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Publications

2019
Levy, L. ; Izbitski, A. ; Mishael, Y. G. Enhanced gemfibrozil removal from treated wastewater by designed “loopy” clay-polycation sorbents: Effect of diclofenac and effluent organic matter. Applied Clay Science 2019, 182. Publisher's VersionAbstract
Novel clay-polymer nano composites (CPN) were designed for the removal of gemfibrozil (GFZ) from treated wastewater (TWW). The pyridine groups of poly-4-vinylpyridine (PVP) were 100% or 50% (randomly) substituted with bromo-ethanol to synthesize OH100PVP and OH50PVP, respectively. The effect of polymer charge density and loading on the structures of the CPNs, were investigated. At high polymer loadings OH100PVP adsorbed mainly in a flat configuration, as trains, while OH50PVP adsorbed in a more extended configuration, as loops and tails. The affinity and capacity of GFZ towards the OH50PVP CPN was significantly higher than to the OH100PVP, despite the latter's higher charge density, this high affinity of GFZ was explained in terms of more accessible adsorption sites due to the extended configuration of OH50PVP. The kinetics of GFZ removal from TWW by the CPN and by granulated activated carbon (GAC) was measured and modeled by the time dependent Langmuir equation. The effect of effluent organic matter (EfOM) and of a competing anionic pharmaceutical, diclofenac (DCF), on the kinetics of GFZ removal was thoroughly explored. Finally, the overall removal of the studied anionic pharmaceuticals was four-fold higher than by GAC at realistic contact times. © 2019 Elsevier B.V.
Ray, J. R. ; Shabtai, I. A. ; Teixidó, M. ; Mishael, Y. G. ; Sedlak, D. L. Polymer-clay composite geomedia for sorptive removal of trace organic compounds and metals in urban stormwater. Water Research 2019, 157, 454 - 462. Publisher's Version
Dor, M. ; Emmanuel, S. ; Brumfeld, V. ; Levy, G. J. ; Mishael, Y. G. Microstructural changes in soils induced by wetting and drying: Effects on atrazine mobility. Land Degradation & Development 2019, 30, 746 - 755. Publisher's VersionAbstract
Abstract Wetting and drying affects soil structure and pesticide migration, which both may lead to land degradation. The effect on soil structure has been mainly addressed by classical methods at the macroaggregate scale, and the effect on herbicide leaching has not been thoroughly addressed. We aimed to characterize the effects of wetting and drying on soil microstructure, aggregate packing and stability, and subsequent effect on pesticide mobility in three agricultural soils. We developed advanced methods to quantitatively describe soil microstructure changes, induced by wetting and drying. Changes in soil packing, observed by micro-CT, indicate that large aggregates in a Clay soil disintegrate, whereas particles from a Sandy Loam form larger aggregates. To reflect these changes in terms of soil stability, we developed an aggregate durability index, based on changes in soil particle-size distribution measured by laser granulometry. For a Clay soil, the index decreased from 17.0% to 1.7%, indicating soil disaggregation upon wetting and drying. Whereas for a Sandy Clay Loam soil, the index increased from 0.4% to 2.6%, indicating formation of more durable aggregates, explained in terms of cementation by CaCO3. As expected, wetting and drying did not alter a Loamy Sand soil structure. The adverse effects of wetting and drying on soil structure correspond with the trends of atrazine mobility. As atrazine is trapped within the Clay soil aggregates, disaggregation leads to a 35% enhancement in pesticide mobility, whereas stabilization of a Sandy Clay Loam aggregates reduced atrazine leaching by 23%. Finally, wetting and drying directly affects the soil microstructure, which has an immense indirect effect on pollutant mobility, with both potentially leading to land degradation.
