Avaliação dos tratamentos eletroquímico e fotoeletroquímico na degradação de corantes têxteis

This paper presents the study of the oxidation of three textile dyes (Remazol black B, Remazol Brilliant Orange 3R and Remazol Golden Yellow RNL) using electrochemical and photoelectrochemical methods. In both methods, electrolysis experiments were performed at a current density of 50 mA cm-2 in an aqueous solution of each dye (30 mg L-1), using a photoelectrochemical flow-cell. For all the dyes studied, the photoelectrochemical method was demonstrated to be more efficient than the electrochemical one. Photoelectrochemical oxidation resulted in complete decoloration after 90 min of electrolysis and total organic carbon (TOC) removal reached up to 36%. It was observed that the dyes presenting chromophores at higher wavelengths are removed the quickest, which indicates that photosensitised (photoassisted) oxidation occurs. The level of color was reduced to levels below the standards presented in the literature, which indicates the viability of the photoelectrochemical process as part of the treatment of textile effluents

Avaliação dos tratamentos eletroquímico e fotoeletroquímico na degradação de corantes têxteis

This paper presents the study of the oxidation of three textile dyes (Remazol black B, Remazol Brilliant Orange 3R and Remazol Golden Yellow RNL) using electrochemical and photoelectrochemical methods. In both methods, electrolysis experiments were performed at a current density of 50 mA cm-2 in an aqueous solution of each dye (30 mg L-1), using a photoelectrochemical flow-cell. For all the dyes studied, the photoelectrochemical method was demonstrated to be more efficient than the electrochemical one. Photoelectrochemical oxidation resulted in complete decoloration after 90 min of electrolysis and total organic carbon (TOC) removal reached up to 36%. It was observed that the dyes presenting chromophores at higher wavelengths are removed the quickest, which indicates that photosensitised (photoassisted) oxidation occurs. The level of color was reduced to levels below the standards presented in the literature, which indicates the viability of the photoelectrochemical process as part of the treatment of textile effluents

Edible active coatings incorporated with Cinnamomum cassia and Myristica fragrans essential oils to improve shelf-life of minimally processed apples

ABSTRACT: The effect of the incorporation of cinnamon (Cinnamomum cassia) and nut meg (Myristicafragrans) essential oils in alginate-based edible coatings that were applied on minimally processed apples, is reported. The minimum inhibitory concentrations were 1.25mg.mL-1 (cinnamon) and 2.50mg.mL-1 (nutmeg), against both Escherichia coli and Penicillium commune. Over storage periods there was a significant reduction in the E. coli and P. commune counts compared to the control. The extent of enzymatic browning was also significantly reduced in the coated samples. In the coated minimally processed apples sensory tests, the flavor had the lowest rating of the properties analyzed, for both treatments, followed by aroma and firmness

Shelf life and sensory analysis comparison of alginate and chitosan edible coating incorporating avocado extract applied to minimally processed apples

The purpose of the present study was to evaluate Persea americana (avocado) in relation to the pulp composition, moisture content, lipids present, proteins, and ash. The P. americana pulp extract was prepared by solvent extraction using pure ethanol, and the chemical composition of the extract was evaluated by GC-MS. The resulting extract was subsequently incorporated in alginate and chitosan-based edible coatings on minimally processed Fuji apples. The edible coatings were evaluated microscopically, for shelf-life improvement and by sensory analysis. The alginate-based coatings were able to inhibit enzymatic browning, improve the appearance of the minimally processed apple samples and obtained the best results in all aspects evaluated in the sensory analysis. The incorporation of P. americana pulp extract contributed to the improvement the shelf life of minimally processed apples for 15 days and the fruits covered with the alginate-based edible coating incorporated with P. americana pulp extract had the best scores in acceptance and appearance

Ofloxacin adsorption by calcined Verde-lodo bentonite clay: Batch and fixed bed system evaluation

