Study On Purifying Crude Product Of Imidaclaprid And Engineering Data

A large quantity of pesticide is produced and consumed in China. Pesticide industry plays an important role in economy of China. With the updating of pesticide products, traditional pesticide, due to its high toxic residue and poor performance, has been gradually replaced by new generation pesticide which is more friendly to environment and mankind. Imidacloprid becomes a typical representative of the new generation pesticide for which gives due weight to its great efficiency, low toxicity and low residue, and has been developed since the 1990s. Currently, it is one of the new competitive pesticides in the world market. However, the original pesticide of imidacloprid contains huge amounts of intermediates (Imidazolidine) and by-products (NMP) which affect the quality of imidacloprid in the producing process. In the paper, the thermodynamic properties and solid-liquid equilibrium on imidacloprid, imidazolidine and NMP were studied in order to solve the problem of the separation and purification of imidacloprid. In addition, the process of wastewater treatment about imidacloprid was also briefly discussed."Study on purifying of crude product imidaclaprid and engineering data" is a subject of which aims at working out the problem of low purification yield from the crude products of imidaclaprid. In this paper, the process of recrystallization for the imidacloprid is designed according to its the physical and chemical properties and obtained the solubility data in our laboratory previously. The purity of imidaclaprid is analyzed by the melting point method, differential scanning calorimetry and high performance liquid chromtography. The simple physical method that is boiling water is used for transfering the mixed crystallization into a single crystal. Eventually, the purity of products meets the requirements of the factory for the first grade products(over 99%).The standard combustion enthalpy of imidacloprid, imidazolidine and (NMP) was determined by XRY-1C calorimeter, which is -5536.34 kJ·mol^-1, -2017.64 kJ·mol^-1 and -7976.88 kJ·mol^-1 at the standard condition, respectively. The reliability of instrument was tested by comparing experimental value and literature value of naphthalene for the standard combustion enthalpy, the absolute error and the relative error are 4.53 kJ·mol^-1 and 0.088% for them. The standard formation enthalpy of imidacloprid , imidazolidine and NMP is calculated to be 216.21 kJ·mol^-1, -20.38 kJ·mol^-1 and 1790.37 kJ·mol^-1 respectively. The melting point, the melting enthalpy and the thermal capacity were determined by DSC-60 for imidacloprid, imidazolidine and NMP, the melting pointing and the the melting enthalpy are respectively 416.8K, 495.13K, 423.85K and -109.93, -265.55, -102.22 J·g^-1 for above-mentioned substances. In addition, the stability of the imidacloprid, imidazolidine and NMP were mearsured by DTG-60, which showed that the decomposing temperatures were 525.1K,510.3K,450.25K ,saparately. The measured Cp of the nitrogenous organic matters have been expressed as a function of temperature. Thus, the thermodynamics basic data are of sufficient helpful for exploiting new synthesis method, doing engineering design and carring out industry production.The SLE data was measured by laser detection technique which can control the heating-rate. To testify the uncertainty of the method, the solubility of benzoic acid in water was made and compared with the literature values. The results show that the relative deviation of them is less than 2%. The supersaturate data of the binary systems of imidacloprid in ethanol, acetone, 2-butanone, dichloromethane, trichloroethane and pyridyl was measured at temperatures range from 293.15K to 353.15K by variable temperature technique. The crystal metastable zone were investigated for imdacloprid in different solvents. And the solubility data of the binary systems of NMP in water, trichloromethane, 2-butanone, methanol, ethanol, 1,2-dichloroethane and acetone was also measured by using laser detection technique at atmospheric pressure, respectively. The experimental data were also correlated with the Apelblat equation, which have not been resported in the literature. The date fill up the blank of the solid-liquid equilibrium data of the imidacloprid.Solid-Liquid Equilibria data for three groups of binary systems, imidacloprid+imidazolidine, imidacloprid+NMP and imidazolidine+NMP were determined by differential scanning calorimetry. The experimental data of DSC illustrate that the binary systems of imidacloprid + imidazolidine , imidacloprid + NMP, imidazolidine + NMP form the single eutectics, corresponding molar composition (xeu) is 0.4962, 0.4229, and 0.5506 , respectively, and the eutectics temperatures (Teu) is 402.41, 407.46 and 383.13K. The fitted eutectics temperature is402.51K,406.81K and 383.57K by BiPhasice quation T=a+bx₁^c, respectively,and the relative error is 0.0248%,0.16221%,0.1147% for above-mentioned binary systems. Solid-Liquid Equilibria data for the ternary systems of imidacloprid + imidazolidine + NMP was also determined with the same mothod. The result show that the mixture system form the single eutectics and corresponding compositon (xeu) and temperatures(Teu) is 0.3507 and 373.77K, respectively. The fitted value of the single eutectics temperatures is 369.81K. The relative error is 1.0708%. Meanwhile, The experimental data were also correlated with the BiPhasic equation. The results show that using the BiPhasic equation to describe the binary or ternary solid-liquid equilibrium system is better for imidacloprid, imidazolidine and NMP. So it is significative to provide important engineering data for the separation and purification of imidacloprid.It is an effective method for treatment of wastewater of imidacloprid by microwave irradiation. The experimental results illustrate that the concentration of imidacloprid is higher, the removal rate of imidacloprid is greater. The method is simple, convenient, short time, and no secondary pollution, which isn't only used for the treatment of wastewater containing imidacloprid, but also is refered for the treatment of other organic wastwater. Therefore, it is more and more extensive in the field of treatment wastwater.