Kohay, H. ; Bilkis, I. I. ; Mishael, Y. G. Effect of polycation charge density on polymer conformation at the clay surface and consequently on pharmaceutical binding. Journal of Colloid and Interface Science 2019, 552, 517 - 527. Publisher's VersionAbstract
Polycation conformation upon adsorption to a negatively charged surface can be modulated by its charge density. At high charge density monomers directly interact with the surface in a ‘trains’ conformation and as charge density decreases a high degree of monomers dangle into solution in a ‘loops and tails’ conformation. In this study, the conformations of polycations upon adsorption to montmorillonite, as a function of polycation charge (20, 50 and 100% of the monomers, denoted as P-Q20, P-Q50 and P-Q100) were characterized and in accordance with their conformation, the adsorption of non-ionic and anionic molecules by the composite was tested. As expected, the adsorption of the nonionic pharmaceuticals increased to a composite with a ‘loops and tails’ conformation, due to both conformation and chemical properties. On the other hand, the anionic molecules, gemfibrozil and diclofenac, preferably adsorbed to composites with higher charge density (Q50 or Q100 composites). However, they showed different tendency toward the composites, i.e. higher adsorption of diclofenac by Q100 composite vs. higher adsorption of gemfibrozil by Q50 composite. To elucidate the differences in adsorption between these two pharmaceuticals, density functional theory calculations were employed. Both gemfibrozil and diclofenac were found to be better stabilized by methyl pyridinium sites (prevail in Q100 composite). The preferable adsorption of gemfibrozil by Q50 composite was explained by the presence of ‘loops and tails’ conformation enabling additional adsorption sites and diverse monomer-target molecule orientations.
2018
Berezniak, A. ; Ben-Gal, A. ; Mishael, Y. G. ; Nachshon, U. Manipulation of Soil Texture to Remove Salts from a Drip-Irrigated Root Zone. Vadose Zone Journal 2018, 17. Publisher's VersionAbstract
Drip irrigation is a useful method for the application of low-quality water because it does not wet the foliage and limits the spread of contaminants. Nevertheless, when using water containing high levels of dissolved salts, drip irrigation may be insufficient for leaching and can lead to soil salinization. A new conceptual model was tested experimentally and numerically to examine if manipulation of the distribution of soils with different textures could promote the removal of salts from the root zone and increase leaching efficiency. The manipulated root zone consisted of a volume of coarse soil, located under a drip irrigation emitter, surrounded by finer texture soil. We hypothesized that the differences in hydraulic properties between the two soils and the capillary barrier developed at their interface would generate a one-directional flow path of the salty water from the location of irrigation to the fine soil. This would enforce salt accumulation beyond the root zone. The concept was tested in a series of lysimeter and Hele–Shaw chamber experiments, together with a two-dimensional flow model created in HYDRUS-2D. Results showed preferential salt accumulation beyond the coarse segment of the manipulated soil, providing a volume of leached soil sufficient to support a healthy root system. Under conditions of homogenous soil texture, a notable buildup of salinity was observed in the central root zone, whereas under the manipulated texture conditions, such salt buildup was not observed.
