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Mechanical and biodegradability properties of synthesized bio-membranes from waste hemp fibers
No full textIn this study, waste hemp fibers were transformed into cationically modified materials through a two-step process. The process began with the collection of agricultural waste fibers after hemp harvesting, followed by a delignification pretreatment, and subsequently, quaternization using the synthesized Deep Eutectic Solvent of chlorocholine chloride and urea. To form the material into membranes, both unmodified and modified fibers were cross-linked under pressure using citric acid as a natural cross-linker. The structural and chemical characteristics of the formed membranes were analyzed using SEM and FTIR techniques. The mechanical properties of the membranes were determined by measuring the breaking force and calculating the tensile strength via the Brazilian test method. Biodegradability was assessed by examining the mass loss of membranes composed of unmodified and cationized hemp fibers over 90 days, using a Soil Burial Test (AATCC Test Method 30-1993) in controlled laboratory conditions (24 °C). The results demonstrated a significant improvement in the tensile strength of the synthesized material (2.41 MPa), attributed to the synergistic effect of physical intermolecular interactions within the cationically modified hemp membranes (WCHM) and enhanced cross-linking using citric acid. The newly synthesized membrane showed great potential as a biodegradable material, with the first signs of degradation, reflected by a 25% mass loss, observed after 14 days. A slightly faster degradation rate was noted for unmodified fibers, highlighting the effectiveness of citric acid as a cross-linker.MME SEE 2025 : 6th Metallurgical & Materials Engineering Congress of South-East Europe; 4-7 June 2025; Trebinje, Bosnia and Herzegovina
Амино–скробни деривати за адсорпцију специфичних фармацеутика и пестцида из загађених вода: испитивање вештачки онечишћених и реалних узорака вода
No full textIn this study, the possibility of using modified potato starch, with nitrogen-containing chemical agents (melamine, cysteine and histidine) as green adsorbents for removing pharmaceuticals and pesticides from water has been investigated. The influence of additional modification of amino-starch with clay and diatomaceous earth was examined. The effect of the applied modification on the structural, surface and morphological properties was determined by FTIR, XRD and SEM analysis, while the adsorption properties were determined through the effectiveness of prepared materials to remove selected pollutants from spiked and real water samples. The efficiency of investigated amino–starches for the adsorption of pharmaceuticals and pesticides decreases in order: starch–histidine > starch–cysteine > starch–melamine, with a slightly better efficiency for pharmaceuticals adsorption. Additional modification of amino–starches with clay/diatomaceous earth did not contribute to the increase in adsorption efficiency. It was found that the influence of the matrix of real water samples on the adsorption efficiency is up to 10%, which represents a promising potential for applying amino–starch as a cheap and effective adsorbent for wastewater treatment. Also, starch–histidine and starch–cysteine showed the possibility of reusing up to three cycles of adsorption. © 2025 Serbian Chemical Society. All rights reserved.У овој студији испитана је могућност употребе модификованог кромпировог скроба, са хемијским агенсима који садрже азот (меламин, цистеин и хистидин) као зеленог адсорбента за уклањање лекова и пестицида из воде. Испитан је и утицај додатне модификације амино-скроба глином и дијатомејском земљом. Ефекат примењене модификације на структурна, површинска и морфолошка својства одређен је FTIR, XRD и SEM анализом, док су адсорпциона својства припремљених адсорбената одређена кроз ефикасност уклањања изабраних загађујућим материја из спајкованих и реалних узорака воде. Ефикасност припремљених амино-скробова за адсорпцију лекова и пестицида смањује се по следећем редоследу: скроб-хистидин > скроб-цистеин > скоб-меламин, уз нешто бољу ефикасност свих материјала за адсорпцију лекова. Додатна модификација амино-скробова глином/дијатомејском земљом није допринела повећању ефикасности адсорпције. Утврђено је да матрица реалних узорака воде утиче на ефикасност адсорпције до 10%, што указује на обећавајући потенцијал за примену амино-скроба као јефтиног и ефикасног адсорбента за третман отпадних вода. Такође, адсорбенти скроб-хистидин и скроб-цистеин су показали могућност поновне употребе кроз три циклуса адсорпције
Removal of pollutants from aqueous solutions using biomass and carbon material from sunflower agro-industrial waste
No full textЦиљ ове докторске дисертације је добијање нових материјала са високим степеном ефикасности уклањања загађујућих супстанци из водених раствора и у ту сврху испитавана је могућност примене материјала произведених од агроиндустријског отпада сунцокрета. Прво су оптимизовани услови за максималну адсорпцију тешких метала из симулираних узорака отпадних вода коришћењем биомасе љуске семена сунцокрета. За евалуацију ефикасности биосорпције тешких метала, по први пут коришћена је спектроскопија ласерски индуковане плазме (LIBS), заснована на угљендиоксидном ласеру, као метода која је у складу са принципима зелене аналитичке хемије. Као референтна метода за валидацију добијених резултата коришћена је оптичко емисиона спектроскопија индуктивно спрегнуте плазме (ICP-OES). Од сировог материјала агроиндустријског отпада сунцокрета добијен је карбонизовани материјал који је хемијски третиран у циљу добијања два различита узорка активираног угљеничног материјала. Један узорак коришћен је за адсорпцију олова и бакра, а