Solvents prepared from natural terpenes (menthol and thymol), as H-bond acceptors, and a series of organic acids (chain lengths of 8, 10, and 14 C atoms), as H-bond donors, were characterized and tested as reaction media for liquid–liquid extraction purposes. Due to their high hydrophobicity, they seem to be promising alternatives to conventional (nonpolar and toxic) solvents, since they possess relatively less toxic, less volatile, and consequently, more environmentally friendly characteristics. Assuming that the equilibrium is established between solvent and analyte during a ligandless procedure, it can be concluded that those nonpolar solvents can efficiently extract nonpolar analytes from the aqueous environment. Previous investigations showed a wide range of applications, including their use as solvents in extractions of metal cations, small molecules, and bioactive compounds for food and pharmaceutical applications. In this work, hydrophobic solvents based on natural terpenes, which showed chemical stability and desirable physicochemical and thermal properties, were chosen as potential reaction media in the liquid–liquid extraction (LLE) procedure for Pb(II) removal from aqueous solutions. Low viscosities and high hydrophobicities of prepared solvents were confirmed as desirable properties for their application. Extraction parameters were optimized, and chosen solvents were applied. The results showed satisfactory extraction efficiencies in simple and fast procedures, followed by low solvent consumption. The best results (98%) were obtained by the thymol-based solvent, thymol–decanoic acid (Thy-DecA) 1:1, followed by L-menthol-based solvents: menthol–octanoic acid (Men-OctA) 1:1 with 97% and menthol–decanoic acid (Men-DecA) 1:1 with 94.3% efficiency.

Selective separation and removal of a metal species from complex matrices of other species is of critical importance in separation sciences and especially in industrial processes. The selectivity and efficiency of Pb(II) ion removal from an aqueous solution in the presence of Ni(II), Zn(II), Co(II), Cu(II), and Cd(II) ions as competing ions in a multi-component aqueous source phase through bulk liquid membrane system were investigated. The influence of the palmitic and oleic acid as supporting surfactants in the membrane phase on the removal of Pb(II) ions was also analyzed. Dicyclohexano-18-crown-6 dissolved in chloroform, proved to be a selective and efficient carrier for Pb(II) ions. In the optimized procedure, 3 hours of equilibrium time was required to achieve the maximum removal efficiency. It was found, that removal of Pb(II) ions was achieved without significant reduction in the efficiency compared to the liquid membrane transport of a single-component system. None of these cations interfered with Pb(II) removal. The presence of the oleic and palmitic acid in the membrane phase increase the content of Pb(II) removed to the receiving phase. In optimal transport conditions, more than 97% efficiencies for the removal of Pb(II) were obtained for a system supported by oleic acid. The excellent efficiency and high degree of selectivity for the Pb(II) ion removal by the proposed BLM system, reveals its potential application for the selective removal, concentration, and purification of lead ions from its different mixtures.

Implementation of the "bulk liquid membrane" (BLM) system was investigated in terms of its efficiency for selective removal of heavy metal ions from natural resources and industrial wastewater. In this paper, the removal of lead (II) ions through a liquid membrane system and factors that influence the process were examined. The research was performed using the homemade transport cell. Two organic solvents were used as liquid membranes: 1,2-dichloroethane and chloroform. Metal ion concentration in aqueous phases was monitored by flame atomic absorption spectrophotometry, after 4 hours of experiment. Macrocyclic ether (dicyclohexano-18-crown-6) was used as ligand for Pb (II) ions. The effects of nonionic surfactants (Triton X-100, Triton X-45 and Triton X-405) added in the receiving phase of BLM system were investigated. The results showed significant increase in transport rate compared to systems without surfactants. Considering the surfactant structure, transport rate of Pb (II) ions followed the order: TX-100 >TX-45>TX-405. Presence of TX-100 increased transport of Pb (II) ions up to 78% through chloroform and 58% through 1,2-dichloroethane.  

