Otimização da extração e da destilação molecular do óleo essencial de patchouli

Abstract

One of the biggest difficulties in working with raw materials and inputs from natural sources is meeting the purification standards. In this sense, the study of the extraction and distillation of the essential oil of patchouli was performed, to improve its quality without causing the degradation of its components. First, a comparative study was conducted between the Pogostemon Cablin and Pogostemon Heyneanus species, cultivated in the Brazilian Northeast, through parameter analysis using the hydrodistillation process. The parameters studied were extraction time, volum and pH of the solvent and part of the plant The extraction yield from leaves of P. Cablin was 4.45 times higher than P. Heyneanus. The optimum conditions for extraction from P. Cablin species were: 180 min extraction time, 700 mL solvent volum and extraction from leaves. For P. Heyneanus species, 150 min extraction time, 700 mL extraction volume, and extraction from leaves were the optimal extraction conditions. Chromatographic analyzes revealed that extracts in neutral, acid and basic medium from P. Cablin showed patchoulol percentages of 60.45%, 7.10%, and 61.05%, respectively. While for P. Heyneanus species, the percentages of patchoulol were 14.72%, 13.79%, and 36.06%, respectively. In the study of extraction kinetics, two kinetic models (pseudo first order and nonstationary diffusion) were applied to adjust the experimental data. The variation of two parameters (solute/solvent ratio and heating power) were analyzed on the kinetics. The results showed that the non-stationary diffusion model best described the patchouli essential oil hydrodistillation process. The highest amount of essential oil was obtained at a ratio of 1:23 solute/solvent (g.mL-1 ) and a heating power of 470 W. After optimization of the extraction process, molecular distillation of the oil was performed to obtain fractions rich in patchoulol using Response Surface Methodology (RSM) and Artificial Neural Network (ANN). Three variables were studied: evaporator temperature, condenser temperature, and agitation speed. The optimal conditions obtained by the experimental design were: evaporation temperature of 85 °C, condenser temperature of 10 °C, and agitation speed of 600 RPM. These conditions generated a concentration of 62.344% of patchoulol in the residue, reaching a recovery of 74.22%. The results obtained by ANN have demonstrated good predictability and can be used in conjunction with RSM for modeling the patchoulol enrichment process. The study of the influence of temperature and percentage of patchoulol on the oil viscosity was carried out for the residual streams. It was observed that percentage of patchoulol is one of the factors that influences the viscosity of the samples. The study showed great relevance with possible industrial application, because it promoted the concentration of patchouli oil in patchoulol.