腐植酸/淀粉复合微球的制备及工艺优化

Preparation and process optimization of humic acid/starch composite mi-crospheres

摘要:

以腐植酸(HA)和可溶性淀粉(St)为原料，N,N'-亚甲基双丙烯酰胺(MBAA)为交联剂，过硫酸钾/亚硫酸氢钠(K2S2O8/NaHSO3)为复合引发剂，采用反相乳液聚合法合成了腐植酸/淀粉复合微球(CSM)。结合响应曲面设计，探讨了HA∕St物料比、K2S2O8/NaHSO3用量、MBAA用量、复合乳化剂用量、反应温度等因素对CSM吸附性能的影响。结果表明，合成CSM的最佳工艺为: m(HA): m(St)=1.51:1、MBAA用量0.6 g、K2S2O8/NaHSO3用量0.6 g/0.6 g、复合乳化剂用量1.2 g，反应温度50℃、油水体积比3:1、反应时间3 h。在此条件下合成的CSM对Cr(Ⅵ) (10 mg/L)的去除率达到99.91%。利用FTIR和SEM对CSM的结构和形貌进行表征，发现HA和St成功反应，所得CSM形状规则，表面粗糙；同时通过激光粒度分布仪、XRD和TGA测试了CSM的粒径分布、结晶度和热分解性能，结果显示CSM粒径分布均匀，体积平均径为19.49μm，结晶度（相较于St）降低，具有较好的热稳定性。

Abstract:

Humic acid (HA) and starch (St) were used as raw materials, N,N'-Methylenebisacrylamide (MBAA) as cross-linking agent, Potassium persulfate/Sodium Hydrogen Sulfite (K2S2O8/NaHSO3) as the composite ini-tiator, and the humic acid/starch composite microspheres (CSM) were synthesized by inverse emulsion polymerization. Combining with response surface methodology, the effects of HA/St material ratio, K2S2O8/NaHSO3 dosage, MBAA dosage, composite emulsifier dosage and temperature on the adsorption properties of CSM were discussed. The results showed that the optimum technological conditions were as follows: m(HA): m(St)=1.51:1, K2S2O8/NaHSO3 dosage 0.6 g/0.6 g, MBAA dosage 0.6 g, composite emul-sifier dosage 1.2 g, temperature 50℃, oil-water volume ratio 3:1 and reaction time 3 h. Under these condi-tions, the removal rate of CSM for Cr(VI) (10 mg/L) reached 99.91%. The structure and morphology of CSM were characterized by FTIR and SEM. It was found that HA and St reacted successfully, CSM has regular shape and the surface was rough. The particle size distribution, crystallinity and thermal decompo-sition performance of CSM were measured by laser particle size analyzer, XRD and TGA. The results showed that the particle size distribution of CSM was uniform and the average volume diameter was 19.49μm, the crystallinity of CSM (compared with St) was reduced, and the thermal stability of CSM was good.