Zinc micronutrient-loaded carboxymethyl tamarind kernel gum-based superabsorbent hydrogels: controlled release and kinetics studies for agricultural applications

To alleviate the adverse effects of pesticide residues on the environment, development of a more safe, economical, and reliable usage approach of pesticides is critically urgent. In the present study, a novel pesticide carrier LA-NSM (lauric acid-modified Nitraria seed meal) with controlled release property was prepared through grafting esterification of lauric acid onto Nitraria seed meal substrates. The structure of the obtained samples was characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and contact angle measurements. The results indicated that LA-NSM products had a well-defined hydrophobic surface and irregular holes for efficient loading of pesticide molecules. Deltamethrin (DEL), a representative insoluble pyrethroid insecticide in water, was deliberately selected as the index pesticide to evaluate the loading and releasing efficiency of LA-NSM. The loading capacity of LA-NSM for DEL can reach about 1068 mg/g. pH, humidity of soil, and temperature had a significant influence on controlled release performance of LA-NSM@DEL. Moreover, the releasing kinetics of LA-NSM@DEL composites could be fitted well with the Higuchi model. Overall, the highly hydrophobic property, excellent loading, and controlled release ability of LA-NSM made it a promising candidate in agricultural applications.

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Superabsorbent hydrogels as carriers for the controlled-release of urea: Experiments and a mathematical model describing the release rate

Biosystems Engineering ◽

10.1016/j.biosystemseng.2008.09.027 ◽

2009 ◽

Vol 102 (1) ◽

pp. 44-50 ◽

Cited By ~ 60

Author(s):

Tong Zheng ◽

Yuhai Liang ◽

Shihuo Ye ◽

Zhongyi He

Keyword(s):

Mathematical Model ◽

Controlled Release ◽

Release Rate ◽

Superabsorbent Hydrogels

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Layered double hydroxide/sepiolite hybrid nanoarchitectures for the controlled release of herbicides

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.10.163 ◽

2019 ◽

Vol 10 ◽

pp. 1679-1690 ◽

Cited By ~ 4

Author(s):

Ediana Paula Rebitski ◽

Margarita Darder ◽

Pilar Aranda

Keyword(s):

Controlled Release ◽

Ion Exchange ◽

Single Step ◽

Basal Spacing ◽

In Vitro Tests ◽

Bidistilled Water ◽

Continuous Release ◽

Agricultural Applications ◽

Double Hydroxides

In this work, organic–inorganic hybrid nanoarchitectures were prepared in a single coprecipitation step by assembling magnesium–aluminum layered double hydroxides (MgAl-LDH) and a sepiolite fibrous clay, with the simultaneous encapsulation of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) as the MgAl-LDH retains its ion exchange properties. The synthetic procedure was advantageous in comparison to the incorporation of MCPA by ion exchange after the formation of the LDH/sepiolite nanoarchitecture in a previous step, as it was less time consuming and gave rise to a higher loading of MCPA. The resulting MCPA-LDH/sepiolite nanoarchitectures were characterized by various physicochemical techniques (XRD, FTIR and 29Si NMR spectroscopies, CHN analysis and SEM) that revealed interactions of LDH with the sepiolite fibers through the silanol groups present on the outer surface of sepiolite, together with the intercalation of MCPA in the LDH confirmed by the increase in the basal spacing from 0.77 nm for the pristine LDH to 2.32 nm for the prepared materials. The amount of herbicide incorporated in the hybrid nanoarchitectures prepared by the single-step coprecipitation method surpassed the CEC of LDH (ca. 330 mEq/100 g), with values reaching 445 mEq/100 g LDH for certain compositions. This suggests a synergy between the inorganic solids that allows the nanoarchitecture to exhibit better adsorption properties than the separate components. Additionally, in the release assays, the herbicide incorporated in the hybrid nanoarchitectures could be completely released, which confirms its suitability for agricultural applications. In order to achieve a more controlled release of the herbicide and to act for several days on the surface of the soil, the hybrid nanoarchitectures were encapsulated in a biopolymer matrix of alginate/zein and shaped into spheres. In in vitro tests carried out in bidistilled water, a continuous release of MCPA from the bionanocomposite beads was achieved for more than a week, while the non-encapsulated materials released the 100% of MCPA in 48 h. Besides, the encapsulation may allow for better handling and transport of the herbicide.

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