Recycling And Utilization Of Co-production Of Ammonium Chloride And Catalyst Silver Sulfate By Propyzamide

Propyzamide,known as 3,5-dichloro-N-?1,1-dimethylpropargyl?benzamide,is a widely used herbicide.In the production of propyzamide,ammonium chloride is co-produced,taking Ag₂SO₄ as catalyst.According to the production practice and relevant literature,the co-production of ammonium chloride contains a small amount of organic matter,so it cannot be used directly.Moreover,Ag₂SO₄ catalyst will also be substituted into ammonium chloride,resulting in the loss of Ag₂SO₄ catalyst.Therefore,in order to improve economic benefits and meet the requirements of environmental protection,this paper mainly studied the quantitative analysis method and removal method of organic matter content from the co-production of ammonium chloride.Moreover,the quantitative analysis method of Ag⁺content in ammonium chloride,the recovery method of Ag and the preparation method of elemental Ag from Ag₂SO₄ were also performed and investigated.Organic matter resulting from co-production of ammonium chloride was measured by firstly using organic solvent elution out of organic material,and then analyzed by both gas chromatography and reversed-phase high-performance liquid chromatography,The results showed that the main organic matter was 3-amino-3-methyl butyl acetylene?denoted as butyne ammonia?and the content detected by aforementioned methods was 131.35 g butyne ammonia/ton ammonium chloride,131.16 g butyne ammonia/ton ammonium chloride,respectively,indicating that the relative standard error of the chromatographic analysis results are both within0.36%,the gas and liquid phase analysis error is 0.14%and thus the analysis methods being reliable.For the analysis of Ag⁺content of Ag₂SO₄ catalyst in ammonium chloride,Ag₂SO₄ in ammonium chloride was firstly converted into precipitates such as Ag₂S.Then,atomic absorption spectrophotometry and chemical analysis were established to measure Ag⁺content in the precipitate.The results showed that Ag⁺content detected was 46.41%,and the relative standard error of the analytical results was all within 1.20%and thus analytisis method being reliable.In order to further confirm the content of organic compounds in ammonium chloride,the total organic carbon of ammonium chloride was analyzed and the sample solution of ammonium chloride was directly determined by TOC analyzer.The analysis results showed that the total organic carbon was 95.09g/ton ammonium chloride and the converted content of butyne ammonia was 131.78 g butyne ammonia/ton ammonium chloride,which was consistent with the above results.The performance of activated carbon adsorbing organic matter in the ammonium chloride,was investigated.The resulats manifested that under the conditions of the quality of the ammonium chloride samples high than 1:30,adsorption temperature at20?,time for 30 min,activated carbon was able to completely adsorb organic carbon from ammonium chloride.In the production process of propyzamide,the catalyst Ag₂SO₄ bringing into the co-production of ammonium chloride was recovered,and Na₂S was used as the anionic precipitation solvent to generate Ag₂S precipitation.Ag in Ag₂S and other precipitates might be recovered by calcining and reduction methods.Calcination method for step:the Na₂CO₃,borax,Fe powder,Ag₂S samples was uniformly mixed in accordance with the quality ratio 5:2:6:7 and then calcined at 1000?for 2 h.The preparation of thick silver with 98.02%purity was obtained and Ag recovery reached to 95.35%.One of reduction methods was followed the steps that Ag₂S was firstly converted to AgCl and then reduced by H₂.The results showed that when the control tube furnace reduction temperature at 360⁴00?,ventilation with H₂ reduction 30min,thick silver with 99.89%purity was obtained and Ag recovery was 99.09%.Another reduction method was to convert Ag₂S into AgCl and added PVP-K30 to form AgCl sol,which was reduced by ascorbic acid to elemental Ag.The results showed that when the pH value of the reaction solution was adjusted to 9¹2 and the AgCl sol was reduced by ascorbic acid under dark conditions for 4 h,silver nanoparticles with different sizes and crystal types could be obtained.