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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.
The goethite-humic acid complexes were prepared by alkaline solution-acid precipitation method, and the XRD results showed that the diffraction peaks of the complexes could be attributed to goethite, but the peak intensities were weaker than those of goethite. The results showed that the surface of goethite in the composites was coated with irregularly-shaped particles of humic acid.Compared with IR spectra of goethite and humic acid, carboxylate (COO ~ -) The frequencies of antisymmetric vibration and stretching vibration of iron (≡ Fe-OH) decreased by 20 cm -1 and 9 cm -1, respectively. The hydroxyl groups (H-O ···· H-O) The vibrational frequencies of the goethite increased by 10 cm -1, and the stretching vibration of the C-O bond and the absorption peak of the free hydroxyl groups disappeared basically.This indicated that the surface Fe atoms in the goethite and the carboxyl groups in the humic acid structure Monodentate coordination as well as the hydrogen bond between the ≡ Fe-OH on the surface of goethite and the free hydroxyl in humic acid are the main interaction mechanisms.The TG / DTG analysis shows that the goethite monomer and The weight loss peaks of ≡ Fe-OH in the complex were 258 ℃ and 276 ℃, respectively, indicating that the coating of humic acid enhanced the thermal stability of goethite. Compared with humic acid monomer, the aliphatic and Loss of aromatic organic matter The peak temperature decreased by 60 ℃ and 26 ℃, respectively, and the ratio of weight loss of aliphatic and aromatic organic compounds in the composite significantly increased. It can be seen that aliphatic components with poor thermal stability in the humic acid component are easier And goethite formed a complex .After ultrasonic dispersion treatment of the sample suspension, the content of large particles (> 2μm) in the humic acid and goethite monomer significantly decreased; the size and content of large particles in the composite But the change is small.This shows that ultrasonic dispersion treatment is not easy to destroy the complex in goethite and humic acid between the cementation.