Bentonite clay is a valuable material in various process industries, thanks to its specific properties. Easy availability, low cost and their effectiveness are the main factors that have made bentonite adsorbent in the edible oil industry. The textural characteristics of bentonite clay play an important role in its performance. In its natural form, as an aluminosilicate material, bentonite does not show satisfactory sorption and catalytic properties, and it needs to be activated. The main goal of this research is to increase the adsorption capacity of bentonite clay by modifying its properties by treatment with organic acid. Activation of bentonite clay in the experimental part was performed with different concentrations of sulfuric acid. The chemical composition of the natural bentonite sample was determined using XRF alongside the influence of acid activation of bentonite with H2SO4 on the surface characteristics (such as specific surface area, pore volume and average pore diameter, adsorption capacity and isotherm type) of bentonite clay. The XRF analysis of the natural bentonite, which contains 56.35% SiO2 and 19.82% Al2O3 as its primary components, confirms that it is an aluminosilicate material. Except for SiO2, which recorded a consistent increase in quantity from 56.35% to 74.15% with increasing acid concentration, the composition of other components, after activation slightly decreased or remained the same. The acid concentration that yielded the highest increase in specific surface area, as measured by the Brunauer–Emmett–Teller (BET) method, was selected as the optimal concentration for activating bentonite. The specific surface area almost tripled (from 95.519 m2/g to 346.467 m2/g)) by activation with 15% sulfuric acid, with an activation time of 3 hours and a bentonite: acid ratio of 1:5. The research results show the effectiveness of acid modification in terms of improving the characteristics of the porous structure of bentonite samples.

Waste water in the galvanic process contains high concentrations of heavy metals that pose a direct danger to humans and the environment. Conventional methods for their removal are quite expensive and generate a large amount of waste. The development of new and improvement of existing methods for the removal of heavy metals from galvanic wastewater are the subject of many studies. Compared to other purification methods, the adsorption is becoming an increasingly popular method of wastewater purification, especially if the adsorbent is cheap, easily available and does not require any other treatment before use. Therefore, the aim of the work was to investigate the possibility of using natural bentonite for the removal of heavy metal ions from multi-component water systems of the galvanic industry. For this purpose, the physico-chemical characterization of natural bentonite was performed, and then the influence of pH value, time and temperature on the adsorption efficiency was examined. The results of adsorption showed that natural bentonite can be used as an adsorbent for the removal of heavy metal ions from waste galvanic waters, and that at pH 5 it achieves the maximum removal efficiency for Cu(II):Cr(III):Ni(II) ions in the percentage ratio 100 : 99.990 : 99.998. The results showed that the highest removal efficiency for Cu (II) ions was achieved in the first 10 minutes, and 20 minutes for Cr (III) and Ni (II) ions. The maximum efficiency of Cu (II) removal was achieved at all temperatures, while for Cr (III) 99.99% and Ni (II) 100% maximum efficiency was achieved at 35°C, which indicates that the adsorption process is endothermic. The experimental results of the adsorption of Cu (II) metal ions are in good agreement with the Langmuir and Freundlich theoretical models, while for Cr (III) and Ni (II) ions they are in better agreement with the Langmuir adsorption model.

Medicinal plants have become an increasing subject of interest worldwide due to the large amount of biologically active substances that have potential beneficial health properties. One of the more interesting popular medicinal plants is hawthorn (Crataegusspp.), a deciduous branched shrub that is increasingly used for health purposes. Various parts of this plant, including berries, flowers and leaves, are rich in nutrients and beneficial bioactive compounds that are effective in the treatment of numerous diseases. Honey is a natural sweetener produced by bees from plant secretions. Known for its nutritional and medicinal values, it gives strength to the body, which is why it is indispensable in the human diet. The combination of these two ingredients represents a significant source of vitamins and minerals in daily use, but also for use in various pharmaceutical and medical purpose. Taking into account all of the above, the aim of the work is to test samples of the mixture of honey and hawthorn in different proportions and determine the physical and chemical characteristics: pH value, electrical conductivity, refractive index, viscosity, water activity, HMF, DPPH. Based on the analysis, appropriate conclusions will be drawn and more information will be obtained about their quality and possible use as a food supplement. On the basis of the conducted analyses, it can be concluded that the parameter values are within the permitted limits defined by the Rulebook (Official Gazette Bosnia and Herzegovina No. 37/09). The analysis of the mentioned parameters showed that the chemical composition of the sample plays a major role in the value of the measurement results, and that Sample III has the best antioxidant properties. KEYWORDS:physicochemical characteristics; honey; hawthorn (Crataegus spp.);mixture; food suplement

