Considering the programmed decrease in oil resources, the concept of biorefinery is in the spotlight of the chemical industry [1-5]. In particular, the use of vegetable oils is a promising alternative to meet future challenges [6-8]. Among the oilseed chemicals, glycerol is an outstanding example with great potential for conversion into valuable products. Glycerol, propan-1,2,3-triol, is a symmetrical polyol with three hydroxy (OH) groups: two identical primary OHs and a secondary OH with a similar pKa and therefore close reactivity. Several chemical modifications obtained by oxidation, hydrogenolysis, etherification, esterification, dehydration and oligomerisation of glycerol have led to the production of a large number of value-added chemicals with specific applications in the polymer, agrochemical and pharmaceutical industries. The continuous oligomerisation of glycerol for the production of polyglycerol was carried out for the first time under microwave activation. In the presence of potassium carbonate, a homogeneous commercial catalyst, different parameters: temperature, flow rate and residence time were studied. The main linear and branched-chain diglycerol and triglycerol regioisomers were characterised and the distribution of the different oligomers was quantified. Further investigations in cyclic mode, combined with short distance distillation, allowed the mixture to be enriched with glycerol digesters and thus to obtain the following mixture: glycerol dimer (50.2 % by weight), glycerol trimer (22.1 wt%), glycerol tetramer (9.5 wt%) and glycerol pentamer (4.3 wt%).

In this work, graphite/paraffin composite electrodes with microparticles nickel (Ni) and Ni-Fe alloy anchored in reduced graphene oxide (RGO) were confection by the electrosynthesis of the microparticles at reduction potentials from -0.7V to -1.2V (v= 50 mV/s) onto RGO nanosheets, reduced by cyclic voltammetry from a solution of 1 mg/mL of GO in PBS solution with pH 9.18, in potential range from -1.5V to 0.5V (v= 10 mV/s). After electrodeposition of metals, oxyhydroxides were formed by cyclic voltammetry in an alkaline medium of 0.1 mol/L of NaOH in a potential range of -0.2V to 1.0V (v= 100 mV/s) with successive scans until stabilization of currents. The composites were investigated by scanning electron microscopy (SEM), it was observed that the Ni microparticles had spherical shapes, while the Ni-Fe alloy did not present a defined shape. In order to evaluate the electrochemical performance of the developed composite electrodes, ethanol and methanol electrooxidation was carried out in an alkaline medium of 0.1 mol/L of NaOH in a potential range of -0.2V to 1.0V (v= 50 mV/s) by cyclic voltammetry and chronoamperometry. The electrodes were able to induce the electrooxidation of ethanol at a potential of around 0.55V for the electrode constituted by the Ni-Fe alloy and around 0.6V for the electrode modified with Ni, and for methanol in a potential around 0.55V for the Ni-Fe alloy and around 0.65V for the Ni electrode. The Ni-Fe alloy electrodes showed the electrocatalysis of the alcohols in relation to Ni electrodes.

Immobilized enzymes are the most sought preparations on the world market. They are used in medicine, veterinary food industry, winemaking and brewing. The simplest method for immobilizing biocatalysts on insoluble carriers is the adsorption. Its advantage is to preserve the natural conformation of the enzyme, which slightly reduces its catalytic ability compared to the native form. Ficin (EC 3.4.22.3), papain (EC 3.4.22.2), bromelain (EC 3.4.22.4) (Sigma) were chosen as objects of study, azocasein (Sigma) was used as a substrate for hydrolysis, and an acid-soluble high molecular weight chitosan (350 kDa, Bioprogress CJSC) was used as an immobilization carrier. Suitable buffer systems for immobilization were identified by the optimal ratio of protein content (mg per g of carrier), total activity (in units per ml of solution) and specific activity (in units per mg of protein). Ficin is immobilized on a chitosan matrix using glycine buffer with pH of 8.6. Glycine buffer with pH of 8.6-10.5 is optimal medium for adsorption of papain on chitosan. Bromelain is immobilized on a chitosan matrix under Tris-glycine buffer with pH 8.5 conditions.

This work was financially supported in the form of a grant from the President of the Russian Federation for state support to young Russian scientists - doctors of sciences (MD-1982.2020.4. Agreement 075-15-2020-325).

Abstract: Ecuador is one of the countries in the Latin American region with high textile production. However, chemical treatment strategies in the Ambato, Tungurahua and Quito areas are inefficient and not systematically applied, and the volumes of dyes and pigment-type contaminants generate serious environmental problems. The treatments of indigo textile wastewater and related indigo derivatives are very complex. Taking theses into consideration, was developed a simple photochemical protocol, in heterogeneous conditions, for degrading “blue-indigo” (Ambato textile group) in solution, using TiO₂ (Degussa P25, with purity of ≈ 99 % and BET surface area 50 ± 15 m²/g) and solar light at lab scale. The photocatalytic oxidation of organic dye“blue indigo” in aqueous solution was assessed by solar irradiation, in the presence of TiO₂ particles. The effect of indigo concentrations, pH and TiO₂ loading for maximum degree of degradation were evaluated. The mineralization of “blue indigo” was reported by measuring COD-i and COD-f of the solution that was irradiated with sun light (60-100 minutes) under optimized conditions. Taking into consideration the results was proposed a probable mechanism of degradation .The results allows to re-design, in eco-sustainable conditions, for Ecuador, the strategies for controlling contamination in textile wastewaters.

Plant enzymes such as ficin (EC 3.4.22.3), papain (EC 3.4.22.2) and bromelain (EC 3.4.22.4) are obtained from tropical plants. These biocatalysts belong to thiol proteases, in the active center of which cysteine is contained. Ficin, papain and bromelain have a wide substrate specificity, which provides a demand for their use in various industries. Enzymes in the free state are less commonly used; immobilized biocatalysts are the preferred form. The aim of this work was to determine the optimal concentration of a crosslinking agent in the covalent immobilization of ficin, papain and bromelain on a chitosan matrix. Ficin, papain, bromelain (Sigma) were chosen as objects of study. An acid-soluble chitosan (350 kDa, Bioprogress CJSC) was used as an immobilization carrier. The concentration range of glutaraldehyde (crosslinking agent) ranged from 1 to 25%. Suitable concentration of glutaraldehyde for covalent immobilization were identified by the optimal ratio of protein content (mg per g of carrier), total activity (in units per ml of solution) and specific activity (in units per mg of protein). It was shown that for covalent immobilization of ficin and bromelain on a chitosan matrix, it is most promising to use 10 % glutaraldehyde. For immobilization of papain on chitosan by covalent means, the concentration of glutaraldehyde equal to 20 % is optimal.

This work was financially supported in the form of a grant from the President of the Russian Federation for state support to young Russian scientists - doctors of sciences (MD-1982.2020.4. Agreement 075-15-2020-325).