Selective Separation Of Molybdenum And Rhenium By Using Chemically Modified Rice Husk And Corn Stalk

In this thesis, two kinds of agricultural waste——rice husk and corn straw were used as raw materials to prepare different characteristics of adsorbents. The different chemical modification methods were used according to the main composition (active ingredient:cellulose) in agricultural waste. Thus, seven kinds of biomass adsorbent were prepared. At the same time, the adsorption behaviors of the adsorbents towards molybdenum and rhenium were investigated systematically, such as the adsorption mechanisms、the adsorption properties of thermodynamics and kinetics, which provided abundant fundamental data for the application of biomass-based adsorbents in industry. And the specified studies were as follows:First of all, rice husk was carbonized at different temperatures (500,550,600,650℃), followed with NaOH ash handling, get four adsorbents were collectively named CRH, which had a high selectivity towards molybdenum and rhenium. In addition, the BET showed CRH had a high specific surface area and the PZC value of CRH was9.12, lower than the raw rice husk (9.52). Boehm titration method was used for the determination of pure rice husk and CRH surface acidic functional groups, and the result showed that the surface acidic functional groups had increased after c carbonization, which was consistent with PZC results.Secondly, rice husk and corn straw were processed by the concentrated sulfuric acid to get two adsorbents ORH and OCS, which had high selectivity towards molybdenum with remarkable adsorption amount1.25mol-Mo (VI)/kg and1.45mol-Mo (VI)/kg, respectively, the adsorption process fitted Langmuir isotherm model, the adsorption of Mo (VI) active site is the phenolic hydroxyl group on the surface of ORH and OCS. Additionally, the excellent adsorption characteristics for the recovery of Mo (VI) were confirmed by the adsorption and elution tests using a column packed with ORH (or OCS), up to89%recoveries towards Mo (VI).Thirdly, the OCS was used as raw material to prepare four amino adsorbents with dimethylamine, diethylamine, di-n-octylamineand diisooctyl amine, named after N-OCS. The adsorption behaviors of Mo (VI) towards other coexisting metal ions were studied as well as the adsorption mechanism. In addition, the adsorption process of the actual feed solution molybdenum using a column packed with OCS and with the series connection of DNOA can achieve the90%recovery of the Mo (Ⅵ) and Re (Ⅶ) in the industrial effluents. And all this provided a fundamental research data for the industrial utilization of DNOA-OCS in the long run.