Water hardness and deposition of incrustation is a problem in households and industry. In this regard, several technologies have been developed with the purpose of water softening and preventing the deposition of incrustation. The ion exchange method is the most commonly used method and is considered a conventional method. However, due to the shortcomings of this method, there is a need to develop adequate alternative methods. The potential of the method using biosorbents such as moss Leucobryum glaucum and Spaghnum peat moss for the purpose of removing water hardness has recently become the subject of intensive research with growing interest. In this study, the method using Leucobryum glaucum as a biosorbent was tested and a comparison was made with the conventional method and previously conducted studies that used other biosorbents.

In this article, the corrosion inhibition of steel DIN 2391 St 37-4 in acidic medium 5% H2SO4 with and without the presence of eco inhibitors of leaf (Petroselinum Sativum) was examined. Inhibitory properties of parsley leaves (Petroselinum Sativum) on steel DIN 2391 St 37-4 were examined by potentiodynamic polarization - Tafel extrapolation, and FTIR method in order to categorize the oxide layer. The test was performed in static medium and with stirring at 600 rpm. By Tafel extrapolation based on changes in corrosion potential, the inhibitor behaves as mixed. Increasing the concentration of inhibitors increases the efficiency of inhibition. Corrosion processes are inhibited by adsorption of organic matter on the surface of steel DIN 2391 St 37-4, forming a film. The obtained results indicate that parsley leaf (Petroselinum Sativum) is an effective eco inhibitor for the tested steel in 5% sulfuric acid.

In this research, the results of bentonite characterization (pH value of bentonite suspension, point of zero charge, cation exchange capacity,  SEM, XRF, DTG) are presented. The results of lead (II) removal efficiency at initial lead (II) concentrations of 200, 300 and 400 mg/L, and biosorbent dosage of 1 gram in 50 ml of lead(II) solution,  are also presented, as well as the values of the Freundlich and Langmuir constants from the Freundlich and Langmuir adsorption isotherms. The obtained results showed that removal efficiency is high for all three examined initial lead (II) concentrations, and it is above 99%. The lead (II) removal efficiency slightly decreases with an increase in initial lead concentration. Experimental data obtained from adsorption experiment with contact time of 2.5 minutes, stirring rate 100 rpm, temperature 250C and pH value 5 are better fitted with the linearized Langmuir equation isotherm, giving an R2 value closest to unity (0.9994), than to linearized Freundlich equation (0.9886).

In this research, the possibility of using Ca(OH)2 in the form of commercial hydrated lime as a catalyst for the methanolysis of refined rapeseed oil was evaluated. Characterization of unused catalyst was performed by SEM-EDS, laser diffraction, XRF, BET, XRD and TG/DTG methods, and vegetable oil was analyzed for physicochemical characteristics. Within methanolysis, the effects of catalyst loading, reaction temperature and reaction time on methyl ester yield, density and viscosity of biodiesel, as well as the possibility of catalyst reuse were investigated. The obtained results showed that hydrated lime is an efficient catalyst for transesterification of vegetable oil, whereby the use of 3 wt% of catalyst relative to oil weight, at temperature 60℃ and mixing rate 1000 rpm after 120 min of transesterification reaction achieved a yield of methyl esters 98.76%. With three reuses of hydrated lime, without intermediate washing and regeneration procedures, the yield of rapeseed oil methyl ester remained above 90%.

