Synthesis of Amino Polyurethane Foam and Its Application in Trace Gold Enrichment in Geological Samples
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摘要: 采用泡塑（PUF）富集，AAS或ICP-OES测定地质样品中痕量金是常用的分析方法。与活性炭相比，PUF的选择性好，但吸附容量偏低，可将泡塑负载不同的萃取剂或修饰不同的官能团提高吸附容量。本文将聚醚型泡塑经盐酸水解制备成氨基泡塑（PUF-NH2）。红外光谱和扫描电镜表征显示，PUF-NH2峰形发生了明显红移（3376.5 cm-1），其中的氨基数量显著增加，另外PUF-NH2的高分子出现明显断裂，发生水解后裸露出的氨基具有还原性，在吸附金的过程中易与金离子在PUF-NH2表面发生氧化还原反应，形成金纳米颗粒。改性后的PUF-NH2吸附容量达到96 mg/g，与PUF相比提高了8倍。将PUF-NH2应用于富集地质样品中的金，经炭化灼烧、50%王水提取后用ICP-OES测定，金的加标回收率在95.0%～105.0%之间，检出限为0.15 μg/g。 实验证明用PUF-NH2处理样品提高了富集倍数和分析灵敏度，有利于低品位矿石的分析。
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关键词:
- 地质样品 /
- 金 /
- 回收率 /
- 氨基泡塑 /
- 电感耦合等离子体发射光谱法
Abstract: The common method for the determination of Au in geological samples is by Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) after enrichment by polyurethane foam (PUF). Compared with activated carbon, PUF has a good selectivity but has a low absorption capacity. PUF loaded by different extraction agents or modified with different functional groups can improve the absorption capacity. PUF was treated with hydrochloric acid to prepare PUF-NH2. Infrared Spectrum and Scanned Electron Microscope results show the peak of PUF-NH2 shows obvious red shift, and the amount of amino group increases obviously. Macromolecule of PUF-NH2 shows obvious fracture. The amino group after hydrolysis is reduced, which is easy to achieve in an oxide-reduction reaction with Au ions during the absorption of Au to form Au nanoparticles. Modified PUF-NH2 achieved absorption capacity of 96 mg/g, which is an 8-fold improvement compared to PUF. Using PUF-NH2 to enrich Au in geological samples, the samples were first ashed and then digested by 50% aqua regia. Gold was determined by ICP-OES. The recovery by standard-addition ranged from 95.0% to 105.0% and the detection limit was 0.15 μg/g. The experimental results show that the enrichment degree and analytical sensitivity are improved by using PUF-NH2, which is suitable for the determination Au in low grade ores. -
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表 1 Langmuir、Freundlich和Dubinin吸附计算参数
Table 1. Parameters of the Langmuir,Freundlich and Dubinin isotherms for the adsorption of Au(Ⅲ)
吸附类型 等温常数 280 K 298 K 323 K Langmuir Qmax (mg/g) 98.94 95.99 78.45 K (L/mg) 0.05890 0.05532 0.03371 R2 0.9900 0.9912 0.9876 RL 0.0215~0.6334 0.0219~6424 0.0351~0.7511 Freundlich Kf(mg/g)(L/mg)1/n 7.808 7.102 4.743 n 2.021 2.001 1.954 R2 0.9794 0.9720 0.9690 Dubinin QD-R (mg/g) 3.451 3.462 3.214 β×10-2(mol2/J2) -8.703 -10.494 -7.726 E 2.390 2.175 2.538 R2 0.5200 0.5561 0.3716 
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表 2 国家标准物质和实际样品测定结果
Table 2. Analytical results of Au in certified reference materials and actual samples
标准物质编号 提取方式 金含量(μg/g) RSD(%) 实际样品编号 金含量(μg/g) 金加标回收率(%) 测量值 标准值 测量值 加标量 总量 GBW07804 灰化硫脲解脱 2.45±0.16 2.50 ± 0.20 3.6 1# 5.88 5.00 10.68 96.2 2.44±0.25 5.0 2# 1.04 1.00 1.99 95.0 GBW(E)070067 灰化硫脲解脱 0.66±0.03 0.64±0.03 4.4 3# 0.24 0.20 0.45 105.0 0.67±0.05 5.1
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