Surface Basicity and Hydrophilic Character of Coal Ash-Derived Zeolite NaP1 Modified by Fatty Acids.

Zeolite NaP1 was found to display the highest affinity for CO2 in preliminary modifications of coal fly ash-derived zeolites (4A, Y, NaP1 and X) by four amines (1,3-diaminopropane, N,N,N',N'-tetramethylethylenediamine, Tris(2-aminoethyl)amine and ethylenediamine). In the second step, different fatty acid loaded NaP1 samples were prepared using palmitic, oleic and lauric acids. CO2 and H2O thermal programmed desorption (TPD) revealed changes in intrinsic basicity and hydrophilic character, expressed in terms of CO2 and H2O retention capacity (CRC and WRC, respectively). Infrared spectroscopy (IR), N2 adsorption-desorption isotherms and scanning electron microscopy allowed for correlating these changes with the type of interactions between the incorporated species and the zeolite surface. The highest CRC values and the lowest CO2 desorption temperatures were registered for NaP1 with the optimum content in palmitic acid (PA) and were explained in terms of the shading effect of surface acidity by the rise of basic Na+-palmitate salt upon cation exchange. The amine/fatty acid combination was found to paradoxically mitigate this beneficial effect of PA incorporation. These results are of great interest because they demonstrate that fatty acid incorporation is an interesting strategy for reversible CO2 capture.

Role of Clay Substrate Molecular Interactions in Some Dairy Technology Applications.

The use of clay materials in dairy technology requires a multidisciplinary approach that allows correlating clay efficiency in the targeted application to its interactions with milk components. For profitability reasons, natural clays and clay minerals can be used as low-cost and harmless food-compatible materials for improving key processes such as fermentation and coagulation. Under chemical stability conditions, clay materials can act as adsorbents, since anionic clay minerals such as hydrotalcite already showed effectiveness in the continuous removal of lactic acid via in situ anion exchange during fermentation and ex situ regeneration by ozone. Raw and modified bentonites and smectites have also been used as adsorbents in aflatoxin retention and as acidic species in milk acidification and coagulation. Aflatoxins and organophilic milk components, particularly non-charged caseins around their isoelectric points, are expected to display high affinity towards high silica regions on the clay surface. Here, clay interactions with milk components are key factors that govern adsorption and surface physicochemical processes. Knowledge about these interactions and changes in clay behavior according to the pH and chemical composition of the liquid media and, more importantly, clay chemical stability is an essential requirement for understanding process improvements in dairy technology, both upstream and downstream of milk production. The present paper provides a comprehensive review with deep analysis and synthesis of the main findings of studies in this area. This may be greatly useful for mastering milk processing efficiency and envisaging new prospects in dairy technology.

Innovative Strategy for Truly Reversible Capture of Polluting Gases-Application to Carbon Dioxide.

This paper consists of a deep analysis and data comparison of the main strategies undertaken for achieving truly reversible capture of carbon dioxide involving optimized gas uptakes while affording weakest retention strength. So far, most strategies failed because the estimated amount of CO2 produced by equivalent energy was higher than that captured. A more viable and sustainable approach in the present context of a persistent fossil fuel-dependent economy should be based on a judicious compromise between effective CO2 capture with lowest energy for adsorbent regeneration. The most relevant example is that of so-called promising technologies based on amino adsorbents which unavoidably require thermal regeneration. In contrast, OH-functionalized adsorbents barely reach satisfactory CO2 uptakes but act as breathing surfaces affording easy gas release even under ambient conditions or in CO2-free atmospheres. Between these two opposite approaches, there should exist smart approaches to tailor CO2 retention strength even at the expense of the gas uptake. Among these, incorporation of zero-valent metal and/or OH-enriched amines or amine-enriched polyol species are probably the most promising. The main findings provided by the literature are herein deeply and systematically analysed for highlighting the main criteria that allow for designing ideal CO2 adsorbent properties.

Ecotoxicity of Diazinon and Atrazine Mixtures after Ozonation Catalyzed by Na+ and Fe2+ Exchanged Montmorillonites on Lemna minor.