Water quality is deteriorating over the years, and the main source of water pollution is industrial, agricultural and municipal wastewater. Heavy metals, organic compounds and microorganisms, present even in traces, can be very dangerous to human health, aquatic organisms and the environment. Therefore, in this study was investigate the possibility of modified and unmodified plum pits as biosorbents for Pb (II) ions removal from aqueous solution. Experimental data have shown that these bisorbents show a certain potential for application in the metal removal process. The feasibility was tested for an unmodified and modified biosorbent based on plum pits in the range of concentrations 150-200 mg/l (unmodified sample) and 100-200 mg/l (modified sample) at a contact time of 30 and 60 minutes . Adsorption parameters were determined using the Freundlich isotherm. The results showed that unmodified biosorbent based on plum pits with increasing concentration from 150 mg/L to 200 mg/L leads to a large increase in the percentage of removal of Pb (II) ions, with no significant effect on contact time. In contrast to the unmodified sample, the modified biosorbent based on plum pits % of removed Pb (II) ions significantly increases the contact time at the initial Pb (II) concentration of 100 mg/L, while at the initial concentration of 150 mg/L and longer mixing, the removal efficiency increases and amounts to 86.032 %. The calculated values of the parameters used in the Freundlich isotherm indicated the existence of high-energy sorption centers in the unmodified bisorbent based on plum pits, while the calculated values of the parameters used in the Freundlich isotherm for the modified biosorbent based on plum pits showed moderate mode adsorption.

To understand the bio-geochemical distribution, activities and environmental consequences of heavy metals, it is very important to know their physico-chemical form and the conditions under which the transformation from one form to another occurs. The bioavailability of heavy metals directly depends on the physico-chemical conditions of the environment, the concentration of anions and cations in water, the content of heavy metals as well as the ionic strength. Depending on the physico-chemical properties of water, metals are found in water as free ions or as complex compounds. Their change in the form in which metals occur is significantly influenced by pH, temperature, alkalinity, water hardness, organic matter, and biological activity. The total concentration of metal in water is only an indicator of pollution, and it is necessary to determine the form of the metal. Differential Pulse Anode Stripping Voltammery with mercury electrode was used for determination of chemical speciation. Manganese belongs to the group of essential heavy metals if its concentration does not exceed the maximum allowed value. The aim of this work is to determine the available forms of manganese in the water of Modrac Lake in relation to the analyzed physico-chemical parameters. In addition to industrial applications, Modrac Lake is also used as an alternative source of drinking water, and it is a strategic resource for water supply of the region of north-eastern Bosnia.

Water sources have become unsafe for human consumption, but also for use in agriculture for irrigation or for the food industry. The deteriorating water quality has led to a shortage of drinking water supply. The aim of this study was to examine the possibility of using agricultural waste, specifically corn residues, (corn cob and silk) as a bioadsorbent to remove Ni and Cd ions from water. Experimental results have shown that corn residues (corn cob and corn silk) have a certain potential for use as bioadsorbents. The possibility of application was tested for corn cob and corn silk (corn cob 3.5g and corn silk 1.5g) for metal concentrations of  20, 40, 100 mg/L for corn cob, and 40 mg/L and 100 mg/L for corn silk. The tests were performed at pH 3 and 6 at a contact time to reach equilibrium of 3.5 hours. Adsorption parameters were determined using the Freundlich isotherm. The morphology of biosorbents before and after the adsorption process was monitored to observe differences in the structure of the biosorbents used. The results showed that in the case of Cd2 + ions, with an initial concentration of 100 mg/L the highest removal efficiency was achieved for all samples used, while in the case of Ni2+ ions the highest removal efficiency was achieved at an initial concentration of 40 mg/L for all samples, while the corn silk based of the maize (Zea mays L.) sample proved to be the best for the removal of these ions where the influence of pH has a great influence on the removal efficiency as well as the physico-chemical properties of the metal. Morphological analysis of samples before and after the adsorption process showed significant differences in the structure of the biosorbents used, which lead to the conclusion that sorption is associated with chemical changes on the surface of the biosorbent. The calculated values ​​of the parameters used in the Freundlich isotherm indicated the existence of high-energy sorption centers in the bisorbent of corn cob and corn silk hybrids maize, and that the adsorption was more pronounced at lower pH values. The corn cob-based  of the maize (Zea mays L.) biosorbent used has been shown to be a heterogeneous surface biosorbent with moderate sorption intensity to Ni and Cd ions, and good sorption intensity to Ni and Cd ions in corn silk-based biosorbent.

