Revista Mexicana de Ingeniería Química 2021-07-28T20:52:04+00:00 Francisco J Valdes Parada Open Journal Systems <div class="_4wyf">The Mexican Journal of Chemical Engineering &nbsp;(ISSN 1665-2738,&nbsp; issn-e: 2395-8472) publishes original research papers with the aim of promoting a rapid share of relevant research in various disciplines of Chemical Engineering and its interfaces with other enigineering disciplines. A volume is published each year and it consists of three issues, which are published every four months.&nbsp;</div> α-L-Fucosidase from Thermotoga maritima: hydrolytic and transfucosylation activities 2021-06-07T15:38:49+00:00 M.A. Robles-Arias F. Guzmán-Rodríguez M. García-Garibay S. Alatorre-Santamaría L. Gómez-Ruiz G. Rodríguez-Serrano A.E. Cruz-Guerrero <p><em>Fucosylated oligosaccharides play several biologically relevant roles. They are naturally present in human milk which offers to infants short- and long-term health benefits. These compounds can be obtained also by enzymatic synthesis. In this work, the effects of pH and temperature on hydrolytic and transfucosylation activities of α-L-fucosidase from Thermotoga maritima were evaluated. The optimal pH for the enzyme-catalyzed hydrolysis was found in a range from 6 to 8 while the highest conversions for transfucosylation reactions were observed within the range of 7-10. The best temperature for both enzymatic activities was 95 °C. Fucosylated oligosaccharides were synthesized with the highest productivity of 3.54 mM/h at pH 8 and 95 °C. Overall, optimization of the conditions of transfucosylation reaction catalyzed by the α-L-fucosidase from Thermotoga maritima allowed for higher yields of fucosylated oligosaccharides as well as shorter reaction time and a lower concentration of the employed enzyme.</em></p> 2021-06-07T15:38:49+00:00 ##submission.copyrightStatement## Enzymatic extraction of limonene, limonin and other relevant compounds from Citrus sinensis (orange) and Citrus aurantiifolia (lime) by-products 2021-06-09T22:53:23+00:00 J.R. Ramos-Ibarra E. Arriola-Guevara G. Toriz G.M. Guatemala-Morales R.I. Corona-Gonzalez <p>The byproducts from orange (<em>Citrus</em><em> sinensis</em>) and lime (<em>Citrus</em><em> aurantiifolia</em>) constitute nearly 50 wt. % of the fresh fruit and, unfortunately, these are discarded. These residues could be utilized to obtain extractable compounds of high added value, such as limonene and limonin.</p> <p>The extraction of limonene from peels and limonin from seeds, from both orange and lime, was evaluated with a commercial enzyme (Macerex). It was found that the yield of limonene was 17-fold higher (4.0 and 4.7 mg/g-peel from orange and lime respectively) using the enzymatic treatment as compared to blank. More bioactive compounds and in a higher concentration were obtained from peels using the enzymatic treatment as compared to blank.</p> <p>Limonin yield was twofold when the enzymes were applied to orange and lime seeds, as compared to blank (2.5 mg/g-orange seeds and 3.0 mg/g-lime seeds). The amounts of extracted limonene and limonin had a correlation with the amount of sugars released during degradation of the vegetal tissue.</p> <p>Enzymatic extraction of bioactive compounds from citrus by-products exhibits high yields, similar to traditional extraction treatment such as hydrodistillation, but under milder conditions.</p> 2021-06-09T22:53:22+00:00 ##submission.copyrightStatement## The importance of carbon and nitrogen sources on exopolysaccharide synthesis by lactic acid bacteria and their industrial importance 2021-07-01T22:00:14+00:00 F. Hernandez-Rosas J.D. Castilla-Marroquín J.M. Loeza-Corte M.A. Lizardi-Jimenez R. Hernández Martínez <p>Exopolysaccharides (EPSs) are classified in two groups, homopolysaccharides (HoPs) and heteropolysaccharides (HePs), are produced by lactic acid bacteria (LAB) and used in a range of industrial applications including the medical and food industries. HoPs are extracellular EPSs and their production depends on extracellular enzymes, while HePs are intracellular EPSs. Their nature (extra or intracellular) directly impacts production rates, HoPs having higher yields. The development of processes for producing EPSs has attracted great interest, since novel application trends have emerged due to the great diversity of recent information generated on EPSs properties. HoPs have been synthesized by fermentation using bacterial cells and a cell-free enzymatic process, while HePs have been produced only by fermentation. The analysis of the EPSs production processes indicates that macronutrients such as the carbon and nitrogen source used in the culture media are very important for the synthesis of EPSs and the enzymes involved, understanding their importance can assist to design processes for production of EPSs with desirable characteristics and yields according to the needs of the processes and products to which they are applicable. This review emphasized in the analyses of carbon and nitrogen sources used for EPSs production and their functional applications and productive aspects.