Shabtai, I. A. ; Mishael, Y. G. Polycyclodextrin–Clay Composites: Regenerable Dual-Site Sorbents for Bisphenol A Removal from Treated Wastewater. ACS Applied Materials & Interfaces 2018, 10, 27088 - 27097. Publisher's VersionAbstract
The greatest challenge of wastewater treatment is the removal of trace concentrations of persistent micropollutants in the presence of the high concentration of effluent organic matter (EfOM). Micropollutant removal by sorbents is a common practice, but sorbent employment is often limited because of fouling induced by EfOM and challenging sorbent regeneration. We directly addressed these two issues by designing regenerable dual-site composite sorbents based on polymerized β-cyclodextrin, modified with a cationic group (pCD+) and adsorbed to montmorillonite (pCD+-MMT). This dual-site composite was tailored to simultaneously target an emerging micropollutant, bisphenol A (BPA), through inclusion in β-cyclodextrin cavities and target anionic EfOM compounds, through electrostatic interactions. The removal of BPA from treated wastewater by the composite was not compromised despite the high removal of EfOM. The composites outperformed many recently reported sorbents. Differences in composite performance was discussed in terms of their structures, as characterized with TGA, XRD, BET and SEM. The simultaneous filtration of BPA and EfOM from wastewater by pCD+-MMT columns was demonstrated. Furthermore, successful in-column regeneration was obtained by selectively eluting EfOM and BPA, with brine and alkaline solutions, respectively. Finally, the composites removed trace concentrations of numerous high priority micropollutants from treated wastewater more efficiently than commercial activated carbon. This study highlights the potential to design novel dual-site composites as selective and regenerable sorbents for advanced wastewater treatment.The greatest challenge of wastewater treatment is the removal of trace concentrations of persistent micropollutants in the presence of the high concentration of effluent organic matter (EfOM). Micropollutant removal by sorbents is a common practice, but sorbent employment is often limited because of fouling induced by EfOM and challenging sorbent regeneration. We directly addressed these two issues by designing regenerable dual-site composite sorbents based on polymerized β-cyclodextrin, modified with a cationic group (pCD+) and adsorbed to montmorillonite (pCD+-MMT). This dual-site composite was tailored to simultaneously target an emerging micropollutant, bisphenol A (BPA), through inclusion in β-cyclodextrin cavities and target anionic EfOM compounds, through electrostatic interactions. The removal of BPA from treated wastewater by the composite was not compromised despite the high removal of EfOM. The composites outperformed many recently reported sorbents. Differences in composite performance was discussed in terms of their structures, as characterized with TGA, XRD, BET and SEM. The simultaneous filtration of BPA and EfOM from wastewater by pCD+-MMT columns was demonstrated. Furthermore, successful in-column regeneration was obtained by selectively eluting EfOM and BPA, with brine and alkaline solutions, respectively. Finally, the composites removed trace concentrations of numerous high priority micropollutants from treated wastewater more efficiently than commercial activated carbon. This study highlights the potential to design novel dual-site composites as selective and regenerable sorbents for advanced wastewater treatment.
Gardi, I. ; Mishael, Y. G. Designing a regenerable stimuli-responsive grafted polymer-clay sorbent for filtration of water pollutants. Science and Technology of Advanced Materials 2018, 19, 588 - 598. Publisher's VersionAbstract
ABSTRACTA novel, stimuli-responsive composite, based on poly(4-vinylpyridine) (PVP) brushes, end-grafted to montmorillonite clay (GPC), was designed as a regenerable sorbent for efficient removal of pollutants from water. We characterized the novel composite sorbent and its response to pH, employing Fourier transform infrared, X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetry analysis and zeta potential measurements. In comparison with conventional, electrostatically adsorbed PVP composites (APC), the GPC presented superior characteristics: higher polymer loading without polymer release, higher zeta potential and lower pH/charge dependency. These superior characteristics explained the significantly higher removal of organic and inorganic anionic pollutants by this composite, in comparison with the removal by APC and by many reported sorbents. For example, the filtration (20 pore volumes) of selenate by GPC, APC and a commercial resin column was complete (100%), negligible (0%) and reached 90% removal, respectively. At low?moderate pH, the grafted polymer undergoes protonation, promoting pollutant adsorption, whereas at high pH, the polymer deprotonates, promoting pollutant desorption. Indeed, ?in-column? regeneration of the GPC sorbents was achieved by increasing pH, and upon a second filtration cycle, no reduction in filter capacity was observed. These findings suggest the possible applicability of this stimuli-responsive sorbent for water treatment.
