To realize the comprehensive utilization of ludwigite ore,an integrated and efficient route for the boron and iron separation was proposed in this work,which via soda-ash roasting under CO–CO_(2)–N_(2) atmosphere fo...To realize the comprehensive utilization of ludwigite ore,an integrated and efficient route for the boron and iron separation was proposed in this work,which via soda-ash roasting under CO–CO_(2)–N_(2) atmosphere followed by grind-leaching,magnetic separation,and CO_(2) carbonation.The effects of roasting temperature,roasting time,CO/(CO+CO_(2))composition,and Na_(2)CO_(3) dosage on the boron and iron separation indices were primarily investigated.Under the optimized conditions of the roasting temperature of 850℃,roasting time of 60 min,soda ash dosage of 20 wt%,and CO/(CO+CO_(2)) of 10 vol%,92%of boron was leached during wet grinding,and 88.6%of iron was recovered during the magnetic separation and magnetic concentrate with a total iron content of 61.51 wt%.Raman spectra and^(11)B NMR results indicated that boron exists asB(OH)_(4)^(-) in the leachate,from which high-purity borax pentahydrate could be prepared by CO_(2) carbonation.展开更多
Developing transition metal-nitrogen-carbon materials(M-N-C)as electrocatalysts for the oxygen evolution reaction(OER)is significant for low-cost energy conversion systems.Further d-orbital adjustment of M center in M...Developing transition metal-nitrogen-carbon materials(M-N-C)as electrocatalysts for the oxygen evolution reaction(OER)is significant for low-cost energy conversion systems.Further d-orbital adjustment of M center in M-N-C is beneficial to the improvement of OER performance.Herein,we synthesize a single-Mn-atom catalyst based on carbon skeleton(Mn_(1)-N_(2)S_(2)C_(x))with isolated Mn-N_(2)S_(2)sites,which exhibits high alkaline OER activity(η10=280 mV),low Tafel slope(44 mV·dec^(−1)),and excellent stability.Theoretical calculations reveal the pivotal function of isolated Mn-N_(2)S_(2)sites in promoting OER,including the adsorption kinetics of intermediates and activation mechanism of active sites.The doping of S causes the increase in both charge density and work function of active Mn center,and ortho-Mn_(1)-N_(2)S_(2)C_(x)expresses the fastest OER kinetics due to the asymmetric plane.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2020YFC1909803)the Basic Science Center Project for the National Natural Science Foundation of China(No.72088101)the Graduate Research and Innovative Project of Central South University(No.506021739)。
文摘To realize the comprehensive utilization of ludwigite ore,an integrated and efficient route for the boron and iron separation was proposed in this work,which via soda-ash roasting under CO–CO_(2)–N_(2) atmosphere followed by grind-leaching,magnetic separation,and CO_(2) carbonation.The effects of roasting temperature,roasting time,CO/(CO+CO_(2))composition,and Na_(2)CO_(3) dosage on the boron and iron separation indices were primarily investigated.Under the optimized conditions of the roasting temperature of 850℃,roasting time of 60 min,soda ash dosage of 20 wt%,and CO/(CO+CO_(2)) of 10 vol%,92%of boron was leached during wet grinding,and 88.6%of iron was recovered during the magnetic separation and magnetic concentrate with a total iron content of 61.51 wt%.Raman spectra and^(11)B NMR results indicated that boron exists asB(OH)_(4)^(-) in the leachate,from which high-purity borax pentahydrate could be prepared by CO_(2) carbonation.
基金supported by the National Natural Science Foundation of China(No.22075099)the Natural Science Foundation of Jilin Province(No.20220101051JC)the Education Department of Jilin Province(No.JJKH20220967KJ)。
文摘Developing transition metal-nitrogen-carbon materials(M-N-C)as electrocatalysts for the oxygen evolution reaction(OER)is significant for low-cost energy conversion systems.Further d-orbital adjustment of M center in M-N-C is beneficial to the improvement of OER performance.Herein,we synthesize a single-Mn-atom catalyst based on carbon skeleton(Mn_(1)-N_(2)S_(2)C_(x))with isolated Mn-N_(2)S_(2)sites,which exhibits high alkaline OER activity(η10=280 mV),low Tafel slope(44 mV·dec^(−1)),and excellent stability.Theoretical calculations reveal the pivotal function of isolated Mn-N_(2)S_(2)sites in promoting OER,including the adsorption kinetics of intermediates and activation mechanism of active sites.The doping of S causes the increase in both charge density and work function of active Mn center,and ortho-Mn_(1)-N_(2)S_(2)C_(x)expresses the fastest OER kinetics due to the asymmetric plane.
