The stalks left after harvesting corn, tomatoes, and tobacco have no further use and are usually burned on agricultural land. In our work samples of this waste were collected and pyrolyzed at 400 ? for 30 min in a nitrogen atmosphere. The solid residue (biochar) obtained by pyrolysis was analyzed, and the results were compared with widely used solid fuels such as wood, coal, coke and charcoal. The heat values of biochar from tomato, tobacco, corn ZP 6263, and corn BC 398 stalks were 24.12, 23.09, 26.24 and 25.78 MJ kg-1, respectively. These values are significantly higher than the heat value of wood, which is about 12.50 MJ kg-1. The ash content of biochar was 12?20 %, which is consistent with the ash content of solid fuels. No heavy metals were found in biochar samples. The results show that biochar obtained from the pyrolysis of agricultural waste, such as tomatoes, tobacco and corn stalks, has good potential for use as a solid fuel.

Due to the increasing consumption of fossil fuels, there is a growing demand for renewable energy resources. At the same time, a significant amount of agricultural waste accumulates, including corn residues, and the efficient management of this waste is a challenge. In this work, the waste biomass, which consisted of the stalks of two types of corn, was characterized and subjected to the pyrolysis process at 400?. The physicochemical characterization of the obtained liquid fraction (bio-oil) was performed, and the obtained data were compared with the literature data for liquid biofuel. The calorific value of bio- -oil was above 22 MJ kg-1, which indicates the good potential of waste corn biomass as an energy source. With appropriate further changes in the composition of waste, by adding materials with a higher carbon and hydrogen content, corn stalks can represent a significant energy source, with better regulation of disposal and storage of agricultural waste.

Peloid maturation is governed by geological settings, duration of water–sediment interaction (microbial reworking), and thermomineral water properties, with molecular distributions providing insights into transformation mechanisms. To assess site-specific biomarker maturity, geochemical parameters were applied to five Serbian therapeutic muds, including spa peloids (Bujanovac, Jošanica, Kanjiža) and natural systems (Vrujci, Rusanda). Mineralogy was determined via X-ray diffraction, and organic matter (OM) was characterized by gas chromatography–mass spectrometry of n-alkanes, steranes and hopanes. Samples are mostly clay-rich, providing favorable catalytic conditions for biomarker transformations. Bujanovac shows a higher plant OM signature (n-C₂₉ maximum) and elevated biomarker maturity (high Ts/Tm, near-equilibrium C₂₉ S/(S + R)), likely inherited from volcanically influenced source material. Jošanica exhibits high CPI but low Ts/Tm and C₂₉ S/(S + R), indicating largely immature OM despite four years of spa aging. Kanjiža shows unexpectedly high apparent maturity after one-day aging, with a pronounced UCM and C₃₁ S/(S + R) (0.58), consistent with incorporation of migrated petrogenic hydrocarbons. Vrujci displays coherent maturity due to prolonged water–sediment interaction, clay-rich mineralogy, extended aging, and regional geothermal gradients. Rusanda exhibits decoupled parameters (CPI 3.91, C₂₉ S/(S + R) 0.69), indicative of hydrocarbon overprinting. Overall, integrating biomarker geochemistry with mineralogy, depositional context, and local thermal/geological conditions provides a robust framework to evaluate peloid maturation.

Peloids are natural materials widely used in balneotherapy and dermatological treatments because of their physicochemical and mineralogical properties. Despite Serbia’s long tradition of spa-based pelotherapy, comprehensive data on the chemical and radiological characteristics of local peloids remain limited. In this study, peloid samples from 13 spa locations across four regions of Serbia were systematically investigated. The aim was to determine their physicochemical properties, elemental composition, and natural radioactivity, to assess their suitability and safety for therapeutic use. The analyzed samples exhibited pronounced variability in pH (6.59–9.52), electrical conductivity (77.5–6610 μS/cm), salinity (below detection limit to 4%), and total dissolved solids, reflecting diverse geological and hydrochemical properties. Inductively coupled plasma optical emission spectrometry revealed site-specific variations in macro- and microelements, influenced primarily by local lithology and sedimentary environments, with limited indications of anthropogenic inputs. Gamma spectrometric analysis showed that the activity concentrations of naturally occurring radionuclides (²²⁶Ra, ²³²Th, ⁴⁰K, ²³⁸U, ²³⁵U, ²¹⁰Pb) were within ranges commonly reported for therapeutic muds worldwide, while anthropogenic ¹³⁷Cs was generally low. Radiological hazard indices were below internationally recommended safety limits. A preliminary screening of dermal exposure to potentially toxic elements indicated no significant noncarcinogenic risk (HI < 1) and acceptable carcinogenic risk (TCR) levels. Overall, this study provides a comprehensive chemical and radiological baseline for Serbian peloids, supporting their safe use in controlled therapeutic and wellness applications and highlighting the importance of site-specific characterization for quality assessment.

