مقاله انگلیسی رایگان در مورد غلظت اسید لاکتیک نسل دوم از تفاله نیشکر – الزویر 2019

Production of lactic acid (LA) from lignocellulosic materials has become increasingly prominent in the market. However, for industrial scale to be reached, several challenges in second-generation lactic acid production must be overcome. Besides obstacles such as the hydrolysis process, one of the major challenges of the lactic acid industry is the separation and purification process. This study evaluates the separation of lactic acid produced from hemicellulose hydrolysate from sugarcane bagasse using a Hybrid Short Path Evaporation (HSPE) system. Results showed that a lactic acid concentration of 3.1 times the feed concentration (27.85 g/L) is achievable. Three operational parameters were studied: evaporator temperature, internal condenser temperature and feed flow rate. Maximum lactic acid concentration was 86.69 g/L with an evaporator temperature of 120 °C, condenser temperature of 13 °C, and feed flow rate of 8.27 mL/min. Separation of LA from hemicellulosic sugars using HSPE was a more difficult process than separation of LA from 6-carbon sugars.

Introduction

Lactic acid (LA) is a high added-value product that has been gaining market share every year [1]. It stands out in the environmental, ecological, and medical areas, especially as a building-block molecule. The use of LA has been common in the food industry for a long time and new uses become available every year [2]. LA production by fermentation has several advantages when compared to chemical synthesis, such as low cost of substrates, relatively low required temperatures, low energy consumption, better environmental traits, high purity [3] and easiness to achieve products with tailor-made characteristics [2]. About 90% of all industrially-produced LA worldwide comes from bacterial fermentation [4]. LA biorefineries can exploit various types of feedstock for obtaining second-generation (2G) LA, for example sugarcane bagasse [5], with many advantages such as employment of cheap and non-food competitive raw materials as substrates in the fermentation process. Brazil is the biggest sugarcane producer in the world. The production of sugarcane bagasse in Brazil (2015/2016) has reached 166.4 million tons [6], making this a substrate of great importance in the biofuel and biochemicals scenario. Downstream processes are decisive for LA industry development. This is especially because in medical and pharmaceutical applications, for example, a high-purity product is often required [7]. It is also necessary to consider environmental issues, with increasingly stringent legislation governing the use of solvents and waste generation, in favor of a sustainable production chain [2]. The traditional LA production chain involves a series of downstream treatments like precipitation, conventional filtration, acidification, carbon adsorption, evaporation, crystallization and others. LA separation and purification require a simpler and cheaper alternative to conventional precipitation process, still achieving high purity and yield. In this sense, Short Path Evaporation (SPE) can be an attractive alternative. Economic feasibility analyses of HSPE have been carried out in a few studies, and in any case the proposed method had fewer separation steps in comparison to conventional LA downstream, allowing for a reduction in equipment and operational costs. Furthermore, industrial interests in the purification of LA via SPE is made abundantly clear by the many published patents [8].