Preparation And Performance Of Polymeric Slow-release NK Fertilizer With Water Absorbency

Two types of polymeric slow-release NK fertilizer(PSRNKF-1 and PSRNKF-2)with high water absorbency were prepared by solution polymerization of partially neutralized(acrylic acid(AA)and acrylic amide(AM))using N,N'-methylene-bis-acrylamide(NNMBA)as a crosslinker and potassium persulfate(KPS)as an initiator in the presence of urea.They have met the orientation of "water absorption","water retention","diversity","slow release" of the developing world fertilizer.The polymeric slow-release NK fertilizer(PSRNKF-1)with high water absorbency were was synthesized with carbamide(urea),acrylic acid(AA)and potassium hydroxide(KOH)as raw material using potassium persulfate(KPS)as an initiator and N,N'-methylene-bis-acrylamide(NNMBA)as a crosslinker.The water absorbency was about 910 g.g-1~925g.g-1 in distilled water.The nitrogen content of PSRNKF-1 synthesized under optimal conditions was 21.32%,the potassium content was 11%.The optimal synthesizing process of PSRNKF-1 was obtained through orthogonal and optimization experiments.The structure of PSRNKF-1 was characterized by infrared absorption spectrum(FITR),which reaction mechanism was also inferred.The water absorption rate of PSRNKF-1 in deionized water and 0.9% Na Cl salt solution were measured,which showed that PSRNKF-1 can reach to moisture saturation within 4.5h and 7.5h respectively.The water absorption of PSRNKF-1 in salt solutions with different anion and cation and p H was investigated.The salt solution of had big effect on the water absorbency of PSRNKF-1,and the sequence of influence of anion of different valence state was H2PO4->SO42->CO32->Cl-,and the sequence of influence of cation of different valence state was monovalence>trivalence>bivalence.PSRNKF-1 applies to the soil of p H for 6 to 8.PSRNKF-1 still has very good water absorption performance after wicking-drying for six times.The water retention capacity of PSRNKF-1 Was studied by soil water leakage test,the results showed that PSRNKF-1 can greatly reduce the leakage of water in the soil,which has a good ability of water conservation.The nutrient release characteristics in water of PSRNKF-1 was studied by water dissolution rate method.The results have showed PSRNKF-1 has the very good slow release performance,its nutrient release characteristic curve was inverted "L" type.The polymeric slow-release NK fertilizer(PSRNKF-2)with high water absorbency were was synthesized with carbamide(urea),acrylic acid(AA),acrylic amide(AM)and potassium hydroxide(KOH)as raw material using potassium persulfate(KPS)as an initiator and N,N'-methylene-bis-acrylamide(NNMBA)as a crosslinker.The water absorbency was about 1398 g.g-1~1425g.g-1 in distilled water.The nitrogen content of PSRNKF-2 synthesized under optimal conditions was 14.14%,the potassium content was 8.95%.The optimal synthesizing process of PSRNKF-2 was obtained through orthogonal and optimization experiments.The structure of PSRNKF-2 was characterized by infrared absorption spectrum(FITR),which reaction mechanism was also inferred.The water absorption rate of PSRNKF-2 in deionized water and 0.9% Na Cl salt solution were measured,which showed that PSRNKF-1 can reach to moisture saturation within 6.5h and 5.5h respectively.The water absorption of PSRNKF-2 in salt solutions with different anion and cation and p H was investigated.The salt solution of had big effect on the water absorbency of PSRNKF-2,and the sequence of influence of anion of different valence state was SO42->CO32->H2PO4->Cl-,and the sequence of influence of cation of different valence state was monovalence>trivalence>bivalence.PSRNKF-2 applies to the soil of p H for 6 to 8.PSRNKF-2 still has very good water absorption performance after wicking-drying for six times.The water retention capacity of PSRNKF-2 Was studied by soil water leakage test,the results showed that PSRNKF-2 can greatly reduce the leakage of water in the soil,which has a good ability of water conservation.The nutrient release characteristics in water of PSRNKF-2 was studied by water dissolution rate method.The results have showed PSRNKF-2 has the very good slow release performance,its nutrient release characteristic curve was inverted "L" type.