Evaluation of phytotoxicity and cytotoxicity of industrial catalyst components (Fe, Cu, Ni, Rh and Pd): A case of lethal toxicity of a rhodium salt in terrestrial plants

Until recently, chemical derivatives of platinum group metals have not been in a systematic direct contact with living organisms. The situation has changed dramatically due to anthropogenic activity, which has led to significant redistribution of these metals in the biosphere. Millions of modern cars are equipped with automotive catalytic converters, which contain rhodium, palladium and platinum as active elements. Everyday usage of catalytic technologies promotes the propagation of catalyst components in the environment. Nevertheless, we still have not accumulated profound information on possible ecotoxic effects of these metal pollutants. In this study, we report a case of an extraordinarily rapid development of lethal toxicity of a rhodium (III) salt in the terrestrial plants Pisum sativum, Lupinus angustifolius and Cucumis sativus. The growth stage, at which the exposure occurred, had a crucial impact on the toxicity manifestation: at earlier stages, RhCl3 killed the plants within 24 h. In contrast, the salt was relatively low-toxic in human fibroblasts. We also address phytotoxicity of other common metal pollutants, such as palladium, iron, nickel and copper, together with their cytotoxicity. None of the tested compounds exhibited phytotoxic effects comparable with that of RhCl3. These results evidence the crucial deficiency in our knowledge on environmental dangers of newly widespread metal pollutants

How to Make a Cocktail of Palladium Catalysts with Cola and Alcohol: Heteroatom Doping vs. Nanoscale Morphology of Carbon Supports

Sparkling drinks such as cola can be considered an affordable and inexpensive starting material consisting of carbohydrates and sulfur- and nitrogen-containing organic substances in phosphoric acid, which makes them an excellent precursor for the production of heteroatom-doped carbon materials. In this study, heteroatom-doped carbon materials were successfully prepared in a quick and simple manner using direct carbonization of regular cola and diet cola. The low content of carbon in diet cola allowed reaching a higher level of phosphorus in the prepared carbon material, as well as obtaining additional doping with nitrogen and sulfur due to the presence of sweeteners and caffeine. Effects of carbon support doping with phosphorus, nitrogen and sulfur, as well as of changes in textural properties by ball milling, on the catalytic activity of palladium catalysts were investigated in the Suzuki–Miyaura and Mizoroki–Heck reactions. Contributions of the heteroatom doping and specific surface area of the carbon supports to the increased activity of supported catalysts were discussed. Additionally, the possibility of these reactions to proceed in 40% potable ethanol was studied. Moreover, transformation of various palladium particles (complexes and nanoparticles) in the reaction medium was detected by mass spectrometry and transmission electron microscopy, which evidenced the formation of a cocktail of catalysts in a commercial 40% ethanol/water solution

Improvement of quality of 3D printed objects by elimination of microscopic structural defects in fused deposition modeling

<div><p>Additive manufacturing with fused deposition modeling (FDM) is currently optimized for a wide range of research and commercial applications. The major disadvantage of FDM-created products is their low quality and structural defects (porosity), which impose an obstacle to utilizing them in functional prototyping and direct digital manufacturing of objects intended to contact with gases and liquids. This article describes a simple and efficient approach for assessing the quality of 3D printed objects. Using this approach it was shown that the wall permeability of a printed object depends on its geometric shape and is gradually reduced in a following series: cylinder > cube > pyramid > sphere > cone. Filament feed rate, wall geometry and G-code-defined wall structure were found as primary parameters that influence the quality of 3D-printed products. Optimization of these parameters led to an overall increase in quality and improvement of sealing properties. It was demonstrated that high quality of 3D printed objects can be achieved using routinely available printers and standard filaments.</p></div

Protons in the molecules of reagents and products for conversion calculation by NMR study.

<p>Protons in the molecules of reagents and products for conversion calculation by NMR study.</p

Printed cylindrical tubes of different wall thickness (l, mm).

<p>For each l value the corresponding wall structure and printing quality are displayed (all items were printed at k = 0.98).</p

Experimental demonstration of sealing properties of 3D-printed tube at different k-values.

<p>(A-F)–Evaluation of the of the number of pores in the wall of the tubes manufactured at different k-values; (G-I)–schematic representation of the effect of k-value on the porosity; (J, K)–electron microscopy image of the outer surface of an object printed at k = 0.85 showing a perforating pore (K); (L, M)—electron microscopy image of the outer surface of an object printed at k = 0.98 showing a smaller pore filled with polymer (M).</p

Objects of various shapes made of PLA by 3D printing.

<p>(A) cylinder, (B) cone, (C) sphere, (D) joined cylinder/cone, (E) pyramid, (F) cube.</p

Operational reliability of 3D printed polypropylene tubes.

<p>PP tubes as chemical reaction vessels in comparison with conventional glass test tubes. Values of k are given below for each 3D-printed tube. Performance in the studied chemical transformation is illustrated by product yield (in %) in each studied case, where ≥ 90% efficiency corresponds to excellent performance.</p

Heck reaction.

<p>Heck reaction.</p