испитивани радни параметри оптимизовани су коришћењем Бокс-Бенкеновог дизајна и методологије одзивне површине. Додатно, овај материјал је тестиран за уклањање бакра из реалног узорка контаминиране воде применом ICP-OES методе. Други узорак коришћен је за уклањање метола из водених раствора. За детекцију метола развијена је волтаметријска метода у којој је коришћена штампана угљенична електрода модификована наночестицама злата које су синтетизоване методом ласерске аблације у течностима. Спектрофотометријском методом оптимизовани су параметара адсорпције, док је новоразвијени волтаметријски сензор, који је показао широк опсег линеарности и високу осетљивост, коришћен за процену ефикасности уклањања метола.The aim of this doctoral dissertation was to obtain new materials with high efficiency for removing pollutants from aqueous solutions. For that purpose, the potential application of materials produced from sunflower agro-industrial waste was investigated. Initially, the conditions for maximizing the adsorption of heavy metals from simulated wastewater samples using sunflower seed husk were optimized. To assess the biosorption efficiency of heavy metals, laser-induced breakdown spectroscopy (LIBS), utilizing a carbon dioxide laser, was employed for the first time as a method that is in accordance with the principles of green analytical chemistry. Inductively coupled plasma optical emission spectroscopy (ICP-OES) served as a reference method to validate the obtained results. Carbonized material was obtained from the sunflower agro-industrial waste and chemically treated to produce two distinct activated carbon samples. One sample was used for lead and copper adsorption, and the operating parameters were optimized using Box-Behnken design and response surface methodology. Additionally, this material was tested for the removal of copper from a real sample of contaminated water using the ICP-OES method. Another sample was used to remove metol from aqueous solutions. A voltammetric method was developed for the detection of metol, using a screen-printed carbon electrode modified with gold nanoparticles obtained by laser ablation in liquids. The spectrophotometric method was used to optimize the adsorption parameters, while the newly developed voltammetric sensor, which showed a wide range of linearity and high sensitivity, was used to evaluate the efficiency of metol removal
Non-stoichiometric Tungsten-oxides as the Anode Catalyst Supports for PEM Fuel Cells
No full textThe mass production and use of fuel cells are limited by the cost of components, primarily the price of catalysts. Fuel impurities lead to the degradation and poisoning of catalysts. Therefore, there is an intensive development of cheaper and more durable catalysts and their interactive supports. In this study, we synthesized non-stoichiometric tungsten oxides as supports for PtRu-based catalysts for Proton Exchange Membrane (PEM) fuel cells. The performance of obtained PtRu/WOx+C catalysts was investigated using cyclic voltammetry and linear sweep voltammetry. Limiting diffusion currents of hydrogen oxidation reactions are reached very quickly and maintain constant values over a wide range of potentials corresponding to anodic potentials of an active PEM fuel cell. The synthesized catalysts show greater catalytic activity and CO tolerance compared to commercial catalysts. The 30% PtRu/WOx+C catalyst, as the catalyst with the highest catalytic activity and tolerance to CO poisoning, could be a good candidate for commercial application.9th International Hydrogen Technologies Congress, 25-28 May 2025
Predicting CO emissions using novel numerical model for particle ignition/combustion
No full textThis work presents development and implementation of sophisticated user defined numerical model for particle ignition/combustion. The proposed model was built in the framework of comprehensive CFD code ANSYS FLUENT. The model is based on structural sub-model for particle devolatilization and realistic mechanism for particle ignition/combustion, which allows for both homogeneous and heterogeneous particle ignition. The user model performance was compared with ANSYS FLUENT standard ignition/combustion models. Models’ calculated values of CO mass fraction from semi-industrial furnace were compared against experimentally determined values. The obtained results showed that the advanced user model is superior, in predicting CO mass fractions in furnace near burner zone, compared with ANSYS FLUENT default models. It is expected that the suggested model will be utilized in calculating ignition/combustion behavior of realistic furnaces and boilers.IOC2025 : 56th International October Conference on Mining and Metallurgy; October 22-25, 2025, Bor Lake, Serbia
The role of aqueous electrolytes in the electrochemical performance of calcium vanadate cathode for Zn-ion storage
No full textIn light of the growing needs for high-performing, safe, low-cost and eco-friendly energy storage systems, herein, the CaV2O6–based composite (CaVO400/C) is studied as a potential cathode host for the Zn2+ion storage in aqueous rechargeable zinc-ion batteries (AZIBs). The CaVO400/C composite, synthesized via malonic acid-assisted solution combustion method (including calcination at 400 °C), is subjected to thorough electrochemical and structural analyses. Its electrochemical performance in a half-cell configuration is evaluated in three different 3 M zinc aqueous electrolytes: Zn(NO3)2, ZnSO4and ZnCl2. Over a large number of CV cycles, the electrochemical behaviour of the composite is markedly different depending on the electrolyte (anion type and pH value). The most favourable electrochemical behaviour is observed in Zn(NO3)2, where high and quite stable redox activity is retained over 400 cycles. In contrast, the performance