氨氮在高岭土上的吸附解吸规律研究

Study on Behaviors of Adsorption and Desorption of Ammonia-nitrogen in Kaolin

治理离子吸附型稀土矿山氨氮污染的首要任务是探清其在矿区土壤中的吸附解吸规律。以化学纯高岭土为吸附剂,硫酸铵为吸附质,研究pH在3、4、5、6条件下氨氮在高岭土表面的等温吸附实验得出,pH越大,氨氮在高岭土表面的单位吸附量越高,其最大吸附量可达9μmol/g;连续提取氨氮解吸实验得到物理吸附态、离子交换吸附态及化学吸附态氨氮最大吸附量分别为0.85μmol/g、3.7μmol/g和3.4μmol/g。根据各吸附态氨氮在黏土矿物表面的吸附解吸规律,在此基础上研究推断,造成离子吸附型稀土矿山氨氮长期性污染的主要氮源是离子交换态氨氮,在原地浸矿结束注完顶水后,再注入高岭土悬浊液,使残留在矿体中的离子交换态氨氮转化成化学吸附态氨氮,则可以很好地治理尾矿山氨氮污染。

The primary task of controlling ammonia nitrogen pollution in ion type rare earth mines is to find out the regularity of adsorption and desorption.Chemical pure kaolin was used as adsorbent and ammonium sulfate was used as adsorbate.The isothermal adsorption experiments of ammonium sulfate on kaolin surface were studied at pH=3,4,5 and 6,the result shows that the larger the pH is,the higher the unit adsorption capacity of ammonia nitrogen on kaolin surface is,and the maximum adsorption capacity can reach 9μmol/g.Through the continuous extraction of ammonia nitrogen desorption experiment,it was found that the maximum adsorption capacity of physically adsorbed ammonia nitrogen is 0.85μmol/g,the ion exchangeable adsorption is 3.7μmol/g,and Chemisorption is 3.4μmol/g,respectively.According to the regularity of adsorption and desorption of the adsorbed ammonia nitrogen on the surface of clay minerals,the ion-exchange ammonia nitrogen is the main source of the long-term pollution of ammonia nitrogen in ion type rare earth mines.After the cleaning water is injected at the end of the in-situ leaching,the kaolin suspension is injected,so that the residual ion-exchange ammonia nitrogen in the ore body can be converted into chemisorption ammonia nitrogen,and the ammonia nitrogen pollution in tailing mines can be well controlled.