</p> 2021-07-01T22:00:14+00:00 ##submission.copyrightStatement## Expression of a synthetic protein with a high proportion of essential amino acids by Pichia pastoris 2021-07-05T15:44:32+00:00 Y. Bartolo-Aguilar C. Chávez-Cabrera J.C. Cancino-Díaz R. Marsch <p><em>It is widely known that an adequate intake of proteins with essential amino acids stimulates the production of essential nonprotein substances for the body, such as serotonin, thyroid hormones, and glutathione. Biotechnology applications can focus on food and its benefits for human health, either by improving the nutritional value of existing foods or developing new alternatives that can help resolve the effects of poor nutrition. The yeast Pichia pastoris has been designated as a GRAS (generally recognized as safe) microorganism and is currently used to produce a large number of recombinant proteins. In this study, a 100% synthetic protein was expressed intracellularly as a protein with high nutritional quality that contains a 75% ratio of essential amino acids using the expression system of the yeast P. pastoris. This approach might offer future possibilities for using the modified yeast as a single-cell protein source in the livestock industry and the food supplement market to reduce total protein intake</em>.</p> 2021-07-05T05:02:15+00:00 ##submission.copyrightStatement## Real-time monitoring of xylitol production in a bioreactor by Candida tropicalis IEC5-ITV using Near-Infrared Spectroscopy (NIRS) 2021-07-07T17:37:42+00:00 A. A. Ortega-Platas V. Corro-Herrera M.G. Aguilar-Uscanga J. Gómez-Rodríguez <p>The use of Near-Infrared Spectroscopy (NIRS) and Chemometrics in-situ or in-line monitoring of xylitol fermentation process by <em>Candida tropicalis </em>IEC5-ITV was investigated in a bioreactor and in a complex analytical matrix. Xylose, xylitol, biomass and glycerol determinations were performed by a transflection fiber optic probe, immersed in the culture broth and connected to a Near-Infrared (NIR) process analyzer. The NIR spectra recorded between 800 and 2,200 nm, these NIR Spectra were pretreated using Savitzky-Golay smoothing and second derivative in order to perform a partial least squares regression (PLSR) and generate the calibration models. These calibration models were tested by external validation and then used to predict concentrations of xylitol fermentations in batch culture. The standard errors of calibration (SEC) and determination coefficients (<em>R<sup>2</sup></em>) for xylose, xylitol, biomass and glycerol were 0.234 (<em>R<sup>2</sup></em> = 0.991), 0.220 (<em>R<sup>2</sup></em> = 0.999), 0.234 (<em>R<sup>2</sup></em> = 0.991) and 0.015 (<em>R<sup>2</sup></em> = 0.999) g/L and standard errors of prediction (SEP) were 1.771, 0.192, 0.011, 0.503 g/L, respectively. Calibration and validation criteria were defined and evaluated in order to generate robust and reliable models of a xylitol fermentation process. For validation models, SEV and SEP were <u>&lt;</u> 10 % of initial concentration of xylose and <em>R<sup>2</sup></em><u> &gt;</u> 0.96 were obtained.&nbsp; These results indicate that in situ NIRS probe is suitable for real-time monitoring of xylitol production.