As the consumption of fossil fuels increases, the demand for alternative energy sources is growing. Current research focuses on alternative energy sources. Significant importance is given on renewable energy sources, such as waste biomass of agricultural origin, which is thermally processed through pyrolysis, producing products that can have further applications. Serbia, an agricultural country with great potential for using waste biomass as energy, such as corn, could significantly reduce environmental pollution by managing agricultural waste and decreasing greenhouse gas emissions from the combustion of fossil fuels through the utilization of pyrolysis technology. While biomass in its raw form may not be suitable for energy production due to its high oxygen and moisture content and lower calorific value, the process of pyrolysis emerges as a pivotal solution. This thermal processing method transforms biomass into solid, liquid, and gaseous products, the quality of which is determined by the initial biomass and process parameters. The critical aspect is that optimizing these pyrolysis conditions can significantly improve the quality of the products, thereby increasing their potential for energy applications. This study investigated two types of corn and their liquid and solid pyrolysis products obtained at a temperature of 400 ℃. The following parameters were compared between the initial biomass and the liquid and solid products: calorific value, pH, moisture content, ash content, and metal ions affecting energy efficiency, such as K, S, Mg, and Al. Based on the obtained results, it can be concluded that the liquid and solid pyrolysis products hold potential as energy sources. However, certain modifications are necessary to enhance their energy potential. For instance, increasing the calorific value can be achieved by increasing the carbon and hydrogen content. This can be done by adding materials abundant in these elements, such as plastic waste. Consideration should also be given to the quality of the products and their subsequent applications, both for energy purposes and other uses such as chemical production (from the liquid fraction) or use as adsorbents or fertilizers (solid fraction).

The paper presents the effect of an organic solvent on the efficiency of vapor condensation from pyrolysis processes applied to agricultural waste, with the intention of optimizing the trapping procedure for more volatile components. Therefore, the effect of the use of acetone in the vapor trapping system on the yield and composition of liquid fractions (bio-oils) obtained from the pyrolysis of selected agricultural waste, including corn, tomato, and tobacco, was investigated. The focus was placed on evaluating how solvents influence the quality, yield, and composition of bio-oil, as well as whether they are necessary in the pyrolysis process. Acetone, a polar solvent with low human toxicity and the possibility of regeneration after pyrolysis, was selected for bio-oil condensation due to its effectiveness in dissolving polar compounds formed during the pyrolysis of lignocellulosic biomass. Pyrolysis was conducted at 400 and 500 °C for 30 min, to collect light and heavy fractions, which were subsequently analyzed to assess acetone’s influence. The results showed that acetone positively affected corn bio-oil yield (from 44.57% without acetone to 52.13% with acetone) and improved quality by reducing moisture (from 61.82% to 12.83%) and oxygen content (from 86.50% to 47.10%). An increase in calorific value was also observed in both corn varieties, while the effect was minimal in tobacco and nearly negligible in tomato. The obtained parameter values indicated that satisfactory results can also be achieved without the use of a solvent, representing a step toward simplified pyrolysis. GC-MS analysis confirmed that phenols and their derivatives were the dominant compounds, while FTIR analysis verified the presence of functional groups of the identified compounds. Increasing the temperature generally increased both the yield and calorific value of most samples. Light and heavy fractions were separated during condensation to improve collection efficiency and enable better quality control. Although this step adds complexity and potential contamination risks, it allows more effective utilization of the fractions. These results provide a valuable foundation for optimizing the valorization of agricultural waste through pyrolysis-based biofuel production.