Quantifying mircoorganism/organic matter interactions in saturated porous media.

Proteins and humic acids are common constituents of waste water. Latex colloids (colloids) acted as surrogates for microorganisms in multiple pulse dynamic column experiments (MPEs) that permitted colloid mobility to be quantified before and after the injection of either BSA (a protein), or Suwannee River humic acid (SRHA).
At low OM coverage colloid breakthrough curves demonstrated both BSA and SRHA reduced colloid deposition rates, but did not affect colloid irreversible deposition mechanisms. By contrast, high levels of SRHA surface coverage not only further reduced the matrix’s ability to attenuate colloids, but also resulted in reversible adsorption of a significant fraction of colloids deposited. Modelling of colloid responses using random sequential adsorption modelling suggested that 1 microgram of SRHA had the same effect as the deposition of 5.90±0.14 x109 colloids; the model suggested that adsorption of the same mass of BSA was equivalent to the deposition of between 7.1x108 and 2.3x109 colloids.
Colloid responses in MPEs where BSA coverage of colloid deposition sites approached saturation demonstrated the sand matrix remained capable of adsorbing colloids. However, in contrast to responses observed in MPEs at low surface coverage, continued colloid injection showed that the sand’s attenuation capacity increased with time, i.e. colloid concentrations declined as more were deposited (filter ripening).
Importance: Study results highlight the contrasting responses that may arise due to the interactions between colloids and OM in porous media. Results not only underscore that colloids can interact differently with various forms of deposited OM, but also that a single type of OM may generate dramatically different responses depending on the degree of surface coverage. The MPE method provides a means of quantifying the influence of OM on microorganism mobility in porous media such as filter beds, which may be used for either drinking water treatment or waste water treatment. In the wider environment study findings have potential to allow more confident predictions of the mobility of sewage derived pathogens discharging to groundwater.

Anion recognition and sensing in organic and aqueous media using luminescent and colorimetric sensors

This review article focuses primarily on the work carried in our laboratories over the last few years using luminescent and colorimetric sensors, where the anion recognition occurs through hydrogen bonding in organic or aqueous solvents. This review begins with the story of the discovery of fluorescent photoinduced electron transfer (PET) sensors for anions using charged neutral urea or thiourea receptors where both fluorescent and NMR spectroscopic methods monitored anion recognition. This work led to the development of dual luminescent and colorimetric anion sensors based on the use of the ICT based naphthalimide chromophore, where ions such as fluoride gave rise to changes in both the fluorescence and the absorption spectra of the sensors, but at different concentrations. Here, the former changes were due to hydrogen bonding interactions, whereas the latter was due to the deprotonation of acidic protons, giving rise to the formation of the bifluoride anion (HF2−). Modification of the 4-amino-l,8-naphthalimide moiety has facilitated the formation of colorimetric anion sensors that work both in organic or aqueous solutions. Such charge neutral receptor motifs have also been incorporated into organic scaffolds with norbomyl and calixarene backbones, which have enabled us to produce anion directed self-assembled structures.

MYCELIAL DEVELOPMENT of Lentinula edodes IN CULTURE MEDIA WITH DIFFERENT ORGANIC SUBSTRATES

The radial mycelial growth of Lentinula edodes (Berk) Pegler, strain LE-96/13, was studied in culture media prepared with organic residues extract, by using substrates prepared with pineapple (Ananas comosus (L.) Merril) crown, Astrocaryum aculeatum Meyer peel, Theobroma grandiflorum Schum shell, Musa sp. (genomic group AAB, subgroup Pacovan) peel, and Musa sp. (genomic group AAB, subgroup Praia) peel, with three supplementation levels with wheat bran (0, 10 and 20%), and incubated at 25 degrees C. The experimental design was totally randomized, in a 5x3 factorial scheme, adding up 15 treatments with 4 repetitions, and each repetition corresponding to a Petri dish. The diameter of the colony was evaluated daily during nine days of incubation. After that period, it was verified that the highest mycelial growth averages of strain LE-96/13 of L. edodes were found in culture media prepared with T. grandiflorum Schum shell (whose supplementation with wheat bran was favorable for Mushroom development) and A. aculeatum Meyer peel (whose supplementation did not favor the mycelial growth of L. edodes in relation to the medium not supplemented).

