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In this work, various electrochemical cells were developed from carbons recovered from mechanical seal carbons, electric motor brush carbons (MBC) and AA battery carbons (BC). After the different types of carbons were conditioned, three electrooxidation devices were assembled, where the carbons were used as anode, and the cathode was stainless steel 304 SS. In each of the devices, three different separations between the anode and the cathode were considered: 1/8”, 3/16” and 1/4”. The electrical characterization of each of the cells was carried out using a sodium bisulfite solution (NaHSO3 ), with and without system agitation. The results indicated that agitation was not a factor that significantly affected the voltage conduction. The voltametric behavior revealed that the highest current density was presented by the MBC (39.2 mA/cm² ) for a separation of 1/8”, followed by the BC (17.45 mA/cm² ) for the same separation. To select the best arrangement, the premature wear of the anode was also considered. In this instance the BC did not present carbon detachment, so it was selected to carry out the degradation of 17-α-ethinyl estradiol. The degradation efficiency was 74% in 2 h. The identification of by-products by gas chromatography coupled to mass spectrometry revealed the majority presence of carboxylic acids. [ABSTRACT FROM AUTHOR]

Introduction-- Previous reactor models have been used to study the dynamic behavior of bioethanol production systems, however, few have elaborated a comparative study of control strategies that stabilize and control the variables of interest. Objective-- The objective of this study is to analyze the stability of a fermentation system to obtain bioethanol, its dynamic behavior, the characterization of equilibrium points and bifurcation points of the mathematical model proposed by Jarzebski in 1992 for a continuous fermentation, taking into account the performance of the reaction in a bioreactor and the application of industrial control techniques for its optimization. Methodology-- Review and design methods of quantitative and systematized type were used. Results-- The comparison between two control strategies to control bioethanol production, PID control and Fuzzy. Conclusions-- This work shows the importance of the stability analysis of a continuous system and how it can define the regions of operational interest, in this case for ethanol production, showing that productivity is inversely proportional to the dilution rate. Finally, it is concluded that a better dynamic behavior of the system is obtained when a Fuzzy controller is used. This work also shows the importance of the stability analysis of a continuous system and how it can define the regions of operational interest, in this case for the production of ethanol. [ABSTRACT FROM AUTHOR]

The performance of palm olein (PO) with different antioxidants during the repeated frying of tortilla chips was analyzed. Butylated hydroxytoluene (BHT) at concentration of 200 mg/kg (primary synthetic antioxidant), ascorbyl palmitate (AP) at 100 mg/kg (secondary synthetic antioxidant), and their blend (in the same concentration than individual addition) were added. Dough included 2% sesame seed, as it is prepared in commercial formulations for tortilla chips in the Guanajuato region (Mexico). Dough was sheeted, cut, and baked. Batches of 0.08 kg of tortillas were deep fat fried at 190°C for 2 min to produce the chips. Chemical indices—such as peroxide value (PV) and free fatty acids (FFA)—color and viscosity of the POs were evaluated. After 20 batches, the values for PO + BHT were PV = 29.6 meq/kg, FFA = 0.19%; PO + AP had PV = 13.3 meq/kg and FFA = 0.27%; and PO + BHT+AP, PV = 11.81 meq/kg and FFA = 0.29%. The best performance—based on lower primary oxidation—was achieved with the blend of antioxidants. Practical applications: Repeated frying with PO is a common operation for production of tortilla chips. The blend of primary (BHT) and secondary (AP) antioxidants at 200 and 100 mg/kg, respectively, is recommended for manufacturers of frying media and for food industry, since it improved the performance (lower primary oxidation) of PO. In this way, safer fried tortilla chips would be offer to consumers, avoiding risks for consumers' health (lower peroxide content) and having a product with good quality. [ABSTRACT FROM AUTHOR]

Non-centrifugal cane sugar (NCS) is a high carbohydrate-content food obtained by boil evaporation of the sugarcane juice. In the manufacturing process, the by-product of NCS called bagasse is used as foul for the boilers, underestimating its potential as a lignocellulosic source for second-generation bioethanol. In order to assess the bioethanol potential of the by-product resulting from the NCS production, pretreatments were applied to breakdown the lignocellulosic structure for the study in hand. Therefore, this study carried out a comparison of two pretreatment methods steam explosion (SE) and acid hydrolysis (AH) applied to the sugarcane bagasse to produce second-generation bioethanol. It was evidenced that both pretreatments redistribute lignin and hemicelluloses and enhances the accessible surface area of the biomass which further benefitted the subsequent fermentation process as the reducing sugars were available enough to foster the production of bioethanol. The study found that the SE pretreatment was likely to obtain more bioethanol as the reducing sugars (glucose) production outperformed other pretreatments under different residence times and concentrations. Considering the necessity to develop second-generation biofuel production, this study presented the sugarcane bagasse as a promising and abundance lignocellulosic substrate to be investigated more in depth in the Colombian context. [ABSTRACT FROM AUTHOR]