</p> 2021-07-07T17:37:42+00:00 ##submission.copyrightStatement## Comparative analysis of microbial diversity in batch reactor with direct interspecies electron transfer system using an effective and inexpensive method mgDNA extraction 2021-07-26T17:56:39+00:00 L. Alzate-Gaviria D. Valero E. España-Gamboa M. González-Muñoz A. Cortés-Velázquez J. Dominguez-Maldonado D. Pérez-Brito R. Tapia-Tussell <p>Recently, metagenomic DNA based analysis gained importance in fields such as environmental sciences and bioenergy, where mixed microbial communities embedded in complex matrixes, play a crucial role. Therefore, financially economical, and high quality metagenomic DNA extraction protocols are needed. In this work, a rapid and inexpensive method for high quality DNA extraction from a variety of complex samples was performed; the average DNA yield was 71.65 ng µL<sup>−1</sup>, with an average purity of 1.68 (A<sub>260</sub>/A<sub>280</sub>). The cost of extraction per sample was about 76 % less in comparison with commercial kits and the time needed to obtain the DNA pellets was about 4 hours. The DNA was suitable for 16S rRNA gene amplification by PCR and for next generation sequencing analysis, employing a MiSeq Ilumina platform. A high microbial diversity was detected in this study, and three main groups of bacteria were observed, which were developed according to the effect of the activated carbon had on them. The analysis performed showed a great difference between the samples, highlighting the differences between the microbial communities developed in the activated carbon biofilm and the bacteria detected in the reactor without activated carbon.</p> 2021-07-26T17:56:39+00:00 ##submission.copyrightStatement## Exopolysaccharide-producing bacteria improves survival and proteolytic profile of Lactobacillus rhamnosus gg added to semi-ripened cheese 2021-07-28T02:35:20+00:00 E. Contreras-López J. Jaimez-Ordaz G.M. Rodríguez-Serrano A.E. Cruz-Guerrero J. Ramírez-Godínez A. Castañeda-Ovando L.G. González-Olivares <p>Currently, the interest of the food industry on the use of probiotics in order to provide beneficial effects is increasing. However, one limitation is getting microorganisms to survive in food matrices. In this work, protective effect of exopolysaccharide produced by <em>Lactobacillus delbrueckii</em> subsp. <em>bulgaricus </em>NCFB 2772 on <em>Lactobacillus rhamnosus</em> GG survival during semi-ripening of cheese, was analyzed. Ripening was carried out at 14 ° C for 28 days in a controlled RH chamber. Scanning electron microscopy (SEM) was performed to determine interactions of probiotic with the exopolysaccharide. During ripening process, the proteolytic activity was determined through TNBS, SDS-PAGE and size exclusion-HPLC techniques. Viability of probiotic was measured by plate count. Cheese inoculated with both strains showed an improvement in probiotic survival. Exopolysaccharide was shown to have an effect on protein aggregation and cheese structural uniformity. Micrographs revealed a direct interaction between probiotic and exopolysaccharide. Proteolytic capacity did not decrease, and the generation and decrease of low molecular weight peptides (less than 3 kDa) was verified throughout the ripening process. Thus, using an exopolysaccharide-producing strain during cheese ripening has a positive effect on probiotic survival when they are used as starter cultures.</p> 2021-07-28T02:35:20+00:00 ##submission.copyrightStatement## Improvement of the physicochemical properties of composite materials based on cassava starch and polycaprolactone reinforced with sodium montmorillonite 2021-06-07T18:56:44+00:00 N. Piñeros-Guerrero R. Marsiglia-Fuentes R. Ortega-Toro <p>The present work aims to study the incorporation effect of montmorillonite and polycaprolactone clays to a matrix of thermoplastic cassava starch plasticized with glycerol, the blends were obtained by extrusion process and the films by compression molding. The physicochemical, mechanical, optical and barrier properties were characterized. The addition of polycaprolactone and montmorillonite reduced the water solubility of the films and improved and the water vapor transmission rate. The oxygen transmission rate of the formulations is lower than that of some conventional polymers and comparable with Ethylene-Vinyl-Alcohol (EVOH). The addition of montmorillonite produced more rigid and less deformable films, with low gloss and low internal transmittance at 650 nm. The materials obtained are friendly to the environment and have functional properties suitable for packaging foods with low humidity, such as bakery products or flours.