4A沸石分子筛对KNO_3和NH_4NO_3的吸持作用

实验研究了4A沸石分子筛经熔融盐处理后对KNO3和NH4NO3的吸持作用。结果表明:在实验条件下,KNO3处理后的4A沸石中含钾(以K2O计)15.01%,含NO3-9.23%;NH4NO3处理后的4A沸石中含NO3-10.78%,含NH4+0.94%。熔融盐处理后的样品X射线衍射峰相对强度发生了变化,红外光谱中1 640 cm-1附近水的吸收带强度减弱,1 390 cm-1附近出现的NO3-离子的强吸收带及825 cm-1附近出现的NO3-离子的弱吸收带,以及热重—差热曲线中KNO3和NH4NO3的热失重和分解热效应均证明沸石中吸持盐的存在。处理后4A沸石分子筛的基本骨架结构没有被破坏,吸持盐的4A沸石对营养盐的储备大大提高,是潜在的缓释肥料。

Occlusion of KNO3 and NH4NO3 in 4A Zeolite Molecular Sieve

The capacity of synthetic 4A zeolite molecular sieve treated with molten salts to occlude ammonium nitrate and potassium nitrate has been determined,and the salt-occluded zeolite 4A has been characterized with XRD,IR and TG-DTA methods.In a laboratory setting,the KNO_(3)-treated zeolite 4A contained 15.01% of K(calculated as K_(2)O)and 9.23% of NO~-_(3),and the NH_(4)NO_(3)-treated zeolite 4A contained 10.78% of NO~-_(3)and 0.94% of NH~ _(4).Molten salt treatment resulted in changes of overall and relative intensities of peaks in X-ray diffractograms of zeolite 4A.The presence of occluded salts in zeolite 4A was confirmed by a decrease of water IR absorption band intensities around 1,640 cm~(-1),which was expected with salt occlusion,and two absorption bands,strong around 1,390 cm~(-1) and weak around 825 cm~(-1),which are identified as V3 and V2 modes of nitrate ions,and weight losses and sequential endo-and exothermal responses of KNO_(3) and NH_(4)NO_(3) in TG-DTA curves.Occlusion of molten salts in zeolite 4A had little or no effects on its framework.This study shows that the capacity of 4A zeolite molecular sieve to store nutrients can be greatly increased by salt occlusion and the salt-occluded zeolite 4A is a potential candidate as slow-release fertilizer.