磁性藻基炭对铁盐除藻的助凝特性

Coagulation-supporting Characteristics of Magnetic Algae-derived Biochar for Algae Removal by Iron Salts

蓝藻水华严重影响水环境健康和用水安全,化学絮凝法能高效去除水中藻类。该文以铁盐和亚铁盐为混凝剂、磁性藻基炭(MAB)为助凝剂去除水中铜绿微囊藻,确定了铁盐的最优投配比和MAB的最佳投加量,探讨了MAB对铁盐去除水中铜绿微囊藻的助凝效果和机理。结果表明,铁盐最优Fe^(2+)∶OH-∶Fe^(3+)投配比例为2∶6∶0.3,投药量以[Fe^(2+)]计为1 mmol/L,MAB最佳投加量为30 mg/L。MAB提高了铁盐去除铜绿微囊藻及相关污染物的混凝效果,促进藻细胞与铁盐水解产物作用生成密实性更好的藻絮体沉淀物,并且具备良好磁响应性能的MAB有助于实现藻絮体的外磁场分离。水中藻细胞和MAB在混凝初期主要通过静电吸附的形式与铁盐水解产物Fe_(x)(OH)_(y)作用,混凝中后期则主要通过无定形Fe(OH)_(3)的网捕卷扫作用得以沉淀去除。表征分析表明,混凝过程中铁盐水解产物与藻细胞表面活性官能团发生作用形成了新的表面基团,可推断Fe_(x)(OH)_(y)及其高聚合体与铜绿微囊藻的胞外聚合物之间发生了共聚络合反应。

Cyanobacterial blooms have seriously affected the health of aquatic environment and the safety of water supply.The method of chemical flocculation can effectively remove algae from water.Microcystis aeruginosa was removed from water with ferric and ferrous salts as coagulant and magnetic algal-derived carbon(MAB)as flocculant aid.The suitable dosage ratio of ferric salts and the optimal dosage of MAB were determined.The coagulation-supporting efficiency and characteristics of MAB for Microcystis aeruginosa removed by ferric salts were discussed.The results showed that the suitable dosage ratio of Fe^(2+)∶OH-∶Fe^(3+)was 2∶6∶0.3,the dosage of ferric salts was 1 mmol/L as[Fe^(2+)],and the optimal dosage of MAB was 30 mg/L.The coagulation efficiency of ferric salts for removing Microcystis aeruginosa and related pollutants was improved with the help of MAB.MAB with good magnetic response performance promoted the interaction between algal cells and hydrolysates of ferric salts to form denser algal floc sediment,and made algal flocs be more easily separated by the external magnetic field.The coagulation of algae and MAB at the initial stage was mainly due to elctrostatic adsorption between ferric hydrolysate Fe_(x)(OH)_(y)and algal cells and MAB.Then algal cells and MAB were precipitated mainly through the sweep flocculation of amorphous Fe(OH)_(3)resulted from further hydrolysis of ferric salts in the later stage of coagulation.The characterization analysis results indicated that the hydrolysates of ferric salts reacted with the active functional groups on the surface of algal cells to form new surface groups in the process of coagulation,which could be concluded that there was copolymerization and complexation reaction between the extracellular organic matters of Microcystis aeruginosa and Fe_(x)(OH)_(y)and its high polymer.