</p> 2021-06-07T18:56:44+00:00 ##submission.copyrightStatement## Physical, phytochemical and sensory characteristics of extruded high-fiber breakfast cereals prepared by combining carrot by-products with wheat and oat bran 2021-06-07T21:23:47+00:00 C.I. Delgado-Nieblas J.A. Ahumada-Aguilar S. Agramón-Velázquez J.J. Zazueta-Morales N. Jacobo-Valenzuela X.A. Ruiz-Armenta A. Carrillo-López A. Quintero-Ramos C. Barraza-Elenes <p>High-fiber breakfast cereals are mainly produced by extrusion, and to improve its nutritional/nutraceutical properties, the addition of raw materials rich in bioactive compounds has been suggested. The aim of this study was to evaluate the physical, phytochemical and sensory characteristics of extruded high-fiber breakfast cereals (HFB) prepared from carrot by-products and bran as affected by feed moisture (FM, 19.34–30.66%) and carrot pomace content (CPC, 5.51–22.49%), under a central composite rotatable experimental design. When FM was increased, flexural modulus (FMO, 54-89 MPa), soluble dietary fiber (SDF, 0.64-4.18%), bound phenolic compounds (BPC, 0.02-0.25 mg GAE/g), and DPPH antioxidant activity from BPC extracts (2.07-2.29 µmol TE/g) increased, whereas expansion index (1.09-0.89) diminished. Also, when CPC was elevated, FMO (54-83 MPa), water solubility index (14.21-18.84%), color b* (26.8-28.8), insoluble dietary fiber (19.43-24.71%), SDF (1.12-3.98%), free phenolic (0.56-0.71 mg GAE/g), and flavonoids compounds (0.05-0.31 mg QE/g) increased, whereas BPC decreased (0.25-0.14 mg GAE/g). The HFB presented good (≥ 69%) sensory acceptability. These extruded products presented appropriate physical, phytochemical, and sensory characteristics, whose consumption has potential nutraceutical benefits.</p> 2021-06-07T19:09:22+00:00 ##submission.copyrightStatement## Design of a hybrid solar collector with a flat plate solar collector and induction heating: evaluation and modelling with principal components regression 2021-07-08T05:30:06+00:00 E. Figueroa-Garcia M.A. Segura-Castruita DMILYS5@HOTMAIL.COM F.M. Luna-Olea O.F. Vázquez-Vuelvas A.M. Chávez-Rodríguez <p><em>Food drying is one of the main food preservation processes, which are supplied with electrical energy (EE). Recently, the EE has had constant increases in its costs, prompting the integration of renewable energy sources for these processes. Therefore, the objective of this research was to design, build and model a hybrid solar collector (HSC-IH) for drying food, made up of solar energy (SE) through a solar collector and EE by means of induction heating. (IH), this work prioritizes the incorporation of an auxiliary heating system for the solar collectors, minimizing temperature variability and increasing its heat capacity, the HSC-IH has a collection surface of 1 m<sup>2</sup>, adjustable flow of 0.3 - 4 CMM and maxim of 80 ° C, the prediction model developed with PCR, to determine the outlet temperature (OT) provided by the HSC-IH with only the use of solar energy and to estimate the energy provided by the EE with the IH, the final model it has an R<sup>2</sup> of 0.934 and can be used to understand the OT of HSC-IH.</em></p> 2021-07-08T05:30:06+00:00 ##submission.copyrightStatement## Effect of adding pineapple (Ananas comosus) flour on the sensory and textural properties of wheat flour (Triticum aestivum) cookies 2021-07-28T20:52:04+00:00 M. López-Fernández G. Méndez-Montealvo G. Velazquez A. Perales-Torres R. Santiago-Adame O. Castillo-Ruiz <p><em>Cookies from wheat flour are one of the most consumed bakery products. As they are deficient in fiber, usually other ingredients are added to improve the organoleptic and nutritional attributes. In this work, three formulations were followed to prepare wheat flour (WF) cookies with pineapple flour (PF) at 5, 10, and 15% of substitution. The acceptance level of the cookies was analyzed by three consumer groups: children, teenagers, and adults. The physicochemical properties and shelf-life were also evaluated. Cookies containing 15 % of PF reached a 16 mg GAE/100 g of total polyphenols. The content of antioxidants remained at acceptable levels after baking. The proximal analysis showed that the ash, fiber, and protein contents in all treatments were significantly higher (p≤0.05) than that of commercial samples. Cookies with 5% PF had the highest level of acceptance in the three consumer groups evaluated. The cookies maintained the sensory characteristics after four weeks of storage. The organoleptic and nutritional properties of the cookies were improved after adding pineapple flour. Replacing what flour by 5-15% pineapple flour allowed obtaining cookies with an adequate content of protein, fiber, and total polyphenols.