Abstract  Wheat plants were cultivated in pots with the objective of evaluating the effect of two sulfur (S) rates (+S and -S) on (i) shoot growth, S and nitrogen (N) uptake and nitrogen use efficiency (NUE) and (ii) root growth and architecture and its relations with S and N uptake. Plant samplings were at Z39, Z51 and Z92 stages. Shoot mass and NUE were greater in +S treatment at the three stages. -S treatment increased root growth at Z39 (14% more length and 16% more tips) in comparison with +S, but the opposite occurred at Z51 (31% less area and 42% less mass). S uptake per unit root mass, area and length were greater in +S treatment at Z39 and Z51. A similar pattern was determined for nitrogen uptake (Nu) at Z39, but the opposite occurred at Z51. This indicates that Nu is mainly controlled by shoot growth and not by root growth.

Abstract  Sustaining good water quality in aquaculture ponds is vital. Without an aerator, the dissolved oxygen in ponds comes primarily from mass transfer at the water-ambient atmosphere interface. As sediment can seriously affect water quality, this study used indoor experiments to examine the nutrient (nitrogen and phosphorus) release mechanisms and fluxes from sediment in aquaculture ponds with moving water but no aeration. The results showed that the ammonia nitrogen (NH3-N) concentration in the overlying water was inversely proportional to flow velocity and that a higher flow velocity tended to result in a lower concentration in the overlying water, a steeper vertical gradient of concentration within the bed sediments, and a faster release rate from the sediments. The sediment disturbed by flowing water released more nitrate nitrogen (NO3-N) and nitrite nitrogen (NO2-N) into the overlying water and NO2-N could become oxidized into NO3-N. In still water, NO3-N was released gradually and some anaerobic NO3-N was nitrified into NO2-N. Phosphorus release from the sediments was controlled by the adsorption-desorption balance, with the phosphorus concentration in the overlying water dropping gradually to a steady value from its initial maximum. The relationship between NH3-N release flux and flow rate is described by a cubic function.

Abstract  Particulate matter and NO x emissions from diesel exhaust remains one of the most pressing environmental problems. We explore the use of hierarchically ordered mixed Fe-Ce-Zr oxides for the simultaneous capture and oxidation of soot and reduction of NO x by ammonia in a single step. The optimized material can effectively trap the model soot particles in its open macroporous structure and oxidize the soot below 400 °C while completely removing NO in the 285-420 °C range. Surface characterization and DFT calculations emphasize the defective nature of Fe-doped ceria. The isolated Fe ions and associated oxygen vacancies catalyze facile NO reduction to N2. A mechanism for the reduction of NO with NH3 on Fe-doped ceria is proposed involving adsorbed O2. Such adsorbed O2 species will also contribute to the oxidation of soot.

Abstract  N-acyl-homoserine lactones (AHLs) serve as quorum-sensing signals, which control a number of bacterial processes in many proteobacteria. Here we report the effects of exogenous short-chain AHL on the denitrifying process of Paracoccus denitrificans, which are capable of aerobic and anaerobic growth by utilizing nitrate. The denitrification activity of these cells was monitored by measuring denitrification products (including nitrate, nitrite, and nitrous oxide), and the individual messenger ribonucleic acid (mRNA) levels of nitrate, nitrite, nitric oxide and nitrous oxide reductases. The results indicated that 2μmol/L C6-homoserine lactone (HSL) has little effect on cell density under either anaerobic or aerobic culture conditions, and the nitrate reduction activity appeared slightly affected by N-hexanoyl-DL-homoserine lactone (C6-HSL). However, exogenous C6-HSL significantly affected the transcription of nitrite reductase and nitric oxide reductase genes in P. denitrificans regardless of the presence of oxygen, and N2O accumulation activity in P. denitrificans was suppressed by C6-HSL under aerobic condition. In contrast, exogenous C6-HSL stimulated the production of N2O under anaerobic condition, suggesting that the regulation of denitrification by quorum sensing may be important in N2O release.

Abstract  Ab initio molecular dynamics (AIMD) calculations were performed to investigate the structural and dynamical properties of different domains (hydrophobic, hydrophilic, and interfacial) occurring in the hydrated Na+-Nafion model systems. Pair distribution functions (PDF) were calculated between different atom pairs to analyze the structural features of the hydration structure of the different Na+-Nafion complexes. The analysis of the H center dot center dot center dot O PDF curves clearly distinguishes water molecules at the ionomer SO3- interface from the rest of the water molecules. It was found that hydrogen bonding of water molecules to the sulfonate group is weaker than hydrogen bonding among water molecules themselves. The vibrational densities of states (VDOSs) were calculated from the autocorrelation function of velocities. Overall, the calculated VDOSs have a good correspondence with experimental IR spectra. The analysis of the VDOS curves shows that the high frequency shift of the OH stretching modes of water molecules comes from the interface region in comparison to the rest of the water molecules. The interfacial water molecules are the main contributors to the high frequency side peak of the OH stretching modes, in good agreement with the observed FTIR spectra of the hydrated Nafion systems. Analysis of the partial vibrational density of states provided the unambiguous assignment of the stretching modes of the structural units that form the Nafion structure (C-O-C, C-C, C-S, SO3, and CFx. AIMD simulations were also performed for Na+-Nafion models hydrated with HDO and D2O molecules, respectively. The calculated PDF curves for Na+center dot center dot center dot O and H center dot center dot center dot O distances showed the same features as PDFs for models with H2O molecules. On the other hand, the O-H and O-D stretching modes in the VDOS spectra of the models with HDO are well separated with a large red shift of about 1000 cm(-1) of the O-D frequencies. A similar shift was also observed for the models with pure D2O having nearly identical VDOS band structures of the stretching modes. Additionally, water bending modes are red shifted from similar to 1630 cm(-1) (H2O) to similar to 1440 cm(-1) (HDO) and similar to 1190 cm(-1) (D2O), respectively.

