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Item type:Publication, Removal of Methylene Blue by Hydrogels based on N, N-Dimethylacrylamide and 2-Oxazoline macromonomer(Springer, 2020-09-01)New hydrogels (HG) were synthesized in aqueous medium by free radical polymerization of N,N-dimethylacrylamide (DMAA) and 2-oxazoline macromonomer (MM) initiated by potassium persulfate (KPS) and catalyzed by N,N,N,N′-tetramethylethylenediamine (TEMED). In this polymerization, the monomer DMAA was also used as a crosslinker because it has the ability of self-crosslinking in the presence of peroxodisulfate initiator type. The macromonomer (DP = 24) was a gradient copolymer of 2-methyl-2-oxazoline and methyl-3-(oxazol-2-yl)-propionate with a styryl end group. 1H high-resolution (HR)-MAS NMR spectroscopy allowed to confirm the structure of hydrogels and to determine the molar content of DMAA and MM in each of them. Hydrogels (HG-H) containing carboxylic groups were obtained by basic hydrolysis of HG. Hydrolyzed hydrogels (HG-H) were used for the adsorption of methylene blue (MB) in aqueous medium. It was found that the MB adsorption increased as the initial MB concentration increased, and maximum adsorption capacities were found. The influence of pH value on MB adsorption was evaluated, showing that the MB adsorption capacity of the hydrogels was higher at pH value ≥ 5.7. Adsorption isotherms were studied using Langmuir and Freundlich models. The latter model describes best the process suggesting a possible adsorption mechanism through electrostatic interactions between MB and HG-H hydrogels. The MB adsorbed inside the hydrogels, could be removed with an acidic solution and therefore the hydrogel could be applied to adsorb MB again. - Some of the metrics are blocked by yourconsent settings
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Item type:Publication, Comparative study of anion removal using adsorbents prepared from a homoionic clay(Elsevier, 2021-05-01)The adsorption capacity of adsorbent materials (organophilic clays) prepared from a homoionic clay was compared for the removal of nitrates and nitrites present in aqueous solution in batch systems at room temperature.The organophilic clays were obtained by replacing the exchange cations present in the precursor clays with quaternary ammonium cations. For this purpose, two precursor clays were used, a natural clay (FS) and the same clay exchanged with sodium (CP) and two ammonium cations with different structure: hexadecyltrimethylammonium (HDTMA) and benzyltriethylammonium (BTEA) with amounts equivalent to 1.5, 2.5 and 4.0 cation exchange capacity (C.E.C.). Ion exchange is important to obtain a good affinity between organoclay and anionic contaminants. The clays were characterized by XRD, FTIR and SEM-EDX. The maximum adsorption capacities of the CP-HDTMA-4.0 clay for nitrate and nitrite ion were 7.23 and 0.65 mg g−1, respectively, indicating that the organophilic clay obtained from the homoionic clay with 4 C.E.C. ion exchange and the surfactant HDTMA had significant effects on the adsorption of nitrate and nitrite ions. Finally, the possible mechanisms and implications of the results for the use of these organophilic clays as adsorbent materials for the removal of the ions under study are discussed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, DFT Assessments of BN, AlN, and GaN Decorated Carbon Cage Scaffolds for Sensing the Thiamazole Drug(Elsevier Ltd, 2023-05-01)Sensing drug substances by nanostructures are very important in accordance with the management of targeted drug delivery processes and drug substances detections. Boron nitride (BN), aluminum nitride (AlN), and gallium nitride (GaN) decorated carbon cage (BN-C, AlN-C, and GaN-C) scaffolds were assessed towards sensing the thiamazole (TMZ) drug through the wB97XD/6–31 + G* level of density functional theory (DFT) computations. The singular models were optimized and their combinations to each other were stabilized to obtain the interacting TMZ@Scaffold bimolecular complexes and their corresponding features. The results indicated the existence of non-covalent physical interactions between the substances and their electronic features indicated possibility of sensing function for the investigated scaffolds. Based on the variations of values of adsorption