Porous temperature-sensitive gel coated slow-release fertilizer prepared by freeze polymerization method and preparation method thereof

Abstract

The invention discloses a porous temperature-sensitive gel coated slow-release fertilizer prepared by a freeze polymerization method and a preparation method thereof. The preparation method comprisesthe following steps: sodium alginate is subjected to oxidization treatment by using sodium periodate as an oxidant, so as to obtain oxidized sodium alginate, and urea is coated by using the oxidized sodium alginate as a base material, so as to obtain sodium alginate-coated urea microspheres; and a polymer poly(N-isopropylacrylamide) gel is synthesized by the freeze polymerization method, so as toobtain a porous structural temperature-sensitive gel, and the slow-release fertilizer is obtained through fluidized bed spray granulation by using the porous structural temperature-sensitive gel as acoated material. According to the porous temperature-sensitive gel coated slow-release fertilizer prepared by the freeze polymerization method and the preparation method thereof, in the synthesis of the poly(N-isopropylacrylamide) gel, the reaction solution is transferred into freeze polymerization after pre-polymerization, so that mutually continuous ice crystal regions can be formed, and pores are left after the poly(N-isopropylacrylamide) gel is thawed at room temperature, therefore, a mutually penetrating open-celled pore structure can be formed, specific surface area of the prepared gel is greatly increased, diffusion resistance of water molecules is small, swelling / deswelling rate of the gel can be improved, and temperature response rate of the gel can be significantly improved.

Description

technical field [0001] The invention relates to the field of slow-release fertilizers, in particular to a porous temperature-sensitive gel-coated slow-release fertilizer prepared by freezing polymerization and a preparation method thereof. Background technique [0002] Coated controlled-release fertilizers are currently the main controlled-release fertilizer varieties. They mainly use granular chemical fertilizers as the core, and the surface layer is coated with a layer of low water-soluble inorganic substances or organic polymers to change the dissolution of fertilizer nutrients and prolong or control fertilizer nutrients. freed. However, the existing coated controlled-release fertilizers have the disadvantages of high cost, difficult degradation of coating materials, and secondary pollution when applied to the soil. Therefore, it is necessary to look for efficient, cheap and environmentally friendly coating materials to develop coated controlled-release fertilizers. It i...

AI Technical Summary

Problems solved by technology

Sodium alginate can undergo ion exchange reaction with divalent metal ions except magnesium and mercury to form alginate hydrogel, but the degradation products of ion-crosslinked SA gel have a higher relative molecular mass, and the divalent positive ions It is easy to lose, so the degradation of the gel is not easy to control, and its aldehyde products are easier to degrade