</em></p> 2021-07-28T20:52:04+00:00 ##submission.copyrightStatement## Decreasing the value of the cell potential using nPt/C|Ti and RuO2|Ti as cathodes in a reactor for electro leaching of electronic e-waste 2021-06-09T22:27:17+00:00 J.C. Ramírez-Castellanos M. Luna-Trujillo V.E. Reyes-Cruz A. Manzo-Robledo G. Urbano-Reyes M.A. Veloz-Rodríguez J.C. Juarez-Tapia J.A. Cobos-Murcia <p><em><span style="font-weight: 400;">This work has to purpose decrease the value of the cell potential (E</span></em><sub><em><span style="font-weight: 400;">cell</span></em></sub><em><span style="font-weight: 400;">) of an electrochemical reactor with a separate compartment with an anionic membrane designed for electro-leaching electronic waste (E-waste). In the anodic compartment using a titanium plate in HNO</span></em><sub><em><span style="font-weight: 400;">3</span></em></sub><em><span style="font-weight: 400;"> as an anolyte, while the electro-leaching of the metals and the evaluation of the oxygen evolution reaction (OER) was studied. Three different cathodes (Platinum; Pt, titanium coated with ruthenium oxide; RuO</span></em><sub><em><span style="font-weight: 400;">2</span></em></sub><em><span style="font-weight: 400;">|Ti and titanium coated with platinum nanoparticles; nPt/C|Ti) were used for the catalysis of the evolution reaction of hydrogen (HER) in a solution of H</span></em><sub><em><span style="font-weight: 400;">2</span></em></sub><em><span style="font-weight: 400;">SO</span></em><sub><em><span style="font-weight: 400;">4</span></em></sub><em><span style="font-weight: 400;">. The results obtained by voltammetry indicate that the electrodes modified with RuO</span></em><em><span style="font-weight: 400;">2</span></em><em><span style="font-weight: 400;"> and nPt/C, promote a greater cathodic current for the HER, decreasing the cell potential and increase the current density of the induced metallic electro-leaching. This implies the decrease of the electrical power that the reactor requires during its operation. Obtaining Space-time yield (STY) values of 123.4 and 64 mol·L</span></em><sup><em><span style="font-weight: 400;">-1</span></em></sup><em><span style="font-weight: 400;">·h</span></em><sup><em><span style="font-weight: 400;">-1</span></em></sup><em><span style="font-weight: 400;">·cm</span></em><sup><em><span style="font-weight: 400;">-2</span></em></sup><em><span style="font-weight: 400;"> for the carbon and platinum nanoparticle and the ruthenium oxide catalysts respectively.</span></em></p> 2021-06-09T22:27:17+00:00 ##submission.copyrightStatement## Voltage production and simultaneous municipal wastewater treatment in microbial fuel cells performed with Clostridium strains 2021-07-04T00:42:59+00:00 J. Dorazco-Delgado J.H. Serment-Guerrero S.M. Fernández-Valverde M.C. Carreño-de-León J.C. Gómora Hernández <p><em>Clostridium</em> strains are known due to their capability to produce hydrogen and free electrons during their metabolism; however, voltage production and electric current generation by Microbial Fuel Cell (MFC) have not been deeply explored yet employing these microorganisms. In this paper we evaluated both voltage generation and Chemical Oxygen Demand (COD) reduction in municipal wastewater by one chamber MFC performed with graphite cloth electrodes and inoculated with <em>Clostridium bifermentans</em>, <em>Clostridium sordellii</em> and native bacteria. <em>Clostridium</em> strains grew properly on both Ravot medium and municipal wastewater reaching the maximum develops at 96 and 120 hours for <em>bifermentans</em> and <em>sordellii</em> respectively. Microbial growth kinetics determined by Gompertz modified model showed low lag times for all tests. <em>Clostridium sordellii</em> showed not only the maximum voltages but also the highest potential to remove organic matter from wastewater since COD diminished around 60% at the end of MFC’s operation. The addition of phosphate salts solution increased the removal of organic matter but was not efficient to generate voltage, moreover, the microorganisms present in wastewater were able to produce voltage but&nbsp; the amount of organic matter removed by them were low. The maximum generated voltage, Power Density (PD), Volumetric Power Density (VPD) and Current Density (CD) values were observed in MFC inoculated with <em>Clostridium sordelli</em> and performed with wastewater with no buffer solution, they were; 0.372 V, 153.43 mW m<sup>-2</sup>, 1.73 W m<sup>-3</sup> and 0.413 A m<sup>-2</sup> respectively. <em>Clostridium</em> strains showed a high potential to reduce COD in wastewater generating green energy as by-product.