The natural plant Cornus mas, sometimes called Cornelian cherry, has been known since ancient times and the fruit is used for various purposes. Cornus mas gives healthy fruits without the use of chemical protection, which are used as healthy, tasty and medicinal food. Cornus mas fruits can be used for eating fresh or in the form of numerous processed products: marmalade, jam, sweet, compote, syrup, juice, fruit yogurt, liqueur, wine and brandy. Due to its antioxidant, antiallergic, antimicrobial and antihistamine properties, it is increasingly used as a dietary supplement, as well as for medical purposes. Taking into account all the above, the aim of this paper is to examine samples of a mixture of honey and fresh wild Cornelian cherry, as well as a sample of honey and Cornelian cherry and determine the physical - chemical parameters: electrical conductivity, pH value, vitamin C content, HMF (hydroxy methyl furfural), as well as individual heavy metals such as iron, cadmium, lead, zinc, copper. Based on the obtained results, appropriate conclusions will be given and the possibility of registering these products as food supplements will be determined.  Based on the performed analyzes, it was shown that the sample of honey and Cornelian cherry mixture had the highest pH value and electrical conductivity, and that the honey sample had the lowest value. Also, the highest value of water activity had the sample of a mixture of honey and Cornelian cherry, while the highest content of hydroxymethylfurfural had the content of Cornelian cherry. The analysis showed the absence of manganese (Mn), cadmium (Cd) and lead (Pb) in all samples, while it was shown that the highest content of Cu and Zn has the sample of Cornelian cherry 2.665 mg/kg Cu ​​and 14.41 mg/kg Zn, followed by a mixture of Cornelian cherry and honey Cu 2.778 mg/kg, Zn 14.670 mg/kg, while the honey sample has the highest Fe content of 16.72 mg/kg. This shows that the samples are rich in zinc, iron and copper, and that they are a good source for those minerals that could meet daily needs.

During the last few years, we have witnessed more frequent floods affecting the northeastern part of Bosnia and Herzegovina, the valley of the Spreca River. Flooded soil has undergone various changes, in terms of numerous deficiencies and heavy metal contamination, where such soil represents a great danger both for people and animals. Therefore, in this paper the physicochemical analysis of soil and degree of pollution is determined. The aim of soil sampling and analysis is to determine its status after water withdrawal, in terms of nutrient supply, and to determine possible chemical pollution. Based on the results obtained, agricultural producers will receive recommendations regarding restoration of production on these areas, the choice of cultivated culture, corrective measures or remediation of these areas. As part of the analysis, hygroscopic moisture, acid-base soil status, oxidoreduction potential, organic matter content, carbonate content and heavy metals content were determined. Based on the performed analyzes, the soil was shown to be of neutral character (determined in 1M KCl), and weakly alkaline (determined in distilled H2O) with predominantly reducing condition prevailing in the soil. The conducted analyzes have shown that the soil is very poor in humus, and that the heavy metals content is within the limit values determined by the Rulebook on Determination of Allowed Quantities of Harmful and Dangerous Substances in Soil and Method of Testing there of (“Official Gazette of Federation of Bosnia and Herzegovina”, number 52/09). Therefore, from the aspect of the pollution degree, the soil from this plot belongs to the first class when it comes to iron, manganese, cadmium and lead, to the second class when it comes to zinc, and the third class when it comes to copper.

During the last few years, we have witnessed more frequent floods affecting the northeastern part of Bosnia and Herzegovina, the valley of the Spreca River. Flooded soil has undergone various changes, in terms of numerous deficiencies and heavy metal contamination, where such soil represents a great danger both for people and animals. Therefore, in this paper the physicochemical analysis of soil and degree of pollution is determined. The aim of soil sampling and analysis is to determine its status after water withdrawal, in terms of nutrient supply, and to determine possible chemical pollution. Based on the results obtained, agricultural producers will receive recommendations regarding restoration of production on these areas, the choice of cultivated culture, corrective measures or remediation of these areas. As part of the analysis, hygroscopic moisture, acid-base soil status, oxidoreduction potential, organic matter content, carbonate content and heavy metals content were determined. Based on the performed analyzes, the soil was shown to be of neutral character (determined in 1M KCl), and weakly alkaline (determined in distilled H2O) with predominantly reducing condition prevailing in the soil. The conducted analyzes have shown that the soil is very poor in humus, and that the heavy metals content is within the limit values determined by the Rulebook on Determination of Allowed Quantities of Harmful and Dangerous Substances in Soil and Method of Testing there of (“Official Gazette of Federation of Bosnia and Herzegovina”, number 52/09). Therefore, from the aspect of the pollution degree, the soil from this plot belongs to the first class when it comes to iron, manganese, cadmium and lead, to the second class when it comes to zinc, and the third class when it comes to copper.