Search Results (8)

Issues encompassing hazardous waste management face challenges, particularly those involving the manufacture of electronic devices such as PCBs that are in high demand with continual growth. Therefore, upcycling to create new products viable for highly valued markets emphasizes alternative solutions towards the circular economy. This research highlights the advantages of copper sulfate recovery from the cupric chloride etching waste solution from PCB manufacturing, combined with the synthesis of copper nanoparticles for antibacterial application. First, aluminium cementation, sulfuric acid leaching, and crystallization were incorporated in the recovery step to ensure a high purity of 99.95% and a recovery of 94.76%. Aluminium cementation selectively offered copper-containing precipitates suitable for leaching to gain high-purity recovered products. In the second step, copper nanoparticles were synthesized using 0.01–0.20 M copper sulfate precursors via sonochemical reduction. In total, 1–5 mL of hydrazine and 5–30 mL of 0.01 M ethylene glycol were added into a 50 mL precursor as reducing and capping agents, respectively. Hydrazine addition under high pH played a key role in controlling the shape, size, and purity of the copper nanoparticles, required for their antibacterial properties. The optimum condition gave spherical or polygonal copper nanoparticles of 54.54 nm at 99.95% purity and >92% recovery. The antibacterial test of the synthesized copper nanoparticles using E. coli via agar well diffusion exhibited a zone of inhibition (ZOI) of 50 mm at 127 mg/mL, similar to the antibiotic-controlled condition, proving their antibacterial potential. Along with process effectiveness, a feasibility study of the inventing process confirmed the environmental and economic impacts of minimizing energy consumption and processing time, which are competitive with respect to the existing recycling technologies. Full article

In this work, we report the synthesis of copper nanoparticles (Cu NPs), employing the chemical reduction method in an aqueous medium. We used copper sulfate pentahydrate (CuSO₄·5H₂O) as a metallic precursor; polyethylenimine (PEI), allylamine (AAM), and 4-aminobutyric acid (AABT) as stabilizing agents; and hydrated hydrazine as a reducing agent. The characterization of the obtained nanoparticles consisted of X-ray, TEM, FTIR, and TGA analyses. Through these techniques, it was possible to detect the presence of the used stabilizing agents on the surface of the NPs. Finally, a zeta potential analysis was performed to differentiate the stability of the nanoparticles with a different type of stabilizing agent, from which it was determined that the most stable nanoparticles were the Cu NPs synthesized in the presence of the PEI/AAM mixture. The antimicrobial activity of Cu/PEI/AABT toward P. aeruginosa and S. aureus bacteria was high, inhibiting both bacteria with low contact times and copper concentrations of 50–200 ppm. The synthesis method allowed us to obtain Cu NPs free of oxides, stable to oxidation, and with high yields. The newly functionalized Cu NPs are potential candidates for antimicrobial applications. Full article

Copper in ionic form (Cu²⁺) should be removed from wastewater because of its harmful effects on human health. Meanwhile, Cu-metal nanoparticles (Cu⁰ NPs) are widely used in various applications such as catalysts, optical materials, sensors, and antibacterial agents. Here, we demonstrated the recovery of Cu²⁺ from wastewater and its subsequent transformation into Cu⁰ NPs, a value-added product, via continuous adsorption followed by chemical reduction by hydrazine. To separate and enrich Cu²⁺ from wastewater, a biosorbent that exhibits excellent selectivity and adsorption capacity toward Cu²⁺, i.e., polyethyleneimine-grafted cellulose nanofibril aerogel (PEI@CNF), was packed into a column and used to treat 20 mg/L Cu²⁺ wastewater at a flow rate of 5 mL/min. The Cu²⁺ adsorption reached equilibrium at 72 h, and the Cu²⁺-saturated column was eluted using 0.1 M of HCl. After five consecutive elutions of Cu²⁺ from the adsorbent column, a Cu²⁺-enriched solution with a concentration of 3212 mg/L was obtained. The recovered Cu²⁺ concentrate was chemically reduced to obtain Cu⁰ NPs by reaction with hydrazine as a reductant in the presence of sodium dodecyl sulfate (SDS) as a stabilizer. The solution pH and hydrazine/Cu²⁺ ratio strongly affected the reduction efficiency of Cu²⁺ ions. When 0.1 M of SDS was used, spherical 50–100 nm Cu⁰ NPs were obtained. The results demonstrate that Cu²⁺-spiked wastewater can be converted into Cu⁰ NPs as a value-added product via adsorption followed by chemical reduction. Full article

