Indirect Measurement of Variables in a Heterogeneous Reaction for Biodiesel Production.

This research focuses on the development of a state observer for performing indirect measurements of the main variables involved in the soybean oil transesterification reaction with a guishe biochar-based heterogeneous catalyst; the studied reaction takes place in a batch reactor. The mathematical model required for the observer design includes the triglycerides' conversion rate, and the reaction temperature. Since these variables are represented by nonlinear differential equations, the model is linearized around an operation point; after that, the pole placement and linear quadratic regulator (LQR) methods are considered for calculating the observer gain vector L(x). Then, the estimation of the conversion rate and the reaction temperature provided by the observer are used to indirectly measure other variables such as esters, alcohol, and byproducts. The observer performance is evaluated with three error indexes considering initial condition variations up to 30%. With both methods, a fast convergence (less than 3 h in the worst case) of the observer is remarked.

High Adsorption of Hazardous Cr(VI) from Water Using a Biofilter Composed of Native Pseudomonas koreensis on Alginate Beads.

Most conventional methods to remove heavy metals from water are efficient for high concentrations, but they are expensive, produce secondary pollution, and cannot remove low concentrations. This paper proposes a biological system to remove Cr(VI) from aqueous solutions; the biofilter is composed of a native Pseudomonas koreensis immobilized in calcium alginate beads. Lab experiments were conducted in batch reactors, considering different operating conditions: Cr(VI) concentration, temperature, pH, and time. At 30 °C and a pH of 6.6, the immobilized bacteria achieved their optimal adsorption capacity. In the chromium adsorption system, saturation was reached at 30 h with a qmax = 625 mg g-1. By adjusting the experimental data to the Langmuir and Freundlich models, it is suggested that P. koreensis forms a biofilm with a homogeneous surface where Cr(VI) is adsorbed and that the bacteria also incorporates the metal in its metabolism, leading to a multilayer adsorption. On the other hand, using Fourier transform infrared spectroscopy, it was inferred that the functional groups involved in the adsorption process were O-H and C=O, which are a part of the P. koreensis cell wall.

Physicochemical Characteristics of Biofuel Briquettes Made from Pecan (Carya illinoensis) Pericarp Wastes of Different Particle Sizes.

Pecan nut (Carya illinoensis) pericarp is usually considered as a waste, with no or low value applications. Its potential as a densified solid biofuel has been evaluated, searching for alternatives to generating quality renewable energy and reducing polluting emissions in the atmosphere, based on particle size, that is an important feedstock property. Therefore, agro-industrial residues from the pecan nut harvest were collected, milled and sieved to four different granulometry: 1.6 mm (N° 12), 0.84 mm (N° 20), 0.42 mm (N° 40), and 0.25 mm (N° 60), used as raw material for biofuel briquette production. The carbon and oxygen functional groups in the base material were investigated by Fourier transform infrared spectroscopy (FTIR) and proximate analyses were performed following international standards, for determining the moisture content, volatile materials, fixed carbon, ash content, and calorific value. For the biofuel briquettes made from base material of different particle sizes, the physical characteristics (density, hardness, swelling, and impact resistance index) and energy potential (calorific value) were determined to define their quality as a biofuel. The physical transformation of the pecan pericarp wastes into briquettes improved its quality as a solid biofuel, with calorific values from around 17.00 MJ/kg for the base material to around 18.00 MJ/kg for briquettes, regardless of particle size. Briquettes from sieve number 40 had the highest density (1.25 g/cm3). Briquettes from sieve number 60 (finest particles) presented the greater hardness (99.85). The greatest susceptibility to swelling (0.31) was registered for briquettes with the largest particle size (sieve number 20). The IRI was 200 for all treatments.

Synthesis and Surface Modification of Small Pore Size Zeolite W for Improving Removal Efficiency of Anionic Contaminants from Water.

The presence of regulated inorganic contaminants in water such as AsO43- and PO43- anions, is becoming a relevant environmental research topic. The harm that these anions cause to human health and the ecosystem have been reported in several works. The adsorption processes using low-cost materials, such as zeolites, have proven to be an option to removal hazardous contaminants from water. The coal fly ash, a waste from thermoelectrical plants, offers a raw pollutant material to synthesis an effective adsorbent (Zeolite W). In this research was studied the removal of arsenic and phosphates anions from water, applying a functionalized by iron and zirconium Zeolite W, which was modified using a fast and efficient process through microwave-assisted method (1 min at 150°C). The obtained Zeolite W did not show significant changes in its structure and morphology. The maximum adsorption capacity (Qm expressed in mg g-1) was found to be 42.31 (Iron-zirconium-zeolite) and 27.82 (Iron-zeolite) for AsO43-, while it reached 50.89 for PO43- using Zirconium-zeolite. Results showed that functionalized zeolites are efficient adsorbents for hazardous anionic species; therefore, it could be useful for aqueous effluents remediation.

