天然斜发沸石的氨氮改性吸附与化学再生

Modification and chemical regeneration of natural clinoptilolite for ammonium nitrogen adsorption

本文采用改性与化学再生方法,探索天然斜发沸石对氨氮吸附的最佳改性及化学再生条件.无机盐改性、热改性、有机改性试验结果表明,最佳改性方法为无机盐NaCl法,改性沸石吸附量较天然沸石提升了近20%,最佳NaCl浓度为1 mol·L^(-1);热改性法不能显著提高沸石的氨氮吸附容量,相反高温会破坏其结构;十二烷基苯磺酸钠改性法可以使改性沸石在其表面形成了新的阳离子吸附点,使其吸附性能提升;而十六烷基三甲基溴化铵改性沸石表面形成的是阴离子吸附点,对带正电的NH_4^+会产生排斥,导致其吸铵性能下降.化学再生试验表明,KCl溶液对铵饱和沸石的再生效果最显著,适宜再生浓度为0.1—0.2 mol·L^(-1).经KCl再生后的沸石再次通过NaCl改性,可延长沸石使用周期以及提高再生沸石的吸附能力.

Modification and chemical regeneration methods were adopted to explore the optimum condition of natural clinoptilolite for ammonium nitrogen adsorption. Salt modification, thermal modification and organic modification results indicated that inorganic salt（ NaCl） solution modification method was the best and the ammonium adsorption capacity increased nearly 20%,with 1 mol·L^（-1）NaCl. Thermal modification method did not improve the ammonia nitrogen adsorption capacity significantly. On the contrary, the structure of clinoptilolite was destroyed by high temperature. When sodium dodecyl benzene sulfonate modification method was used,there were new positive ion adsorption sites on the surface of modified clinoptilolite and its ammonium adsorption capacity increased. However,cetyl trimethyl ammonium bromide modification increased negative ion adsorption sites,which were ammonium repellent,and decreased the ammonium adsorption capacity.Chemical regeneration tests showed that, KCl solution was the best regeneration method of ammonium saturated clinoptilolite,with suitable KCl concentration of 0. 1—0. 2 mol·L^（-1）. KCl modified clinoptilolite which were remodified by NaCl solution might have longer life cycle and higher adsorption capacity than before.