The toxicity of two pesticides, diazinon (DAZ) and atrazine (ATR), before and after montmorillonite-catalyzed ozonation was comparatively investigated on the duckweed Lemna minor. The results allowed demonstrating the role of clay-containing media in the evolution in time of pesticide negative impact on L. minor plants. Pesticides conversion exceeded 94% after 30 min of ozonation in the presence of both Na+ and Fe2+ exchanged montmorillonites. Toxicity testing using L. minor permitted us to evaluate the change in pesticide ecotoxicity. The plant growth inhibition involved excessive oxidative stress depending on the pesticide concentration, molecular structure, and degradation degree. Pesticide adsorption and/or conversion by ozonation on clay surfaces significantly reduced the toxicity towards L. minor plants, more particularly in the presence of Fe(II)-exchanged montmorillonite. The results showed a strong correlation between the pesticide toxicity towards L. minor and the level of reactive oxygen species, which was found to depend on the catalytic activity of the clay minerals, pesticide exposure time to ozone, and formation of harmful derivatives. These findings open promising prospects for developing a method to monitor pesticide ecotoxicity according to clay-containing host-media and exposure time to ambient factors.

Role of Silica on Clay-Catalyzed Ozonation for Total Mineralization of Bisphenol-A.

Catalytic ozonation for the total mineralization of bisphenol-A (BPA) from aqueous solution was investigated in the presence of various silica-based catalysts such as mesoporous silica, acid-activated bentonite (HMt) and montmorillonite-rich materials (Mt) ion-exchanged with Na+ and Fe2+ cations (NaMt and Fe(II)Mt). The effects of the catalyst surface were studied by correlating the hydrophilic character and catalyst dispersion in the aqueous media to the silica content and BPA conversion. To the best of our knowledge, this approach has barely been tackled so far. Acid-activated and iron-free clay catalysts produced complete BPA degradation in short ozonation times. The catalytic activity was found to strongly depend on the hydrophilic character, which, in turn, depends on the Si content. Catalyst interactions with water and BPA appear to promote hydrophobic adsorption in high Si catalysts. These findings are of great importance because they allow tailoring silica-containing catalyst properties for specific features of the waters to be treated.

Clay-Catalyzed Ozonation of Hydrotalcite-Extracted Lactic Acid Potential Application for Preventing Milk Fermentation Inhibition.

An unprecedented route for mitigating the inhibitory effect of lactic acid (LA) on milk fermentation was achieved through lactate adsorption on hydrotalcite (Ht) from simulated lactate extracts. During its regeneration by ozonation, Ht displayed catalytic activity that appeared to increase by addition of montmorillonite (Mt). Changes in the pH, Zeta potential and catalyst particle size during LA ozonation were found to strongly influence LA-LA, LA-catalyst and catalyst-catalyst interactions. The latter determine lactate protonation-deprotonation and clay dispersion in aqueous media. The activity of Mt appears to involve hydrophobic adsorption of non-dissociated LA molecules on silica-rich areas at low pH, and Lewis acid-base and electrostatic interactions at higher pH than the pKa. Hydrotalcite promotes both hydrophobic interaction and anion exchange. Hydrotalcite-smectite mixture was found to enhance clay dispersion and catalytic activity. This research allowed demonstrating that natural clay minerals can act both as adsorbents for LA extract from fermentation broths and as catalysts for adsorbent regeneration. The results obtained herein provide valuable and useful findings for envisaging seed-free milk clotting in dairy technologies.

Synthesis of Metal-Loaded Carboxylated Biopolymers with Antibacterial Activity through Metal Subnanoparticle Incorporation.