Heterogeneous photocatalytic treatment of organic dyes in air and aqueous media

This review focuses on the heterogeneous photocatalytic treatment of organic dyes in air and water. Representative studies spanning approximately three decades are included in this review. These studies have mostly used titanium dioxide (TiO2) as the inorganic semiconductor photocatalyst of choice for decolorizing and decomposing the organic dye to mineralized products. Other semiconductors such as ZnO, CdS, WO3, and Fe2O3 have also been used, albeit to a much smaller extent. The topics covered include historical aspects, dark adsorption of the dye on the semiconductor surface and its role in the subsequent photoreaction, semiconductor preparation details, photoreactor configurations, photooxidation kinetics/mechanisms and comparison with other Advanced Oxidation Processes (e.g., UV/H2O2, ozonation, UV/O3, Fenton and photo-Fenton reactions), visible light-induced dye decomposition by sensitization mechanism, reaction intermediates and toxicity issues, and real-world process scenarios. © 2008 Elsevier B.V. All rights reserved.

Natural organic matter and colloid-facilitated arsenic transport and transformation in porous soil media

Prediction of arsenic transport and transformation in soil environment requires understanding the transport mechanisms and proper estimation of arsenic partitioning tong all three phases in soil/aquifer systems: mobile colloids, mobile soil solution, and immobile soil solids. The primary purpose of this research is to study natural dissolved organic matter (DOM)/colloid-facilitated transport of arsenic and understand the role of soil derived carriers in the transport and transformation of both inorganic and organoarsenicals in soils. ^ DOM/colloid facilitated arsenic transport and transformation in porous soil media were investigated using a set of experimental approaches including batch experiment, equilibrium membrane dialysis experiment and column experiment. Soil batch experiment was applied to investigate arsenic adsorption on a variety of soils with different characteristics; Equilibrium membrane dialysis was employed to determine the 'free' and 'colloid-bound/complexed' arsenic in water extracts of chosen soils; Column experiments were also set up in the laboratory to simulate arsenic transport and transformation through golf course soils in the presence and absence of soil-derived dissolved substances. ^ The experimental results revealed that organic matter amendments effectively reduced soil arsenic adsorption. The majority of arsenic present in the soil extracts was associated with small substances of molecular weight (MW) between 500 and 3,500 Da, Only a small fraction of arsenic was associated with higher MW substances (MW > 3,500 Da), which was operationally defined as colloidal part in this study. The association of arsenic and DOM in the soil extracts strongly affected arsenic bioavailability, arsenic transport and transformation in soils. The results of column experiments revealed arsenic complicated behavior with various processes occurring in soils studied, including: soil arsenic' adsorption, facilitated arsenic transportation by dissolved substances presented in soil extracts and microorganisms involved arsenic species transformation. ^ Soil organic matter amendments effectively reduce soil arsenic adsorption capability either by scavenging 'soil arsenic adsorption sites or by interactions between arsenic species and dissolved organic chemicals in soil solution. Close attention must be paid for facilitated arsenic transport by dissolved substances presented in soil solution and microorganisms involved arsenic species transformation in arsenic-contaminated soils.^

Influence of organic matter in road deposited particulates in heavy metal accumulation and transport

The research study discussed in the paper investigated the influence of organic matter on heavy metal adsorption for different particle size ranges of build-up solids. Samples collected from road surfaces were assessed for organic matter content, mineral composition, particle size distribution and effective cation exchange capacity. It was found that the organic matter plays a key role in >75µm particles in the adsorption of Zinc, Lead, Nickel and Copper, which are generated by traffic activities. Clay forming minerals and metal oxides of Iron, Aluminium and Manganese was found to be important for heavy metal adsorption to <75µm particles. It was also found that heavy metals adsorbed to organic matter are strongly bound to particles and these metal ions will not be bio-available if the chemical quality of the media remains stable.

