Abstract

Surfactant-modified zeolite as a controlled nitrate release mechanism

In nitrate fertilizers used today, much of the nitrate is not absorbed by plants and instead leeches into the environment, causing pollution of groundwater. As such, zeolites were investigated as a method to control the release of nitrate in order to mitigate such pollution. This experiment examined the sorption of nitrate of raw zeolite versus surfactant-modified zeolite (SMZ) in order to determine if SMZs would allow for more control over nitrate release. The SMZs were created by modifying raw zeolite with a cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), in order to increase the sorption of the anionic nitrate. SMZs saw a 43.2 percent increase from 10.8 mmol kg-1 to 15.5 mmol kg-1 in nitrate sorption when modified to 100 percent of their cation exchange capacity (CEC) as compared to raw zeolite. Desorption testing showed the SMZs to have a slower rate of desorption when compared to that of raw zeolite. The increased rate of sorption and the decreased rate of desorption show potential for this method as a technique to control nitrate release and reduce nitrate pollution. Greenhouse testing done using Hoagland’s No.2 Basal Salt Solution over 40 days, as well as with nitrogen free Hoagland’s Solution with added potassium nitrate.