Understanding the Mobilization of a Nitrification Inhibitor from Novel Slow Release Pellets, Fabricated through Extrusion Processing with PHBV Biopolymer

Levett, Ian; Pratt, Steven; Donose, Bogdan C.; Brackin, Richard; Pratt, Chris; Redding, Matthew; Laycock, Bronwyn

doi:10.1021/acs.jafc.8b05709

Cited by 21 publications

(34 citation statements)

References 46 publications

(73 reference statements)

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“…One approach to achieve this is through slow release formations, where the NI is protected from degradation within a polymer matrix and gradually mobilizes into the soil profile 10–13 . The present study builds on our previous work, 13 where DCD was extruded as a composite material within a biodegradable polymer matrix, namely poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyvalerate) (PHBV).…”

Section: Introductionmentioning

confidence: 99%

Designing for effective controlled release in agricultural products: new insights into the complex nature of the polymer–active agent relationship and implications for use

et al. 2020

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BACKGROUND Various active chemical agents, such as soil microbial inhibitors, are commonly applied to agricultural landscapes to optimize plant yields or minimize unwanted chemical transformations. Dicyandiamide (DCD) is a common nitrification inhibitor. However, it rapidly decomposes under warm and wet conditions, losing effectiveness in the process. Blending DCD with an encapsulating polymer matrix could help overcome this challenge and slow its release. Here, we encapsulated DCD in a biodegradable matrix of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and investigated the effects of DCD crystal size and loading rates on release rates. RESULTS Three DCD crystal size fractions (0–106, 106–250 and 250–420 μm) were blended with PHBV at 200, 400, 600 and 800 gkg−1 loadings through extrusion processing and release kinetics were studied in water over 8 weeks. For loadings ≥ 600 g kg−1, more than 95% release was reached within the first 7 days. By contrast, at 200 g kg−1 loading only 10%, 36% and 57% of the DCD was mobilized after 8 weeks in water for 0 to 106 μm, 106 to 250 μm and 250 to 420 μm crystal size fractions, respectively. CONCLUSION The lower percolation threshold for this combination of materials lies between 200 and 400 g kg−1 DCD loading. The grind size fraction of DCD significantly affects the quantity of burst release from the surface of the pellet, particularly below the lower percolation threshold. The results presented here are likely translatable to the encapsulation and release of other crystalline materials from hydrophobic polymer matrices used in controlled release formulations, such as fertilizers, herbicides and pesticides. © 2020 Society of Chemical Industry

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Section: Introductionmentioning

confidence: 99%

Designing for effective controlled release in agricultural products: new insights into the complex nature of the polymer–active agent relationship and implications for use

et al. 2020

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“…The research of Ian et al (2019) revealed that the release of DCD from DCD-PHBV pellets in sand and clay soil was driven by water [59] . Therefore, it is useful for us to understand the basic release mechanism of DCD in soil by conducting the water release experiment at the first step.…”

Section: Release Of Dcd Into Watermentioning

confidence: 99%

“…(2) Read the plate at 230 nm (peak DCD absorbance [59,60] ) using a Biotek Powerwave XS plate reader.…”

Section: Release Of Dcd Into Watermentioning

confidence: 99%

“…The University of Queensland The predicted constants for the three models are shown in Table 3-4, and the predicted DCD release profiles are shown in Figure 3-9. (1) Washing out of DCD crystals on surface of pellets [59] ;…”

Section: Mathematical Modelling Of Dcd Release Profiles From Dcd-phbvmentioning

confidence: 99%

“…(2) Permeation of water through the channels, pores and voids created into the matrix as DCD dissolves [38,59] ;…”

Section: Mathematical Modelling Of Dcd Release Profiles From Dcd-phbvmentioning

confidence: 99%

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Tailoring the release of DCD from biopolymer matrices: The effect of DCD crystal size, loading, blends of PHBV and PCL and temperature on DCD release kinetic