Strength properties of composite clay balls containing additives from industry wastes as new filter media in water treatment

Pebble matrix filtration (PMF) is a water treatment technology that can remove suspended solids in highly turbid surface water during heavy storms. PMF typically uses sand and natural pebbles as filter media. Hand-made clay pebbles (balls) can be used as alternatives to natural pebbles in PMF treatment plants, where natural pebbles are not readily available. Since the high turbidity is a seasonal problem that occurs during heavy rains, the use of newly developed composite clay balls instead of pure clay balls have the advantage of removing other pollutants such as natural organic matter (NOM) during other times. Only the strength properties of composite clay balls are described here as the pollutant removal is beyond the scope of this paper. These new composite clay balls must be able to withstand dead and live loads under dry and saturated conditions in a filter assembly. Absence of a standard ball preparation process and expected strength properties of composite clay balls were the main reasons behind the present study. Five different raw materials from industry wastes: Red Mud (RM), Water Treatment Alum Sludge (S), Shredded Paper (SP), Saw Dust (SD), and Sugar Mulch (SM) were added to common clay brick mix (BM) in different proportions. In an effort to minimize costs, in this study clay balls were fired to 1100 0C at a local brick factory together with their bricks. A comprehensive experimental program was performed to evaluate crushing strength of composite hand-made clay balls, using uniaxial compression test to establish the best material combination on the basis of strength properties for designing sustainable filter media for water treatment plants. Performance at both construction and operating stages were considered by analyzing both strength properties under fully dry conditions and strength degradation after saturation in a water bath. The BM-75% as the main component produced optimum combination in terms of workability and strength. With the material combination of BM-75% and additives-25%, the use of Red Mud and water treatment sludge as additives produced the highest and lowest strength of composite clay balls, with a failure load of 5.4 kN and 1.4 kN respectively. However, this lower value of 1.4 kN is much higher than the effective load on each clay ball of 0.04 kN in a typical filter assembly (safety factor of 35), therefore, can still be used as a suitable filter material for enhanced pollutant removal.

Synthesis of some copper(II)-chelating (dialkylamino)pyridine amphiphiles and evaluation of their esterolytic capacities in cationic micellar media

Three new (dialkylamino)pyridine (DAAP)-based ligand amphiphiles 3-5 have been synthesized. All of the compounds possess a metal ion binding subunit in the form of a 2,6-disubstituted DAAP moiety. In addition, at least one ortho-CH2OH substituent is present in all the ligands. Complex formation by these ligands with various metal ions were examined under micellar conditions, but only complexes with Cu(II) ions showed kinetically potent esterolytic capacities under micellar conditions. Complexes with Cu(II) were prepared in host comicellar cetyltrimethylammonium bromide (CTABr) media at pH 7.6. Individual complexes were characterized by UV-visible absorption spectroscopy and electron paramagnetic resonance spectroscopy. These metallomicelles speed the cleavage of the substrates p-nitrophenyl hexanoate or p-nitrophenyl diphenyl phosphate. To ascertain the nature of the active esterolytic species, the stoichiometries of the respective Cu(II) complexes were determined from the kinetic version of Job's plot. In all the instances, 2:1 complex ligand/Cu(II) ion are the most kinetically competent species. The apparent pK(a) values of the Cu(II)-coordinated hydroxyl groups of the ligands 3, 4, and 5, in the comicellar aggregate, are 7.8, 8.0, and 8.0, respectively, as estimated from the rate constant vs pH: profiles of the ester cleavage reactions. The nucleophilic metallomicellar reagents and the second-order "catalytic" rate constants toward esterolysis of the substrate p-nitrophenyl hexanoate (at 25 degrees C, pH 7.6) are 37.5 for 3, 11.4 for 4, and 13.8 for 5. All catalytic systems comprising the coaggregates of 3, 4, or 5 and CTABr demonstrate turnover behavior in the presence of excess substrate.

Photodimerization of coumarin in aqueous and micellar media

The photochemical and photophysical processes of many organic compounds are a function of the environment in which they are present. In this connection we have chosen to investigate the environmental perturbations on the photodimerization of coumarin,l and the results of our study in aqueous and micellar media are presented in this paper. Coumarin has historically been the subject of intense photochemical and spectroscopic interest, mainly as a consequence of its importance in biological systems. Coumarin has been chosen for our investigation as its fascinating photochemical behavior has been fairly well explored,2 and therefore the environmental influence, which is the subject of our concern, would be easily understandable.

