Studies On Modification Of Mesoporous MCM-48and Its Performance Of The Separation And Preconcentration For Precious Metals

Precious metals are in great demand, its resource is rare, the price is expensive,and precious metals usually used in national defense, or the high-tech industry. Theirdevelopment, test have a high request, the separation and preconcentration detectionfor trace precious metals are more and more important. The key to the adsorptionmethod of preconcentration and separation of precious metals is to find excellentadsorption materials. Because of mesoporous molecular sieves have large surface areaand their pore structure with rules, Two mesoporous molecular sieves Ti-MCM-48and Al-MCM-48were synthesized and used as adsorption materials in separation andpreconcentration for trace precious metals such as silver, palladium and gold byFlame atomic absorption spectrometry. The methods were accurate、simple and fast.The main contents are as follows:1. The introduction part briefly introduces the practical application of preciousmetals and its resource status, the meaning of the precious metal analysis and theanalysis methods, and all kinds of adsorption materials used in preconcentration andseparation the precious metals. Focus on introducing the adsorp tion application ofmesoporous molecular sieves MCM-48and their modified materials and then putforward the main ideas of this article.2. Mesoporous molecular sieves Ti-MCM-48was synthesized by addingtitanium source, and the product was determined by SEM, BJH and IR. The adsoptioncharacteristics of trace silver on Ti-MCM-48under static condition were studied,FAAS method for the detection. The capacity was2.96mg/g, the linear rang from0.02to5.00μg/mL, with detection limit of21.39ng/mL. And the method applied indetermination of silver in core samples and standard material with satisfactory results.3. The mesoporous molecular sieves Ti-MCM-48glass separation column wasused in the simultaneous separation of gold and palladium. The optimal condition ofadsorbi ng and desorbing gold and palladium were investigated. The two preciousmetals could be totally adsorbed by mesop orous molecular sieves Ti-MCM-48glassseparation column at pH4.0, and the dynamic satu ration adsorption capacities were7.94mg/g and7.12mg/g with detection limit were26.10ng/mL and11.98ng/mL, theRSD were1.39%and1.75%.The method applied in preconcentration and separationgold and palladium in core samples and flame atomic absorption spectrometry（FAAS） for detection.4. The mesoporous Al-MCM-48was synthesized with TEOS and NaAlO2as rawmaterials and CTAB as surfactant. At pH4.6、sampling time100s、flowing rate at2.5mL/min, Ag+was adsorbed quantitatively by mesoporous Al-MCM-48micro colum,then use0.5mol/L HNO₃as elute, at a rate of1.9mL/min, combined Flow injectionwith FAAS for online inspection.The method was applied in determination of silverin core samples with satisfactory results.