in ZnSO4is diminished by dissolution of active vanadium species during initial cycling (pH = 4) or prolonged cycling (pH = 2), while after cycling, the formation of Zn4(SO4)(OH)6·nH2O phase is detected on the electrode. The ZnCl2electrolyte leads to a complete loss of activity due to vanadium consumption: for pH = 5 - caused by irreversible transformation of the electrochemically active phase into the inactive one, Zn3(OH)2V2O7·2H2O, and for pH = 2 – caused by consecutive formation and dissolution of Zn3(OH)2V2O7·2H2O. It is suggested that formation of the proton-doped vanadium oxide species as the active phase, during cycling in Zn(NO3)2electrolyte, facilitates the efficient Zn2+storage in the CaVO400/C electrode, enabling insertion/deinsertion specific capacity of ∼167/145 and ∼119/115 mAh g−1at 500 and 2000 mA g−1, respectively, in a half-cell configuration
Application of Carbon Materials Derived from Nocino Walnut Liqueur Pomace Residue for Chlorpyrifos Removal from Water
No full textThis study explores the use of carbon materials derived from Nocino walnut liqueur pomace residue for the removal of chlorpyrifos, a widely used organophosphate pesticide, from water. Carbon adsorbents were synthesized from young walnut biomass under different thermal and chemical treatment conditions, and their structural and surface properties were characterized using BET analysis, FTIR, SEM-EDX, Boehm titration, and zeta potential measurements. The materials exhibited distinct textural and chemical features, including high surface areas and varied surface functionalizations. Batch adsorption studies revealed that the chlorpyrifos removal followed pseudo-second-order kinetics and was best described by the Freundlich and Langmuir isotherms, indicating a combination of pore filling and physisorption via π-π and van der Waals interactions. The highest adsorption capacity of 45.2 ± 0.2 mg g−1 was achieved at 30 °C. Thermodynamic analysis confirmed the process to be endothermic, spontaneous, and entropy-driven, with desolvation effects enhancing the performance at elevated temperatures. Dynamic filtration experiments validated the practical applicability of the materials, while moderate reusability was achieved through ethanol-based regeneration. These findings demonstrate the potential of walnut pomace-derived carbons as low-cost, renewable, and effective adsorbents for sustainable water decontamination. © 2025 by the authors
Characterization of thin crystals by rainbow scattering effect
No full textThis study presents novel approach to characterizing very thin crystals using the theory of rainbow scattering in channeling mode, a technique that hasn't been previously applied for this purpose. We explore potential of this approach for detailed analysis of crystal structures and properties. For characterization of very thin crystals, we employed numerical simulation methods to model and analyze rainbow scattering in channeling mode. Simulations were designed to predict the scattering patterns of protons channeled through cubic crystals in different orientations and structural configurations. This framework enabled us to generate detailed predictions regarding how various parameters influence proton scattering behavior. The integration of numerical simulations revealed distinct rainbow scattering patterns, offering valuable insights into the internal structures and orientations of analyzed crystals. Rainbow scattering in channeling mode with numerical simulation methods introduces a novel and effective technique for characterization of very thin crystals, while laying the groundwork for future experimental analysis. © 2025 Elsevier B.V
Adsorption of Methylene Blue from an Aqueous Solution by Carbon Materials: A Kinetic Study
No full textThis study aimed to investigate the kinetic properties of methylene blue adsorption on carbon cryogel samples and nitrogen-doped and nitrogen-and-sulfur-co-doped carbon cryogel. Nitrogen and sulfur were incorporated into the carbon structure to enhance surface, electronic and textural properties. Methylene blue, a widely utilized dye in the textile industry, has become one of the most commonly detected substances in water systems. Experimental data were fitted with four kinetic models and showed excellent fits with the linear pseudo-second-order model. The results indicated that doping with nitrogen and sulfur did not significantly affect the adsorption of methylene blue.Proceedings of The IX International Congress “Engineering, Environment and Materials in Process Industry”—EEM2025 ; 2–4 April 2025; Bijeljina, Bosnia and Herzegovina
Influence of surfactants in solvotermal synthesis of hematite (Α−FE2O3)
No full textThis work presents a systematic investigation into the role of surfactants, specifically sodium hydroxide and acetic acid, in directing the morphological evolution of hematite (α-Fe2O3) nanoparticles synthesized via the solvothermal method. By precisely modulating surfactant concentrations, a controlled transition from irregularly shaped nanoparticles to well-defined plate-like structures is achieved, significantly influencing their magnetic and biomedical properties. This work establishes a direct correlation between nanoparticle shape and coercivity, demonstrating that plate-like nanoparticles exhibit a markedly higher coercivity (HC =1725 Oe) compared to their irregular counterparts (HC =235 Oe). This enhancement is attributed to increased shape anisotropy, domain wall pinning, and interparticle exchange interactions, which collectively reinforce magnetic hardness. Moreover, this work provides novel insights into the morphology-dependent magnetic resonance imaging (MRI) relaxivity of hematite nanoparticles.International Scientific Conference on Military Sciences Vojna 2025, Belgrade, Serbia, 11-12 September 2025