Articles

One of the challenges brought by the circular economy requires a reconsideration of waste, which may under certain circumstances turn into genuine resources. By extension, soil pollution with heavy metal is a major concern since it directly affects the health of the population. The goal of the present research work is to analyze the impact of the use of waste from other technological processes in agriculture: fly ash (resulting ash from thermal power plants), zeolite bush (resulting from the processing of rock from zeolite quarries), and manure (garbage from zoo technical farms). In this respect, complex treatments based on inorganic substances (fly ash and volcanic indigenous tuff with 70% clinoptilolite) were applied to less-favored agricultural soils in the absence and in the presence of an organic fertilizer (manure), respectively. After cultivating sunflower ( Helianthus annuus L.),a semi-early hybrids grown in the type soil which fly ash has been applied,there have been obtained\ seed crops 15.8% higher than the seed crops grown in the soil on which no fertilizer has been applied. The results obtained when combining fly ash and manure tend to amoun to those obtained when combining manure with indigenous volcanic tuff with 70% clinoptilolite.The quality of the seed crops, obtained in the case of the three types of soil on which amendments were added in the absence/presence of the fertilizer, corresponds to the requirements of the national rules and allows their food processing.

This paper is reporting the data of a preliminary study on heavy metals distribution in the fluid and solid phases involved in dry and classified aluminum hydroxide production through the Bayer process. For heavy metals released in the fluid phases, the main source of contamination is the bauxite through its mineralogical phases soluble or insoluble in alkaline solution. It was shown that the predominant way to transfer contaminating elements in aluminum hydroxide particles is the occlusion of very fine particles coming from mineralogical phases of bauxite residue. Newborn mineralogical phases from bauxite residue, like poor crystallized sodalite and cancrinite, are the most active occlusion contaminants.

Nanosized cobalt aluminate (CoAl2O4) was prepared by thermolysis of heteronuclear coordination compound, namely [Al2Co(C2O4)4(OH2)6]. The synthesized precursor was characterized by chemical analysis, vibrational spectra and thermal analysis. The cobalt aluminate obtained after a heating treatment of the precursor at 700C was characterized by IR, XRD, TEM coupled with SAED measurements. Two types of carbon-based electrodes, glassy carbon and boron-doped diamond electrodes were decorated with the obtained cobalt aluminate in order to enhance the electroanalytical performance for the tetracycline (TC) detection in the aqueous solutions. Cyclic voltammetry technique was used to determine the effect of the nanosized CoAl2O4 on the electrochemical oxidation of C and as consequence, for TC detection at both carbon-based electrodes. The obtained cobalt aluminate exhibited the electrocatalytic activity toward TC detection in direct relation with the type of the carbon substrate, which allowed enhancing the electroanalytical parameters of TC detection in the aqueous solution.