Carboxymethyl starch (CMS) and carboxymethyl cellulose (CMC) loaded by highly dispersed metal subnanoparticles (MSNPs) showed antibacterial activity against E. coli and B. subtilis strains. Copper and silver were found to act in both cationic and zero-valence forms. The antibacterial activity depends on the metal species content but only up to a certain level. Silver cation (Ag+) showed higher antibacterial activity as compared to Ag0, which was, however, more effective than Cu0, due to weaker retention. The number of carboxyl groups of the biopolymers was found to govern the material dispersion in aqueous media, the metal retention strength and dispersion in the host-matrices. Cation and metal retention in both biopolymers was found to involve interactions with the oxygen atoms of both hydroxyl and carboxyl groups. There exists a ternary interdependence between the Zeta potential (ZP), pH induced by the biocidal agent and its particle size (PS). This interdependence is a key factor in the exchange processes with the surrounding species, including bacteria. Clay mineral incorporation was found to mitigate material dispersion, due to detrimental competitive clay:polymer interaction. This knowledge advancement opens promising prospects for manufacturing metal-loaded materials for biomedical applications.

Silica-catalyzed ozonation of 17α -ethinyl-estradiol in aqueous media-to better understand the role of silica in soils.

A promising route for thorough removal of 17α-ethinyl estradiol (EE2) from aqueous media was achieved through ozonation using mesoporous silicas such SBA-15, SBA-16, MCM-41 and MCM-48 as catalysts. Comparison with aluminosilicates along with Zeta potential and particle size measurements allowed demonstrating that EE2 interaction with silanols and hydrophobic -Si-O-Si- groups are essential requirements for the catalytic activity. Acid-base interactions, if any, should have minor contribution. EE2 hydroxylation appears to be an early step in the ozonation on all catalysts, but MCM-41 showed increased activity in phenolic ring cleavage. Confrontation of HPLC-UV and UV-Vis and HPLC-UV measurements revealed highest catalytic activity for MCM-41 and to a lesser extend of MCM-48 due to their higher specific surface area and weaker acid character. These results provide valuable findings for judiciously tailoring optimum [EE2-Silica:Water] interactions for thorough oxidative degradation of endocrine disrupting compounds (EDC).

Insight into natural medium remediation through ecotoxicity correlation with clay catalyst selectivity in organic molecule ozonation.

The oxidative degradation of diazinon (DAZ) and diclofenac sodium (DCF) in aqueous media was comparatively investigated and correlated with the mortality of Artemia salina in the presence of clay catalysts. For this purpose, montmorillonites (Mt) exchanged with Na+ and Fe2+ cations (NaMt and Fe(II)Mt), acid activated bentonites and hydrotalcite were used as clay catalysts. Surface interaction and adsorption on the clay surface were found to govern the catalyst dispersion in aqueous media and both activity and selectivity in ozonation. These catalysts' features were correlated with the ecotoxicity of ozonised reaction mixtures as expressed in terms of mortality rates of Artemia salina. DAZ and DCF display specific intrinsic ecotoxicity that evolves differently during ozonation according to the catalyst. The ecotoxicity was found to strongly depend on the distribution of the ozonation intermediates, which, in turn, was narrowly correlated with the acid-base properties of the catalyst surface. These valuable findings allow the prediction of the behaviour of the clay-containing media in natural remediation.

Clay-Catalyzed Ozonation of Organic Pollutants in Water and Toxicity on Lemna minor: Effects of Molecular Structure and Interactions.

The use of clays as adsorbents and catalysts in the ozonation of organic pollutants (Atrazine, bis-Phenol A, Diazinon, and Diclofenac sodium) allowed simulating their natural oxidative degradation in clay soils and to evaluate the ecotoxicity of mixtures partially oxidized on the species Lemna minor, a biodiversity representative of plants in the aquatic environment. Kinetic data showed that the adsorption of organic pollutants on clay particles obeys the pseudo-second-order model, while the adsorption isotherms satisfactorily fit the Langmuir model. Adsorption reduces the dispersion of the organic pollutant in the environment and prolongs its persistence and its natural degradation probability. Measurements of the Zeta potential and particle size as a function of pH demonstrate that the catalytic activity of clay depends on its cation, its silica/alumina ratio, and therefore on its permanent and temporary ion exchange capacities. These factors seem to govern its delamination and dispersion in aqueous media, its hydrophilic-hydrophobic character, and its porosity. Tests conducted on Lemna minor in contact with ozonation mixtures revealed that the toxicity could be due to pH decrease and to the toxicity of the intermediates yielded. Ecotoxicity would depend on the structure of the organic molecules, the chemical composition of the clay surface and ozonation time, which determines the oxidation progress. These results are of great importance for further research because they allow concluding that the negative impact of the persistence of an organic molecule in clay-containing media depends on the type and composition of the very clay mineral.