This paper presents the results of influence of extraction technique on phytochemical composition and biological activity of aqueous extracts of commercial apricot kernels. Three techniques were used for extraction: maceration, ultrasonic and Soxhlet extraction. The content of total phenols, flavonoids, bioelements, antioxidant and antimicrobial activity was analyzed in the extracts. Antioxidant activity was analyzed in vitro using DPPH and FRAP methods. Antimicrobial screening was performed by diffusion technique on reference strains from the ATCC collection. The content of total phenols and flavonoids is highest in extracts obtained by ultrasonic extraction and maceration. These techniques have proven to be the best for the extraction of macro and micronutrients. The aqueous extract obtained by maceration at 300 rpm for 3 hours showed a greater inhibitory effect against the tested microorganisms, compared to the extracts obtained by other techniques. The least efficient method of extracting bioactive components from apricot kernels is Soxhlet extraction, with the lowest dry extract yield of 5.5%.   

The conductometric study of ligand structure influence on the Pb(II) complexation with crown ethers in different solvents has been investigated. In this paper, the complexation reaction of macrocyclic ligand, 18-crown-6 (18C6), dibenzo-18-crown-6 (DB18C6), and Pb(II) cation was studied in different solvents: dichloromethane (DCM) and 1,2- dichloroethane (1,2-DCE). The effects of surfactant structure (Triton X-100 and Triton X-45) on the conductivity of the Pb(II) complex with 18-crown-6 and dibenzo-18-crown-6 ether have been investigated. The conductance data showed that the stoichiometry of the complexes in most cases is 1:1(ML). It is also demonstrated that the influence of crown ethers is deeply affected by the organic solvent used. In the solvents studied, the stability of the resulting complexes showed higher stability in dichloromethane comparing with 1,2- dichloroethane. Macrocyclic ligand 18-crown-6 showed more suitable for complexation of Pb(II) ions compared to dibenzo-18-crown-6. Adding a surfactant affected the higher absolute values of the conductivity of systems, but not the change in the stoichiometric ratio between a metal ion and macrocyclic ligand.

Schiff bases are organic compounds formed by the reaction of the primary amine with carbonyl compounds (aldehydes or ketones). These are mainly bi- or tridentate ligands capable of forming very stable complexes with transitional metals. They are used as catalysts in oxygenation, hydrolysis, electro-reduction and decomposition reactions. Many Shiff bases show significant anti-tumor and antimicrobial activity, which is why they are the subject of research by many scientists in the world. In this paper Schiff's base from benzidine and 1,3-diphenyl-1,3-propanedione was synthesized. To characterize the product, FTIR spectroscopy and stereo-microscopy were used. In order to determine biological activity, antibacterial, antifungal and antioxidant activity of the product was tested. The results showed that the interaction of benzidine and 1,3-diphenylpropandione results in a Schiff base showing antibacterial, antifungal and antioxidant activity. Keywords: Schiff base, benzidine, FTIR, UV/Vis, antimicrobial activity.

Among numerous techniques for successful separation and removal of metal cations, transport through bulk liquid membranes attracts special attention of researchers. In this paper, different ligands were applied as possible carriers for Cd(II) ions. Influence of substituents in macrocyclic ligands derived from 18-crown-6 reflected in decreased amount of transported Cd(II) ions, compared to 18-crown-6 (61,26%), in all used solvents, following the order: DCH18C6<DB18C6<B18C6<18C6. Addition of nonionic surfactants as possible carriers for Cd(II) ions within the liquid membranes also resulted with decreased transport rates, due to additional interactions of Cd(II) ions and carriers within the membrane.

Green Tea, made from Camellia sinensis plant leaves, is one of the most popular drinks in the world. For the past decades, scientists have studied this plant in terms of potential health benefits. Research has shown that green tea helps prevent stroke, malignancy and infections. In this paper, antioxidant activity and total phenol content of 4 samples of green tea from local Tuzla stores were investigated, of which two were of foreign origin. The antioxidant activity of the samples was analyzed using FRAP and DPPH methods. The obtained results show that the highest content of total phenols and the largest antioxidant capacity has a sample of foreign origin. The content of total phenols in the samples ranges from 60.01 to 79.34 mg GAE/g. The highest FRAP value is 3.34 mmol/g. The antioxidant capacity was also confirmed by the DPPH method. The IC50 value ranges from 0.014 to 0.030 mg/mL. Keywords-Phenol, FRAP, DPPH, Green Tea