纳米SiO_(2)—淀粉—PVA复合膜材料的制备及其在炭基肥中的应用

Preparation of nano-SiO_(2)-starch-polyvinyl alcohol composite membrane material and its application in carbon-based fertilizer

淀粉—聚乙烯醇(polyvinyl alcohol,PVA)作为缓释肥包膜材料具有价格低廉、环保等优点,但其高吸水性限制其应用,采用纳米二氧化硅(SiO_(2))改性可提高其疏水性。首先探讨PVA浓度、交联剂用量、增塑剂用量对淀粉—PVA复合膜吸水率的影响,之后用纳米SiO_(2)对淀粉—PVA复合膜进行改性,探讨纳米SiO_(2)添加量对复合膜吸水率和力学性能的影响,并找出最优原料配比,最后将此复合膜液作为黏结剂,制备生物质炭基肥并进行土柱淋溶试验。试验结果表明:在150 mL蒸馏水中控制淀粉与PVA的添加质量之和为10 g,当淀粉与PVA的质量之比为2∶3、交联剂硼砂添加量为0.1 g、增塑剂甘油添加量为3 mL时,所制成复合膜的吸水率最低,为78%。添加纳米SiO_(2)后,各处理膜的吸水率随纳米SiO_(2)添加量的增加呈现先升高后降低的变化,当纳米SiO_(2)添加量为2.4 g时,与未添加的相比,复合膜的吸水率下降38.4%,水接触角提高89.5%,拉伸强度提高49.0%,此时制备的复合膜材料性能最佳。将纳米SiO_(2)—淀粉—PVA复合膜材料应用于生物质炭基肥的制备,制备出的炭基肥颗粒包覆完整,粒径主要分布在3.8~4.4 mm之间,在28 d时氮素累计释放率为65%,具有良好的缓释效果,为炭基肥的开发应用提供新途径。

Starch-polyvinyl alcohol(PVA)as a slow-release fertilizer coating material has the advantages of low price and environmental protection,but its high water absorption limits its application.The use of nano-silica(SiO_(2))can improve its hydrophobicity.This article first discussed the influence of PVA concentration,crosslinking agent dosage,and plasticizer dosage on the water absorption of starch-PVA composite film,then modified the starch-PVA composite film with nano-SiO_(2),explored the effect of nano-SiO_(2) addition on the water absorption of the composite film,found out the optimal ratio of raw materials,and finally,used the composite membrane liquid as a binder to prepare biomass carbon-based fertilizer.The test results show that when the sum of the added mass of starch and PVA in 150 mL of distilled water is controlled to be 10 g,the mass ratio of starch to PVA is 2∶3,0.1 g of crosslinking agent borax is added,and 3 mL of plasticizer glycerin is added,the water absorption rate of the composite membrane made is the lowest at 78%.After adding nano-SiO_(2),the water absorption rate of each treatment film increased first and then decreased with the increase of nano-SiO_(2) addition amount.When the addition amount of nano-SiO_(2) was 2.4 g,the water absorption rate of the composite film decreased 38.4%compared with that without addition,the water contact angle increased by 89.5%,and the tensile strength increased by 49.0%.The composite membrane material prepared at this time has the best performance.The nano-SiO_(2)-starch-PVA composite film material is applied to the preparation of biomass carbon-based fertilizer.The prepared carbon-based fertilizer particles are completely coated,and the particle size is mainly distributed between 3.8 and 4.4 mm.The cumulative nitrogen release rate at 28 d is 65%.It has a good slow-release effect and provides a new way for the development and application of carbon-based fertilizers.