Cellulose Microbeads: Toward the Controlled Release of Nutrients to Plants

Abstract

The use of conventional fertilizers is associated with pollution due to leaching and a mismatch between release rates and crop requirements for optimal development. Slow-release fertilizers could address both problems. Here, the synthesis and properties of a zinc fertilizer composed of cellulose microbeads loaded with aqueous ZnSO4 are reported for the first time. UV–vis spectrophotometry showed that the beads immersed in water released all Zn2+ in about 30 min, regardless of the initial Zn2+ concentration. In two sandy substrates (a pure sand and a sandy loam substrate), microprobe X-ray fluorescence spectroscopy determined Zn2+ release from beads to the substrate corresponding to count rates of about 0.115 mm min–1 s–1, irrespective of the substrate and with a low sensitivity for the water content, except in a very dry range. These results indicate that these microbeads could represent a practical and sustainable solution for efficient nutrient supply in agriculture.

Cellulose Acetate Microbeads for Controlled Delivery of Essential Micronutrients

“…In a previous work by the authors, cellulose beads were first formed by precipitation in water, dried, and then immersed in a zinc solution to impregnate them with the metal . Here, impregnation has been made more efficient by precipitating the cellulose acetate droplets directly into an aqueous antisolvent containing a zinc salt.…”

“…In a previous work by the authors, cellulose beads were first formed by precipitation in water, dried, and then immersed in a zinc solution to impregnate them with the metal. 29 Here, impregnation has been made more efficient by precipitating the cellulose acetate droplets directly into an aqueous antisolvent containing a zinc salt. Initial experimentation using zinc chloride highlighted that zinc uptake in the beads increased with increasing concentration of zinc within the antisolvent.…”

“…The release of zinc sulfate from beads produced using microcrystalline cellulose occurred within ∼400 min within both loamy and sandy soils. 29 Other formats involve coating urea with Zn-fortified nano-bentonite and ZnO nanoparticles using various binders which could release zinc, but with full zinc release occurring at around 30 days. 64 …”

“… 28 The authors have recently demonstrated that cellulose can be used for the controlled delivery of micronutrients to plant roots from soil. 29 However, cellulose is neither easily dissolved nor easily processed, requiring derivatization to undergo dissolution using common solvents or, in the absence of a derivatization regime, the use of expensive ionic liquids to dissolve standard cellulose. 30 On the other hand, a number of cellulose derivatives—such as ethyl cellulose and cellulose acetate—are soluble in a wide range of solvents deemed “green/sustainable”, such as ethanol and DMSO.…”

Cellulose Microspheres as Controlled Release Carriers for Fertilizer

“…Natural biopolymers such as starch, cellulose, and chitosan are favorable materials for the fabrication of controlled release carriers [4,[7][8][9][10][11] as they are renewable, cost-effective, low toxic, and abundantly available. Cellulose as the most abundantly available polysaccharide on earth has been extensively studied for fabrication of the microspheres, nanoparticles, lms and hydrogels for food and non-food applications [12][13][14][15][16][17][18][19][20]. Spray-dried cellulose microparticles were studied as a vehicle to slow release and enhanced the utilization e ciency of fertilizers [18].…”