环境友好型保水剂的合成、性能及应用

目的]以过硫酸铵(APS)为引发剂,N,N'-亚甲基双丙烯酰胺(NMBA)为交联剂,通过壳聚糖(CTS)和瓜尔胶(GG)接枝丙烯酸(AA)制备新型高耐盐保水剂,探究其合成过程最佳反应条件,研究其对盐碱地土壤保水保肥的效果。方法]利用水溶液聚合法制备保水剂,通过单因素试验(AA中和度、GG投加量、APS用量、NMBA用量)研究保水剂的最佳合成条件,用FTIR和SEM对产物进行表征,并对产物的环境适应性(盐溶液类型及浓度、溶液pH值)及其加入盐碱土后对于土壤水肥保持的效果进行研究。结果]当AA中和度为85%,GG投加量为0.2g,APS与NMBA用量分别为单体总量的0.3%和0.02%时,该保水剂在去离子水和0.9%NaCl溶液中的吸收效率分别为1 128g/g和185g/g,此时产物的吸收效果达到最佳。红外光谱与电镜扫描分析结果表明CTS,GG和AA都参与了聚合反应,产物具有较好的空间网络结构与表面形态。该保水剂在溶液pH值为4~10的范围内吸收效率较稳定,但是当溶液中存在阳离子时其吸收效率明显降低,阳离子类型对其吸收效率的抑制作用从大到小依次为:Mg2+Ca2+Na+K+。当保水剂加入到盐碱土时,既能提高土壤持水能力又能抑制土壤氮肥和钾肥的淋溶损失。结论]本研究自制保水剂具有较好的耐盐效果,环境适应性强,单体环境友好,将其加入盐碱土壤时能够有效降低土壤水肥的淋溶损失。

Synthesis, Characterization and Application of Environment-friendly Superabsorbent Plymers

Objective] A new type of high salt-tolerant superabsorbent polymer was prepared by grafting acrylic acid (AA) with chitosan (CTS) and guar gum (GG), with ammonium persulfate (APS) as initiator and N, N''-methylene bisacrylamide (NMBA) as crosslinker. The optimal reaction conditions in the synthetic process were investigated to study the effect of the superabsorbent polymer on the water and nutrient retention in the saline alkali soil.Methods] The superabsorbent polymer was prepared by aqueous solution polymerization and the optimized reaction conditions were studied based on single factor experiment (degree of neutralization of AA, addition of GG, APS and NMBA). The molecular structure and characteristics of the product were confirmed by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The absorbent efficiency of product was studied in different saline solutions with different pH value. In addition, the effect of superabsorbent polymer in reforming saline alkali soil was studied by leaching test.Results] The absorbent efficiency of the product reached the highest when the degree of neutralization of AA was 85%, the amount of GG was 0.2 g, the addition of APS and NMBA were 0.3% and 0.02% of the total monomer, respectively. Under this condition, the absorbent efficiency of product were 1 128 and 185 g/g in deionized water and 0.9% NaCl solution, respectively. The results of FTIR and SEM showed that CTS, GG and AA were involved in the polymerization, and the products had a good spatial network structure and surface morphology. The superabsorbent polymer had a relatively stable absorbent efficiency in the pH value range of 4~10. However, the absorbent efficiency decreased obviously when there were the co-existing cation in the solution, and inhibitory effect of cations on the absorption efficiency was ranked as:Mg²⁺ > Ca²⁺ > Na⁺ > K⁺. And the superabsorbent polymer could not only improve the water holding capacity of the soil but also inhibit the leaching loss of nitrogen and potassium fertilizer.Conclusion] The superabsorbent polymer prepared in this experiment has better salt tolerant effect and wide range of solution pH value adaptability. The synthetic monomers of the superabsorbent polymer are environmentally friendly, and can effectively reduce the leaching loss of the soil water and fertilizer in the saline-alkali soil.