聚谷氨酸作为安全无毒的天然高分子聚合物,可用作绿色絮凝剂,但其絮凝微藻能力不佳。该研究采用聚谷氨酸(γ-polyglutamic acid,γ-PGA)和壳聚糖(chitosan,CTS)2种生物高分子,相同质量混合,在酸性条件下与2,3-环氧丙基三甲基氯化铵(2,3-epoxypropyl trimethyl ammonium chloride,GTA)反应,制备了一种用于微藻采收的PGA-CTS-GTA生物絮凝剂。通过单因素试验确定了最佳的制备条件,通过红外光谱、扫描电镜、及zeta电位等分析方法对改性物进行了表征,并探究了其絮凝机理。结果显示最适反应条件为:反应pH=3,GTA与PGA-CTS混合物质量比7∶1,反应时间4 h,反应温度75 ℃,在100 mg/L投加量下300 r/min搅拌1 min、沉降1 h后絮凝效果达到了91.2%。对表征结果进行分析可知PGA-CTS-GTA絮凝过程中除了电荷中和外,架桥与网扑卷扫也发挥了重要作用。
Polyglutamic acid, a biocompatible and environmentally friendly natural polymer, has potential as a green flocculant;However, its efficiency in microalgae harvesting remains suboptimal.In this study, a novel bioflocculant, PGA-CTS-GTA, was synthesized for microalgae harvesting.The preparation involved mixing two biopolymers, polyglutamic acid (γ-PGA) and chitosan (CTS), in equal proportions, followed by reaction with 2,3-epoxypropyl trimethyl ammonium chloride (GTA) under acidic conditions.The optimal preparation conditions were determined through single-factor experiments.The modified flocculant was systematically characterized through infrared spectroscopy, scanning electron microscopy, and zeta potential analysis, with its flocculation mechanism comprehensively studied.The results indicated that the optimal reaction conditions were as follows:A reaction pH of 3, a mass ratio of 7∶1 for GTA to the PGA-CTS mixture, a reaction duration of 4 hours, and a temperature of 75 ℃.At a dosage of 100 mg/L, the flocculation efficiency reached 91.2% under conditions of stirring at 300 r/min for 1 minute and settling for 1 hour.Analysis of the characterization results revealed that, apart from charge neutralization, bridging and sweeping mechanisms were also critical in the flocculation process of PGA-CTS-GTA.
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