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3. Hydrophilization of rice seeds by plasma treatments – super-hydrophilic surface finish and hydrophobic recoveryAlenka Vesel, Anca Macovei, Alma Balestrazzi, Dane Lojen, Gregor Primc, Rok Zaplotnik, Nives Ogrinc, Marián Lehocký, Miran Mozetič, 2025, izvirni znanstveni članek Povzetek: The hydrophobic character of rice seeds protects them from quick water adsorption and, thus, premature germination. This property is, however, a drawback in modern agriculture, where rapid and uniform germination represents a high-quality trait. A method for rapid hydrophilization of the Lomello variety of rice is presented. The rice seeds were treated with low-pressure gaseous plasma to tailor the wettability. The treatment of seeds with hulls with oxygen plasma afterglow enabled the super-hydrophilic surface finish within 10 ms. Such extremely fast hydrophilization was attributed to irreversible surface oxidation by neutral oxygen atoms whose flux onto the seeds was approximately 3 × 1023 m−2s−1. Dehulled seeds were made super-hydrophilic by subsequent treatments with hydrogen and oxygen plasma, and the required dose of O atoms was between 2 × 1023 and 6 × 1024 m−2. Larger doses caused a loss of the super-hydrophilicity. Hydrophilization kinetics is proposed and supported by measuring surface wettability, morphology, and composition using various techniques. The hydrophobic recovery of seeds with hulls is marginal within the first few days after plasma treatments, but dehulled seeds lose the super-hydrophilic surface finish within a few minutes after the plasma treatment when stored at ambient conditions.
Ključne besede: rice seed, water adsorption, surface treatment, wettability, super-hydrophilicity
Objavljeno v DiRROS: 10.11.2025; Ogledov: 672; Prenosov: 542
 Celotno besedilo (13,19 MB)
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5. Upcycling of plastic waste into multi-walled carbon nanotubes as efficient organic dye adsorbentGordana Bogoeva Gaceva, Meri Sokolovska, Viktor Stefov, Metodija Najdoski, Sebastijan Kovačič, 2025, izvirni znanstveni članek Povzetek: Multi-walled CNTs with an average diameter of about 80 nm, a length of several micrometers and surface area (SBET) of 100 m2 g–1 were obtained by pyrolysis of low-density polyethylene waste. The potential of the resulting MWCNTs material to purify water containing organic dyes was tested with Bezaktiv Blau HE-RM (BB) and Bezaktiv Rot S-3B (BR) reactive dyes. 200 mg L–1 MWCNT material was used to follow the adsorption of 30 mg L–1, 40 mg L–1, 50 mg L–1 and 60 mg L–1 BB and BR at pH 3 and a temperature of ~25 °C. The results have shown that this material has a high potential as a sorbent, and its adsorption capacity of 257 mg g–1 (for Bezaktiv BlauHE-RM) and 213 mg g–1 (for Bezaktiv Rot) is close to some commercial MWCNTs and functionalized MWCNT-based adsorbents. The adsorption process was very fast, reaching 80–90% of the dye removal in 10–15 minutes, and the equilibrium time was reached in 40–60 minutes. The adsorption isotherm showed that the Langmuir model was more suitable than the Freundlich model for describing the adsorption properties of the pollutants.
Ključne besede: adsorption, anionic dyes, upcycling plastic waste, carbon nanotubes
Objavljeno v DiRROS: 21.08.2025; Ogledov: 899; Prenosov: 519
Celotno besedilo (1,09 MB)
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7. A general-purpose adsorption isotherm for improved estimation of standard adsorption free energyAnton Kokalj, 2023, izvirni znanstveni članek Povzetek: A new general-purpose Type–I adsorption isotherm is proposed to improve standard adsorption Gibbs energy estimation. This new isotherm stems from considering a functional dependence of various adsorption models on the �∕� vs. � plot, where � is the fractional surface coverage and � the concentration. It can accurately describe many adsorption isotherms, implying that it is flexible enough to describe various adsorption scenarios. Among the tested adsorption models that the new isotherm can describe are those that consider lateral inter-adsorbate interactions, molecular size, surface heterogeneity, and mobile adsorption.
