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A ZnS nano-sorbent to remove copper(II) and lead(II) ions from aqueous solutions was prepared via a hydrothermal reaction and characterized by X-ray diffraction. The zinc sulfide nanoparticle size was determined to be 7.0 ± 0.22 nm. The effects of pH, light conditions, time, capacity, and interferences on the zinc sulfide ability to remove copper(II) and lead(II) ions from aqueous solutions were investigated. pH studies showed that pH 5 was the optimal value for zinc sulfide binding both copper(II) and lead(II) ions. Under ambient light, the binding of both ions occurred within the first 5 min. Binding capacities ranged from 116.2 to 243.9 mg/g for copper(II), 39.1 to 147.1 mg/g for lead(II) ions, and 36.1–79.4 mg/g for lead(II) ions in the dark over temperature range from 4 to 45 °C. The thermodynamic parameters showed that the binding process for both copper(II) and lead(II) ions was either spontaneous or close to equilibrium. Light conditions were also investigated in the context of cation interference and showed that the presence of hard cations had no effect on the binding of lead(II) ions. On the other hand, the presence of hard cations showed small decrease in the binding of copper(II) ions.

The application of nanomaterials as a method to overcome plant stress and increase crop yield is relatively new as compared to the use of fertilizers and pesticides in agricultural production. In t...

Bulk Cu compounds such as Cu(OH)2 are extensively used as pesticides in agriculture. Recent investigations suggest that Cu-based nanomaterials can replace bulk materials reducing the environmental impacts of Cu. In this study, stress responses of alfalfa (Medicago sativa L.) seedlings to Cu(OH)2 nanoparticle or compounds were evaluated. Seeds were immersed in suspension/solutions of a Cu(OH)2 nanoform, bulk Cu(OH)2, CuSO4, and Cu(NO3)2 at 25 and 75 mg/L. Six days later, the germination, seedling growth, and the physiological and biochemical responses of sprouts were evaluated. All Cu treatments significantly reduced root elongation (average = 63%). The ionic compounds at 25 and 75 mg/L caused a reduction in all elements analyzed (Ca, K, Mg, P, Zn, and Mn), excepting for S, Fe and Mo. The bulk-Cu(OH)2 treatment reduced K (48%) and P (52%) at 75 mg/L, but increased Zn at 25 (18%) and 75 (21%) mg/L. The nano-Cu(OH)2 reduced K (46%) and P (48%) at 75 mg/L, and also P (37%) at 25 mg/L, compared with control. Confocal microscopy images showed that all Cu compounds, at 75 mg/L, significantly reduced nitric oxide, concurring with the reduction in root growth. Nano Cu(OH)2 at 25 mg/L upregulated the expression of the Cu/Zn superoxide dismutase gene (1.92-fold), while ionic treatments at 75 mg/L upregulated (∼10-fold) metallothionein (MT) transcripts. Results demonstrated that nano and bulk Cu(OH)2 compounds caused less physiological impairments in comparison to the ionic ones in alfalfa seedlings.

In the present study, catalytic systems based on La-doping were developed to improve the activity and performance of CoMoS2 hydrodesulfurization catalysts. Lanthanum-doped at 5, 10, or 25% of the Co content in CoMoS2 hydrodesulfurization catalysts were synthesized through a solvothermal process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses confirmed the catalysts were triphasic consisting of Co9S8, MoS2, and La2S3. The La doped catalysts showed enhanced catalytic activity compared with CoMoS2 synthesized under the same conditions. The CoMoS2 prepared under solvothermal synthesis conditions showed a catalytic activity of 6.80 mol g-1 s-1, however, the La0.05Co0.95MoS2 doping showed a catalytic activity of 6.51 mol g -1 s-1 whereas the La0.1Co0.9MoS2 and La0.25Co0.75MoS2 samples showed catalytic activities of 10.7 mol g-1 s-1. The reaction products indicated the major reaction pathway was direct desulfurization. The La0.25Co0.75MoS2 catalyst after one reaction cycle showed a lower amount of carbon, than the undoped CoMoS2 catalyst.

