壳聚糖/浮石浮上式复合除藻材料的制备及其除藻性能和除藻机制

Study on the preparation of chitosan-pumice floating composite material for removing algae and its performance and mechanism of removing algae

鉴于江河湖库有害藻华现象频发,目前较多使用的是高效絮凝剂与天然粘土矿物联合除藻,但存在着用量大、淤泥多、使底泥增厚、沉下去的藻类仍会伺机爆发等缺点,无法达到令人满意的除藻效果。本文使用轻质漂浮矿物浮石作为载体,制备一种不产生底泥的壳聚糖/浮石浮上式复合除藻材料,以铜绿微囊藻为受试对象,研究了物料配比、投加量、藻悬液p H、反应时间等因素对其絮凝除藻性能的影响,对复合除藻材料的表面形貌及成分进行了SEM和XRF表征,并通过Zeta电位方法探讨了该材料的除藻机制。结果表明:其最佳制备和使用条件为:壳聚糖/浮石配比为10∶1,当藻悬液pH为7,100 mL藻悬液中投加复合除藻材料6 g,反应时间180 min时,复合材料对浊度(NTU)去除率最高为94%,对叶绿素Chlorophyll a(Chla)的去除率可达98%;其性能优良的原因在于,该材料的表面凹凸不平,表面积大,且其Zeta电位为正值,极易与带负电的藻发生吸附絮凝和电荷中和,使藻细胞不断聚集形成大絮体,表现出良好的除藻效果。

In view of the frequent occurrence of harmful algal blooms in rivers,lakes and reservoirs,high-efficiency flocculants and natural clay minerals are commonly used to remove algae,but there are some problems,such as large amounts of clay minerals,silt and thickening of sediments.The sunken algae will still wait for an opportunity to erupt and other shortcomings,unable to achieve a satisfactory algae removal effect.In this paper,a lightweight floating mineral pumice was used as a carrier to prepare a chitosan-pumice floating composite algae-removing material that does not produce sediment.With microcrystal aeruginosa as the test object,the material ratio,dosage,the effect of pH and reaction time of the algae suspension on its flocculation and algae removal performance,the surface morphology and composition of the composite algae removal material were characterized by SEM and XRF,and the algae removal mechanism of the material was discussed by Zeta potential measurement.The results show that the optimal preparation and use conditions are:chitosan-pumice ratio is 10∶1,the pH of the algae suspension is 7,100 mL of the algae suspension is added 6 g of the composite algae-removing material,and the reaction time is 180 minutes,the maximum removal rate of the composite material for turbidity(NTU)is 94%,and the removal rate for Chlorophyll a(Chl-a)can reach 98%;the reason for its excellent performance is that the surface of the material is uneven,large surface area,and its Zeta potential is positive.It is easy to adsorb and flocculate and neutralize the charge with negatively charged algae,causing the algae cells to continuously aggregate to form large flocs,showing a good floating algae removal effect.