Special Issue "Role of Colloid and Surface Science in Decontaminating Ground and Groundwater Systems"

A special issue of ChemEngineering (ISSN 2305-7084).

Deadline for manuscript submissions: closed (12 October 2021).

Special Issue Editors

Dr. David Harbottle
E-Mail Website
Guest Editor
School of Chemical and Process Engineering, University of Leeds, Woodhouse, Leeds LS2 9JT, UK
Interests: colloids; surface science; environmental remediation; polymers; membrane science
Dr. Timothy Hunter
E-Mail Website
Guest Editor
School of Chemical and Process Engineering, University of Leeds, Woodhouse, Leeds LS2 9JT, UK
Interests: ultrasonics; particle stabilised foams and emulsions; surfactant and polymer sol. structure and adsorption; suspension rheology and settling; flocculation and stability control; ion-exchange for effluents

Special Issue Information

Dear Colleagues,

Environmental contamination is an unfortunate consequence of many chemical industries, with ground and groundwater polluted by heavy metals, radionuclides, and oils released from effluent discharges. When released from a point source, most contaminants are mobile and if not contained or recovered, these pollutants can render vast areas of the environment unusable, while in some cases, their bioavailability can lead to bioaccumulation in humans to severely impact human health.

Current engineering strategies to either clean-up liquid effluents or remediate the environment post-release, while often crude, do provide some solutions to the problem. However, the levels of decontamination may be compromised by the complexity of the environment from which the pollutants are extracted, as well as the limitations from the processing equipment to remove the multitude of inorganic or organic contaminants that are often present. Adsorption capacity and removal kinetics by adsorbents, as well as their selectivity, are key performance parameters, which can be improved through the design of new materials and processes that rely on fundamentally understanding the nature of surface and interfacial interactions governing pollutant-environment behavior. Importantly, new nanotechnology-based solutions are also increasingly being investigated, due to their enhanced surface properties leading to high decontamination factors and tunable selectivities.

This Special Issue aims to capture the latest material and technological advancements that are capable of achieving high decontamination levels of ground and groundwater systems, through applications of colloid and surface science and related nanotechnologies. Additionally, it will be showcasing novel approaches to decontaminate environments via in situ methods.

Dr. David Harbottle
Dr. Timothy Hunter
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. ChemEngineering is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Heavy metals
  • Radionuclides
  • Oil spill
  • Adsorbents
  • Ion exchange
  • Decontamination methods
  • Environmental remediation
  • In situ remediation

Published Papers (3 papers)

