Reduction of nitrate by zero-valent iron is a highly exergonic reaction that has long been known to occur. Use of scrap iron filings (SIF) as the PRB (Permeable Reactive Barrier) material can be used to recycle certai...Reduction of nitrate by zero-valent iron is a highly exergonic reaction that has long been known to occur. Use of scrap iron filings (SIF) as the PRB (Permeable Reactive Barrier) material can be used to recycle certain by-products, and identify cheaper replacements for expensive conventional PRB materials, especially pure metallic iron. The feasibility of reductive denitrification of nitrate by SIF was studied by batch experiments. Operational parameters such as pH value, SIF dosage and initial concentration of nitrate were investigated. The removal efficiency of nitrate reached 80% under the conditions of pH of 2.5, nitrate initial con- centration of 45 mg/L and SIF dosage of 100 g/L within 4 h. Results indicated that nitrate removal is inversely related to pH. Low pH value condition favors for the nitrate transformation. Different from the results of others who studied nitrate reduction using iron powder, we found that there was a lag time before nitrate reduction occurs, even at low pH. Finally, the possible mechanism of nitrate reduction by Fe0 is discussed.展开更多
An exergy life cycle assessment(ELCA) model based on life cycle assessment(LCA) and exergy methodology was developed to assess a 2×300 MW coal-fired power plant,and the results indicated that the exergy input in ...An exergy life cycle assessment(ELCA) model based on life cycle assessment(LCA) and exergy methodology was developed to assess a 2×300 MW coal-fired power plant,and the results indicated that the exergy input in operation phase of power plant accounts for 99.89% of the total input and only 0.11% in construction and decommission phases. Direct and indirect exergy inputs account for 93.03% and 6.97%,respectively. Compared with coal-fired power generation system before carbon emission reduction,exergy input-output ratio of life cycle "CO2 zero-emission" energy system and exergy efficiency are about 5.563 and 17.97%,respectively,which increases by 62.47% and declines by 11.21% approximately. The model quantifies the energy,resource consumption and pollutant emissions of system life cycle using exergy as the basic physical parameter,which will make the assessment more objective and reasonable.展开更多
基金Project (No. 20407015) supported by the National Natural Sci-ence Foundation of China
文摘Reduction of nitrate by zero-valent iron is a highly exergonic reaction that has long been known to occur. Use of scrap iron filings (SIF) as the PRB (Permeable Reactive Barrier) material can be used to recycle certain by-products, and identify cheaper replacements for expensive conventional PRB materials, especially pure metallic iron. The feasibility of reductive denitrification of nitrate by SIF was studied by batch experiments. Operational parameters such as pH value, SIF dosage and initial concentration of nitrate were investigated. The removal efficiency of nitrate reached 80% under the conditions of pH of 2.5, nitrate initial con- centration of 45 mg/L and SIF dosage of 100 g/L within 4 h. Results indicated that nitrate removal is inversely related to pH. Low pH value condition favors for the nitrate transformation. Different from the results of others who studied nitrate reduction using iron powder, we found that there was a lag time before nitrate reduction occurs, even at low pH. Finally, the possible mechanism of nitrate reduction by Fe0 is discussed.
基金supported by the National Natural Science Foundation of China (Grant Nos.40972102,50936001,51021065)the National Basic Research Program of China ("973" Project) (Grant No.2010CB227003)
文摘An exergy life cycle assessment(ELCA) model based on life cycle assessment(LCA) and exergy methodology was developed to assess a 2×300 MW coal-fired power plant,and the results indicated that the exergy input in operation phase of power plant accounts for 99.89% of the total input and only 0.11% in construction and decommission phases. Direct and indirect exergy inputs account for 93.03% and 6.97%,respectively. Compared with coal-fired power generation system before carbon emission reduction,exergy input-output ratio of life cycle "CO2 zero-emission" energy system and exergy efficiency are about 5.563 and 17.97%,respectively,which increases by 62.47% and declines by 11.21% approximately. The model quantifies the energy,resource consumption and pollutant emissions of system life cycle using exergy as the basic physical parameter,which will make the assessment more objective and reasonable.