The photocatalytic degradation of simazine (SIM) was investigated using zinc oxide/graphene oxide (ZnO/GO) composite materials under visible light irradiation. The reaction kinetics was studied to optimize the reaction parameters for efficient degradation of SIM. Batch studies were performed to investigate the effects of initial reaction pH, the loading of the ZnO onto GO, and mass of catalyst on the removal of SIM from aqueous solution. A pH of 2 was determined to be the optimal reaction pH for the different ZnO-loaded GO catalysts. In addition, a mass of 40 mg of catalyst in the reaction was observed to be the most effective for the catalysts synthesized using 20 and 30 mmol of Zn2+ ions; whereas a mass of 10 mg was most effective for the ZnO/GO composite material synthesized using 10 mmol Zn2+ ions. The reaction was observed to follow a second-order kinetics for the degradation process. Furthermore, the synthesized ZnO/GO composite catalysts resulted in higher reaction rates than those observed for pure ZnO. The 30 mmol ZnO/GO composite expressed a rate of SIM degradation ten times greater than the rate observed for pure ZnO, and sixty-two times greater than the rate of photolysis. In addition, the catalyst cycling exhibited a constant photocatalytic activity for the ZnO/GO composite over three reaction cycles without the need of a conditioning cycle.

Upconversion (UC) particles are currently under intensive investigation, normally for their visible instead of ultraviolet (UV) light luminescence under near-infrared (NIR) irradiation. As a commonly studied host, NaYF4 in particular is known to have low phonon energy and high UC efficiency. Here, we present our work on enhancing UC luminescence in the UV region by adding a third dopant into a binary-doped NaYF4:Yb3+,Tm3+ host. More specifically, neodymium (Nd3+) or gadolinium (Gd3+) ions was co-doped into parent NaYF4:20mol%Yb3+,0.5mol%Tm3+ UC particles to enhance their UV UC luminescence. Experimental results demonstrated that these particles exhibited the highest degree of UV UC enhancements when co-doped with 0.05mol% Nd3+ or 2.0mol% Gd3+, expanding the potential of this type of materials into many possible applications by directly converting NIR irradiation into UV light. Fundamentally, the UV UC emission dependence of these triply doped NaYF4:Yb3+,Tm3+ particles with different Nd3+ and Gd3+ doping concentrations was investigated in terms of ground state absorption, excited state absorption and energy transfer UC mechanisms.

Tin oxide, SnO(2), nanomaterial was synthesized and tested for the removal of Cu(2+) and Ni(2+) ions from aqueous solutions. Various parameters for the binding were investigated in batch studied, which included pH, time, temperature, and interferences. In addition, isotherm studied were performed to determine the maximum binding capacity for both Cu(2+) and Ni(2+) ions. The optimal binding pH determined from the effects of pH were to be at pH 5 for both the Cu(2+) and Ni(2+) ions. The isotherm studies were performed at temperatures of 4°C, 25 °C, and 45 °C for both the Cu(2+) and Ni(2+) ions and were found to follow the Langmuir isotherm model. The binding capacities for the Cu(2+) ions were 2.63 mg/g, 2.95 mg/g and 3.27 mg/g at the aforementioned temperatures, respectively. Whereas the binding capacities for Ni(2+) were 0.79 mg/g, 1.07 mg/g, and 1.46 mg/g at the respective temperatures. The determined thermodynamic parameters for the binding showed that the binding processes for the reactions were endothermic, as the ΔG was observed to decrease with decreasing temperatures. As well the ΔH was 28.73 kJ/mol for Cu(2+) (III) and 13.37 kJ/mol for Ni(2+). The ΔS was observed to be 92.65 J/mol for Cu(2+) and 54.53 J/mol for Ni(2+). The free energy of adsorption for the Cu(2+) was determined to be 13.99 kJ/mol and the activation energy for the binding of Ni(2+) was determined to be 8.09 KJ/mol. The activation energy data indicate that the reaction was occurring through chemisorption