Flow devices fabricated by means of 3D-printing offer an economic and effective approach for testing different electrochemical systems at the laboratory scale. Here, the fabrication and optimization of a novel filter-press electrochemical reactor is described. 3D-printing is used to obtain critical components of the device as a sustainable and efficient manufacturing approach. Hydrodynamics and mass transfer of different flow distributors, turbulence promoters, and nickel foam, as a three-dimensional (3D) electrode, were evaluated by a convenient set of well-known techniques for filter-press reactor characterization. Furthermore, the chemical stability of 3D-printed materials was assessed in several electrolytes used for common electrochemical applications. Designed configurations and geometries exhibited enhanced turbulence and large mass transfer coefficients, which make them adequate for processes such as electrosynthesis, electrodeposition, and electrochemical water splitting. Ultimately, superior performance was validated for nickel foam, demonstrating robustness of the reactor for realistic evaluation of electrocatalytic materials. Therefore, the proposed electrochemical reactor provides a low-cost and versatile alternative for testing electrochemical systems in a wide range of applications.

Background Rhus trilobata Nutt. ( Anacardiaceae ) (RHTR) is a plant of Mexico that is traditionally used as an alternative treatment for several types of cancer. However, the phytochemical composition and potential toxicity of this plant have not been evaluated to support its therapeutic use. Therefore, this study aimed to evaluate the biological activity of RHTR against colorectal adenocarcinoma cells, determine its possible acute toxicity, and analyze its phytochemical composition. Methods The traditional preparation was performed by decoction of stems in distilled water (aqueous extract, AE), and flavonoids were concentrated with C 18 -cartridges and ethyl acetate (flavonoid fraction, FF). The biological activity was evaluated by MTT viability curves and the TUNEL assay in colorectal adenocarcinoma (CACO-2), ovarian epithelium (CHO-K1) and lung/bronchus epithelium (BEAS-2B) cells. The toxicological effect was determined in female BALB/c mice after 24 h and 14 days of intraperitoneal administration of 200 mg/kg AE and FF, respectively. Later, the animals were sacrificed for histopathological observation of organs and sera obtained by retro-orbital bleeding for biochemical marker analysis. Finally, the phytochemical characterization of AE and FF was conducted by UPLC-MS E . Results In the MTT assays, AE and FF at 5 and 18 μg/mL decreased the viability of CACO-2 cells compared with cells treated with vehicle or normal cells ( p ≤ 0.05, ANOVA), with changes in cell morphology and the induction of apoptosis. Anatomical and histological analysis of organs did not reveal important pathological lesions at the time of assessment. Additionally, biochemical markers remained normal and showed no differences from those of the control group after 24 h and 14 days of treatment ( p ≤ 0.05, ANOVA). Finally, UPLC-MS E analysis revealed 173 compounds in AE-RHTR, primarily flavonoids, fatty acids and phenolic acids. The most abundant compounds in AE and FF were quercetin and myricetin derivates (glycosides), methyl gallate, epigallocatechin-3-cinnamate, β -PGG, fisetin and margaric acid, which might be related to the anticancer properties of RHTR. Conclusion RHTR exhibits biological activity against cancer cells and does not present adverse toxicological effects during its in vivo administration, supporting its traditional use. Electronic supplementary material The online version of this article (10.1186/s12906-019-2566-9) contains supplementary material, which is available to authorized users.

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The electrochemical oxidation of sulfite ions offers encouraging advantages for large-scale hydrogen production, while sulfur dioxide emissions can be effectively used to obtain value-added byproducts. Herein, the performance and stability during sulfite electrolysis under alkaline conditions are evaluated. Nickel foam (NF) substrates were functionalized as the anode and cathode through electrochemical deposition of palladium and chemical oxidation to carry out the sulfite electro-oxidation and hydrogen evolution reactions, respectively. A combined analytical approach in which a robust electrochemical flow cell was coupled to different in situ and ex situ measurements was successfully implemented to monitor the activity and stability during electrolysis. Overall, satisfactory sulfite conversion and hydrogen production efficiencies (>90%) at 10 mA·cm–2 were mainly attributed to the use of NF in three-dimensional electrodes with a large surface area and enhanced mass transfer. Furthermore, stabilization processes associated with electrochemical dissolution and sulfur crossover through the membrane induced specific changes in the chemical and physical properties of the electrodes after electrolysis. This study demonstrates that NF-based electrocatalysts can be incorporated in an efficient electrochemical flow cell system for sulfite electrolysis and hydrogen production, with potential applications at a large scale.

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