Modified hydrotalcite for phosphorus slow-release: kinetic and sorption-desorption processes in clayey and sandy soils from North of Parana state (Brazil)

Published: 15 June 2020| Version 1 | DOI: 10.17632/75pjrg66vb.1


New technologies have been developed to slow down the phosphorus release in the soil and prevent the loss to the environment by using layered double hydroxides (LDH). However, slow-releasing mechanisms in inorganic matrices are not often discussed in the literature, and post-release sorption-desorption processes have also not been taken into account. Thus, kinetic and sorption processes of P in soils were herein investigated employing a modified LDH. The modification was carried out by the reconstruction method in the P solution. The material (HTCP) was characterized by FT-IR and XRD. The release of P to the soil solution was slow. Around 11% of the P introduced in the LDH was released to the clayey soil solution, and 5.5% to the sandy soil solution over 45 days (1080 h). Kinetic models of first-order and second-order, Elovich, intraparticle diffusion, and power function were applied. The intraparticle diffusion model best described the P release in clayey soil, characterizing ion exchange, while the second-order model better adjusted the release in sandy soil. The dual-mode Langmuir-Freundlich model appropriately described the sorption of P in the soil samples, being the desorption almost null. Although some of the P was sorbed, the post-sorption pH remained in a viable range for making P available to the plants, revealing the benefits of using HTCP for slow-release fertilizers. Keywords: hydrotalcite, phosphorus, slow-release, sorption-desorption



Universidade Estadual de Londrina Centro de Ciencias Exatas


Chemistry, Soil, Adsorption Kinetics, Anion Adsorption, Clay Mineral, Mobilisation