开氏法测定煤中氮含量的消解条件改进研究OA

To explore the use of potassium sulfate and copper sulfate as catalysts to replace the current national stand⁃ard's Kjeldahl method for coal nitrogen determination,this study conducted sample digestion experiments with cata⁃lyst dosage,concentrated sulfuric acid dosage,digestion temperature,and digestion time as variables.Through sin⁃gle⁃factor experiments and orthogonal experiments,six coal samples with varying degrees of metamorphism were tested to determine optimal digestion conditions.The single⁃factor experiment results showed that the optimal catalyst dosage was 5 g,the optimal concentrated sulfuric acid dosage was 6 mL～10 mL,the optimal digestion temperature was 420℃,and the optimal digestion time was 120 min～240 min.The orthogonal experiment results indicated that the influ⁃ence order of factors on coal sample digestion was:digestion temperature>concentrated sulfuric acid dosage>catalyst dosage>digestion time.Both digestion temperature and concentrated sulfuric acid dosage significantly affected the measurement results,while catalyst dosage and digestion time showed minimal impact.Combining the single⁃factor and orthogonal experiment results,when 0.2 g coal sample was weighed and 5 g potassium sulfate and copper sulfate(as catalysts)along with 8 mL concentrated sulfuric acid were added,digestion at 420℃for 120 minutes achieved the best digestion efficiency,yielding accurate nitrogen content measurements for all samples.