Insights into the metal retention role in the antibacterial behavior of montmorillonite and cellulose tissue-supported copper and silver nanoparticles.

The role of the retention strength of Cu0 and Ag0 nanoparticles on the induced antibacterial properties of montmorillonite and cellulose-supported polyol dendrimer was comparatively investigated. An unprecedented approach involving X-ray photoelectron spectroscopy, thermal analyses, and surface charge measurements allowed correlating the host-matrix features to the different antibacterial activities of Cu0 and Ag0 nanoparticles against both the bacterial strains. Optimal metal-matrix interactions appear to favor high dispersion of both metal particles and material grains, thereby improving the contact surface with the cultivation media. This was explained in terms of hydrophilic character and judicious compromise between the metal retention by the host-matrix and release in the impregnating media. Competitive Lewis acid-base interactions appear to occur between MNP, solid surface and liquid media. These findings are of great importance, providing a deeper understanding of the antibacterial activity of metal-loaded materials. This opens promising prospects for vegetal fibers and clay-supported drugs to treat dermatological and gastro-intestinal infections.

Clay-catalyzed ozonation of endocrine-disrupting compounds in solvent-free media - to better understand soil catalytic capacity.

An original approach never tackled so far allowed correlating the basicity and hydrophilic character of clay catalysts to surface interaction with 17α-Ethinylestradiol (EE2) during ozonation in water. The clay catalysts were found to behave specifically according to their silica/alumina ratio like soils in natural oxidative processes. Acid-activated bentonites (HMt) and ion-exchanged montmorillonite (NaMt and Fe(ii)Mt) showed catalytic activity in the ozonation of 17α-ethinylestradiol (EE2) in aqueous media. In the absence of catalysts, the degradation of (EE2) reached 72% after one minute of ozonation and 99.5% after 60 minutes. In the presence of Fe(ii)Mt, EE2 degradation (96%) was achieved after only one minute of ozonation. Under similar conditions, almost total degradation to 99.99% was registered in 15 minutes of ozonation but without total mineralization of the intermediates. Moderately acid-activated bentonites exhibited higher activity affording total mineralization within a short period of ozonation. The catalytic activity of clay catalysts was found to correlate with their surface basicity and hydrophilic character. The results obtained herein allow understanding soil behavior in natural oxidative degradation of organic molecules and envisaging effective soil-based catalysts with surface properties judiciously tailored according to the nature of organic pollutants in solvent free media.

Aluminosilicate-catalyzed electrochemical removal of ammonium cation from water -kinetics and selectivity.

Aluminosilicate-catalyzed electrochemical decomposition of ammonium cation (NH4+) in water was investigated using NH4+-saturated clinoptilolite and copper-nickel electrodes in the presence of different salts and acidic species. The results showed beneficial roles of chloride anion and moderately acidic media. NH4+ adsorbed by the zeolites was converted with a 98% selectivity into nitrogen. The process was found to obey zero-order kinetics in the presence of clinoptilolite and a first order process when NaCl is added. Beneficial buffering effects of the zeolite and acidic species were registered. Clinoptilolite turned out to act as both catalyst and NH4+ reservoir. These results allow envisaging effective and waste-free technology in treating NH4+-rich aqueous effluents through total electroconversion into nitrogen using low cost aluminosilicates. Clay minerals, soils, sludges and natural water turbidity are potential catalysts for this purpose.

Iron-loaded amine/thiol functionalized polyester fibers with high catalytic activities: a comparative study.

