin等温方程式更好地描述沸石吸附氨氮的行为。

The ammonium absorption characteristics of the zeolite were studied in batch experiments with ammonium chloride solution and domestic wastewater. The influences of zeolite dosage, contact time, suspended solid and the presence of other cations and anions on ammonium removal were examined. The results showed that the ammonium adsorption capacity of zeolite per gram in wastewater was lower than that of ammonium chloride so- lution. The ammonium removal rate could be improved with the increase of zeoite dosage while the ammonium adsorption amount of zeolite per gram will be lower. It was also found that the ammonium was absorbed by zeolite was a fast adsorption but a slow equilibrium processed. Addition of different cations and anions in solution led to different adsorption characteristics of ammonium. The valencies of different cations played the dominating role in affecting the adsorption of ammonium on zeolite. The higher the valencies cations, the greater the hindering effect was. When the cation equivalent concentration was more than 2 meq/L, the effect of cations on the removal of ammonium followed the order Ca2＋〉Mg2＋ 〉Na＋, which was also influenced by the ammonium concentration. Equilibrium adsorption of the zeolite for ammonium were found to fit the Langmuir adsorption isotherm better than Freundich, Dubinin Radushkevieh, Koble Corrigan and Temkin adsorption isotherm.