Due to the increasing consumption of antibiotic agents and the fact that conventional effluent treatment methods are inefficient in removing these compounds, new and more effective treatment processes need to be investigated and improved. This work evaluated the adsorption of the emerging contaminant ofloxacin (OFL, antibiotic) in static and dynamic systems using calcined Verde-lodo (CVL) bentonite clay. The use of CVL bentonite clay for this purpose has not been investigated, furthermore, there are no reported studies regarding OFL adsorption in a fixed bed system. The molecular structure of ofloxacin was obtained by molecular simulation showing a stable and minimum local energy structure. The characterization study before and after the adsorption process indicated the presence of OFL in the CVL clay. The analyzes indicated that the CVL clay exhibits a lamellar structure with some roughness, with pores of 80,000 nm larger than macropores (>50 nm). In addition, the thermogravimetric analysis indicated that the clay is thermally stabile up to 1000 °C. External mass transfer resistance and pseudo-second-order models best described the kinetic data. The Dubinin-Radushkevick model was best adjusted to the equilibrium assays, indicating heterogeneous adsorbent surface. The system reached a maximum Langmuir adsorption capacity (55 °C) of 0.445 mmol g−1 (160.81 mg g−1). Fixed bed assays indicated the occurrence of multilayer adsorption. Under operating conditions of 0.4 mL min−1 and 0.05 mmol L−1, the system operated for 140 h with practically 100% removal until the breakthrough time was achieved. The clay showed high reuse capacity, with removal efficiency >93% after 3 cycles315CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP406193/2018-5sem informação2016/05007-

Precipitation reaction of clavulanic acid: thermodynamic and electronic study

In the present article the theoretical calculation of thermodynamic parameters for the two main precipitation agents, potassium 2-ethylhexanoate and t-octylamine, employed by the pharmaceutical industry to obtain potassium clavulanate for clinical use, is described. The results obtained using the standard thermochemistry calculation in the Gaussian package and by calculation of the reactivity indexes of the reagents and products are compared. The calculated thermodynamic parameters indicate that the reactivity indexes present a better correlation with the experimentally obtained percentage yield. In addition, a series of additional precipitation agents that are also used in industrial procedures to obtain potassium clavulanate for clinical use, were compared. This was done to verify if any present, a priori, better properties than potassium 2-ethylhexanoate or t-octylamine. The consistency of the reactivity indexes calculated clearly suggests that the methodology employed can be used to screen future precipitation agents for possible use in the production of potassium clavulanate

Nitroisatin dithiocarbazate: Synthesis, structural characterization, DFT, and docking studies

The reaction between 5-nitroisatin with S-benzyl dithiocarbazate affords a new isatindithio carbazate so-called NO2Isadtc (Benzyl 2-(5-nitro-2-oxoindolin-3-ylidene)hydrazinecarbodi thioate) which was characterized by means of 1H NMR, FT-IR, UV-visible and single crystal X-ray diffraction - Crystal data for C16H12N4O3S2 (M =372.42 g/mol): triclinic space group P-1, (n°. 02), a = 6.640 Å, b = 8.256 Å, c = 15.908 Å, V = 849.6 Å3, Z = 2, T = 293 K, μ(MoKα) = 0.337 mm-1, Dcalc = 1.456 g/cm3, 27515 reflections measured (2.499° ≤ 2Θ ≤ 26.524°), 3518 unique (Rint = 0.0533, Rsigma =0.0222) which were used in all calculations. The final R1 was 0.0367 (I > 2σ(I)) and wR2 was 0.1045 (all data). Computational methods were applied to NO2Isadtc and its nonsubstituted parent compound Isadtc for structure optimization, electronic distribution, and infrared calculations using B3LYP functional with 6-31G(d,p) basis set in ethanol as a polarizable continuum model. Furthermore, docking studies using human thioredoxin reductase 1 (TrxR) as enzyme target also were performed using NO2Isadtc and the optimized structure of Isadtc. The results demonstrated that both NO2Isadtc and Isadtc may act as inhibitors of TrxR, having different interactions detected, highlighting the contact between the NO2 group and the S111 at the helix which is found for NO2Isadtc