摘要
用碱溶-酸沉淀法制备了针铁矿-胡敏酸复合物.XRD分析表明,复合物的衍射峰都可归属于针铁矿,但其峰强度略弱于针铁矿单体.TEM图像显示,复合物中针铁矿表面包被了形貌不规则的胡敏酸颗粒.与针铁矿和胡敏酸两种单体的IR图谱比较,复合物中羧酸根(COO^-)反对称振动和铁羟基(≡Fe—OH)伸缩振动的频率分别降低了20 cm^(-1)和9 cm^(-1),缔合羟基(H—O····H—O)的振动频率升高了10 cm^(-1),羧酸C—O键的伸缩振动和游离羟基的吸收峰都基本消失.这表明针铁矿表面Fe原子与胡敏酸结构中羧基之间的单齿配位以及针铁矿表面≡Fe—OH与胡敏酸中游离羟基之间的氢键都是二者之间的主要交互作用机制.TG/DTG分析显示,针铁矿单体和复合物中≡Fe—OH的失重峰分别为258℃和276℃,表明胡敏酸的包被作用增强了针铁矿的热稳定性;与胡敏酸单体比较,复合物中脂肪族和芳香族有机质的失重峰温度分别降低了60℃和26℃,且复合物中脂肪族与芳香族有机质的失重量之比明显增大.可见,胡敏酸组分中热稳定性较差的脂肪族组分更容易与针铁矿胶结形成复合物.样品的悬浮液超声分散处理后,胡敏酸和针铁矿单体中大颗粒(>2μm)的含量都明显减少;复合物中大颗粒的尺寸和含量的变化却较小.这表明超声分散处理不易破坏复合物中针铁矿与胡敏酸间的胶结作用.
Goethite-humic acid complex was prepared in a suspension containing goethite and humic acid.X-ray diffraction（XRD）results showed that the crystal structure of this complex had no obvious changes compared to pure goethite,but the peak intensity of the complex was slightly reduced.Transmission electron microscopy（TEM） images indicated that the surface of the goethite was coated by particles of humic acid.Compared to the infra-red（IR） spectra of goethite and humic acid,the anti-vibrational frequencies of COO^- and the vibrational frequencies of ≡Fe—OH decreased by 20 cm^-1 and 9 cm^-1,respectively,while the vibrational frequencies of the associated hydroxyls increased by 10 cm^-1 and the absorption band of carboxylic C—O and free hydroxyls almost disappeared.This indicates that the interactional mechanisms between goethite and humic acid include the monodentate coordination of Fe（Ⅲ）-carboxylate and hydrogen-bonds.Thermogravimetry/differential thermogravimetry（TG/DTG） analysis showed that the temperature of the weight loss peak for ≡Fe—OH in goethite and the complex were 258℃ and 276℃,respectively.This indicates that the coating of humic acid enhances the heat stability of ≡Fe—OH in goethite.Compared with humic acid,the temperature of the weight loss peak for aliphatic organics and aromatic organics in complex decreased by 60℃ and 26℃,respectively and the ratio of weight loss from aliphatic organics to aromatic organics in complex increased.This indicates that organics with a lower heat stability may be more easily adsorbed onto goethite and the affinity to goethite was higher for the aliphatic organics than for aromatic organics.After ultrasonic dispersion,the content of large particles（≥2 μm） decreased significantly for both goethite and humic acid,but the content and the size of large particles in the complex changed only slightly.
作者
王锐
朱朝菊
向文军
方敦
杨小洪
吴少尉
魏世勇
WANG Rui;ZHU Chao-ju;XIANG Wen-jun;FANG Dun;YANG Xiao-hong;WU Shao-wei;WEI Shi-yong(Department of Chemistry and Environmental Engineering, Hubei University for Nationalities, Enshi 445000, China;School of Chemistry and Chemical Engineering, Sichuan University of Arts and Scienee, Dazhou 635000, China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2017年第11期4860-4867,共8页
Environmental Science
基金
国家自然科学基金项目(41561053
41261060
21565013)
四川省教育厅科研项目(15ZA0317)
关键词
针铁矿
胡敏酸
复合物
胶结作用
稳定性
goethite
humic acid
goethite-humic acid complex
interaction
stability
