Humic acids impact on heavy metal phytoextraction in Tagetes patula L.

In a model study, we analysed the impact of humic acids (HAs, 500 ppm) on the accumulation of heavy metals (HMs; Pb, Cu, Ni and Zn) in roots and aboveground organs of the annual ornamental plant Tagetes patula (Scarlet variety) cultivated on the Terra Vita nutritive substrate used in modern cultural landscape mulching to imitate the upper fertile root layer (UR-RAT) of contaminated urban soils in megacities. Plants were grown in full photoculture (at no sunlight) in pots placed in a closed grow box, maintaining internal microclimate. A modern HLG Quantum Board QB288 V2 Rspec LED panel enabled with vegetation modes was used as light source. HMs were introduced in substrate as aqueous saline. Each setting was quadruplicated. Total experiment duration was 30 days. Tagetes patula was proved a particularly effective phytoextractor of Zn applied at 40 mg/kg (p<0.01). At the same time, the plants showed high tolerance to toxic growth inhibition (in biometry of the above- and underground organ length and mass) and preserved external aesthetics. Metals were further graded by phytomass accumulation as follows: Cu>Pb>Ni. Ni at 30 mg/kg had a major impact on plant weight and length, which sets off the variety as a sensitive phytoexcluder for this metal. HAs increased aboveground mass in all settings and decreased the HM mass impact. A sharp root mass reduction was observed in combinations of the two factors (HMs+HAs), which was clearly reflected in impaired root mass in zinc settings. A single metal addition reduced the mass by average 12.0 % (p<0.01) vs. control (no HAs or HMs), whilst a combined HAs+HMs administration induced its 65.0 % reduction (p<0.01). The results obtained indicate a good root buffering capacity for HM translocation from the rhizosphere to aboveground parts. In general, HA usage is promising for creating the green space and phytoremediation of urban HM-contaminated soils.

Toxic Metals (As, Cd, Ni, Pb) Impact in the Most Common Medicinal Plant (Mentha piperita)

This study aimed to evaluate the behavior of Mentha piperita under Cd, Pb, Ni, and As soil contamination and their transfer from soil in plants as well as translocation in the roots/stems/leaves system compared with a control without metal addition. The mint seedlings were exposed for a three-month period using two metal mixtures in the same concentrations such as AsCd and AsCdNiPb (23.7 mg/kg As, 5 mg/kg Cd, 136 mg/kg Ni, and 95 mg/kg Pb). The results of metal concentration in plants showed that Cd, Ni, and Pb were accumulated in different parts of the plant, except for As. In plants organs, the order of metal accumulation was roots > stems > leaves. No significant impact on the growth, development, and chlorophyll content compared to the control was observed in the first month of exposure. After three months of exposure, phytotoxic effects occurred. Generally, the transfer coefficients and translocation factors values were less than 1, indicating that Mentha piperita immobilized the metals in root. The laboratory experiments highlighted that for a short period of time, Mentha piperita has the capacity to stabilize the metals at the root level and was a metal-tolerant plant when using a garden rich-substrate.

Hydrogen Production From Steam Gasification of Palm Kernel Shell Using Sequential Impregnation Bimetallic Catalysts

Zeolite β supported bimetallic Fe and Ni catalysts have been prepared using sequential impregnation method and calcined at temperatures between 500-700 ºC. The catalytic activity of these catalysts in a steam gasification of palm kernel shell was tested in a fixed-bed quartz micro-reactor at 700 ºC. Both Fe and Ni active metals present in FeNi/BEA and NiFe/BEA catalysts are corresponding to Fe2O3 and NiO. Different calcination temperatures and different sequence in metal addition have a significant effect to the catalytic activity where FeNi/BEA (700) shows the highest hydrogen produced than other catalysts.

Effect of Noble Metal Addition on the Disorder Dynamics of Ni3Al by Means of Monte Carlo Simulation

In this work, the effect of the addition of noble metals on the order–order disorder process of the L12 structure corresponding to the intermetallic Ni3Al is analyzed. Stoichiometric, nonstoichiometric, and quasi-binary compositions doped with noble metals such as Ag, Au, Pd, and Pt (1 at%) were analyzed. It was observed that depending on the composition, there is a modification in the activation energies calculated from the two time constants that characterize the disorder process. The statistic of atomic jumps was typified based on the configuration of the window to be crossed and, with this, it was identified that the origin of the negative activation energy of the long disorder process is due to an increase in the corresponding energy of the AlAl-Ni jump through unnatural windows.