Phosphorus is essential to the growth of living organisms, and, therefore, its pres ence is considered vital for all forms of life. Research shows that phosphate rock reserves are reducing. Phosphate rock is used as raw material for the production of phos -phate-based fertilizers, and its lack of supply could have adverse effects on the global food supply. New resources that can be a potential replacement for phosphate rock in the production of fertilizers and other phosphorus-containing substances are investigated. This paper provides an overview of technology implementations, methods, and process es, as well as the latest achievements in the field of phosphorus recovery from waste streams. Different methods of phosphorus regeneration from sewage sludge and solid waste, and forms of phosphate regeneration are described. In addition, an overview of the following methods is given: nanonucleation, adsorption and ion exchange, solar evapora tion, biological assimilation of P, and membrane technologies.

Abstract: The paper presents results of the measurements of the sulfur dioxide (SO2) and nitrogen dioxide (NO2) concentration and meteorological parameters: temperature, air pressure, relative humidity and wind speed. The data were collected from January 2019 to December 2020 at two stations, namely Center and Heating plant, in the City of Bijeljina, Republic of Srpska, Bosnia and Herzegovina. SO2 and NO2 are one of the major air pollutants that could negatively affect the human health. Levels of SO2 and NO2 in air samples and meteorological variables from urban zone of Bijeljina were determined at both localities, which represent a highly-populated area with intensive traffic. This topic has not been studied up to now in Bijeljina, although the recent research data indicates that there is a correlation between meteorological parameters and air pollutants. Statistical analysis confirms direct corelation between SO2 and NO2 and meteorological parameters, specially temperature in locality Center (r = -0.639), the wind speed in locality Heating plant (r = 0.399) and relative humidity (r = 0.162). Correlation of NO2 with temperature is not confirmed in both localities. The wind speed increase is followed by rises of the NO2 concentration values and vice versa. Correlation of NO2 with pressure is confirmed in locality Center (r = 0.128) but it is not confirmed in locality Heating plant. Correlation between NO2 and relative humidity found to be negative in locality Center (r = -0.062). These parameters are the most important meteorological factors influencing the variation in SO2 and NO2 concentration in the air during the research. Depending on the obtained correlation, meteorological parameters had a positive or negative impact on air pollution.

The suitable characteristics of fly ash from thermal power plants make it a proper adsorbent for removing various pollutants from water and aqueous solutions. Valorization and utilization of fly ash can reduce the use of conventional adsorbents. The paper presents an overview of the possibility of using raw and modified fly ash to remove fluorides from water and aqueous solutions, as well as the influence of different process parameters (sorbent dose, contact time, pH value, temperature, etc.) on the value of adsorption capacity and adsorption efficiency of used sorbent. Fly ash can be used as an effective sorbent for the removal of fluoride, both in raw and modified form, with given optimal process parameters. Raw fly ash shows better adsorption properties when performing the experiment in a column, with a higher dose of sorbent and longer contact time, in an acidic environment (pH = 2-3), compared to batch experiments. Various authors have modified fly ash by treatment with certain chemical agents (HCl, Ca (OH)2…) or by synthesis of zeolite based on fly ash. Modification of fly ash improves its adsorption properties, so in slightly acidic conditions (pH = 6), for a relatively short contact time (10-30 min), in batch conditions, significant adsorption efficiency (~ 90%) can be achieved.

Through the use of hydrogen bond driven solid-state synthesis, mononuclear complexes are transformed into crystalline materials.

Biofuels are environmentally friendly alternative fuels produced from animal and plant raw materials. They have great significance due to limited availability of crude oil and increased ecological requirements. The development of biofuels is followed by the development of new and more efficient analytical procedures for monitoring the composition and physical-chemical properties. This paper presents the application of chromatographic and spectroscopic methods in the analysis of different types of biofuels. The results of the determination of the hydrocarbon composition and functional groups important for the application of biofuels as blending components are shown. In this paper, it has confirmed the possibility of using NMR spectroscopy, HPLC and IC chromatography in biofuel and biomass analysis.

The reaction of two methoxy substituted salinazid-based hydrazones, 4-methoxysalicylaldehyde isonicotinoyl hydrazone (L1) and 3-methoxysalicylaldehyde isonicotinoyl hydrazone (L2), with HCl, HBr, HNO3 and H2SO4 in methanol yielded salts of different stoichiometries (1 : 1 or 2 : 1) and/or polymorphic forms. In such a way, (HL1)+X− and (HL2)+X− salts, where X = Cl, Br, NO3, HSO4, as well as [H(L1)2]+Br− and (HL1)2+SO42− were obtained. The solid state properties and the propensity for transformation between different forms in solution were also investigated. The crystal structures of compounds (HL1)+Cl−, (HL1)+Br− (α and β), [H(L1)2]+Br−, (HL1)2+SO42−, (HL2)+Br−·MeOH and (HL2)+NO3− were solved by the single-crystal X-ray diffraction method while the structures of (HL1)+NO3− and (HL1)+HSO4− (α and β) were solved by the powder diffraction method. The details of anion binding with the isoniazid functionality are discussed. The aroylhydrazone salts were evaluated for cytotoxic activity in vitro. All compounds exhibited weak cytotoxicity against THP-1 and no cytotoxicity against HepG2 cells. In a preliminary antimicrobial screening assay, these compounds were not only active against antibiotic susceptible Gram-positive bacteria, but also exhibited antibacterial effects on a wide range of multidrug-resistant Gram-positive as well as multidrug resistant Gram-negative bacterial pathogens.