Lignin–Clay Nanohybrid Biocomposite-Based Double-Layer Coating Materials for Controllable-Release Fertilizer

Abstract

Bio-based slow-release fertilizers (SRFs) have drawn significant attention because their applications for crop production can improve nutrient utilization efficiency as well as prevent environmental pollution. However, current commercial SRFs still exhibit uncontrollable release patterns, use a large quantity of synthetic coating materials, and are unable to adapt to complex soil conditions (e.g., arid soil). In this study, a double-layer SRF was formulated from a low-cost lignin−clay nanohybrid composite to not only achieve controllable and slow nitrogen fertilizer release but also improve the water-holding property. The low-cost and hydrophobic lignin−clay nanohybrid was cross-linked with bio-based alginate to prepare the core-layer material, followed by a coating process using a highly water-absorbent polymer poly(acrylic acid) (PAA) to achieve a double-layer SRF. We examined the chemical structures, urea release rates, and water-holding capacities of the double-layer PAA−lignin−clay nanohybrid composite coated SRF (PLC-SRF). The results showed that PLC-SRF released 13−40% less urea and absorbed 23% more water than SRFs coated with only alginate. Its urea release rate is slower than that of previously reported SRFs using other materials. This nanocomposite coating material has great potential for producing a new type of bio-based SRFs that are beneficial to sustainable crop production.

Understanding the Role of a Silane-Coupling Agent in Bio-Based Polyurethane Nanocomposite-Coated Fertilizers

“…Currently, a variety of modification techniques including physical blending, chemical grafting, and nanoparticle addition are used to improve the performance of BCRFs. − Due to the small size, high surface activity, and great specific surface area, nanomaterials can produce a strong interfacial interaction with polymers, which gives new or improved properties to polymers, such as high hydrophobicity and mechanical performance. − Therefore, the nanocomposite modification technology has become one of the important research directions. Li prepared a polyurethane (PU)/zeolite 4A composite via an in situ reaction on the surface of urea granules.…”

Recent Advances on Lignocellulosic-Based Nanopesticides for Agricultural Applications

“…Kraft lignin (KL) has a tunable amphiphilic nature due to the abundant phenolic hydroxyl groups capable of forming a stable double-layered nanomaterial with ionic surfactants (Ela et al, 2020), nanocapsules with olive oil (Falsini et al, 2020), and is also able to chelate cationic metals (Sipponen et al, 2017). Other nanopesticides have also been synthesized with alkali lignin (AL) (Yin et al, 2020), organosolv lignin (Zhang et al, 2020a), and methacrylate lignin (Yiamsawas et al, 2021).…”

Dense and superhydrophobic biopolymer-coated large tablet produced with energy efficient UV-curing for controlled-release fertilizer

“…[21][22][23] However, due to the low cross-linkage and high hydrophilicity of most biopolymer coating materials, 24 the controlled-release longevity of LCRFs hardly exceeds 90 days, which limits the application in major eld crops, thus making it difficult to promote the use of LCRFs on a large scale. Furthermore, the conventional heat-curing process [23][24][25][26][27][28][29] is time and energy consuming and has low curing efficiency. The semi-cured and ropy coating materials on the surface of fertilizer particles tend to adhere to each other during the curing process and are then separated and torn apart during continuous curing and rolling.…”