</p> 2021-07-04T00:42:59+00:00 ##submission.copyrightStatement## Modification of wettability and reduction of interfacial tension mechanisms involved in the release and enhanced biodegradation of heavy oil by a biosurfactant 2021-07-04T07:21:18+00:00 E. Castillo-Campos V. Mugica-Álvarez T. Roldán-Carillo P. Olguín-Lora G. Castorena-Cortés <p>Bioremediation of hydrocarbon contaminated soils requires releasing the oil from the porous matrix to render it bioavailable. This work aims at evaluating a biosurfactant produced by a <em>Bacillus subtilis</em> strain to improve the release and biodegradation of heavy crude oil contaminating limestone sand. The biosurfactant effect on biodegradation of crude oil was elucidated, using a <em>Rhodococcus </em><em>sp</em>. strain. The CO<sub>2</sub> production rate was used as indicator of biological activity that improved by 32.84%. Moreover, at least 67% of the &gt;C<sub>20 </sub>fraction was degraded in the systems with biosurfactant, reducing aromatic and resin fractions (12.5% and 2%, respectively), whereas without biosurfactant only 37% of the &gt; C<sub>20</sub> fraction was removed compared with the null reduction in aromatics and resin. The decrease in surface and interfacial tension, as well as the modification to wettability caused by biosurfactant activity, were the main mechanisms promoting the release of heavy oil, thus making it bioavailable</p> 2021-07-04T07:21:18+00:00 ##submission.copyrightStatement## Synthesis of adsorbents from wheat hulls, extracted cellulose and modified with Cetyl trimethyl ammonium chloride to remove Congo Red in aqueous solution 2021-07-25T18:26:56+00:00 Angel Villabona-Ortiz Candelaria Tejada-Tovar Rodrigo Ortega Toro Fabián Aguilar-Bermúdez Yeraldine Pájaro-Moreno <p>Adsorbents from the wheat husk (WH), wheat husk cellulose (WHC) and the cellulose modified with Cetyl trimethyl ammonium chloride (MWHC), in the removal of Congo Red were evaluated. Experiments were carried out in batch at different concentrations (40, 70 and 100 mg/L) and adsorbent doses (15, 25 and 35 mg), following a multifactorial 3<sup>3</sup> design of experiments. It was found the adsorption efficiency of Congo red increased with initial concentration and decrease in adsorbent dosage using all adsorbents. WHC and MWHC showed a rapid adsorption rate in the initial minutes of the process, reaching equilibrium at 480 and 120, respectively. The adsorption equilibrium on WHC and MWHC was described by the Freundlich model; showing this affinity: MWHC&gt;WHC&gt;WH. It was concluded wheat residues are a good precursor for the preparation of efficient adsorbents to remove Congo Red. CTAC functions as an adsorbent modifying agent for use in the removal of anionic contaminants. These results have a potential application in the treatment of wastewater from industries such as food and textiles.</p> 2021-07-25T18:26:56+00:00 ##submission.copyrightStatement## Treatment of waste activated sludge by steam explosion and alkaline acidogenesis 2021-07-26T20:28:43+00:00 R. Tafolla F. Ramírez R. Ortiz E. Cortés I. Ortiz O. Monroy <p>A process improvement of the anaerobic digestion of waste activated sludge (WAS) is needed to produce energy and chemicals to compensate the costs of the full wastewater treatment process. Alkaline steam explosion (A-SE) @160°C and 0.67 MPa absolute pressure, followed by thermophilic alkaline acidogenesis (50°C, pH 9) improves the WAS digestibility and the methane yields by breaking the cell walls and the extracellular polymers. This work studies the treatment time and alkalinity effects on the number of destroyed solids measured as cell damage and particle size reduction. To monitor the process a flow cytometer (FCM), through light scattering signals, proved to be an alternative to the measurement of total suspended solids by gravimetry.</p> <p>The effect of alkaline acidogenesis on the volatile fatty acids (VFA) yield is studied with the A-SE suspension which is cooled down to 50°C and fed to a continuous acidogenic reactor at pH 9 under several organic loads to find the optimum (6 g COD<sub>VSS</sub>/L<sup>.</sup>d) with the highest soluble COD and VFA production rates (1.4 and 0.8 g COD/L,d respectively). This effluent can be fed to a methanogenic reactor to produce 0.5 L<sub>CH4</sub>/L<sup>.</sup>d or the VFA can be separated for the chemical industry.