B.H. Lunelli

Poly-lactic acid synthesis for application in biomedical devices — A review

Bioabsorbable polymers are considered a suitable alternative to the improvement and development of numerous applications in medicine. Poly-lactic acid (PLA,) is one of the most promising biopolymers due to the fact that the monomers may produced from non toxic renewable feedstock as well as is naturally occurring organic acid. Lactic acid can be made by fermentation of sugars obtained from renewable resources as such sugarcane. Therefore, PLA is an eco-friendly product with better features for use in the human body (nontoxicity). Lactic acid polymers can be synthesized by different processes so as to obtain products with an ample variety of chemical and mechanical properties. Due to their excellent biocompatibility and mechanical properties, PLA and their copolymers are becoming widely used in tissue engineering for function restoration of impaired tissues. In order to maximize the benefits of its use, it is necessary to understand the relationship between PLA material properties, the manufacturing process and the final product with desired characteristics. In this paper, the lactic acid production by fermentation and the polymer synthesis such biomaterial are reviewed. The paper intends to contribute to the critical knowledge and development of suitable use of PLA for biomedical applications.

A New Process for Acrylic Acid Synthesis by Fermentative Process

With the synthesis of chemical products through biotechnological processes, it is possible to discover and to explore innumerable routes that can be used to obtain products of high added value. Each route may have particular advantages in obtaining a desired product, compared with others, especially in terms of yield, productivity, easiness to separate the product, economy, and environmental impact. The purpose of this work is the development of a deterministic model for the biochemical synthesis of acrylic acid in order to explore an alternative process. The model is built-up with the tubular reactor equations together with the kinetic representation based on the structured model. The proposed process makes possible to obtain acrylic acid continuously from the sugar cane fermentation.

Real-time optimization for lactic acid production from sucrose fermentation by Lactobacillus plantarum

Abstract A great obstacle in the lactic acid fermentative process is the inhibition of the growth cell by final product as well as by substrate high concentration. A highly efficient process can be developed from a continuous fermentative process with low feed rate of substrate and continuous removal of product. In this work, an investigation study of the optimization and optimal control of operational parameters of a continuous fermentative process for lactic acid production from sucrose is presented. The general idea is to develop suitable tools for defining the optimal operational condition or the set points in the optimization layer in order to obtain an efficient process for lactic acid production. This is in fact a realt-time optimization procedure that should be able to avoid cell growth inhibition and increasing the final concentration of the product. The results show that it is possible to run the system at the best operating conditions, and a highly efficient process for lactic acid production from the sucrose fermentation can be obtained.

The Effect of Evaporator Temperature on Lactic Acid Purity and Recovery by Short Path Evaporation

In this work, the evaluation of lactic acid concentration from a synthetic mixture of water and lactic acid (3 wt% of lactic acid) was carried out using short path evaporation (SPE). The evaporator temperature of a SPE is one of the important technological parameters that determine an evaporator’s operation. In this study, the effect of the evaporator temperature on the lactic acid purity and recovery was observed from 303 to 443 K. The results showed that, in the studied range, the evaporator temperature of 353 K can be regarded as the best, since an increase of 2.15 times in the solution concentration was obtained.

Syngas production from sugar cane bagasse in a circulating fluidized bed gasifier using Aspen Plus™: Modelling and Simulation

The gasification of the sugar cane bagasse produces synthesis gas (syngas) in which CO and H2 are the essential components. The composition of producer gas depends on the types of gasifier and the gasification conditions among others. This work is developed by using the model of biomass gasification in a circulating fluidized bed gasifier using the ASPEN PLUS simulator. The Gibbs free energy minimization method was used to predict the composition of the produced gas. The influence of operating conditions as temperature, equivalence ratio (ER), and steam injection on gasifier performance are investigated. The model predicts syngas composition, heating values and conversion efficiency in good agreement with published experimental data.

