Chemistry Journal of Moldova

DOI: https://doi.org/10.19261/cjm.2020.718

Abstract (PDF)

Graphical Abstract: The application of a new hydrometallurgical process for gold extraction by thiosulphate leaching from Romanian mining wastes, coming from Balan and Deva deposits, was studied. There was obtained 85% of Au extraction after leaching; moreover, an integrated flow-sheet, including recycling of process solution and carbon, was outlined, based on results obtained at a laboratory scale, using a schematic chemical circuit of treatment. Global recovery of the process (leaching-adsorption-desorption-electrodeposition) of about 75-80% of Au was achieved. The developed integrated flow-sheet, allows to recycle the reagents during the process, with a loss of only 5-10%, in particular thiosulphate and alcohol, for each complete circuit of treatment.


 

DOI: https://doi.org/10.19261/cjm.2020.672   

 

Abstract (PDF)
Graphical Abstract: The level, composition, and distribution of hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) residues were determined by GC-ECD technique in soil samples from the Soroca district, Republic of Moldova. The concentrations of DDTs and HCHs were up to 1100 and 640 mg/kg, respectively. The high concentration and the degradation rates of the pesticides in soil suggest that the contaminated sites are acting as continuous sources of pollution for the environment. Thus, remediation measures are required to reduce the level of the contaminants in soil.


 

DOI: https://doi.org/10.19261/cjm.2020.664   

 

Abstract (PDF)
Graphical Abstract: Gismondine, laumontite and levyne type zeolites have been synthesized based on the natural minerals of Nakhchivan and the optimal crystallization conditions have been established. The initial components and the reaction products have been examined by X-ray diffraction, thermogravimetric and elemental analysis. It was found that changes in the temperature, alkalinity, ratio of starting components and time of processing of the reaction have different effects on the rate of formation of products, on their degree of crystallinity and on the phase purity of the obtained zeolite.


 

DOI: https://doi.org/10.19261/cjm.2019.650   

Abstract (PDF)
Supplementary Material (PDF)

Graphical Abstract: The aim of this paper is to evaluate an integrated multidisciplinary strategy for the characterization of mining waste, their possible recycling and reuse. The use of Fe-Mn rich wastes in arsenic removal and phosphorus recovery from water and the phytoextraction potential of metals and their possible recovery from biomass are evaluated.


 

DOI: http://dx.doi.org/10.19261/cjm.2019.584   

 

Abstract (PDF)
Graphical Abstract: A total of 5206 samples from twenty-one different vegetables and fruits were collected. Residues of pesticides in concentrations exceeding the maximum residue levels were found in 22.9% of analysed samples. Thirteen insecticides, four fungicides, two acaricides and one herbicide were detected in the analysed samples. The highest value of hazard index was calculated for diazinon – 0.15. The obtained results show that the long-term consumption of vegetables and fruits could pose a health risk for the population of the Republic of Moldova.


 

DOI: http://dx.doi.org/10.19261/cjm.2019.636   

 

Abstract (PDF)
Graphical Abstract: Silver nanoparticles colloids were prepared using the extract from the leaves of Vitex agnus-castus. The effect of temperature on the reduction of silver ions and on the growth of silver nanoparticles was followed by measuring the intensity of the surface plasmon resonance band in the UV spectra. It was found that fast reduction of silver ions occurs even at 40°C, while effective synthesis of silver nanoparticles requires elevated temperatures of 60-80°C.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.541   

Abstract (PDF)
Graphical Abstract: This study presents an assessment of water quality of Prut River using the Water Quality Index (WQI), calculated according to the weighted arithmetic water quality index method. The obtained results show that the water of Prut River may be classified according to WQI as good water quality of grade B for sampling points Sculeni and Cislita-Prut villages, and very poor water quality of grade D collected in the sampling point Criva village.

 

DOI: http://dx.doi.org/10.19261/cjm.2018.537   

Abstract (PDF)

Graphical Abstract: This study presents an assessment of water quality of Prut River using the Water Quality Index (WQI), calculated according to the weighted arithmetic water quality index method. The obtained results show that the water of Prut River may be classified according to WQI as good water quality of grade B for sampling points Sculeni and Cislita-Prut villages, and very poor water quality of grade D collected in the sampling point Criva village.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.544

Abstract (PDF) 

Graphical Abstract: Toxic heavy metals within a reclaimed section of the Orji mechanic village in Nigeria were determined using X-ray fluorescence and atomic adsorption spectrophotometric methods. The data were analyzed using geo-statistical techniques. Results showed that the soil was strongly contaminated by lead, and extremely contaminated by cadmium at some of the sampling points. The activities at the mechanic village in this area significantly affected the accumulation of these heavy metals and immediate soil remediation has been recommended.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.475   

 

Abstract (PDF)
Graphical Abstract: The contact non-equilibrium low-temperature plasma technique is used to synthesize silver nanoparticles (AgNPs) employing trisodium citrate as capping agent. The AgNPs were characterized using UV-Vis spectroscopy, scanning electron microscopy, X-ray diffraction and zeta potential analysis. Additionally, the antibacterial properties of the synthesized AgNPs were assessed.