</p> 2021-07-26T20:20:47+00:00 ##submission.copyrightStatement## Natural Mexican Clinoptilolite for ethanol dehydration: adsorption–regeneration experimental parameter determination and scaling–up at Pilot Plant 2021-06-06T06:13:45+00:00 G. Leo-Avelino G.R. Urrea-Garcia J. Gómez-Rodríguez S. Perez-Correa M.G. Aguilar-Uscanga <p>The separation of ethanol-water azeotropic mixtures by adsorption-regeneration process using a natural Mexican Clinoptilolite has been studied. For this, the equilibrium parameters were determined from experimental data obtained at the laboratory level, which were used as a starting point for the calculation of a column at Pilot Plant scale. First, on the basis of experimental data from three different sizes of natural Mexican clinoptilolite (1-2, 3 and 5 mm) and two artificial ones with 1 and 3 mm, and from the application of standard fitting techniques: Langmuir, Freundlich and linear model parameters are calculated and compared. Then, the breakthrough curves (BTC) are determined for each zeolite in a packed bed, yielding that the adsorption and capability of natural clinoptilolite is similar to those presented by artificial zeolites. The regeneration method PSA was evaluated for each zeolite. Finally, according to the experimental parameters set, a calculation of a pilot-plant scale column is included for a validation and the results are compared with the results obtained at the laboratory scale, which presented a similar behavior. We can conclude that the use of Mexican zeolite in the ethanol dehydration process could be a good low-cost alternative that is easy to apply</p> 2021-06-06T05:55:26+00:00 ##submission.copyrightStatement## Comparative study of chemical process and biotechnological process for the removal of bismuth from mining concentrates 2021-06-06T06:13:45+00:00 K.I. Vargas-Rubio H. Medrano-Roldan D. Reyes-Jáquez <p>In 2018, approximately 17.7 billion metric tons of minerals were produced worldwide, which represent a great importance in the industrial sector. However, most of the minerals are bound with metallic elements, which lower the price of the metals of interest. Secondary materials in valuable metal extraction processes can cause various problems in the mining industry, both economic and environmental. This research aimed evaluate two treatments for the reduction of the bismuth concentration in gold and silver mineral concentrates: Bioleaching and co- precipitation with trioxide arsenic treatment, in the first, native microorganisms of the mineral to be treated were used to reduce the concentration of bismuth; in the second, arsenic trioxide was added in order to form a precipitate that contained bismuth.. The results showed that the chemical co-precipitation treatment with arsenic trioxide can decrease the Bi concentration to a greater extent compared to the bioleaching treatment, up to 16% of the initial concentration, in addition to reducing the concentration of other undesirable elements in metals such as antimony and cadmium by 32 and 11% respectively. From this research work, a collaboration of two techniques can be proposed for a higher reduction of concentration and with greater efficiency.</p> 2021-05-24T00:00:00+00:00 ##submission.copyrightStatement## High removal of toxic crystal violet dye using a thermally treated activated carbon fiber felt 2021-07-02T01:45:46+00:00 O.G. Rojas-Valencia M. Estrada-Flores C.M. Reza-San-Germán J.L. Ledezma-Martínez J. Hernández-Fuentes <p>In the present work, the reuse of activated carbon fiber felt (ACFF) is suggested to remove the cationic methyl violet, commonly called as Crystal Violet (CV), dye present in a synthetic solution. The morphological structure of the ACFF was analyzed by High Resolution Scanning Electron Microscopy (HRSEM). The dye removal processes were carried out discontinuously at room temperature and pH of 10, by reusing the FFCA up to 10 times. After each removal process, the ACFF was thermally treated by calcination that allowed to transform the adsorbed dye into CO and CO<sub>2</sub> wherewith its useful lifetime was extended. The results show that the adsorption process follows the Langmuir isotherm with pseudo-first order kinetics, which suggests that a chemisorption was carried out by the covalent attraction between the carbonyl groups of the ACFF and the cationic species of the dye. The novelty of the work focuses on the reuse of the ACFF for up to 10 removal cycles with a high removal rate, which can lead to a reduction in the acquisition costs of the adsorbent material.</p> 2021-07-02T01:45:46+00:00 ##submission.copyrightStatement##