Kinetic Modeling and Parameter Estimation in a Tower Bioreactor for Bioethanol Production

In this work, a systematic method to support the building of bioprocess models through the use of different optimization techniques is presented. The method was applied to a tower bioreactor for bioethanol production with immobilized cells of Saccharomyces cerevisiae. Specifically, a step-by-step procedure to the estimation problem is proposed. As the first step, the potential of global searching of real-coded genetic algorithm (RGA) was applied for simultaneous estimation of the parameters. Subsequently, the most significant parameters were identified using the Placket–Burman (PB) design. Finally, the quasi-Newton algorithm (QN) was used for optimization of the most significant parameters, near the global optimum region, as the initial values were already determined by the RGA global-searching algorithm. The results have shown that the performance of the estimation procedure applied in a deterministic detailed model to describe the experimental data is improved using the proposed method (RGA–PB–QN) in comparison with a model whose parameters were only optimized by RGA.

A computer tool for the development of poly(lactic acid) synthesis process from renewable feedstock for biomanufacturing

Abstract The advances in medicine and engineering to treat loss or bad function of organs or tissues have motivated the development of biomaterials and techniques for biomanufacturing to improve life quality. Among these biomaterials (biopolymers), the poly(lactic acid) (PLA) has received significant attention. PLA is produced from lactic acid, a product that can be obtained by fermentation of sugars from renewable sources such as sugarcane and corn. PLA is thermoplastic and high strength material, and it is degraded in the body by simple hydrolysis of the ester at a rate that can be controlled. PLA and its copolymers are being used in the medical field in the form of implants or devices due to its excellent biocompatibility and biodegradability. PLA is a versatile polymer which can be produced with a wide spectrum of properties. It is extremely difficult to, experimentally, find out the optimal values of the many variables to achieve the required properties, since it is time consuming and expensive. Bearing this in mind, this work aims to simulate the PLA synthesis process from renewable feedstock in a commercial simulator (ASPEN PLUS®) identifying the polymer properties relation with operational conditions to obtain a final product with desired characteristics.

Study of Lactic Acid Thermal Behavior Using Thermoanalytical Techniques

Actually, there is a growing interest in the biotechnological production of lactic acid by fermentation aiming to substitute fossil fuel routes. The development of an efficient method for its separation and purification from fermentation broth is very important to assure the economic viability of production. Due to its high reactivity and tendency to decompose at high temperatures, the study of lactic acid thermal behavior is essential for its separation processes and potential application. In the present study, differential scanning calorimetry (DSC) analyses showed endothermic peaks related to the process of evaporation. Data of thermogravimetry (TG/DTG) were correlated to Arrhenius and Kissinger equations to provide the evaporation kinetic parameters and used to determine the vaporization enthalpy. Activation energies were 51.08 and 48.37 kJ·mol−1 and frequency values were 859.97 and 968.81 s−1 obtained by Arrhenius and Kissinger equations, respectively. Thermogravimetry, coupled with mass spectroscopy (TG-MS), provided useful information about decomposition products when lactic acid was heated at 573 K for approximately 30 min.

Analysis of Kinetic and Operational Parameters in a Structured Model for Acrylic Acid Production through Experimental Design

In biotechnological processes, a great number of factors can influence the income productivity and conversion. Normally, it is not evident which of these factors are the most important and how they interact. In this work, multivariate analysis techniques are used as experimental design coupled to a detailed deterministic model to identify the parameters with the most significant impact on the model to represent well the acrylic acid production process. It is proposed as an alternative process, having sugarcane as feedstock, to the petrochemical-based ones that have significant environmental impacts for their production. To increase the competitiveness of renewable acrylic-acid-based process, it is necessary to find out working conditions near the optimal region, which is not an easy task, as the process is multivariable and non-linear. The mapping of the dynamics of the developed process is made using techniques of factorial design together with the methodology of Plackett–Burman. It is shown that it is possible to increase the process performance by choosing optimized conditions for the reactor operation.