Ključne besede: standard adsorption free energy, corrosion inhibitors, adsorption isotherms
Objavljeno v DiRROS: 29.04.2025; Ogledov: 1205; Prenosov: 616
Celotno besedilo (2,52 MB)
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8. On the use of the Langmuir and other adsorption isotherms in corrosion inhibitionAnton Kokalj, 2023, izvirni znanstveni članek Povzetek: In corrosion inhibition studies, the standard adsorption Gibbs energy is often estimated via the linear regression of the Langmuir isotherm in the �∕� = 1∕� + � form, where both the intercept and the slope are estimated, although the Langmuir isotherm requires the slope of 1. Hence, �∕� = 1∕� +�� is actually used, where � is the slope. Herein, a theoretical basis for this equation is established. It is demonstrated to be an effective equation that can decently describe various adsorption models and provide relatively accurate estimates of the standard adsorption Gibbs energy, provided surface coverages are reliably determined experimentally. However, any significant deviation from the slope of 1 signals non-Langmuir adsorption due to inter-adsorbate interactions, multi-site adsorption, or surface heterogeneity. Among these three causes, only attractive inter-adsorbate interactions lead to a slope of less than 1.
Ključne besede: Langmuir isotherm, Flory–Huggins isotherm, Temkin isotherm, corrosion inhibition, standard adsorption free energy
Objavljeno v DiRROS: 23.04.2025; Ogledov: 1738; Prenosov: 568
Celotno besedilo (2,79 MB) |
9. Considering the concept of synergism in corrosion inhibitionAnton Kokalj, 2023, izvirni znanstveni članek Povzetek: Synergism in corrosion inhibition and how to best quantify it is explored conceptually. In the equation for the synergistic parameter, the mixture’s inhibition efficiency is evaluated against a threshold inhibition efficiency based on the performance of pure compounds. However, the choice for the threshold value is not unique. In the literature, the threshold of Aramaki–Hackerman is usually used. Herein, several other reasonable choices are developed, which are based on (i) the Langmuir adsorption model, (ii) the requirement that a mixture’s inhibition efficiency is higher than the highest inhibition efficiency of pure compounds, or (iii) that corrosion resistance in a mixture is higher than the sum of resistances in pure compounds. The presented synergistic models are also extended to multi-component mixtures.
Ključne besede: corrosion inhibition, synergism, Langmuir adsorption model
Objavljeno v DiRROS: 23.04.2025; Ogledov: 1149; Prenosov: 347
Celotno besedilo (1,65 MB) |
10. Adsorption efficiency of cadmium (II) by different alkali-activated materialsNataša Mladenović Nikolić, Ljiljana Kljajević, Snežana B. Nenadović, Jelena Potočnik, Sanja Knežević, Sabina Dolenec, Katarina Trivunac, 2024, izvirni znanstveni članek Povzetek: The objective of this study was to demonstrate the potential utilization of fly ash (FA), wood ash (WA), and metakaolin (MK) in developing new alkali-activated materials (AAMs) for the removal of cadmium ions from waste water. The synthesis of AAMs involved the dissolution of solid precursors, FA, WA, and MK, by a liquid activator (Na2SiO3 and NaOH). In concentrated solutions of the activator, the formation of an aluminosilicate gel structure occurred. DRIFT spectroscopy of the AAMs indicated main vibration bands between 1036 cm−1 and 996 cm−1, corresponding to Si-O-Si/Si-O-Al bands. Shifting vibration bands were seen at 1028 cm−1 to 1021 cm−1, indicating that the Si-O-Si/Si-O-Al bond is elongating, and the bond angle is decreasing. Based on the X-ray diffraction results, alkali-activated samples consist of an amorphous phase and residual mineral phases. The characteristic “hump” of an amorphous phase in the range from 20 to 40◦ 2θ was observed in FA and in all AWAFA samples. By the XRD patterns of the AAMs obtained by the activation of a solid three-component system, a new crystalline phase, gehlenite, was identified. The efficiency of AAMs in removing cadmium ions from aqueous solutions was tested under various conditions. The highest values of adsorption capacity, 64.76 mg/g (AWAFA6), 67.02 mg/g (AWAFAMK6), and 72.84 mg/gmg/g (AWAMK6), were obtained for materials activated with a 6 M NaOH solution in the alkali activator. The Langmuir adsorption isotherm and pseudo-second kinetic order provided the best fit for all investigated AAMs.
Ključne besede: fly ash, metakaolin, wood ash, adsorption kinetics, cadmium (II)
Objavljeno v DiRROS: 23.05.2024; Ogledov: 2881; Prenosov: 1193
Celotno besedilo (7,68 MB)
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