Facultatea de Chimie şi Tehnologie Chimică / Faculty of Chemistry and Chemical Technology

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Start date: 2020Subject: search.filters.subject.adsorption

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    Using of waste sorbent from food industry for the removal of copper ions from water [Articol]
    (2025) Khudoiarova, Olha; Blazhko, Oleg; Blazhko, Alina
    The purpose of the work was to investigate the effectiveness of using a previously regenerated spent food industry sorbent modified with sulphide and hydrosulphide ions for the removal of copper(II) ions from water. A comparative analysis of the degree of removal and adsorption of copper(II) ions by the regenerated sorbent (RS) and its modified form (MS) was carried out. Insignificant adsorption of Cu2+ on the surface of the RS is explained both by the nature of the adsorbate and the morphology of the adsorbent after its acid-alkaline activation. Modification of the surface of the regenerated sorbent with more active sulphide and hydrosulphide ions leads to an increase in the removal of copper(II) cations from the studied solutions by 65.5 times. IR-spectroscopy and X-ray phase analysis have shown that topochemical reactions occur on the surface of the MS, leading to the formation of copper(II) sulphide CuS and elemental sulphur. The obtained results allow us to recommend the use of a RS of the food industry, modified with sulphide and hydrosulphide ions, to remove copper(II) ions from water.
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    Insights on metal doped graphene in the adsorption of arsenic Via dft calculation [Articol]
    (2025) Ayeni, Ibraheem Olusola; Oyegoke, Toyese
    Arsenic contamination in drinking water poses significant health risks worldwide, making the development of efficient removal technologies a critical area of research. This study explores the enhancement of graphene’s arsenic (As) adsorption capabilities through metal doping at various positions on its surface. Using density functional theory, the interactions between arsenic and graphene doped with selected metals were simulated, evaluating the influence of different doping positions on adsorption efficiency. The results demonstrated that metal doping significantly improves the arsenic removal capacity of graphene, with variations observed depending on the doping configuration. These findings contribute to a deeper understanding of the adsorption mechanisms in graphene-based materials and offer a computational approach for designing advanced adsorbents for environmental remediation.
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    Preparation and characterization of biochar-iron oxide-palygorskite composites for uranium(VI) removal from aqueous solutions [Articol]
    (2025) Pylypenko, Ihor; Kovalchuk, Iryna; Tsyba, Mykola; Lytvynenko, Yurii; Shyrokov, Oleksandr
    This paper details the synthesis of palygorskite/biochar/iron oxide composites and their utilization for the remediation of water solutions contaminated with uranium(VI). The synthesis procedure involved the combination of iron chloride, starch, and palygorskite with subsequent pH adjustment, drying of the formed precipitate, and pyrolysis at 600°C. The synthesis of mesoporous materials, primarily composed of iron oxides, including magnetite and hematite, was confirmed using various characterization techniques, including FTIR, SEM, and XRD. It was shown that the adsorption of uranium(VI) reached a maximum of 100.2 μmol/g, exhibiting the highest affinity, which is associated with significant magnetite involvement, which facilitates the reduction processes of uranium(VI) to uranium(IV). The findings demonstrated that the uranium removal process was enhanced by a rise in pH, with significant adsorption and possible precipitation occurring under neutral conditions, so using these composite materials is suitable for in situ remediation of water solutions contaminated by uranium(VI).
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    Spectroscopic properties of ZnPc(COOH)4/Ch/Fe3O4 supramolecular architectures [Articol]
    (CEP USM, 2024) Druță, Alexandrina; Lungu, Ion; Popușoi, Ana; Potlog, Tamara; Bulmaga, Petru; Rusnac, Roman
    This paper presents the synthesis of ZnPc(COOH)4/Ch/Fe3O4 supramolecular architectures at various ZnPc(COOH)4 and Ch/Fe3O4 concentrations explored in the synthesis process. Ch/Fe3O4 composite was prepared by a simple solution mixing-evaporation method. The validation of the synthesis was achieved through FTIR analysis and UV-Vis spectroscopy. FTIR of composite indicated an interaction between chitosan and Fe3O4 NPs. The chemical interaction of ZnPc(COOH)4 with Ch/F3O4 composite is confirmed by the shift of the signal from ν(C=O)) of protonated COOH groups in the FTIR spectrum of ZnPc(COOH)4, associated with spitting, to (νsym(COO)) and (νasym(COO)) that correspond to deprotonated carboxylic group. The absorption spectra of ZnPc(COOH)₄ revealed IR Q band with two subbands situated at 640 nm 700 nm. Also, the effect of various ZnPc(COOH) and Ch/Fe3O4 concentrations on absorbance of ZnPc(COOH)4/Ch/Fe3O4 supramolecular architecture is discussed.
