Special Issue "Nanoparticles for Dye Adsorption"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Energy and Catalysis".

Deadline for manuscript submissions: closed (23 October 2020).

Special Issue Editor

Dr. Ioannis Anastopoulos
E-Mail Website
Guest Editor
Department of Electronics Engineering, School of Engineering, Hellenic Mediterranean University, Chania 73100 Crete, Greece
Interests: soil chemistry; soil fertility; soil pollution; wastewater treatment; water pollution; adsorption; heavy metals; dyes; pharmaceuticals; climate change; composting
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Special Issue Information

Dear Colleagues,

Wastewater polluted with dyes remains a challenging topic that society must face. It is necessary for wastewater to be purified before its discharge to land or to water receptors. There are many methods for the decontamination of dye-loaded wastewater, such as chemical oxidation, coagulation, membrane separation processes, and electrochemical, aerobic, and anaerobic microbial degradation. The aforementioned methods have some limitations and disadvantages. For this reason, scientists have focused on finding other, more attractive methods. In this context, adsorption-based processes have attracted attention, because they are simple, low-cost, easily operable, and ecofriendly methods. There are various adsorbents (both organic and inorganic) that could be used in wastewater treatment processes, such as agricultural wastes, activated carbons, etc. The high cost of activated carbons and the sometimes low adsorption efficiencies of agriculture wastes have initiated a search for new types of adsorbents. Nanomaterials have attracted the attention of many researchers because they have high surface areas and adsorption capacities and are relatively low-cost materials.

This Special Issue of Nanomaterials titled ‘‘Nanomaterials for Dye Adsorption’’ aims to gather reviews and/or research articles on recent fabrication processes and applications of novel nanomaterials regarding their ability to remove dyes from wastewater. It is recommended that research articles contain a full characterization of nanomaterials, isotherm and kinetic modeling, thermodynamic studies, reusability studies, or a description of the application of nanomaterials in real (waste)water systems.

Dr. Ioannis Anastopoulos
Guest Editor

Manuscript Submission Information

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Keywords

  • nanomaterials
  • adsorption
  • dyes
  • equilibrium modeling
  • isotherms
  • kinetics
  • thermodynamic studies

Published Papers (2 papers)

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Research

Article
Experimental and Theoretical Studies of Methyl Orange Uptake by Mn–Rich Synthetic Mica: Insights into Manganese Role in Adsorption and Selectivity
Nanomaterials 2020, 10(8), 1464; https://doi.org/10.3390/nano10081464 - 26 Jul 2020
Cited by 5 | Viewed by 1296
Abstract
Manganese–containing mica (Mn–mica) was synthesized at 200 °C/96 h using Mn–carbonate, Al–nitrate, silicic acid, and high KOH concentration under hydrothermal conditions. Mn–mica was characterized and tested as a new adsorbent for the removal of methyl orange (MO) dye from aqueous solutions. Compared to [...] Read more.
Manganese–containing mica (Mn–mica) was synthesized at 200 °C/96 h using Mn–carbonate, Al–nitrate, silicic acid, and high KOH concentration under hydrothermal conditions. Mn–mica was characterized and tested as a new adsorbent for the removal of methyl orange (MO) dye from aqueous solutions. Compared to naturally occurring mica, the Mn–mica with manganese in the octahedral sheet resulted in enhanced MO uptake by four times at pH 3.0 and 25 °C. The pseudo–second order equation for kinetics and Freundlich equation for adsorption isotherm fitted well to the experimental data at all adsorption temperatures (i.e., 25, 40 and 55 °C). The decrease of Langmuir uptake capacity from 107.3 to 92.76 mg·g−1 within the temperature range of 25–55 °C suggested that MO adsorption is an exothermic process. The role of manganese in MO selectivity and the adsorption mechanism was analyzed via the physicochemical parameters of a multilayer adsorption model. The aggregated number of MO ions per Mn–mica active site ( n ) was superior to unity at all temperatures signifying a vertical geometry and a mechanism of multi–interactions. The active sites number (DM) of Mn–mica and the total removed MO layers (Nt) slightly changed with temperature. The decrease in the MO adsorption capacities (Qsat = n·DM·Nt) from 190.44 to 140.33 mg·g−1 in the temperature range of 25–55 °C was mainly controlled by the n parameter. The results of adsorption energies revealed that MO uptake was an exothermic (i.e., negative ΔE values) and a physisorption process (ΔE < 40 kJ mol −1). Accordingly, the adsorption of MO onto Mn–mica was governed by the number of active sites and the adsorption energy. This study offers insights into the manganese control of the interactions between MO ions and Mn–mica active sites. Full article
(This article belongs to the Special Issue Nanoparticles for Dye Adsorption)
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Article
Exfoliated Clay Decorated with Magnetic Iron Nanoparticles for Crystal Violet Adsorption: Modeling and Physicochemical Interpretation
Nanomaterials 2020, 10(8), 1454; https://doi.org/10.3390/nano10081454 - 24 Jul 2020
Cited by 7 | Viewed by 1127
Abstract
Surfactant–modified exfoliated Fayum clay (CTAB–EC) obtained after chemical treatment with a CTAB/H2O2 solution was further decorated with magnetic Fe3O4 nanoparticles (MNP). The final nanocomposite (MNP/CTAB–EC) was characterized by XRD, SEM, FTIR, TEM and its adsorptive capability against [...] Read more.
Surfactant–modified exfoliated Fayum clay (CTAB–EC) obtained after chemical treatment with a CTAB/H2O2 solution was further decorated with magnetic Fe3O4 nanoparticles (MNP). The final nanocomposite (MNP/CTAB–EC) was characterized by XRD, SEM, FTIR, TEM and its adsorptive capability against a model cationic dye, crystal violet (CV), was evaluated. A comparison of the adsorption performance of the raw clay and its modified counterparts using H2O2, CTAB, CTAB/H2O2 or MNP indicated that the adsorption capacity of MNP/CTAB–EC was the highest for CV removal at pH 8.0. The pseudo‒second order for the kinetics and Freundlich model for adsorption equilibrium fitted well the CV removal experimental data at all tested temperatures (25, 40 and 55 °C). The enhancement of the Langmuir adsorption capacity from 447.1 to 499.4 mg g−1 with increasing the temperature from 25 to 55 °C revealed an endothermic nature of the removal process. The interactions between CV and MNP/CTAB–EC were interpreted using advanced statistical physics models (ASPM) in order to elucidate the adsorption mechanism. Multilayer model fitted the adsorption process and therefore, the steric and energetic factors that impacted the CV adsorption were also interpreted using this model. The aggregated number of CV molecules per MNP/CTAB–EC active site ( n ) was more than unity at all temperatures, representing thus a vertical adsorption orientation and a multi‒interactions mechanism. It was determined that the increase of CV uptake with temperature was mainly controlled by the increase of the number of active sites (NM). Calculated adsorption energies (ΔE) revealed that CV removal was an endothermic and a physisorption process (ΔE < 40 kJ mol −1). MNP/CTAB–EC was magnetically separated, regenerated by NaOH, and reused without significant decrease in its adsorption efficiency, supporting a prosperity of its utilization as an effective adsorbent against hazardous dyes from wastewaters. Full article
(This article belongs to the Special Issue Nanoparticles for Dye Adsorption)
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