Simulation-Based Evaluation of Zeolite Adsorbents for the Removal of Emerging Contaminants

10.26434/chemrxiv.11695482.v2 ◽

2020 ◽

Author(s):

Michael Fischer

Keyword(s):

Emerging Contaminants ◽

Zeolite Y ◽

Experimental Studies ◽

Pollutant Removal ◽

Experimental Investigations ◽

Good Correspondence ◽

Emerging Organic Contaminants ◽

High Silica ◽

High Silica Zeolites ◽

Energy Configurations

A number of experimental studies have evaluated the potential of hydrophobic high-silica zeolites for the adsorptive removal of emerging organic contaminants, such as pharmaceuticals and personal care products, from water. Despite the widespread use of molecular modelling techniques in various other fields of zeolite science, the adsorption of pharmaceuticals and related pollutants has hardly been studied computationally. In this work, inexpensive molecular simulations using a literature force field (DREIDING) were performed to study the interaction of 21 emerging contaminants with two all-silica zeolites, mordenite (MOR topology) and zeolite Y (FAU topology). The selection of adsorbents and adsorbates was based on a previous experimental investigation of organic contaminant removal using high-silica zeolites (Rossner et al., Water Res. 2009, 43, 3787–3796). An analysis of the lowest-energy configurations revealed a good correspondence between calculated interaction energies and experimentally measured removal efficiencies (strong interaction – high removal), despite a number of inherent simplifications. This indicates that such simulations could be used as a screening tool to identify promising zeolites for adsorption-based pollutant removal prior to experimental investigations. To illustrate the predictive capabilities of the method, additional calculations were performed for acetaminophen adsorption in 11 other zeolite frameworks, as neither mordenite nor zeolite Y remove this pharmaceutical efficiently. Furthermore, the lowest-energy configurations were analysed for selected adsorbent-adsorbate combinations in order to explain the observed differences in affinity.

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Simulation-Based Evaluation of Zeolite Adsorbents for the Removal of Emerging Contaminants

10.26434/chemrxiv.11695482.v1 ◽

2020 ◽

Author(s):

Michael Fischer

Keyword(s):

Emerging Contaminants ◽

Zeolite Y ◽

Experimental Studies ◽

Pollutant Removal ◽

Experimental Investigations ◽

Good Correspondence ◽

Emerging Organic Contaminants ◽

High Silica ◽

High Silica Zeolites ◽

Energy Configurations

A number of experimental studies have evaluated the potential of hydrophobic high-silica zeolites for the adsorptive removal of emerging organic contaminants, such as pharmaceuticals and personal care products, from water. Despite the widespread use of molecular modelling techniques in various other fields of zeolite science, the adsorption of pharmaceuticals and related pollutants has hardly been studied computationally. In this work, inexpensive molecular simulations using a literature force field (DREIDING) were performed to study the interaction of 21 emerging contaminants with two all-silica zeolites, mordenite (MOR topology) and zeolite Y (FAU topology). The selection of adsorbents and adsorbates was based on a previous experimental investigation of organic contaminant removal using high-silica zeolites (Rossner et al., Water Res. 2009, 43, 3787–3796). An analysis of the lowest-energy configurations revealed a good correspondence between calculated interaction energies and experimentally measured removal efficiencies (strong interaction – high removal), despite a number of inherent simplifications. This indicates that such simulations could be used as a screening tool to identify promising zeolites for adsorption-based pollutant removal prior to experimental investigations. To illustrate the predictive capabilities of the method, additional calculations were performed for acetaminophen adsorption in 11 other zeolite frameworks, as neither mordenite nor zeolite Y remove this pharmaceutical efficiently. Furthermore, the lowest-energy configurations were analysed for selected adsorbent-adsorbate combinations in order to explain the observed differences in affinity.

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Adsorption of Lower Alcohols from Water Solutions on High Silica Zeolites, Mesoporous MCM-41 and AlPO4-5

Adsorption Science & Technology ◽

10.1177/026361749701500404 ◽

1997 ◽

Vol 15 (4) ◽

pp. 289-299 ◽

Cited By ~ 8

Author(s):

Ivar M. Dahl ◽

Elisabeth Myhrvold ◽

Åse Slagtern ◽

Michael Stöcker

Keyword(s):

Zeolite Y ◽

Micropore Volume ◽

Water Solutions ◽

Alkyl Chains ◽

Β Zeolite ◽

High Silica ◽

High Silica Zeolites ◽

Hydrophobic Adsorbents ◽

Enhanced Adsorption ◽

Mcm 41

Two dealuminated β-zeolites, zeolite Y and MCM-22 as well as silicalite, MCM-41 and AlPO4-5 have been studied as hydrophobic adsorbents in water solutions. Dealuminated β-zeolite, MCM-22 and silicalite all adsorb alcohols from water solutions. Enhanced adsorption is obtained for alcohols with longer alkyl chains. Adsorption in the practically most interesting 10–80% range of zeolite filling may adequately be described by Langmuir isotherms. The Langmuir adsorption constants are similar for β-zeolite, MCM-22 and silicalite. This indicates that the adsorption is independent of the pore structure for the alcohols tested in this study. The surface silanol density is however important, such that a low SiOH density is required to give lipophilic properties. In line with this, dealuminated zeolite Y, as prepared here, and MCM-41 give only a poor preference for alcohols from water. For the β-zeolite, the dealumination procedure is important for retaining the micropore volume and adsorption capacity of the zeolite. AlPO4-5 shows no potential as an adsorbent for alcohols from water solutions.

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Experimental Evaluation of Airlift Performance for Vertical Pumping of Water in Underground Mines

Mine Water and the Environment ◽

10.1007/s10230-021-00807-w ◽

2021 ◽

Author(s):

Parviz Enany ◽

Oleksandr Shevchenko ◽

Carsten Drebenstedt

Keyword(s):

Water Flow ◽

High Efficiency ◽

Experimental Studies ◽

Theoretical Models ◽

Injection System ◽

Experimental Investigations ◽

Flow Mode ◽

New Device ◽

Riser Pipe ◽

Airlift Pump

AbstractThis paper presents experimental studies on the optimization of air–water flow in an airlift pump. Airlift pumps use compressed gas to verticall transport liquids and slurries. Due to the lack of theoretical equations for designing and predicting flow regimes, experimental investigations must be carried out to find the best condition to operate an airlift pump at high efficiency. We used a new air injection system and different submergence ratios to evaluate the output of a simple pump for vertical displacement of water in an underground mine. The tests were carried out in a new device with 5.64 m height and 10.2 cm circular riser pipe. Three air-jacket pipes, at different gas flows in the range of 0.002–0.09 m3/s were investigated with eight submergence ratios. It was found that with the same air flow rate, the most efficient flow of water was achieved when an air jacket with 3 mm diameter holes was used with a submergence ratio between 0.6 and 0.75. In addition, a comparison of practical results with two theoretical models proposed by other investigators showed that neither was able to accurately predict airlift performance in air–water flow mode.

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