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    Regenerarea cărbunelui activ ag-3 utilizat în procesele de potabilizare a apelor de suprafață [Articol]
    (CEP USM, 2023) Ciobanu, Mihai; Lupașcu, Tudor; Țîmbaliuc, Nina; Boldurescu, Nina
    S-a studiat procesul termic de regenerare a cărbunelui activ AG-3 uzat de la stația de potabilizare a apei din municipiul Chișinău. Procesul de regenerare s-a efectuat la diferite temperaturi și la diferite intervale de timp cu vapori de apă. Pentru evaluarea gradului de regenerare a mostrelor de cărbuni activi s-au măsurat izotermele de adsorbție a benzenului și a albastrului de metilen din soluții apoase. S-a constatat că la temperaturi ridicate se produce regenerarea integrală a cărbunelui activ AG-3 uzat. Acest fapt se confirmă prin valorile adsorbției albastrului de metilen practic egale pe cărbunele activ regenerat și pe cel intact. La temperaturi apropiate de 8000 C, capacitatea adsorbțională a cărbunelui activ AG-3 uzat, dar regenerat este chiar mai mare decât a cărbunelui activ AG-3 intact, fapt care poate fi explicat prin oxidarea completă a carbonului amorf restant în carbonizat din structura poroasă.
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    Adsorption of Lanthanide (III) Cations on Cross-Linked Ionic Polymer, Composition and Thermal Analysis of the Formed Composites [Articol]
    (2021) Guțanu, Vasile; Lisă, Gabriela; Rusu, Daniela
    The adsorption of lanthanide(III) cations by a strongly basic cross-linked polymer containing R4N+ groups was studied at 21 and 50°C. At both temperatures the sorption is best described with the Langmuir model. The maximum adsorption at both 21 and at 50°C increases in the series: La3+ < Eu3+ < Nd3+ < Er3+. The results show that polymers containing strongly basic groups can, under certain conditions, be used to separate lanthanide(III) cations in solutions containing mono- and bivalent cations. SEM EDX studies show that La3+, Nd3+, Eu3+ and Er3+ form composites in the polymer phase. The elemental composition of structural units of the composites is La1Cl13.7S64.3O287.7N122.6C2869, Nd1Cl27.4S50.7O391.6N169.3C2896, Eu1Cl8.5S50.8O285N130C2118 and Er1Cl36.8S263.9O1106N447C8657. The thermodynamic parameters of the sorption process are calculated: free energy, enthalpy, and entropy. Thermogravimetric analysis made it possible to determine the stability of the formed composites, the stages of their decomposition and the corresponding kinetic parameters.
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    Studiul proceselor de adsorbție a vitaminei B6 pe adsorbanți carbonici autohtoni [Articol]
    (CEP USM, 2023) Țîmbaliuc, Nina; Petuhov, Oleg; Lupașcu, Tudor; Boldurescu, Nina
    În lucrare sunt prezentate rezultatele studiului adsorbției vitaminei B6 pe două mostre de cărbune activ autohton: AC-C și CAN-8. Datele cineticii de adsorbție, determinate la trei valori ale concentrației inițiale, denotă că rata imobilizare a adsorbatului crește odată cu creșterea timpului de contactare dintre cele două faze și este funcție de de concentrația inițială. Izotermele de adsorbție a vitaminei B6 au fost prelucrate utilizând ecuațiile de adsorbție Langmuir și Freundlich. S-a stabilit că imobilizarea vitaminei B6 pe adsorbanții cercetați este mai bine descrisă de modelul Langmuir. Valorile adsorbției maximale înregistrate pentru cărbunii activi AC-C și CAN-8 sunt în concordanță cu parametrii de structură a cărbunilor cercetați. Cercetările realizate atestă că contaminanții emergenți, cu o masă moleculară și proprietăți chimice similare cu vitamina B6, pot fi eficient imobilizați și îndepărtați din soluții apoase folosind cărbunii activi autohtoni AC-C și CAN-8 în calitate de adsorbanți obținuți din materie primă locală.
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    Изучение адсорбции и кинетики адсорбции метиленового синего из водных растворов на трепеле [Articol]
    (CEP USM, 2021) Тутован, Елена; Исак-Гуцул, Татьяна
    A fost studiată adsorbția colorantului albastru de metilen (AM) pe tripol natural autohton. S-a stabilit că adsorbția AM pe tripol crește cu creșterea pH-ului. Forma izotermei de adsorbție a AM pe tripol este de tip Langmuir. Au fost determinate constantele din izoterma Langmuir (qmax = 107,527 mgг/g, K = 0,046 L/mg ) și Freundlich ( = 10,021 мг/г, 1/n = 0,517) și a fost stabilit că procesul de adsorbție este mai exact descris de modelul Langmuir. S-a observat că echilibrul se stabilește, practic, după 8 ore de contactare a soluției AM cu tripolul. Cinetica procesului de adsorbție a AM pe tripol este descrisă de modelul cinetic de ordinul pseudo-doi (к2 = 2,13  10-2 gh-1mg-1)