Dispersion of iron nanoparticles (Fe-NPs) was achieved on polyester fabrics (PET) before and after the incorporation of dendrimers (PAMAM), 3-(aminopropyl) triethoxysilane (APTES) or thioglycerol (SH). The catalytic activity of the resulting materials (PET-Fe, PET-PAMAM-Fe, PET-APTES-Fe and PET-SH-FE) was comparatively investigated in the degradation of 4-nitrophenol (4-NP) and methylene-blue (MB). Full characterization through diverse instrumental methods allowed correlating the type of the organic moiety incorporated with the Fe content, catalytic properties and stability. The highest 4-NP degradation yield reached 99.6% in 12 min for PET-SH-Fe. The catalytic activity was explained in terms of reactant interaction with Fe-NPs. The 1st order reaction kinetics and pseudo-1st order adsorption kinetics provide evidence of the key role of reactant adsorption. These findings allow envisaging the preparation of fiber-based catalysts for potential uses in environmental and green chemistry.

Acid-treated clay catalysts for organic dye ozonation - Thorough mineralization through optimum catalyst basicity and hydrophilic character.

Catalytic ozonation of Methylene Blue, Methyl Green, Methyl Orange and Methyl-thymol Blue was investigated in the presence of ion-exchanged montmorillonite (NaMt and Fe(II)Mt), crude bentonite and acid-activated counterparts. An original approach never tackled so far consisted in correlating the basicity and hydrophilic character to the dye-catalyst interactions occurring on the catalyst surface. This was achieved through CO2 and water thermal programmed desorption. Kinetics study revealed that ozonation starts in the bulk solution, and dye adsorption turns out to be an essential requirement for high catalytic effectiveness. On NaMt, dye molecules appear to adsorb mainly via hydrophobic interaction. On Fe(II)Mt, the contributions of hydrophobic interaction, cation-exchange and Fe2+ mobility to the catalytic activity prevail. Acid activated clay catalysts exhibited lowest hydrophilic character favoring adsorption through organophilic interaction and affording thorough and fast dye mineralization. This was explained in terms of increased number of silanols and -Si-O-Si- groups. For all catalysts, short ozonation of all dye molecules resulted in similar end-chain products, which were totally eliminated after prolonged reaction times. This result is of great importance because it provides valuable theoretical findings that allow envisaging total mineralization of organic molecules by recyclable metal-free clay catalysts.

Effect of Dendrimer Generation and Aglyconic Linkers on the Binding Properties of Mannosylated Dendrimers Prepared by a Combined Convergent and Onion Peel Approach.

An efficient study of carbohydrate-protein interactions was achieved using multivalent glycodendrimer library. Different dendrimers with varied peripheral sugar densities and linkers provided an arsenal of potential novel therapeutic agents that could be useful for better specific action and greater binding affinities against their cognate protein receptors. Highly effective click chemistry represents the basic method used for the synthesis of mannosylated dendrimers. To this end, we used propargylated scaffolds of varying sugar densities ranging from 2 to 18 for the attachment of azido mannopyranoside derivatives using copper catalyzed click cycloaddition. Mannopyranosides with short and pegylated aglycones were used to evaluate their effects on the kinetics of binding. The mannosylated dendrons were built using varied scaffolds toward the accelerated and combined "onion peel" strategy These carbohydrates have been designed to fight E. coli urinary infections, by inhibiting the formation of bacterial biofilms, thus neutralizing the adhesion of FimH type 1 lectin present at the tip of their fimbriae against the natural multiantennary oligomannosides of uroplakin 1a receptors expressed on uroepithelial tissues. Preliminary DLS studies of the mannosylated dendrimers to cross- link the leguminous lectin Con A used as a model showed their high potency as candidates to fight the E. coli adhesion and biofilm formation.

Cu0-Loaded organo-montmorillonite with improved affinity towards hydrogen: an insight into matrix-metal and non-contact hydrogen-metal interactions.

Copper-loaded organo-montmorillonite showed improved affinity towards hydrogen under ambient conditions. Clay ion exchange with a propargyl-ended cation followed by thiol-yne coupling with thioglycerol resulted in a porous structure with a 6 fold higher specific surface area, which dramatically decreased after copper incorporation. X-ray diffraction and photoelectron spectrometry, nuclear magnetic resonance (1H and 13C) and CO2-thermal programmed desorption revealed strong sulfur:Cu0 and oxygen:Cu0 interactions. This was explained in terms of structure compaction that 'traps' Cu0 nanoparticles (CuNPs) and reduces their mobility. Transmission electron microscopy showed predominant 1.0-1.5 nm CuNPs. Hydrogen capture appears to involve predominantly physical interaction, since differential scanning calorimetry measurements gave low desorption heat and almost complete gas release between 20 °C and 75 °C. Possible hydrogen condensation within the compacted structure should hinder gas diffusion inside CuNPs and prevent chemisorption. These results allow safe hydrogen storage with easy gas release to be envisaged even at room temperature under vacuum. The reversible capture of hydrogen can be even more attractive when using natural inorganic supports and commercial plant-derived dendrimers judiciously functionalized, even at the expense of porosity.

