J. Fund. Appl. Chem. Eng., 2023, 4 (1), 9-12 eISSN 2964-710X Purification of Lactic Acid Using Alkaline Precipitation Followed by Reactive Distillation Tri Widjaja 1,* , Siti Nurkhamidah 1 , Ali Altway 1 , Atha Pahlevi 1 , Bayu Yusuf Eka Saputra 1 , Aisyah Alifatul Zahidah Rohmah 1 I. INTRODUCTION 1 actic acid (LA) is a carboxylic acid with the molecular formula (CH3CHOHCOOH). Lactic acid has two isomeric forms, namely L (+) or D (-) lactic acid, which is an organic acid that belongs to multifunctional acids and is often used in the cosmetic, food, chemical and pharmaceutical industries. Lactic acid can be applied commercially in the biodegradable polymer industry. Given its wide use, it is hoped that through this research a lactic acid industry in Indonesia can be developed. Lactic acid can be made from various sources that contain carbohydrates. Various types of plants or agricultural waste containing cellulose can be used as raw material for lactic acid. production of environmentally friendly PLA (Poly Lactic Acid) biopolymers. PLA can be degraded by nature for 6 months - 2 years, much faster than polystyrene (PS) and polyethylene (PE) which take 500-1000 years for the process of degradation by the environment. The production of PLA requires lactic acid with pure isomers as its raw material, therefore the process of producing lactic acid through biological fermentation pathways is preferred over through chemical synthesis processes that produce mixed (racemic) lactic acid. The separation process is a process that is commonly carried out in the purification process. Precipitation is a conventional method to separate lactic acid from fermentation. Precipitation is carried out in 2 stages, 1 Department of Chemical Engineering, Institut Teknologi Sepuluh Nopember, Surabaya 60111, Indonesia. *E-mail: triw@chem-eng.its.ac.id namely neutralization and acidification. In the process of neutralizing the fermented solution, bases such as Ca(OH)2 are added; NaOH and KOH to precipitate specific lactic acid. Furthermore, the acidification process is carried out by adding acids such as sulfuric acid to take back the precipitated lactic acid. Distillation of a raw fermented mixture can produce very pure LA. This is an effective method for separating LA from other organic acids. The reactive distillation process is a chemical process in which the chemical reaction and the distillation process are carried out in one unit. In reactive distillation, LA forms esters with lower alcohols such as methanol and ethanol with an acid catalyst. Esters have much lower boiling points than LA. Therefore, separation can be achieved by distillation. Seo et al. studied the effect of operational variables, such as catalyst concentration, reactant-lactic acid:methanol mole ratio, feed concentration, type of alcohol (methanol, ethanol and 2-propanol) and partial condenser temperature, on yield. The yield of lactic acid obtained reached 90%. In addition, the yield of lactic acid will increase with the increase in the concentration of the catalyst in the esterification section and the mole ratio of the reactants and the concentration of lactic acid in the feed decreases [1]. In addition, Kumar et al. studied the effect of catalyst charge, mole-lactic acid : methanol ratio, boil- up rate, and feed concentration. The experimental results L Abstrak⎯ Lactic acid (LA) can be applied commercially in the biodegradable polymer industry. The production of PLA biopolymers requires lactic acid with pure isomers as its raw material, therefore the process of producing lactic acid through biological fermentation pathways is preferred over through chemical synthesis processes that produce mixed (racemic) lactic acid. In general, lactic acid purification process is carried out by several methods including precipitation and distillation. Precipitation is a conventional method for separating fermented lactic acid which is carried out through 2 stages, namely neutralization and acidification. In the process of neutralizing the fermented solution, base is added to precipitate specific lactic acid and then an acidification process is carried out by adding acid to take back the precipitated lactic acid. Distillation of a raw fermented mixture can produce very pure LA. This is an effective method for separating LA from other organic acids. The reactive distillation process is a chemical process in which the chemical reaction and the distillation process are carried out in one unit. In reactive distillation, LA forms esters with alcohols in the presence of an acid catalyst. Esters have much lower boiling points than LA. Therefore, separation can be achieved by distillation. In this research, the lactic acid purification process was carried out by combining the precipitation process followed by the distillation process. The lactic acid solution obtained from the precipitation process is then mixed with Received April 17, 2023; Revised July 04, 2023; Accepted September 28, 2023 DOI: 10.12962/j2964710X.v4i1.14672 Kata Kunci⎯ Alkaline precipitation, Reactive distillation, Lactic acid, Ethanol JFAChE Journal of Fundamentals and Applications of Chemical Engineering iptek.its.ac.id/index.php/ekstrak Article 9