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Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer.

Zhou Z, Du C, Li T, Shen Y, Zhou J - Sci Rep (2015)

Bottom Line: Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear.The nutrient-release model of CRF post-treated at 30 °C was the inverse "L" curve, but an increased duration of the post-treatment had no effect.The nutrient-release model was "S" curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.

ABSTRACT
Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the polyacrylate membrane, and hence to analyze the mechanism of nutrient release, Fourier transform mid-infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were employed. The nutrient-release model of CRF post-treated at 30 °C was the inverse "L" curve, but an increased duration of the post-treatment had no effect. The nutrient-release model was "S" curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action. CRF equipped with specified nutrient-release behaviors can be achieved by optimizing the thermal post-treatment parameters, which can contribute to the development and application of waterborne polymer-coated CRF and controlled-release technologies.

No MeSH data available.


Cross-section thickness of the polymer membrane on the CRF post-treated at 30 °C, 60 °C, and 80 °C for 2, 4, 8, 12, and 24 h, factorially.Bars indicate standard error of the mean (n = 5). Treatment details are given in Methods. Values with different lowercase letters are different at a significance level of P < 0.05 for each post-treatment temperature. Values with different uppercase letters are different at a significance level of P < 0.05 for each post-treatment duration. The interaction between post-treatment temperature and duration had no significant effect on membrane cross-section thickness (P = 0.705).
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f4: Cross-section thickness of the polymer membrane on the CRF post-treated at 30 °C, 60 °C, and 80 °C for 2, 4, 8, 12, and 24 h, factorially.Bars indicate standard error of the mean (n = 5). Treatment details are given in Methods. Values with different lowercase letters are different at a significance level of P < 0.05 for each post-treatment temperature. Values with different uppercase letters are different at a significance level of P < 0.05 for each post-treatment duration. The interaction between post-treatment temperature and duration had no significant effect on membrane cross-section thickness (P = 0.705).

Mentions: An electron digital caliper and SEM were employed to reveal the cross-section structure of the coating membrane. Figure 4 shows that using an electron digital caliper, the cross-section thickness of the coating membrane decreased as the post-treatment temperature and duration increased. The CRF post-treatment at 30 °C for 2 h was the thickest (~0.11 mm), whereas that treated at 80 °C for 24 h was the thinnest (~0.07 mm). Using SEM, we examined coating membranes post-treated at 30 °C, 60 °C, and 80 °C for 2 h and 8 h each, to demonstrate cross-section morphological structures (Fig. 5). The membrane cross-section thickness of CRF post-treated at 30 °C was the thickest (~0.085 mm), whereas that at 80 °C for 8 h was the thinnest (~0.055 mm). The trends for the cross-section thicknesses in response to increased post-treatment temperature and duration were similar between the two measurement methods, although the electron digital caliper indicated thicker membranes than those measured using SEM. This might be attributed to inconsistent whole membrane thickness, or fertilizer dust adhering to the membrane. Furthermore, cross-sections of membranes post-treated at 30 °C for 2 h showed the largest number of pores, whereas no observable pores were observed in cross-sections of membranes post-treated at 80 °C. Therefore, the pore size and pore density of the post-treated membranes significantly decreased with an increase in post-treatment temperature and duration, and increased temperature significantly compacted the coating membrane.


Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer.

Zhou Z, Du C, Li T, Shen Y, Zhou J - Sci Rep (2015)

Cross-section thickness of the polymer membrane on the CRF post-treated at 30 °C, 60 °C, and 80 °C for 2, 4, 8, 12, and 24 h, factorially.Bars indicate standard error of the mean (n = 5). Treatment details are given in Methods. Values with different lowercase letters are different at a significance level of P < 0.05 for each post-treatment temperature. Values with different uppercase letters are different at a significance level of P < 0.05 for each post-treatment duration. The interaction between post-treatment temperature and duration had no significant effect on membrane cross-section thickness (P = 0.705).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562308&req=5

f4: Cross-section thickness of the polymer membrane on the CRF post-treated at 30 °C, 60 °C, and 80 °C for 2, 4, 8, 12, and 24 h, factorially.Bars indicate standard error of the mean (n = 5). Treatment details are given in Methods. Values with different lowercase letters are different at a significance level of P < 0.05 for each post-treatment temperature. Values with different uppercase letters are different at a significance level of P < 0.05 for each post-treatment duration. The interaction between post-treatment temperature and duration had no significant effect on membrane cross-section thickness (P = 0.705).
Mentions: An electron digital caliper and SEM were employed to reveal the cross-section structure of the coating membrane. Figure 4 shows that using an electron digital caliper, the cross-section thickness of the coating membrane decreased as the post-treatment temperature and duration increased. The CRF post-treatment at 30 °C for 2 h was the thickest (~0.11 mm), whereas that treated at 80 °C for 24 h was the thinnest (~0.07 mm). Using SEM, we examined coating membranes post-treated at 30 °C, 60 °C, and 80 °C for 2 h and 8 h each, to demonstrate cross-section morphological structures (Fig. 5). The membrane cross-section thickness of CRF post-treated at 30 °C was the thickest (~0.085 mm), whereas that at 80 °C for 8 h was the thinnest (~0.055 mm). The trends for the cross-section thicknesses in response to increased post-treatment temperature and duration were similar between the two measurement methods, although the electron digital caliper indicated thicker membranes than those measured using SEM. This might be attributed to inconsistent whole membrane thickness, or fertilizer dust adhering to the membrane. Furthermore, cross-sections of membranes post-treated at 30 °C for 2 h showed the largest number of pores, whereas no observable pores were observed in cross-sections of membranes post-treated at 80 °C. Therefore, the pore size and pore density of the post-treated membranes significantly decreased with an increase in post-treatment temperature and duration, and increased temperature significantly compacted the coating membrane.

Bottom Line: Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear.The nutrient-release model of CRF post-treated at 30 °C was the inverse "L" curve, but an increased duration of the post-treatment had no effect.The nutrient-release model was "S" curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.

ABSTRACT
Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the polyacrylate membrane, and hence to analyze the mechanism of nutrient release, Fourier transform mid-infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were employed. The nutrient-release model of CRF post-treated at 30 °C was the inverse "L" curve, but an increased duration of the post-treatment had no effect. The nutrient-release model was "S" curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action. CRF equipped with specified nutrient-release behaviors can be achieved by optimizing the thermal post-treatment parameters, which can contribute to the development and application of waterborne polymer-coated CRF and controlled-release technologies.

No MeSH data available.