Study On Mg-al Layered Double Hydroxide And Its Calcined Products Purification Of Gossypol In Cottonseed Meal

In this paper,gossypol extract from cottonseed meal as the object,gossypol was separated and purified with hydrotalcite like compounds.The adsorption and elution properties of Mg-Al hydrotalcite like compounds and its calcined products of gossypol were studied.Based on the results of FT-IR,XRD and XPS before and after adsorption,combined with thermodynamic parameters,the adsorption mechanism was analyzed.This study provides a new adsorbent for gossypol purification,and has laid a theoretical basis for the gossypol separation and purification from cottonseed meal extract by hydrotalcite like compounds.The results are as follows:1 Preparation and characterization of hydrotalcite and its calcined products.Mg-Al hydrotalcite was prepared by co-precipitation method,and calcined hydrotalcite was obtained by roasting at 500?.The results of FT-IR and XRD show that the hydrotalcite has the infrared absorption peak and phase structure,with high purity of the crystal.The specific surface area increased after calcination.2 Study on static adsorption and desorption of gossypol by calcined hydrotalcit.The adsorption of gossypol by calcined hydrotalcite accords with pseudo-two-order kinetics equation,and thermodynamics accords with Freundlich model.The optimum conditions for the adsorption of gossypol by calcined hydrotalcite used by response surface methodology were: PH 5,adsorption time 11 h,adsorption temperature 52?.Under these conditions,the adsorption capacity was as high as 68.79mg/g.The best static elution conditions were ethanol volume fraction of 90%,eluent dosage 0.75L/g,elution time 14 h,elution rate of up to 65.12%.3 Study on the adsorption mechanism of hydrotalcite and calcined hydrotalcite.The thermodynamic parameters of the adsorption process were small,and the enthalpy change is range from 0 KJ/mol to 20 KJ/mol.This was speculated that the adsorption process was the physical adsorption of hydrogen bonds and dipole interactions.XRD analysis showed that the adsorption on the surface,FT-IR,XPS results show that the existence of hydrogen bonding interactions,combined with the effect of p H,indicating that the adsorption mechanism as follows: the main function of hydrotalcite is hydrogen bonding,which is accompanied by electrostatic and dipolar interactions.The main components of calcined hydrotalcite are electrostatic adsorption,accompanied by hydrogen bonding and dipole interaction.4 The dynamic adsorption and desorption result of calcined hydrotalcite as follow:the sample concentration 0.2mg/m L,sample speed 1.5BV/h.The maximum adsorption capacity was 68.68mg/g.The elution rate of 90% ethanol solution was 0.5BV/h,and the elution volume was 84 m L.5 The purity of gossypol acetic acid was 86.06% by HPLC analysis.The infrared spectrum of the product and the UV absorption peak were basically the same as the standard sample.There was 1.28% of residual aluminum and magnesium in the product.Thermal regeneration for re-use of c LDH4 after gossypol sorption was feasible within the first three cycles.