Optimization of Lactide synthesis from Lactic Acid in biorefinery of palm oil waste using Response Surface Methodology

Ring open polymerization is one of the production polylactic acid by formation of monomer before. Lactic acid is converted into lactide in two stages, polycondensation and depolymerization. Yield lactide will determine the molecular weight which produced. This study is to optimize the lactide production from lactic acid 90% by the variations of temperature (190-220°C), vacuum pressure (5-15 cmHg), and zinc acetate catalyst (0,3-0,6% w/w). As the temperature, vacuum pressure, and catalyst is increased, lactide that is produced also increases. Optimum condition of lactide production is obtained by Response surface methodology at the temperature 220°C, catalyst 0,45%w/w, and 10 cmHg in vacuum pressure. Equation or model from this study by using RSM is yield lactide = -258,75 + 7,79A + 2,90B + 3,51C + 0,48AB - 0,06AC – 3,97x10^-3BC – 105,42A² – 7,17B²– 0,10C²(A:catalyst; B:temperature; C:pressure). (paper)