Characterization, swelling and slow-release properties of a new controlled release fertilizer based on wheat straw cellulose hydrogel

A novel wheat straw based semi-interpenetrating polymer networks (semi-IPNs) hydrogel with slow-release fertilizers of nitrogen and phosphorus was prepared by the method of solution polymerization. The influences of particle sizes, salt solutions, ionic strength and pH changes on the swelling and fertilizer releasing properties of the product were investigated. Effect of cations on both swelling and fertilizer release properties were observed in the order of Na+ > K+ > Ca2+. The product could hold more water in the pH range of 6-9. The swelling behaviors of the product in various salt solutions, ionic strength and pHs conditions were evaluated by Schott's second-order swelling kinetics model. The fertilizers diffusion parameters of the product could be assessed by a cubic form perfectly according to the diffusion coefficients in the kinetic equation. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.