Applications of Chemically Modified Clay Minerals and Clays to Water Purification and Slow Release Formulations of Herbicides

42 páginas.- 6 figuras.- 9 talas.- 140 referencias.- © 2020 by the authors.This review deals with modification of montmorillonite and other clay-minerals and clays by interacting them with organic cations, for producing slow release formulations of herbicides, and efficient removal of pollutants from water by filtration. Elaboration is on incorporating initially the organic cations in micelles and liposomes, then producing complexes denoted micelle- or liposome-clay nano-particles. The material characteristics (XRD, Freeze-fracture electron microscopy, adsorption) of the micelle– or liposome–clay complexes are different from those of a complex of the same composition (organo-clay), which is formed by interaction of monomers of the surfactant with the clay-mineral, or clay. The resulting complexes have a large surface area per weight; they include large hydrophobic parts and (in many cases) have excess of a positive charge. The organo-clays formed by preadsorbing organic cations with long alkyl chains were also addressed for adsorption and slow release of herbicides. Another examined approach includes “adsorptive” clays modified by small quaternary cations, in which the adsorbed organic cation may open the clay layers, and consequently yield a high exposure of the siloxane surface for adsorption of organic compounds. Small scale and field experiments demonstrated that slow release formulations of herbicides prepared by the new complexes enabled reduced contamination of ground water due to leaching, and exhibited enhanced herbicidal activity. Pollutants removed efficiently from water by the new complexes include (i) hydrophobic and anionic organic molecules, such as herbicides, dissolved organic matter; pharmaceuticals, such as antibiotics and non-steroidal drugs; (ii) inorganic anions, e.g., perchlorate and (iii) microorganisms, such as bacteria, including cyanobacteria (and their toxins). Model calculations of adsorption and kinetics of filtration, and estimation of capacities accompany the survey of results and their discussion.T. Undabeytia acknowledges financial support by the Spanish Ministry of Science and Innovation (project CTM2016-77168–R; this project received funding by the European Social Fund). S. Nir acknowledges financial support by the Ministry of Science & Technology, Israel & The Ministry of Science and Technology of the People’s Republic of China (grant No. 3-15707).Peer reviewe

Network Analysis of the Tel Aviv Mass Transit Plan

This paper analyzes the strategic transit network plan for the Tel Aviv metropolitan area, using graph theory and other recently developed transit network measures. The different transit modes included in the strategic plan are emphasized by adding weights to distinguish metro lines from light rail lines (LRT). This approach can help compare the combined metro or LRT alternatives of the new Tel Aviv plan to the metro-only alternatives  as well as measure the performance relative to the metro systems in other cities around the world. The analysis of the alternative plans in Tel Aviv showed that when metro and LRT lines were treated as homogeneous modes, in which all were considered as metro, the alternatives resembled medium developed metro systems, such as in Barcelona and Washington DC. In contrast, when the distinguished weights were included, the combined metro/LRT alternatives resembled less developed systems, such as in Lyon and Lisbon, and only the metro-only alterative score remained high. The results also showed that the alternatives have regional coverage, and the alternatives with more LRT lines score lower in coverage. The network structure analysis showed that the metro-oriented networks score higher in both directness and connectivity. When using the weighted measures, the existing plan (LRT-only) scores low on both directness and connectivity. The analysis of the results emphasizes the need for more metro lines in the Tel Aviv metropolitan area. The results also suggest that the analysis of the complex mass transit networks based on graph theory should consider differences in line technology reflected in the line speed and coverage. Document type: Articl

Organo-clay formulations of pesticides: reduced leaching and photodegradation

Adsorption of organic cations on several clay minerals is reviewed with an emphasis on the effect of ionic strength and modeling. The clay exchanged with suitable organic cations forms a basis for ecologically acceptable formulations of herbicides with reduced leaching, ground water contamination and enhanced weed control efficacy. Incomplete neutralization of the clay surface charge by an organic cation may be advantageous in achieving maximal adsorption of hydrophobic herbicides. One conclusion from these studies is that optimization of clay-based herbicide formulations requires a selection of structurally compatible organic cations preadsorbed on the clay at optimal coverage. New experimental results are presented for alachlor formulations, which significantly reduce herbicide leaching under conditions of heavy irrigation. We were able to demonstrate that organo-clay formulations of alachlor and

Adsorption of benzyltrimethylammonium to montmorillonite: application to herbicide formulations Adsorption du benzyltriméthylammonium sur la montmorillonite: application à la …

MATERIALS AND METHODS The clay mineral used was Wyoming Na-montmorillonite SWy-1 obtained from the Source Clays Repository (Clay Minerals Society, Columbia, MO). BTMA was purchased from Aldrich (Milwaukee, WI, USA). Analytical grade alachlor (Chem Service, West Chester, PA) was used for making the formulations, whereas a commercial formulation (EC)(Alanex, 480g ai/kg, Agan Chemical Manufactures LTD., Ashdod, Israel) was used as a standard formulation. The electrolytes used were: NaCl, LiCl, NaClO4, Na2SO4, CsCl

Interaction of cationic liposomes and their DNA complexes with monocytic leukemia cells

