In situ immobilization of tannin of Larix gmelini and its adsorption to Au(Ⅲ)
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摘要: 以富含单宁的落叶松树皮为原料制备吸附材料,研究了该吸附材料对水溶液中Au(Ⅲ)的吸附特性.结果表明:以甲醛作为交联剂可以实现落叶松树皮中单宁的原位固化;当温度为303K,pH=4.0,Au(Ⅲ)的初始浓度为522.3m/gL时,该吸附材料对Au(Ⅲ)的平衡吸附量达到Au(Ⅲ)1821.9mg/g,而且平衡吸附量随温度的升高进一步增大.pH对吸附容量的影响较大,最佳pH为4.0.该吸附材料对Au(Ⅲ)的吸附平衡符合Langmuir方程,吸附动力学可以用拟二级速度方程来描述.固定床吸附实验表明,当原料液的浓度为Au(Ⅲ)239.2m/gL,流出液的体积约为117个床层体积时才达到穿透点.分析表明,原位固化落叶松单宁对Au(Ⅲ)的吸附为氧化-还原吸附.Abstract: Tannins in the bark of Larix gmelini were immobilized in situ by cross-linking reaction of formaldehyde. The adsorption behavior of this new adsorbent to Au(Ⅲ) in aqueous solution was investigated. It was found that the adsorption capacity of this adsorbent to Au(Ⅲ) was Au 1 821.9 mg/g at 303 K when the initial concentration of Au(Ⅲ) was 522.3 mg/L.The optimal pH for the adsorption of Au(Ⅲ) was 4.0, and that higher temperature led to higher adsorption capacity. The adsorption isotherm of Au(Ⅲ) on the immobilized tannin of L.gmelini could be described by the Langmuir equation. The data of adsorption rate could be well fitted by the pseudo-second-order rate model. The breakthrough point of adsorption column was at 117 bed volumes when the inlet concentration of Au(Ⅲ) was 239.2 mg/L, indicating that this adsorbent has outstanding ability of recovering Au(Ⅲ). Further studies indicated that the adsorption mechanism of immobilized tannin of L.gmelini to Au(Ⅲ) was mainly redox adsorption.
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Keywords:
- tannin of L.gmelini /
- bark of L.gmelini /
- in situ immobilization /
- adsorption /
- Au(Ⅲ)
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