2017
Shabtai, I. A. ; Mishael, Y. G. Catalytic polymer-clay composite for enhanced removal and degradation of diazinon. J Hazard Mater 2017, 335, 135-142.Abstract
It is well established that organophosphate pesticides, such as diazinon, pose environmental and health risks. Diazinon is prone to rapid acidic hydrolysis, forming the less toxic compound 2-isopropyl-6-methyl-4-pyrimidinol (IMP). In this study, diazinon surface catalyzed hydrolysis was achieved by its adsorption to a composite, based on protonated poly (4-vinyl-pyridine-co-styrene) (HPVPcoS) and montmorillonite (MMT) clay. The adsorption affinity and kinetics of diazinon to HPVPcoS-MMT were significantly higher than those obtained to the deprotonated PVPcoS-MMT, emphasizing the importance of hydrogen bonding. Correspondingly, diazinon filtration by HPVPcoS-MMT columns was highly efficient (100% for 100 pore volumes), while filtration by columns of PVPcoS-MMT or granular activated carbon (GAC) reached only 55% and 85%, respectively. Regeneration of HPVPcoS-MMT by pH increase was demonstrated and sorbent reuse was successful, whereas regeneration and reuse of GAC and PVPcoS-MMT were inefficient. Proton transfer from HPVPcos-MMT to diazinon, investigated by FTIR analysis, supports the suggested mechanism of surface catalyzed hydrolysis. These findings demonstrate the applicability of such bi-functional sorbents, to adsorb and degrade pollutants, for efficient water treatment.
Lelario, F. ; Gardi, I. ; Mishael, Y. G. ; Dolev, N. ; Undabeytia, T. ; Nir, S. ; Scrano, L. ; Bufo, S. A. Pairing micropollutants and clay-composite sorbents for efficient water treatment: Filtration and modeling at a pilot scale. Applied Clay Science 2017, 137, 225 - 232. Publisher's VersionAbstract
Organically modified clay minerals have been widely developed, tested and employed as sorbents for organic pollutants. However, the process of pollutant-composite pairing is not commonly addressed, which would be valuable for efficient pollutant filtration by such sorbents. This study presents an approach for achieving efficient pollutant removal by large-scale composite filters, based on pairing chemically compatible pollutants and composites and by employing a predictive filtration model. The removal of three organic pollutants, simazine, sulfentrazone and diclofenac by lab-scale filtration columns containing one of three sorbents, a polymer-, micelle- or liposome-clay composite, was measured. Understanding the factors governing pollutant-organic modifier interactions enabled to pair an efficient sorbent to each pollutant. The high removal (80%) of simazine by the polymer composite, was attributed to hydrogen bonds and π-π interactions, compared to less than 20% removal by the surfactant composites. The removal of the anionic diclofenac (pKa=4.1) was mainly governed by electrostatic attraction, explaining its high removal by the most positively charge sorbent, the liposome composite. Sulfentrazone (pKa=6.5) removal was mostly affected by micellar solubilization and upon its removal, the zeta potential of the micelle-composite was not reduced as obtained for diclofenac removal. The filtration of the successful pairs was modelled to determine sorbent capacity and adsorption and desorption rate constants. The pilot filtration experiments were well described by the model and demonstrated efficient removal of paired pollutants and sorbents. Model simulations predicted promising treatment at environmental pollutant concentrations in the μgL−1 range. This pairing approach along with model calculations can be a strong and valid tool for efficient pollutant-sorbent filtration.
