天冬氨酸对亚铁混凝剂絮体结构及磷酸盐去除效果的影响  

Effect of aspartic acid on the floc composition of Fe(II) coagulant and its deep phosphorus removal

作　　者：罗义[1] 赵丙昊 邢波波 俞文正[2] LUO Yi;ZHAO Binghao;XING Bobo;YU Wenzheng(Hebei University of Architecture,Zhangjiakou 075000,China;Key Laboratory of Drinking Water Science and Technology,Research Centre for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China)

机构地区：[1]河北建筑工程学院,张家口075000 [2]中国科学院生态环境研究中心,环境水质学国家重点实验室,北京100085

出　　处：《环境工程学报》2022年第6期1815-1822,共8页Chinese Journal of Environmental Engineering

摘　　要：铁混凝剂广泛应用于水处理领域,形成的絮体大小、形态和结晶度直接决定其混凝效果。然而小分子有机物对混凝的影响机制尚不清楚。本研究以FeSO_(4)作为混凝剂,通过添加特定的小分子有机物(分子质量<1 000 Da)天冬氨酸,研究了天冬氨酸对絮体生长过程及其产物的影响。结果表明,天冬氨酸通过影响金属的水解和纳米颗粒的性质进而影响其混凝性能。在pH=7时,天冬氨酸的存在延缓了絮体的初始生长时间,但增大了絮凝体的最大粒径(从0.05μm大小的碎片和小球状参杂的絮体变化至0.1μm的褶皱状絮体)和磷酸盐的去除率。当添加0.4 mmol·L^(-1)的天冬氨酸时,纤铁矿(γ-FeOOH)为絮体的主要成分,这可能少量的天冬氨酸存在时,体系中部分亚铁离子会被包裹,Fe(OH)_(2)纳米颗粒由于铁化合物的饱和快速形成,随后作为晶核生长;Fe(OH)_(2)纳米颗粒表面通过被氧化转化成三价铁,最终形成γ-FeOOH;当添加天冬氨酸大于0.4 mmol·L^(-1)时,絮体的主要成分为四方纤铁矿(β-FeOOH),此时部分亚铁离子被完全包裹,剩余的亚铁离子被氧化成三价铁后形成β-FeOOH。经过天冬氨酸诱导后形成的絮体对磷酸盐的去除率均增加了1.57倍左右,处理后的磷酸盐浓度降低到了0.02 mg·L^(-1),且在添加1.5 mmol·L^(-1)天冬氨酸时絮体的尺寸最大,此时的絮体更加容易沉降分离。Iron flocculants are widely used in water treatment applications where the size,morphology,and crystallinity of the flocs directly determine the adsorption activity and settling performance.However,the effect mechanism of small molecular organics on coagulation is still unclear.In this study,FeSO_(4) was used as coagulant,its effects of adding specific small molecule organic matter(molecular weight <1 000 Da) of aspartic acid(containing two carboxyl groups and one amino group) on flocs growth process and products were investigated.The results show that aspartic acid affected metal hydrolysis,nanoparticles properties and the coagulation performance.At pH=7,the presence of aspartic acid delayed the initial growth time of flocs,but increased the maximum particle size of flocs,changing from 0.05 μm sized flocs with fragments and small spherical participations to 0.1 μm folded flocs,and the phosphate removal rate.When 0.4 mmol·L^(-1) aspartic acid was added,lepidocrocite(γ-FeOOH) was the main component of the floc.Due to the rapid hydrolysis of Fe(Ⅱ)ions in aqueous solution,when there was a small amount of aspartic acid in the system,part of the Fe(Ⅱ) ions in the system would be wrapped,and Fe(OH)_(2) nanoparticles would form rapidly due to the saturation of iron compounds.Afterwards,Fe(OH)_(2) nanoparticles continued to grow as the crystal,its surface was oxidized into Fe(Ⅲ),finally γ-FeOOH formation occurred.When the dosage of aspartic acid was higher than 0.4 mmol·L^(-1),the main component of flocs was akaganeite(β-FeOOH).At this time,part of Fe(Ⅱ) ions were completely wrapped,and the remaining Fe(Ⅱ) ions were oxidized into Fe(Ⅲ) irons and hydrolyzed to form β-FeOOH.The phosphorus removal rate by the flocs induced by aspartic acid increased by about 1.57 times,and the phosphate concentration decreased to 0.02 mg·L^(-1) after treatment.Moreover,the FI index of flocs was the highest when1.5 mmol·L^(-1) aspartic acid was added,and the flocs were easier to settle and separate.

关 键 词：天冬氨酸 絮体 纤铁矿和四方纤铁矿 除磷 

分 类 号：X703.1[环境科学与工程—环境工程]