energy and energy gap, the features of recovery time and conductance rate were achieved to predict a sensing function for the models; TMZ@GaN-C was found at the highest suitability in comparison with TMZ@AlN-C and TMZ@BN-C models. The obtained thermochemistry results indicated a spontaneous process for the formation of TMZ@Scaffold complexes. Based on all the obtained results, an order of TMZ@GaN-C > TMZ@AlN-C > TMZ@BN-C was found for describing stability, formation, and electronic features suitability by assigning specific features for each of the singular BN-C, AlN-C, and GaN-C scaffolds towards the TMZ drug. As a consequence, two purposes of detections and adsorptions were approached for the investigated scaffolds to develop sensing functions of BN-C, AlN-C, and GaN-C scaffolds for the TMZ drug. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Adsorption of Thiotepa Anticancer by the Assistance of Aluminum Nitride Nanocage Scaffolds: A Computational Perspective on Drug Delivery Applications(Elsevier B.V., 2023-06-05)This work was carried out by the importance of providing insights into the nano-based drug delivery of anticancers. To this aim, a representative model of aluminum nitride (AN) nanocage scaffold and two of its boron and gallium doped forms (BAN and GAN) were investigated towards the adsorption of thiotepa (Tep) anticancer. Density functional theory (DFT) calculations were performed to evaluate the stabilized structures and their corresponding electronic features. The results indicated the contribution of N-head and S-head of Tep to interactions with each scaffold resulting six complexes; NTep@AN and STep@AN, NTep@BAN and STep@BAN, NTep@GAN and STep@GAN. In each complex model, the characteristic features were obtained based on the interactions details and frontier molecular orbitals related features. In this regard, the investigated scaffolds were found suitable for adsorbing the Tep substance with different strengths and frontier molecular orbitals levels yielding the possibility of assigning specified recovery time and conductance. As a consequence, the models of investigated scaffolds were found suitable to work as possible carriers of Tep anticancer for approaching the nano-based drug delivery purposes. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Comparative study of iron and trace element mobilization during Fe-oxide bioreduction in mine tailings: a case study of Ensenada Chapaco (Chile) and Portman Bay (Spain): Bioreduction and metal release in mine-tailings(Universitat de Barcelona, 2025-01-01)elements (e.g. Ti, Ni, Cd, Pb), leading to contamination of the marine environment. Sea-Tailings Disposal (STD) along the northern coast of Chile (Ensenada Chapaco) and along the eastern coast of Spain (Portman Bay) results in an adverse impact on the environment. This paper focuses on bioreduction under marine conditions. To this end, two column experiments were carried out with samples from Portman Bay and Ensenada Chapaco. Lactate (i.e. organic matter source) was supplied during the experiments. The results obtained are compared with those from batch experiments performed under similar conditions.In the column filled with Portman Bay tailings, the high content of magnetite (15wt%) in contact with water gives rise to a large magnetite surface area and abundant Fe(III), which results in a high release of Fe(II) and Trace Elements (TE). Since Fe(II) adsorbs onto the magnetite surface reducing the availability of Fe(III), the magnetite bioreduction and the consequent TE release decrease after 2000h. By contrast, the magnetite bioreduction lasts longer (3000h) in the column with Ensenada Chapaco tailings. This is because a lower magnetite content in the tailings (1wt%) provides a smaller reactive surface area yielding less Fe(III). Consequently, the concentrations of Fe(II) and TE in the output solutions are lower, which slows down the Fe(II) adsorption onto magnetite. This results in a longer magnetite bioreduction. Bioreduction is regulated by the availability of Fe(III) in both columns.It is inferred that the bioreduction rate diminishes as a function of time and increases as a function of soluble Fe(II) concentration. Moreover, the concentrations of TE released from the two bioreduced tailings exceed the elemental concentrations under marine conditions.4