Production of fatty acid methyl esters and bioactive compounds from citrus wax.

Citrus wax is a waste generated during the purification process of the citrus essential oil. A lot of citrus wax wastes are globally produced, despite this, its composition and properties are not well known. Here we present comprehensive results proving the chemical composition and the physical properties of citrus wax. Additionally, our study provides the basis for obtaining value-added products from citrus wax wastes. The qualitative/quantitative analysis revealed the presence of different compounds, which range from flavonoids, saponins, carbohydrates, unsaturated compounds, phenolic hydroxyls, and long-chain fatty acid esters. Given that citrus wax is a source of many bioactive compounds, they were preferably extracted with ethanol. The ethanolic extracts demonstrated the presence in citrus wax of different bioactives, such as 5-5'-dehydrodiferulic acid, 3,7-dimethylquercetin, 5,6-dihydroxy-7,8,3',4'-tetramethoxyflavone, tangeretin, and limonene. After the extraction of bioactives from citrus wax, a washed waxy material with high content of long-chain fatty acid esters was obtained. It was shown that this washed wax can be used for the production of biodiesel. The transesterification reactions in acid media was the preferred process because higher content of fatty acid methyl esters (such as hexadecanoic acid methyl ester and 9,12-octadecadienoic acid (Z,Z)-, methyl ester) were obtained. Currently, citrus wax does not have any industrial application, here we shown that under the concept of waste biorefinery, the citrus wax wastes are useful sources for producing value-added products such as bioactive compounds and biodiesel.

Interaction Between Cobalt Ferrite Nanoparticles and Aspergillus niger Spores.

The immobilization of microorganisms has been reported as an alternative to improve the efficiency of processes such as fermentation, anaerobic digestion, bioadsorption, and many others. Since the kinetics of bioprocesses are governed by the adsorbent/adsorbate interaction, it is important to know the mechanisms of interaction between biological materials and supports. This could help to define optimal operating conditions. In this research, the fungus that produces the cellulases, was selected, and the characterization of the interaction between fungal spores and cobalt ferrite magnetic nanoparticles, was performed. In order to select a fungal strain produces cellulase enzymes, a qualitative Congo Red test was carried out with a culture medium rich in carboxymethylcellulose. From five strains, Aspergillus niger was selected. Chitosan coated cobalt ferrite magnetic nanoparticles (CoMNP-C) were synthesized by single-step co-precipitation. The nano-size of CoMNP-C was demonstrated by XRD. The presence of a high content of amino groups (0.144 mM g-1) was observed, that could have an important role in the interaction between nanoparticles and spores. Adsorption kinetic studies were carried out. The pseudo-equilibrium time was estimated as 90 min. Spores adsorption isotherm was obtained with 3.45 mg of synthesized material at 30 °C. It was found that the adsorption of spores may be described by both models (Langmuir and Freundlich), suggesting a homogeneous surface of the nanoparticles and a multilayer adsorption phenomenon. These results can have transcendence in multiple applications based on the studied process.

Bactericidal In-Vitro Effect of Zinc Ferrite Nanoparticles and the Orange Wax Extracts on Three Phytopathogen Microorganisms.

Phytopathogenic bacteria affect a wide variety of crops, causing significant economic losses. Natural biocides are the alternative to chemical methods of phytopathogens control. The goal of the present study is the evaluation of the biocidal activity of the following: 1) the extract of orange wax (EOW); 2) zinc ferrite nanoparticles (ZF-NPs); 3) the EOW adsorbed on the ZF-NPs; and 4) the EOW/ZF-NPs washed with 40% ethanol. For the biocidal activity, three phytopathogenic bacteria were used, namely, Xanthomonas axonopodis pv. Vesicatoria (Xav) Erwinia amylovora (Ew), and Pseudomonas syringae pv. Phaseolicola (Psph). For the ZF-NPs, an inhibitory effect higher than 50% ( ) was observed for Xav respect to the antibiotic used as positive control. On the other hand, the ZF-NPs did not show inhibitory effects on both Ew and Psph. In addition, the EOW in dimethyl sulfoxide (DMSO) at 100% caused growth inhibition on Xav, bacteriostatic activity on Ew, and had not biological activity on Psph. To the best of our knowledge, the control of Xav by zinc ferrites and orange wax, and the bacteriostatic effect produced by orange wax extract on Ew have not been reported elsewhere. Orange wax and zinc ferrite nanoparticles show potential in control of phytopathogenic bacteria. However, the bactericidal effect depends on the bacterium, the concentration of treatments, and the method of preparation.