Catalytic ozonation of Orange-G through highly interactive contributions of hematite and SBA-16 - To better understand azo-dye oxidation in nature.

Hematite-SBA-16 mixture (HS) exhibited high catalytic activity in Orange-G (OG) ozonation in water. Total OG discoloration was achieved in half the time required with hematite or SBA-16 alone, all UV-Vis bands disappeared in less than 2 min. Liquid chromatography- Mass spectrometry (LC-MS) revealed that OG ozonation triggers via both hydroxylation and desulfonation of the aromatic rings into specific intermediates. Prolonged ozonation in the presence of hematite and SBA-16 alone resulted in different distributions of common derivatives. The latter were not detected after 25 min ozonation with HS. Stochastic modeling of the evolution in time of the UV-Vis bands of OG revealed strong binary interaction between the initial pH and catalyst concentration. This was explained in terms of reciprocal contributions of: i. the catalytic properties of hematite in spite of its low porosity; ii. the high specific surface area of SBA-16 for adsorption and surface reaction notwithstanding its low intrinsic catalytic activity. The weak basicity of SBA-16 surface seems to play a key-role in adsorption. These findings are of great interest for envisaging flexible oxidative treatments, where Fe3+ containing soils or mixtures of sand and rust may also act as catalyst for total mineralization of various azo-dyes, regardless to their structures.

Total mineralization of sulfamethoxazole and aromatic pollutants through Fe2+-montmorillonite catalyzed ozonation.

The catalytic activity and selectivity of montmorillonite exchanged with Na(+), Fe(2+), Co(2+), Ni(2+) and Cu(2+) cations were comparatively investigated in the ozonation of sulfamethoxazole (SMX). Chlorobenzene, benzoic acid, 4-nitrobenzoic acid, 3-hydroxybenzaldehyde, 4-nitrophenol and phenol were used as probe molecules having structural similarity with SMX oxidation intermediates. UV-vis spectrophometry and chemical oxygen demand (COD) measurements showed that Fe(II)-Mt and, to a lesser extent, Co(II)-Mt produce total mineralization of all organic substrates in less than 40 min. Combined HPLC-mass spectrometry revealed a reverse proportionality between the degradation time and molecular size of the organic substrates. Oxalic acid was recognized as a common bottleneck in the ozonation of any organic substrates. Ozonation initially obeyed a first order kinetics, but adsorption took place after 3-5 min, inducing changes in the mechanisms pathways. These findings may be useful for tailoring optimum oxidative treatment of waters without accumulation of hazardous derivatives.

Metal-inorganic-organic matrices as efficient sorbents for hydrogen storage.

Stabilization of metal nanoparticles (MNPs) without re-aggregation is a major challenge. An unprecedented strategy is developed for achieving high dispersion of copper(0) or palladium(0) on montmorillonite-supported diethanolamine or thioglycerol. This results in novel metal-inorganic-organic matrices (MIOM) that readily capture hydrogen at ambient conditions, with easy release under air stream. Hydrogen retention appears to involve mainly physical interactions, slightly stronger on thioglycerol-based MIOM (S-MIOM). Thermal enhancement of desorption suggests also a contribution of chemical interactions. The increase of hydrogen uptake with prolonged contact times arises from diffusion hindrance, which appears to be beneficial by favoring hydrogen entrapment. Even with compact structures, MIOMs act as efficient sorbents with much higher efficiency factor (1.14-1.17 mmol H 2 m(-2)) than many other sophisticated adsorbents reported in the literature. This opens new prospects for hydrogen storage and potential applications in microfluidic hydrogenation reactions.