Extraction of levodopa from mucuna pruriens seed using water in fixed bed column

The objective of this research is to determine the overall volumetric mass transfer coefficient (K_ca) on the extraction of levodopa (L-dopa, L-3,4-dihydroxyphenylalanine) from mucuna pruriens seed using water as solvent in fixed bed column. The parameters studied in this research were solvent (water) flow rate and particle diameter. The effect of those two parameters on the values of K_ca were studied. The research was carried out in three steps, i.e., seed preparation, extraction process, and results analysis. In the seed preparation step, mucuna pruriens seed was cleaned and sieved to separate solid particles by size. Before being used in the extraction process, the solid particles of seed was dried to attain the moisture content of about 8.8%. The extraction process was carried out by filling the extraction column of 30 mm in diameter and 300 mm in height with solid particle of seed of certain particle diameter. Then water as solvent with a fixed flow rate was flowed from a 5 liters water reservoir pass through seed bed in the column. Water containing with the extracted levodopa then be recycled to the reservoir. The levodopa concentration in the reservoir was analysis using high performance liquid chromatography in every 10 minutes interval until one hour of the extraction process. The results showed that the K_ca values increased with decreasing the particle diameter of seed for a fixed water flowrate and the K_ca is also increased with increasing water flow rate for a fixed particle diameter of seed. In this experimens, the K_ca values were ranged from 0.0273 to 0.0364 with the unit of 1/minute. The relationship between the K_ca and the influenced parameters is expressed as follows with the relative mean error of 0.05%. k_ea.p.d_φ²/μ=3,28.10^-8(p.v.D_φ/μ)^0.71. The equation is valid for the range of solvent - low rate of 2.25 cm³/s to 10.75 cm³/s and range of particle diameter of 1.08 mm to 4.33 mm. D_p is the particle diameter (cm), ν is the liniar velocity of solvent (cm/s), ρ is the solvent density (g/cm³), and μ is the solvent viscocity (g/cm·s).