Study On The Regenerable Sulfur-resistant Sorbent For High Efficiency Removal Of Mercury From Nonferrous Smelting Flue Gas

Mercury is one of the most world widely concerned pollutants because of its toxicity,bioaccumulation and persistence in the environment.the Minamata Convention on Mercury came into force on 16 August 2017in order to protect huaman health and the environment from the pollution of mercury,which indicated that the world has taken an important step to reduce mercury emissions and control the mercury pollution.The mercury emissions from nonferrous metal smelting flue gas was considered as one of the primary sources among the anthropogenic sources.The sorbent used to removal mercury from nonferrous metal smelting flue gas faced some questions:the sorbents were poor at the resistant of SO₂;the mercury capacity of sorbents were low and sorbents could not be recycled.Study on the regenerable sulfur-resistant sorbents for high efficiency removal of mercury from nonferrous metal smelting flue gas was carried out to solve those questions.The primary research contens and conclutions are summarized as follows:The related research about the cobalt sulfide S-2 we synthesized has been carried out.The main research contents and results summaried as follows:cobalt sulfide S-2 has the maximum mercury removal efficiency at 100 ^oC;the results shown that O₂,SO₂,H₂O and NO had negligible impact on mercury adsorption of sorbents,cobalt sulfide S-2 posed excellent resistant of SO₂;the emormous mercury adsorption capacity of S-2 at 100 ^oC with 50%breakthrough threshold was 43.03mg/g;the mercury desorption activation energy of S-2 calculated based on a model built by the mercury temperature-programmed desorption data was63.9kj/mol;the used sorbents were regenerated after treating by hot sulfur solution;the sorbents showed highly mercury removal efficiency after 5cycles of adsorption,desorption and regeneration.Most of the mercury could be recovered by a simple mercury temperature-programmed desorption treatment.We considered that the Co³⁺in S-2 played an important role in the removal of mercury based on series of characterization and experimental data when we studied on the mercury removal mechanism.We synthesized Co-Fe composite sulfide used Fe²⁺to modify cobalt sulfide S-2 in order to improve the mercry removal performance.The main research contents and results summaried as follows:the doping of Fe²⁺to S-2 could greatly improve the mercury removal performance of material,Co-Fe composite sulfide showed optimum mercury removal performance when the Co/Fe mole ratio was 0.9:0.1;Co_0.9Fe_0.1S_y has the maximum mercury removal efficiency at 100 ^oC;the results shown that O₂,SO₂,H₂O and NO had negligible impact on mercury adsorption of sorbent,Co_0.9Fe_0.1S_y posed excellent resistant of SO₂;the emormous mercury adsorption capacity of Co_0.9Fe_0.1S_y at 100 ^oC with 50%breakthrough threshold was 85.5mg/g;the mercury desorption activation energy of Co_0.9Fe_0.1S_y calculated based on a model built by the mercury temperature-programmed desorption data was 54.94kj/mol;the used sorbent was regenerated after treating by hot sulfur solution;the sorbent showed highly mercury removal efficiency after 5 cycles of adsorption,desorption and regeneration.Most of the mercury could be recovered by a simple mercury temperature-programmed desorption treatment.We considered that Co³⁺,Co⁰ and Fe³⁺in Co_0.9Fe_0.1S_y may have worked for the Hg⁰ removal based on series of characterization and experimental data when we studied on the mercury removal mechanism.The cobalt sulfides and its modified material showed huge mercury capacity,highly efficient mercury removal and excellent resistant of SO₂in this study.The study have solved the problem of sorbents at present and supplied a guidance for the research work on follow-up materials,the sorbents we synthesized have certain application prospects.