Kohay, H. ; Sarisozen, C. ; Sawant, R. ; Jhaveri, A. ; Torchilin, V. P. ; Mishael, Y. G. PEG-PE/clay composite carriers for doxorubicin: Effect of composite structure on release, cell interaction and cytotoxicity. Acta Biomater 2017, 55, 443-454.Abstract
A novel drug delivery system for doxorubicin (DOX), based on organic-inorganic composites was developed. DOX was incorporated in micelles (M-DOX) of polyethylene glycol-phosphatidylethanolamine (PEG-PE) which in turn were adsorbed by the clay, montmorillonite (MMT). The nano-structures of the PEG-PE/MMT composites of LOW and HIGH polymer loadings were characterized by XRD, TGA, FTIR, size (DLS) and zeta measurements. These measurements suggest that for the LOW composite a single layer of polymer intercalates in the clay platelets and the polymer only partially covers the external surface, while for the HIGH composite two layers of polymer intercalate and a bilayer may form on the external surface. These nanostructures have a direct effect on formulation stability and on the rate of DOX release. The release rate was reversely correlated with the degree of DOX interaction with the clay and followed the sequence: M-DOX>HIGH formulation>LOW formulation>DOX/MMT. Despite the slower release from the HIGH formulation, its cytotoxicity effect on sensitive cells was as high as the "free" DOX. Surprisingly, the LOW formulation, with the slowest release, demonstrated the highest cytotoxicity in the case of Adriamycin (ADR) resistant cells. Confocal microscopy images and association tests provided an insight into the contribution of formulation-cell interactions vs. the contribution of DOX release rate. Internalization of the formulations was suggested as a mechanism that increases DOX efficiency, particularly in the ADR resistant cell line. The employment of organic-inorganic hybrid materials as drug delivery systems, has not reached its full potential, however, its functionality as an efficient tunable release system was demonstrated. STATEMENT OF SIGNIFICANCE: DOX PEG-PE/clay formulations were design as an efficient drug delivery system. The main aim was to develop PEG-PE/clay formulations of different structures based on various PEG-PE/clay ratios in order to achieve tunable release rates, to control the external surface characteristics and formulation stability. The formulations showed significantly higher toxicity in comparison to "free" DOX, explained by formulation internalization. For each cell line tested, sensitive and ADR resistant, a different formulation structure was found most efficient. The potential of PEG-PE/clay-DOX formulations to improve DOX administration efficacy was demonstrated and should be further explored and implemented for other cancer drugs and cells.
2016
Shabtai, I. A. ; Mishael, Y. G. Efficient Filtration of Effluent Organic Matter by Polycation-Clay Composite Sorbents: Effect of Polycation Configuration on Pharmaceutical Removal. Environmental Science & TechnologyEnvironmental Science & Technology 2016, 50, 8246 - 8254. Publisher's Version
Chotzen, R. A. ; Polubesova, T. ; Chefetz, B. ; Mishael, Y. G. Adsorption of soil-derived humic acid by seven clay minerals: A systematic study. Clays and Clay Minerals 2016, 64, 628-638. Publisher's VersionAbstract
Humic acid (HA)-clay complexes are well known for their contribution to soil structure and environmental processes. Despite extensive research, the mechanisms governing HA adsorption are yet to be resolved. A systematic study was conducted to characterize the adsorption of a soil-derived HA to seven clay minerals. Clay surfaces affected HA adsorption directly due to structural differences and indirectly by altering solution pH. The following order of HA removal was obtained for the clay minerals at their natural pH: illite >> palygorskite > kaolinite > sepiolite > montmorillonite = hectorite >> talc. Removal of HA (precipitation and adsorption) by kaolinite and illite was attributed to the low pH they induce, resulting in protonation of the clay and HA surfaces. In spite of the low pH, the zeta potential for HA remained negative, which promoted HA adsorption to the protonated clay surfaces by ligand exchange. Ionic strength did not affect HA adsorption to clay minerals with low zeta potentials, indicating that charge screening is not a major mechanism of HA adsorption for these minerals, and supporting the suggestion that ligand exchange is the main adsorption mechanism to pH-dependent sites. The increase in ionic strength did, however, promote HA adsorption to clay minerals with high zeta potentials. At pH 89 the order of HA affinity for clay minerals was: palygorskite > sepiolite > montmorillonite = hectorite > kaolinite > illite > talc, emphasizing strong HA interactions with the fibrous clays. This strong affinity was attributed to their large surface areas and to strong interactions with OH groups on these clay surfaces. Results indicated that HA did not enter the intracrystalline channels of the fibrous clays but suggested that their macro-fiber structure facilitates HA adsorption. The sorption of HA to kaolinite further increased in the presence of Cu2+, and the sorption of Cu2+ increased in the presence of HA, due to a number of synergistic effects. This study emphasizes the diverse effects of clay structure and solution chemistry on HA adsorption.