沸石的活化及其对水中氨氮的吸附

Zeolite activation and ammonia-nitrogen removal from wastewater by adsorption on activated zeolite

对天然沸石进行了盐活化、盐加酸活化、盐加碱活化、热活化和热活化后加盐二次活化的处理,分别考察了活化后沸石对氨氮的吸附性能,并进行了等温吸附、解吸试验以及对经SBR-氧化处理后焦化废水的吸附试验.结果表明,沸石在100℃下经0.3mol·L-1NaCl活化后,对氨氮的吸附效果最佳;当活化沸石投加量为10g·L-1、接触时间为40min时,氨氮去除率可达88.08%,比未活化条件下的47.35%提高了40.73%.沸石投加量、废水的pH和接触时间对活化沸石吸附氨氮都存在一定的影响.活化沸石对氨氮废水的吸附等温线可用Freundlich方程拟合.吸附氨氮后的沸石经1.5mol·L-1的NaCl溶液再生4h,解吸率可达到89.30%.活化沸石用于经SBR-氧化处理后焦化废水的吸附试验,当活化沸石投加量为120g·L-1时,其氨氮可从219.18mg.L-1降到4.8mg·L-1,去除率达到97.81%;活化沸石吸附焦化废水的吸附等温线可用Freundlich方程和Langmuir方程来描述.

The ammonia-nitrogen adsorption capacity of natural zeolite was evaluated after activation by salt, salt plus acid, salt plus alkali, heat, and heat activation followed by salt modification. The adsorption and desorption isotherms were examined. The activated zeolite was also used to adsorb ammonia-nitrogen from coal-coking wastewater pretreated by SBR-oxidation. The results show that the removal of NH4^＋ -N by activated zeolite was the highest after activation in 0.3 mol· L^-1 NaCI solution at 100℃. When the zeolite dosage was 10 g· L^-1 and the contact time was 40 min, the NH1^＋ -N removal rate reached 88.08%, 40.73% higher than that （47. 35% ） of non-activated zeolite. The removal rate is dependent on zeolite dosage, wastewater pH and contact time. The adsorption isotherm curve of ammonia-nitrogen on salt-activated zeolite was well described by the Freundlich function. After the zeolite was regenerated by soaking in 1.5 mol· L ^-1 NaCl solution for 4 h, the efficiency of desorption of ammonia-nitrogen reached 89.30%. When 120 g· L ^- 1 of the best modified zeolite was used to adsorb ammonia-nitrogen from coal coking wastewater pretreated by SBR-oxidation, the NH4^＋ -N concentration dropped from 219.18 mg·L^- 1 to 4.8 mg. L^- 1, a removal rate of 97.81%. The adsorption isotherm of zeolite reaction with coking wastewater can be described by both the Freundlich and Langmuir functions.