木质素/黏土复合材料对尿素分子的缓释作用

Slow releasing properties for urea molecules of composite materials made of lignin and clay

以木质素和黏土为原料制备对尿素分子有缓释作用的复合材料。扫描电镜显示复合改性后木质素从球核形聚集结构变为蜂窝状的富孔结构,木质素和黏土可能通过羟基间的氢键相互复合。采用淋溶实验检验了木质素/黏土复合材料对尿素分子的缓释作用。结果表明,富孔结构的复合材料能对肥料中的尿素分子起到有效的缓释作用,m(木质素):m(黏土):m(尿素)=2∶1∶4的复合材料缓释效果较好。另外有机高分子聚乙烯醇作为成膜剂的加入能进一步提高木质素/黏土复合材料对尿素分子的缓释效果。木质素/黏土复合材料能吸收空气中的水分,具有保持土壤水分的作用。在对土壤的脲酶活性抑制实验中,木质素/黏土复合材料显示了一定的抑制土壤脲酶活性的作用,特别是当复合材料吸附铜离子后,对土壤中的脲酶活性的抑制显著增强。

Composite materials with the property of slowly releasing urea had been prepared by using lignin and clay as starting materials in this research.SEM pictures of lignin/clay composite material prepared showed that sphere-like assembling structure of lignin had been transferred into honeycomb assembling structure with more pores for hydrogen bonding between hydroxyl groups of both of the starting materials.Leaching experiments confirmed that the prepared lignin/clay composite materials with the porous structure owning a function of slow releasing property for urea molecules,and the weight ratio of m（lignin）∶m（clay）∶m（urea） was 2∶1∶4 in the composite.Also,what had been confirmed experimentally was that the addition of polyvinyl alcohol as filmogen could improve the slow releasing properties of lignin/clay composite materials for urea molecules.Water adsorption experiments showed that the lignin/clay composite materials prepared could adsorb the water in air,which was helpful for promoting dry soil to keep their water.Soil urease activity inhibition experiments showed that the prepared composite materials could reduce urease activity which could transfer urea into volatile ammonia.Specially,when copper ions were introduced into between layers of clay of composite materials,the prepared lignin/clay composite materials inhibited urease activity more seriously in soil.