Ionic Liquids and Microwaves in Promotion of Organic Synthesis : Friedel-Crafts reaction, deuterolabelling and O-Demethylation

The use of ionic liquids in chemical research has gained considerable interest and activity in recent years. Due to their unique and varied physicochemical properties, in comparison to molecular solvents, the potential applications for ionic liquids are enormous. The use of microwave irradiation, as a powerful dielectric heating technique, in synthetic organic chemistry has been known since 1986. Since then, it has gained significant recognition for its research and application in both academia and industry. The use of either ionic liquids or microwave irradiation in synthetic organic chemistry has been known to afford improved, alternative or complimentary selectivities, in comparison to traditional processes. In this study, the use of ionic liquids as solvents, co-solvents and catalytic media was explored in Friedel-Crafts, deuterolabelling and O-demethylation reactions. Alternative methods for the production of a variety of aromatic ketones using the Friedel-Crafts acylation methodology were investigated using ionic liquid catalyst or ionic liquid acidic additive systems. The disclosed methods, i.e. metal bistriflamides and chloroindate ionic liquids systems, possessed good catalytic activity in the synthesis of typical benzophenones. These catalytic systems were also recyclable. Microwave irradiation was found to be useful in the synthesis of various polyhydroxydeoxybenzoins and arylpropanones as synthetic precursors to naturally occurring or potentially bioactive compounds. Under optimized condition, the reaction occurred in only four minutes using systems such as [bmim][NTf2]/HNTf2 and [bmim][BF4]/BF3·OEt2. Naturally occurring polyphenols, such as isoflavones, can possess various types of biological or pharmacological activity. In particular, some are noted for their beneficial effects on human health. Isotopically labelled analogues of polyphenols are valuable as analytical standards in the quantification of these compounds from biological matrices. A new strategy for deuterolabelling of polyphenols was developed using ionic liquids as co-solvents and 35% DCl/D2O, as a cheap deuterium source, under microwave irradiation. Under these conditions, perdeuterated compounds were achieved in short reaction times, in high isotopic purity and in excellent yields. An O-demethylation reaction was developed, using an ionic liquid reaction medium with BBr3 for the deprotection of a variety methyl protected polyphenolic compounds, such as isoflavons and lignans. This deprotection procedure was found to be very practical as the reaction occurred under mild reaction conditions and in short reaction times. The isolation and purification steps were particularly straightforward and high yielding, in comparison to traditional methods.

Dimethyl sulfide and other biogenic volatile organic compound emissions from branching coral and reef seawater: Potential sources of secondary aerosol over the Great Barrier Reef

Volatile organic compounds (VOCs) in the headspace of bubble chambers containing branches of live coral in filtered reef seawater were analysed using gas chromatography with mass spectrometry (GC-MS). When the coral released mucus it was a source of dimethyl sulfide (DMS) and isoprene; however, these VOCs were not emitted to the chamber headspace from mucus-free coral. This finding, which suggests that coral is an intermittent source of DMS and isoprene, was supported by the observation of occasional large pulses of atmospheric DMS (DMSa) over Heron Island reef on the southern Great Barrier Reef (GBR), Australia, in the austral winter. The highest DMSa pulse (320 ppt) was three orders of magnitude less than the DMS mixing ratio (460 ppb) measured in the headspace of a dynamically purged bubble chamber containing a mucus-coated branch of Acropora aspera indicating that coral reefs can be strong point sources of DMSa. Static headspace GC-MS analysis of coral fragments identified mainly DMS and seven other minor reduced sulfur compounds including dimethyl disulfide, methyl mercaptan, and carbon disulfide, while coral reef seawater was an indicated source of methylene chloride, acetone, and methyl ethyl ketone. The VOCs emitted by coral and reef seawater are capable of producing new atmospheric particles < 15 nm diameter as observed at Heron Island reef. DMS and isoprene are known to play a role in low-level cloud formation, so aerosol precursors such as these could influence regional climate through a sea surface temperature regulation mechanism hypothesized to operate over the GBR.