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Research

Article
Synthesis and Structural Characterisation of Yttrium-Doped α-Zirconium Phosphate
ChemEngineering 2021, 5(4), 83; https://doi.org/10.3390/chemengineering5040083 (registering DOI) - 02 Dec 2021
Viewed by 137
Abstract
There has been a considerable amount of interest in the ion-exchange properties of layered zirconium phosphates. Potential applications in the remediation of nuclear waste have renewed interest in these inorganic materials, due to their high stability under the acidic conditions typically found in [...] Read more.
There has been a considerable amount of interest in the ion-exchange properties of layered zirconium phosphates. Potential applications in the remediation of nuclear waste have renewed interest in these inorganic materials, due to their high stability under the acidic conditions typically found in legacy waste pools. It has been well documented that the substitution of metals with different ionic radii into the frameworks of inorganic materials can alter the chemical properties including ion-exchange selectivity. The work presented here focusses on the synthesis and characterisation of yttrium-doped α-zirconium phosphates which are reported for the first time. Two different synthetic methods were used, reflux and hydrothermal syntheses, and the products were characterised by various methods such as powdered X-ray diffraction, MAS-NMR and scanning electron microscopy. It was found that up to 15% of zirconium could be replaced by yttrium before any noticeable impurity phases could be observed. Rietveld refinement from the doping showed that the products did not obey the Vegard’s law. However, the ion-exchange results clearly showed enhanced capacities and selectivity towards Co2+ ions for the substituted materials. Full article
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Article
Coagulated Mineral Adsorbents for Dye Removal, and Their Process Intensification Using an Agitated Tubular Reactor (ATR)
ChemEngineering 2021, 5(3), 35; https://doi.org/10.3390/chemengineering5030035 - 06 Jul 2021
Viewed by 753
Abstract
The aim of this study was to understand the efficacy of widely available minerals as dual-function adsorbers and weighter materials, for the removal of toxic azo-type textile dyes when combined with coprecipitation processes. Specifically, the adsorption of an anionic direct dye was measured [...] Read more.
The aim of this study was to understand the efficacy of widely available minerals as dual-function adsorbers and weighter materials, for the removal of toxic azo-type textile dyes when combined with coprecipitation processes. Specifically, the adsorption of an anionic direct dye was measured on various mineral types with and without the secondary coagulation of iron hydroxide (‘FeOOH’) in both a bench-scale stirred tank, as well as an innovative agitated tubular reactor (ATR). Talc, calcite and modified bentonite were all able to remove 90–95% of the dye at 100 and 200 ppm concentrations, where the kinetics were fitted to a pseudo second-order rate model and adsorption was rapid (<30 min). Physical characterisation of the composite mineral-FeOOH sludges was also completed through particle size and sedimentation measurements, as well as elemental scanning electron microscopy to determine the homogeneity of the minerals in the coagulated structure. Removal of >99% of the dye was achieved for all the coagulated systems, where additionally, they produced significantly enhanced settling rates and bed compression. The greatest settling rate (9 mm min−1) and solids content increase (450% w/w) were observed for the calcium carbonate system, which also displayed the most homogenous distribution. This system was selected for scale-up and benchmarking in the ATR. Dye removal and sediment dispersion in the ATR were enhanced with respect to the bench scale tests, although lower settling rates were observed due to the relatively high shear rate of the agitator. Overall, results highlight the applicability of these cost-effective minerals as both dye adsorbers and sludge separation modifiers to accelerate settling and compression in textile water treatment. Additionally, the work indicates the suitability of the ATR as a flexible, modular alternative to traditional stirred tank reactors. Full article
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Article
Kinetic Studies of Cs+ and Sr2+ Ion Exchange Using Clinoptilolite in Static Columns and an Agitated Tubular Reactor (ATR)
ChemEngineering 2021, 5(1), 9; https://doi.org/10.3390/chemengineering5010009 - 11 Feb 2021
Cited by 2 | Viewed by 1285
Abstract
Natural clinoptilolite was studied to assess its performance in removing caesium and strontium ions, using both static columns and an agitated tube reactor (ATR) for process intensification. Kinetic breakthrough curves were fitted using the Thomas and Modified Dose Response (MDR) models. In the [...] Read more.
Natural clinoptilolite was studied to assess its performance in removing caesium and strontium ions, using both static columns and an agitated tube reactor (ATR) for process intensification. Kinetic breakthrough curves were fitted using the Thomas and Modified Dose Response (MDR) models. In the static columns, the clinoptilolite adsorption capacity (qe) for 200 ppm ion concentrations was found to be ~171 and 16 mg/g for caesium and strontium, respectively, highlighting the poor material ability to exchange strontium. Reducing the concentration of strontium to 100 ppm, however, led to a higher strontium qe of ~48 mg/g (close to the maximum adsorption capacity). Conversely, halving the column residence time to 15 min decreased the qe for 100 ppm strontium solutions to 13–14 mg/g. All the kinetic breakthrough data correlated well with the maximum adsorption capacities found in previous batch studies, where, in particular, the influence of concentration on the slow uptake kinetics of strontium was evidenced. For the ATR studies, two column lengths were investigated (of 25 and 34 cm) with the clinoptilolite embedded directly into the agitator bar. The 34 cm-length system significantly outperformed the static vertical columns, where the adsorption capacity and breakthrough time were enhanced by ~30%, which was assumed to be due to the heightened kinetics from shear mixing. Critically, the increase in performance was achieved with a relative process flow rate over twice that of the static columns. Full article
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