Separation And Application Of The Wastes That Produced During The Production Of M-Dinitrobenzene

m-Dinitrobenzene is an important organic intermediate in the organic chemical industry and is widely used in many fields such as pesticides,dyes,energetic materials and so on.However,the related wastes are often produced during the production process,which will bring serious safety risk to the production and life if there is not properly and promptly processed.The recovery and reuse of the main components of the wastes is of great significance to reduce the potential hazards,reduce environmental pollution and realize the resource utilization of the wastes.In this study,a more comprehensive safety performance and component analysis were carried out on the wastes that produced during the production of m-dinitrobenzene;the appropriate solvents were selected by testing the solubility of the main components in different solvents,and the separation and recovery of the main components were continued to be studied;the applications of the main components were further expanded through molecular design,performance prediction,and experimental exploration.(1)The safety performance of the wastes that produced during the production of m-dinitrobenzene has been studied by DSC,5s burst point,friction sensitivity and impact sensitivity.It can be seen that the wastes have poor thermal stability,with high thermal sensitivity,friction sensitivity,and impact sensitivity.Which shows that the wastes have potential explosion risk and greater safety hazards.The thin layer chromatography,high performance liquid chromatography and other methods were used to analyze the components of the wastes.The structures of the organic components were characterized by X-ray single crystal diffraction,melting point,infrared spectroscopy and so on.It can be concluded that the wastes contain five organic components(p-dinitrobenzene,m-dinitrobenzene,o-dinitrobenzene,2,4,6-trinitrophenol and 2/3 hydrate of 2,4,6-trinitroresorcinol),and some inorganic components such as water,sulfuric acid,and sodium sulfate.The contents of each components are:the average content of water is 26.10%,the average content of SO₄^2-type inorganic substances(H₂SO₄/Na₂SO₄)is 6.28?9.09%,the contents of 2,4,6-trinitroresorcinol hydrate and2,4,6-trinitrophenol are 56.13%and 9.41%,respectively.(2)The solubility of the main organic components of the wastes(2/3 hydrate of 2,4,6-trinitroresorcinol and 2,4,6-trinitrophenol)was measured in six single solvents,and the solubility of 2/3 hydrate of 2,4,6-trinitroresorcinol was measured in three mixed solvent systems by the laser dynamic method.Different solubility models were used to fit the solubility data,and the thermodynamic properties of dissolution were calculated based on the solubility data.According to the comprehensive analysis,it can be seen that toluene,xylene,ethanol-water(x₂=0.63?0.69)and isopropanol-water(x₂?0.73)(x₂ is the mole fraction of organic components in the mixed solvent)are more suitable as the solvents for solution crystallization to separate 2/3 hydrate of 2,4,6-trinitroresorcinol from the mixture of 2,4,6-trinitrophenol and2/3 hydrate of 2,4,6-trinitroresorcinol.The polynomial empirical equation and the Modified Apelblat equation are better equations for fitting the solubility data in the single solvents,while the Van't Hoff equation is a better equation for fitting the solubility data in the mixed solvent systems.And the dissolution of the two substances in the selected solvents is an“endothermic and non-spontaneous”process,and the contribution of enthalpy is greater than that of entropy to Gibbs free energy.(3)The separation process of 2,4,6-trinitroresorcinol hydrate in the wastes was studied by leaching method and cooling crystallization method.Take the yield and purity of the product as indicators to optimize process parameters such as extractant,crystallization solvent,initial temperature,cooling rate,etc.And the optimal separation process conditions are obtained:the separation method is cooling crystallization,the crystallization solvent is toluene,the initial temperature is 90?,the cooling rate is 0.3?/min and twice crystallization.Under this condition,the comprehensive yield of the two crystallizations is 62.1%and the content of 2,4,6-trinitroresorcinol hydrate close to 100%.The separation scheme of 2,4,6-trinitroresorcinol hydrate,which is the main component of m-dinitrobenzene wastes,was proposed,and the recovery rate of 2,4,6-trinitroresorcinol hydrate in the wastes is 73.1%.(4)A series of energetic compounds were designed using 2,4,6-trinitroresorcinol and2,4,6-trinitrophenol as molecular skeletons,and with imino,hydrazine,azo and ether bonds as the connecting units,respectively.The Gaussian09 software package was used to optimize the geometric structure of the target molecules at the B3LYP/6-31G*level,and their molecular structure,stability,detonation performance and safety performance were studied.It can be concluded that the hydrazine group is the better linking group,which helps to increase the energy level and reduce the sensitivity on the basis of 2,4,6-trinitroresorcinol and 2,4,6-trinitrophenol.The preparation of the compound with better properties was experimentally explored,but the preparation of the target compound and the designed series of compounds still need further study.The research results have important application value for the composition analysis,separation,recovery and reuse of the wastes that produced during the production of m-dinitrobenzene,and lay an important foundation for the harm reduction,emission reduction and resource utilization of the wastes.