Direct and sensitized (energy and electron transfer) geometric isomerization of stilbene within zeolites: a comparison between solution and zeolite as reaction media

The trans- and cis-stilbenes upon inclusion in NaY zeolite are thermally stable. Direct excitation and triplet sensitization results in geometric isomerization and the excited state behavior under these conditions are similar to that in solution. Upon direct excitation, a photostationary state consisting of 65% cis and 35% trans isomers is established. Triplet sensitization with 2-acetonaphthone gave a photostationary state consisting of 63% cis and 37% trans isomers. These numbers are similar to the ones obtained in solution. Thus, the presence of cations and the confined space within the zeolite have very little influence on the overall chemistry during direct and triplet sensitization. However, upon electron transfer sensitization with N-methylacridinium (NMA) as the sensitizer within NaY, isomerization from cis-stilbene radical cation to trans-stilbene occurs and the recombination of radical ions results in triplet stilbene. Prolonged irradiation gave a photostationary state (65% cis and 35% trans) similar to triplet sensitization. This behavior is unique to the zeolite and does not take place in solution. Steady state fluorescence measurements showed that the majority of stilbene molecules are close to the N-methylacridinium sensitizer. Diffuse reflectance flash photolysis studies established that independent of the isomer being sensitized only trans radical cation is formed. Triplet stilbene is believed to be generated via recombination of stilbene radical cation and sensitizer radical anion. One should be careful in using acidic HY zeolite as a medium for photoisomerization of stilbenes. In our hands, in these acidic zeolites isomerization dominated the photoisomerization. (C) 2002 Elsevier Science B.V. All rights reserved.

Michael addition of masked thiolates to conjugated systems in aqueous media promoted by ammonium tetrathiomolybdate

Thiolates generated in situ by the action of ammonium tetrathiomolybdate on alkyl halides, thiocyanates and disulfides undergo Michael addition to alpha,beta-unsaturated esters, nitriles :and ketones in water under neutral conditions.

Role of spacer lengths of gemini surfactants in the synthesis of silver nanorods in micellar media

In this work, we have prepared Ag-nanorods using biscationic gemini surfactant micelles as the media by a seed-mediated wet synthesis method. Towards this end, we first synthesized Ag-nanoseeds of diameter similar to 7 nm stabilized by trisodium citrate (as the capping agent). Then these Ag-nanoseeds were used to synthesize Ag-nanorods of different aspect ratios. With decreasing Ag-nanoseed concentration, the aspect ratios of the Ag-nanorods stabilized by these gemini surfactants increased gradually. Various Ag-nanoseeds and Ag-nanospecies were characterized using UV-Vis spectroscopy (to know the surface plasmon bands), transmission electron microscopy (to find out their particle sizes and distribution), energy-dispersive X-ray spectroscopy and X-ray diffraction. When we used micelles derived from gemini surfactants of shorter spacer-(CH(2))(n)-(n = 2 or 4) to stabilize the Ag-nanorods, the lambda(max) of the longitudinal band shifted more towards the blue region compared to that of the gemini surfactant micelles with a longer spacer-(CH(2))(n)-(n = 5, 12) at a given amount of the Ag-nanoseed solution. So, the growth of Ag-nanorods in the gemini micellar solutions depends on the spacer-chain length of gemini surfactants employed.

Dynamic Internal Cavities of Dendrimers as Constrained Media. A Study of Photochemical Isomerizations of Stilbene and Azobenzene Using Poly(alkyl aryl ether) Dendrimers

Dendritic rnicroenvironments defined by dynamic internal cavities of a dendrimer were probed through geometric isomerization of stilbene and azobenzene. A third-generation poly(alkyl aryl ether) dendrimer with hydrophilic exterior and hydrophobic interior was used as a reaction cavity in aqueous medium. The dynamic inner cavity sizes were varied by utilizing alkyl linkers that connect the branch junctures from ethyl to n-pentyl moiety (C(2)G(3)-C(5)G(3)). Dendrimers constituted with n-pentyl linker were found to afford higher solubilities of stilbene and azobenzene. Direct irradiation of trans-stilbene showed that C(5)G(3) and C(4)G(3) dendrimers afforded considerable phenanthrene formation, in addition to cis-stilbene, whereas C(3)G(3) and C(2)G(3) gave only cis-stilbene. An electron-transfer sensitized trans-cis isomerization, using cresyl violet perchlorate as the sensitizer, also led to similar results. Thermal isomerization of cis-azobenzene to trans-azobenzene within dendritic microenvironments revealed that the activation energy of the cis- to trans-isomer was increasing in the series C(5)G(3) < C(4)G(3) < C(3)G(3)