A winemaking waste was used as a precursor of activated carbon used for the removal of hazardous Cr(VI) from solutions. The preparation process consisted of a hydrothermal process and a chemical activation of the resulting product, with KOH. The adsorption results show that the adsorption of Cr(VI) on the obtained activated carbon is strongly dependent on the stirring speed applied to the carbon/solution mixture, pH of the solution, and temperature. The equilibrium isotherm was well fitted to the Langmuir Type-II equation, whereas the kinetic can be described by the pseudo-second-order kinetic model. Thermodynamic studies revealed that Cr(VI) adsorption was an exothermic and spontaneous process. Finally, desorption experiments showed that Cr(VI) was effectively desorbed using hydrazine sulfate solutions, and, at the same time, the element was reduced to the less hazardous Cr(III) oxidation state. Full article

Carbon nanostructures are promising electrode materials for energy storage devices because of their unique physical and chemical properties. Modification of the surface improves the electrochemical properties of those materials because of the changes in morphology, diffusion properties, and inclusion of additional contributions to redox processes. Oxygen-containing functional groups and nitrogen doped into the carbon matrix significantly contribute to the electrochemical behavior of reduced graphite oxide (RGO). In this work, RGO was synthesized during hydrothermal treatment of graphite oxide with a hydrazine sulfate aqueous solution. Different amounts of hydrazine sulfate were used to synthesize RGO with different nitrogen contents in the structure, and the same synthesis conditions made it possible to obtain a material with a similar composition of oxygen-containing functional groups. The materials with different nitrogen concentrations and similar amounts of oxygen were compared as electrode materials for a supercapacitor and as a negative electrode material for a Li-ion battery. It was shown that the presence of oxygen-containing functional groups has the greatest influence on the behavior and efficiency of supercapacitor electrode materials, while nitrogen atoms embedded in the graphene lattice play the largest role in lithium intercalation. Full article

A new series of 5-acetylbarbituric based thiosemicarbazones named 5-acetylbarbituric hydrazine-1-carbothioamide (Acb4NDH, 1), N-methyl-(5-acetylbarbituric)hydrazine- 1-carbothioamide (Acb4NM, 2), N-ethyl-(5-acetylbarbituric)hydrazine-1-carbothioamide (Acb4NE, 3), N,N-dimethyl-(5-acetylbarbituric)hydrazine-1-carbothioamide (Acb4NDM, 4), N′-piperidine- (5-acetylbarbituric)-1-carbothiohydrazide (Acb4Npip, 5) and N′-hexamethyleneimine- (5-acetylbarbituric)-1-carbothiohydrazide (Acb4Nhexim, 6), has been synthesized from 5-acetylbarbituric acid and N-unsubstituted/substituted thiosemicarbazides. The synthesized compounds were well characterized by elemental analyses, FT-IR, ¹H, ¹³C NMR and mass spectroscopic methods. Three-dimensional molecular structures of three compounds (1, 2 and 6) and of N,3-dimethyl-4-(5-(methylamino)-1,3,4λ⁴-thiadiazol-2-yl)-5-oxo-2,5-dihydro-1H-pyrazole- 1-carbothioamide ethyl sulfate salt (7) were determined by single crystal X-ray crystallography. The compounds were evaluated for their in vitro cytotoxicity against HeLa-229 cancer cell line. Full article

The activity of betulin-3,28-diphosphate (BDP) in combination with the cytostatics such as 5-fluorouracil (5-FU) and hydrazine sulfate (HS) was demonstrated by using the transplanted Ehrlich ascites carcinoma (EAC) in mice. The dose-dependent effect of combination drugs BDP + HS and BDP + 5-FU was revealed by in vitro experiments on rats. The synergetic effect of HS and BDP on oxidative stress and energy metabolism was established. The malonic dialdehyde (MDA) level both in plasma and erythrocytes decreased by 87 ± 2%, and the superoxide dismutase (SOD) activity increased by 105 ± 7% in comparison with the control. The combination of BDP + HS promoted the increase of lactate dehydrogenase (LDH) activity in the reverse reaction by 195 ± 21% compared to the control. The combination drug of 5-FU with BDP caused the synergetic decrease of the lipid peroxidation (LPO) intensity estimated by the MDA level decrease up to 14 ± 4% compared to pure compounds. Betulin-3,28-diphosphate in combination with cytostatics for EAC treatment improved the animal health status, as well as decreased the cytostatics dose that can be used in palliative therapy. Full article

1-Amino-3-nitroguanidine (ANQ, 1) was synthesized by hydrazinolysis of nitroguanidine (NQ) with hydrazine hydrate. Four different amino-nitroguanidinium salts (chloride (2), bromide (3), iodide (4) and sulfate (5)) were synthesized and structurally characterized by low-temperature X-ray diffraction. The halides 2–4 could only be obtained crystalline as monohydrates. In addition, they were characterized by NMR and vibrational spectroscopy, elemental analysis and the sensitivities towards impact, friction and electrostatic discharge were determined. The compounds can be used in silver (AgX, X = Cl, Br, I) and barium (BaSO₄) based metathesis reactions in order to form more complex salts of 1-amino-nitroguanidine. Full article