TRPO萃淋树脂从碱性氰化液中固相萃取Au(Ⅰ)机理研究

Mechanism of Gold Solid Extraction from Aurocyanide Solution Using D3520 Resin Impregnated with TRPO

研究了TRPO-D3520萃淋树脂从碱性氰化液中固相萃取Au(CN)-2的性能,并借助傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和扫描电镜(SEM)等方法对固相萃取Au(Ⅰ)的机理进行了讨论。结果表明:阳离子表面活性剂CTMAB在固相萃取中起到了关键的作用,当待萃水相中加入的CTMAB与Au(CN)-2的摩尔比达到1∶1时,TRPO-D3520萃淋树脂即对金具有良好的萃取性能;萃淋树脂负载金后,FTIR分析表明Au(CN)-2中的C≡N伸缩振动吸收峰位于2 144cm-1,TRPO中的PO伸缩振动峰由1 153cm-1向低频移至1 150cm-1;N(1s),Au(4f7/2)和Au(4f5/2)XPS谱揭示了树脂中金的价态和配位环境未发生变化,仍以Au(CN)-2形态存在于萃淋树脂中;O(1s)XPS谱图表明,经固相萃取后,树脂中化学结合水的含量明显增加,化学结合水的峰面积由30.74%增加至42.34%;固相萃取后,P(2p)XPS谱图峰位由132.15eV增加至132.45eV,说明PO基团与水分子存在一定的氢键作用,生成P=O…H—O—H。综上可推测,TRPO-D3520树脂固相萃取Au(CN)-2的过程为:[CTMA+·Au(CN)-2]离子对扩散至树脂孔内,被孔内的TRPO借助水分子为桥的氢键作用溶剂化而固相萃取。

Trialkyphosphine oxides （TRPO） was successfully used for the impregnation of D3520 resin to prepare an extractant-impregnated resin （EIR）. Solid extraction of Au（Ⅰ） from alkaline cyanide solution was studied using this extractant-impregna-ted resin （EIR） ,with addition of cetyltrimethylammonium bromide （CTMAB） ,directly into the aurous aqueous phase in ad-vance. The mechanism of solid extraction was further investigated by means of FTIR ,XPS and SEM. The column separation studies have shown that cationic surfactant CTMAB played a key role in the solid phase extraction ,and the resin containing TR-PO were effective for the extraction of gold when the molar ratio of CTMAB ：Au（Ⅰ） reached 1：1. FTIR spectroscopy of gold loaded EIR showed that the frequency of C≡N stretching vibration was at 2144 cm-1 ,and the frequency of PO stretching vibration shifted to lower frequency from 1153 to 1150 cm -1. The XPS spectrum of N （1s） ,Au（4 f7/2 ） and Au（4 f5/2 ） sugges-ted that the coordination environment of gold did not change before and after extraction ,and gold was still as the form of Au （CN）2- anion exiting in the loaded resin ;O（1s） spectrum showed that the chemically combined water significantly increased after solid extraction from 30.74% to 42.34% ;Comparing to the P（2 p） spectrum before and after extraction ,the binding energy in-creased from 132.15 to 132.45 eV ,indicating there maybe existing hydrogen-bond interaction between PO and water mole-cule ,such as P=O… H-O- H. The above results obtained established that in the solid extraction process ,the hydrophobic ion association [CTMA＋ ＆#183; Au（CN）2-] diffused from the bulk solution into the pores of the EIR ,and then be solvated by TRPO ad-sorbed in the pores through hydrogen bonding bridged by the water molecules.