Study On The Conversion Oil Shale Industrial Solid Wastes Into Uranium Adsorbents

With the rapid development of social economy,the non-renewable resources,such as fossil oil and coal are gradually drying up.It is urging to obtain alternative energy sources.Oil shale may be taken as the supplement of conventional energy resources because oil shale possesses the properties of unconventional oil and gas resource and its enormous reserves.If the oil shale were to be enploited,the energy structure of our country may be optimized and the security of national energy may be guaranteed.However,the industrial wastes produced in the enploiting of oil shale have done much harm to the environment.The problems in waste disposing of oil shale have attracted more attention.Mineral ash and semicoke were utilized successfully to synthesize a hydrotalcite-like compounds(HTlc),calcium silicate hydrate,meso-porous silicon and modified silicon-aluminum-carbon materials.The chemical component,structural and morphological properties were characterized by a series of analytical testing techniques and characterization methods.HTlc was prepared via facile sodium roasting activation and extraction of sulfuric acid method.The results showed that the maximum adsorption parameter adsorption process was well followed by Langmuir isotherm model,the adsorption of uranium on HTlc followed the pseudo-second-order rate model and the uranium adsorption on HTlc was found to be endothermic and spontaneous in nature.Comparison with similar adsorbents shows that hydrotalcite-like compound is an effective and economic adsorbent to remove uranium from aqueous solution.The aluminum-silicate minerals from oil shale ash were separated by the microwave-assisted method.After being purified in high temperature calcination,the content of CaO in the white mud is more than 90%.Oil shale ash and white mud were transformed into the raw materials of preparing the adsorbents.The hydrotalcite-like compounds,in which the calcium-aluminum ratios was set to be 2:1,3:1,4:1,5:1,were prepared.Calcium silicate hydrate was synthesized,in which the calcium-silicon ratio is set to be,1.5:1 and 1:1.The results show that calcium silicate hydrate has excellent adsorption ability,the process is endothermic and spontaneous in nature,and the experimental data fit the pseudo-second-order equation and Langmuir model well.Combining use of two kinds industrial wastes can reduce the amount of the chemical reagents in preparation of adsorbents,reducing the generation of the secondary waste.The research results on the structure and performance of the products for different raw material ratios shows that the waste contents can be adjusted in a wide range.It is of great significance to optimize the comprehensive utilization of waste according to the actual amount of waste in the process of waste disposal.The aluminum-silicate-carbon minerals from oil shale semicoke were separated in the microwave-assisted and acid/alkali extracting methods.By using P123 as the template agent,the mesoporous silica materials were prepared.The results show that mesoporous silica materials exhibit a very good recycling performance,the process is endothermic and spontaneous in nature,and the experimental data are fitted well by a pseudo-second-order equation and Langmuir model.By microwave-assisted and acid-oxidation method,oil shale semicokes were modified.The yield of modified product by sulfuric acid oxidation was 97.25%.Hydroxyl groups and carboxyl groups are mainly contained in the product,which can significantly decreased the concentration of uranium in high concentration waste liquid.With the increasing of nitric acid content,the oxidation ability to oil shale semicoke was significantly improved,which increases uranium ion coordination sites,and improves the absorption efficiency.The removal rate of 100mg/L uranium solution reachs up to 87%when the volume ratio of sulfuric acid and nitric acid was set to be 1:1 in modifying the semicoke.In this paper,all the products were prepared from oil shale ash and semicoke which establish an important base for the resources,harmless,functional and engineering utilization of oil shale industry waste,and provide technical support for the rapid and sustainable development of oil shale industry in China.