Self-improvement Value of Monoammonium Phosphate by Complexation Effect of β-Cyclodextrin in Soil
2015
Liao, Wenju | Tang, Dehua | Huang, Xing | Wang, Hongjuan | Dang, Xinghu
Unlike traditional phosphorus fertilizers, a new fertilization concept which is based on the complexation effect of β-cyclodextrin (β-CD) has been developed in this paper. For this purpose, the UV–vis absorption spectrum was applied to study the inclusion behavior of monoammonium phosphate (MAP) with β-CD. The results revealed that MAP with β-CD can form a 1:1 stoichiometry inclusion compound; the applicable inclusion time was 10 h, and the formation process of the inclusion compound was an exothermic process. The 1:1 β-CD-MAP inclusion compound was further characterized by FT-IR, ¹H NMR, and ³¹P NMR. The adsorption–desorption processes of MAP without and with β-CD in the soil solution was studied. It was found that the Kf value of MAP with β-CD was 3.293 and was lower than the Kf value of MAP without β-CD; the n value of MAP with β-CD was 0.8050 and was higher than the n value of MAP without β-CD. Furthermore, the total percentages of MAP desorbed (η) at the different employed MAP initial concentrations in the presence of β-CD were 9.3%, 15.7%, and 18.6%, and were higher than the η in the absence of β-CD, respectively. The results showed that the effectiveness of MAP has been improved in soil and the presence of β-CD can play an important role in the adsorption of MAP on soil surfaces. In addition, the morphologies of soil particles in the presence of MAP and the β-CD-MAP inclusion compound were observed by SEM. SEM observations revealed that the β-CD-MAP inclusion compound fertilizer system could over soil hardening.
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