Liao¹

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To increase the efficiency of nitrogen fertilizers, stabilized fertilizers have been developed by the fertilizer industry. These stabilized fertilizers can slow down the nitrification of ammonium using nitrification inhibitors (NI). Dicyandiamide (DCD) is a commonly used NI used in agriculture today, but its lifetime in soil exponentially declines with increasing temperature. Controlled-release of DCD can protect the molecule from bacterial degradation and prolong the duration of inhibition. This can be achieved by encapsulating it in a biodegradable polymer matrix. Biopolymer matrices include poly(3-hydroxybutyrate-co-3hydroxyvalerate) (PHBV) and polycaprolactone (PCL). In this research, DCD-PHBV pellets with DCD crystal sizes of 0-106 μm, 106-250 μm, >250 μm at DCD loadings of 20% (w/w), 40%, and 60% were produced by extrusion processing. In addition, an 80% loading with 0-106 μm DCD was fabricated. Further, 0-106 μm DCD was extruded at 40% loading with PHBV, PCL and 3:1, 1:1 and 1:3 PHBV/PCL blends. The release kinetics of DCD from these materials was monitored in water over eight weeks. Firstly, the effect of loading and DCD crystal size was investigated at 23℃. Following this, the effect of blends of PHBV and PCL were studied at 10℃, 23℃ and 40℃. The pellets were characterized using micro-computed tomography (µ-CT), Raman spectroscopy mapping and differential scanning calorimetry (DSC). The water release experiments confirm that the release profiles of DCD can be tailored by controlling the DCD loading, DCD crystal grind size, and the compositions of PHBV/PCL blends for specific applications and climatic conditions. Increasing loading increased the amount and rate of DCD release of DCD-PHBV pellets. This is due to a higher degree of connected channels to the outside, confirmed by the µ-CT results. For DCD-PHBV/PCL pellets, it is likely molten PCL filled the in voids/cracks forming in the PHBV matrix during production, which resulted in a diffusion controlled release mechanism. This is supported by Raman mapping and DSC results. The release profiles of DCD from DCD-PHBV pellets were modelled using a power law for the initial surface wash (0-5 h), modified first order model for II release via connected pathways (5 h-21 d) and a linear regression for the slow diffusion controlled release (21 d-56 d), based on which we predicted the release profile of DCD-PHBV pellets with other loadings. Our research indicated that DCD-loaded PHBV/PCL pellets is a practicable delivery system for the controlled release of DCD.

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Release Kinetics of Potassium, Calcium, and Iron Cations from Carboxymethyl Cellulose Hydrogels at Different pH Values

Qu,

Haverkamp,

Jin

et al. 2023

ChemPlusChem

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In an in‐depth study of the mechanism of cation release from carboxymethyl cellulose hydrogels synthesized through Schiff base reaction, we analyze the differences in the release kinetics of potassium, calcium, and iron cations with Peleg model at pH values of pH 3.5 and pH 8.5 using ICP‐OES (inductively coupled plasma optical emission spectroscopy) technique. It is confirmed that the higher valence and alkaline condition favors slow cation release compared to acidic condition. Regardless of the pH value, the correlation length of the hydrogel determined by SAXS method (small‐angle X‐ray scattering) has a decisive influence on the cation release rates, which becomes larger as the correlation length increases.

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Understanding the Mobilization of a Nitrification Inhibitor from Novel Slow Release Pellets, Fabricated through Extrusion Processing with PHBV Biopolymer

Cited by 21 publications

References 46 publications

Designing for effective controlled release in agricultural products: new insights into the complex nature of the polymer–active agent relationship and implications for use

Designing for effective controlled release in agricultural products: new insights into the complex nature of the polymer–active agent relationship and implications for use

Tailoring the release of DCD from biopolymer matrices: The effect of DCD crystal size, loading, blends of PHBV and PCL and temperature on DCD release kinetic

Release Kinetics of Potassium, Calcium, and Iron Cations from Carboxymethyl Cellulose Hydrogels at Different pH Values

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