Cationic liposomes complexed with DNA have been used extensively as non-viral vectors for the intracellular delivery of reporter or therapeutic genes in culture and in vivo. We examined the relationship between the characteristics of the lipoplexes, their mode of interaction with monocytic THP-1 cells and their ability to transfect these cells. We determined the size and ζ potential of cationic liposomes (composed of 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and its mixtures with neutral lipids), and lipoplexes at different (+/-) charge ratios. As the (+/-) charge ratio of the lipoplexes decreased to (1/1), a significant reduction in ζ potential and an increase in size was observed. The increase in size resulted from fusion between liposomes promoted by DNA, as demonstrated by a lipid mixing assay, and from aggregation of the complexes. Interaction of liposomes and lipoplexes with THP-1 cells was assessed by monitoring lipid mixing (\u27fusion\u27) as well as binding and cell association. While no lipid mixing was observed with the 1/2 (+/-) lipid/DNA complexes, lipoplexes with higher (+/-) charge ratios underwent significant fusion in conjunction with extensive cell binding. Liposome binding to cells was dependent on the positive charge of the liposomes, and their fusion could be modulated by the co-lipid. DOTAP/phosphatidylethanolamine (1:1) liposomes fused with THP-1 cells, unlike DOTAP/phosphatidylcholine (1:1) liposomes, although both liposome types bound to the cells to a similar extent. The use of inhibitors of endocytosis indicated that fusion of the cationic liposomes with cells occurred mainly at the plasma membrane level. The presence of serum increased the size of the cationic liposomes, but not that of the lipoplexes. Low concentrations of serum (3%) completely inhibited the fusion of cationic liposomes with cells, while inhibiting binding by only 20%. Our results suggest that binding of cationic liposomes and lipoplexes to cells is governed primarily by electrostatic interactions, whereas their fusion is regulated by the lipid composition and sterically favorable interactions with cell surface molecules. In addition our results indicate no correlation between fusion of the lipoplexes with the plasma membrane and the levels of transfection. Copyright (C) 1999 Elsevier Science B.V

Removal of amoxicillin and cefuroxime axetil by advanced membranes technology, activated carbon and micelle–clay complex

Two antibacterials, amoxicillin trihydrate and cefuroxime axetil spiked into wastewater were completely removed by sequential wastewater treatment plant’s membranes, which included activated sludge, ultrafiltration (hollow fibre and spiral wound membranes with 100 and 20 kDa cut-offs), activated carbon column and reverse osmosis. Adsorption isotherms in synthetic water which employed activated carbon and micelle–clay complex (octadecyltrimethylammonium– montmorillonite) as adsorbents fitted the Langmuir equation. Qmax of 100 and 90.9 mg g–1, and K values of 0.158 and 0.229 L mg–1 were obtained for amoxicillin trihydrate using activated carbon and micelle–clay complex, respectively. Filtration of antibacterials in the ppm range, which yielded variable degrees of removal depending on the volumes passed and flow rates, was simulated and capacities for the ppb range were estimated. Stability study in pure water and wastewater revealed that amoxicillin was totally stable for one month when kept at 37°C, whereas cefuroxime axetil underwent slow hydrolysis to cefuroxime.The authors thank Julius (the Hebrew University, Rehovot) for technical assistance

A Common Mechanism for Influenza Virus Fusion Activity and Inactivation

The fusion of influenza virus (A/PR/8/34 strain) with PC-12 cells was monitored by a fluorescence assay, and the results were analyzed with a mass-action model which could explain and predict the kinetics of fusion. The model accounted explicitly for the reduction in the fusion rate constant upon exposure of the virus to low pH, either for the virus alone in suspension or for the virus bound to the cells. When the pH was lowered without previous viral attachment to cells, an optimal fusion activity was detected at pH 5.2. When the virus was prebound to the cells, however, reduction of pH below 5.2 resulted in enhanced fusion activity at the initial stages. These results were explained by the fact that the rate constants of both fusion and inactivation increased severalfold at pH 4.5 or 4, compared to those at pH 5.2. At pH 5.2, lowering the temperature from 37 to 20 or 4 °C resulted in a decrease in the fusion rate constant by more than 30- or 1000-fold, respectively. Inactivation of the virus when preincubated in the absence of target membranes at pH 5 was found to be rapid and extensive at 37 °C, but was also detected at 0 °C. Our results indicate a strong correlation between fusion and inactivation rate constants, suggesting that the rate-limiting step in viral hemagglutinin (HA)-mediated fusion, that is, rearrangement of viral glycoproteins at the contact points with the target membrane, is similar to that involved in fusion inactivation. © 1993, American Chemical Society. All rights reserved

Efficiency of membrane technology, activated charcoal, and a micelle-clay complex for removal of the acidic pharmaceutical mefenamic acid

The efficiency of sequential advanced membrane technology wastewater treatment plant towards removal of a widely used non-steroid anti-inflammatory drug (NSAID) mefenamic acid was investigated. The sequential system included activated sludge, ultrafiltration by hollow fibre membranes with 100 kDa cutoff, and spiral wound membranes with 20 kDa cutoff, activated carbon and a reverse osmosis (RO) unit. The performance of the integrated plant showed complete removal of mefenamic acid from spiked wastewater samples. The activated carbon column was the most effective component in removing mefenamic acid with a removal efficiency of 97.2%. Stability study of mefenamic acid in pure water and Al-Quds activated sludge revealed that the anti-inflammatory drug was resistant to degradation in both environments. Batch adsorption of mefenamic acid by activated charcoal and a composite micelle (otadecyltrimethylammonium (ODTMA)–clay (montmorillonite) was determined at 25.0◦C. Langmuir isotherm was found to fit the data with Qmax of 90.9 mg g−1 and 100.0 mg g−1 for activated carbon and micelle-clay complex, respectively. Filtration experiment bymicelle-clay columnsmixed with sand in themg L−1 range revealed complete removal of the drug with much larger capacity than activated carbon column. The combined results demonstrated that an integration of a micelle-clay column in the plant system has a good potential to improve the removal efficiency of the plant towards NSAID drugs such as mefenamic acid.Bir-zeit Pharmaceutical Co. is thanked for the supply of mefenamic acid. This work was supported by the European Commission in the framework of the Project ‘Diffusion of nanotechnology based devices for water treatment and recycling - NANOWAT’ (ENPI CBC MED I-B/2.1/049, Grant No. 7/1997)