| SCR combined with limestone-gypsum method is a technology mainly adopted in power stations in China to treat smoke pollutants.However,the secondary pollution to the environment,caused by the concentration of desulphurizing slurry and heavy metals in wet desulphurization,is increasingly serious.Based on the Natural Science Foundation of Jiangsu Province(BK20161558),this paper aims to study the effects of graphene oxide composites on the accumulation and migration of mercury ions in desulfurization slurry and the removal mechanism,to investigate and optimize the preparation process of the composites and to characterize the physical and chemical properties of graphene oxide composites.As a result,the effects of physical and chemical properties and removal process conditions on the mercury ion adsorption and removal characteristics of desulfurization slurry are obtained,which provides a basis for the harmless treatment of desulfurization slurry in thermal power plants.In this paper,the hydrothermal method was employed to prepare EDTA-GO and TMT15@GO under different working conditions.FTIR,XRD,DTG-TG,SEM,wettability analysis,XPS,BET and TEM were used to characterize and analyze the physical and chemical properties of the composite graphene oxide.The results exhibit that the oxygen-containing groups of EDTA-GO show an obvious rise,and the vibration of C-O lattice is enhanced;the thermal stability of EDTA-GO is better than that of GO and TMT15@GO at the same temperature range;the contact angle of EDTA-GO is larger than that of GO and TMT15@GO and has better dispersion;and the modification of EDTA also promotes the improvement of the pore properties of GO.Based on graphene oxide-based materials,the optimal preparation experiments of EDTA-GO composites were carried out,and the optimum preparation process and parameters were obtained:the time of preparation should be controlled as 6 hours or 24 hours,and the pore structure of EDTA-GO was better under this condition.The preparation temperature exerted no substantial effect on the modification of GO by EDTA.The addition and modification amount of EDTA should be controlled to an excess of 2ml with 1000 mg GO,to obtain the optimal pore structure and morphology of the adsorbent and the adsorption efficiency in the desulfurization slurry.With the EDTA-GO prepared under optimized conditions,the adsorption experiments of Hg2+in desulfurization slurry were carried out on a cyclotron oscillator with different graphene-based materials.The effects of initial pH value,initial temperature,coexisting ions,initial Hg2+concentration and preparation parameters on the removal characteristics of Hg2+were obtained.The experimental results show that pH has a great influence on adsorption efficiency,and both strong acid and strong alkali environment show a inhibition effect.The best performance of adsorption efficiency is around pH=8;with the increase of adsorbent concentration,the adsorptive efficiency increases first and then tends to be stable.The adsorption process of Hg2+by EDTA-GO is endothermic,and the higher the temperature,the better the adsorption process.With the increase of chloride ion(Cl-)and sulfite ion(SO32-)concentration in desulfurization slurry,the adsorption efficiency of EDTA-GO is inhibited.According to the experimental data,the adsorption kinetics and thermodynamic analysis of mercury in desulfurization slurry by modified graphene composites were carried out The results show that physical and chemical adsorption influence synergistically the adsorption of the heavy metal-Hg2+in which chemical adsorption played a leading role.Sips thermodynamic adsorption model is more consistent with the process of EDTA-GO's adsorption of Hg2+in desulfurization slurry,which indicates that there is a multiphase site adsorption and multi-molecular layer overlay adsorption in the adsorption process.?G was negative,showing that EDTA-GO absorbs Hg2+in the slurry in a spontaneous way.The adsorption driving force increases directly with the increase in the absolute value of ?G,the better the adsorption efficiency. |
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