Abstract  Soil and plant nutrient status (N, P, K, B, Cu, Fe, Mn, and Zn) of sugarcane fields with the spatial variation and associated was investigated plant nutrient concentrations of sugarcane grown in district Thatta of lower Sindh, through a field survey approach. Soils were low in nitrogen (NO3(-N) 0.55-9.20 mg kg(-1)), low to medium in phosphorus (1.20 to 9.48 mg kg(-1)), and adequate in extractable potassium (above 108 mg kg(-1)). Among the micronutrients, zinc was low (0.80 mg kg(-1)), boron was medium (0.56) while copper and iron were adequate (3.02 and 19.48 mg kg(-1), respectively). The soil test values had spatial structure especially in case of soil phosphorus, nitrate, copper and manganese, which better fit in the linear model implying that variance in these soil nutrients was yet increasing with the distance of sampling scale. The spatial structure of soil potassium and zinc fit the spherical model indicating that they varied in a "patchy" way; and the range of spatial correlation provides an average extent of these patches.

The nugget/ sill value between 25 and 75 % indicated medium spatial dependence with the range of 89 km for plant available zinc. Among plant nutrients, the mean nitrogen (1.76%) was slightly below the critical value in 49% samples and phosphorus with mean content of 0.18% blow critical level in 43% plant samples suggesting deficiencies of these nutrients, while the potassium content (1.87%) was indicative of a luxurious uptake. Among micronutrients plant zinc level with mean value of 19.52 mg kg(-1) was below critical level in 24% and boron with mean value of 6.81 mg kg(-1) was below in 21% plant samples. While copper, iron and manganese were in optimum range.

Abstract  To accomplish a rational tuning of the surface chemistry of graphene flakes (GF), four different one-step protocols towards the selective oxidation of GF were performed, using different oxidants: nitric acid, potassium permanganate/sulfuric acid, ozone and 3-chloroperbenzoic acid. The characterization of the resulting materials confirmed the successful preparation of oxidized GF with C/O atomic ratios varying in the range of 21.2-4.9, with distinct types of oxygen functionalities. While the oxidation of GF with nitric acid exclusively promotes the introduction of carboxylic groups and carbonyl/quinones, 3-chloroperbenzoic acid is responsible for the introduction of epoxyl groups and carboxylic anhydrides, potassium permanganate favours the introduction of epoxyl and hydroxyl groups and some content of carboxylic anhydrides, and ozone promotes predominantly the introduction in graphene structure of epoxyl groups, carboxylic anhydrides, phenols, quinones and lactones, and in a lesser extension carbonyl groups in alpha-substituted ketones and aldehydes if the oxidation is performed in the solid phase, or hydroxyl groups and a moderate content of carbonyl groups and aldehydes if GF are in a water dispersion. Furthermore, this work highlighted the possibility of identifying and distinguishing labile groups, namely hydroxyl and epoxyl groups, which are predominant in the structure of GF oxidized with potassium permanganate/sulfuric acid, ozone and 3-chloroperbenzoic acid. This is the first comprehensive study on the fine tuning of the surface of oxidized GF and a major contribution for the rational design of graphene composites since the application of these specific strategies can be useful in the anchoring of other molecules or nanoparticles.

Abstract  The lack of statistically robust relationships between IEPOX (isoprene epoxydiol)-derived SOA (IEPOX SOA) and aerosol liquid water and pH observed during the 2013 Southern Oxidant and Aerosol Study (SOAS) emphasizes the importance of modeling the whole system to understand the controlling factors governing IEPOX SOA formation. We present a mechanistic modeling investigation predicting IEPOX SOA based on Community Multiscale Air Quality (CMAQ) model algorithms and a recently introduced photochemical box model, simpleGAMMA. We aim to (1) simulate IEPOX SOA tracers from the SOAS Look Rock ground site, (2) compare the two model formulations, (3) determine the limiting factors in IEPOX SOA formation, and (4) test the impact of a hypothetical sulfate reduction scenario on IEPOX SOA. The estimated IEPOX SOA mass variability is in similar agreement (r(2) ∼ 0.6) with measurements. Correlations of the estimated and measured IEPOX SOA tracers with observed aerosol surface area (r(2) ∼ 0.5-0.7), rate of particle-phase reaction (r(2) ∼ 0.4-0.7), and sulfate (r(2) ∼ 0.4-0.5) suggest an important role of sulfate in tracer formation via both physical and chemical mechanisms. A hypothetical 25% reduction of sulfate results in ∼70% reduction of IEPOX SOA formation, reaffirming the importance of aqueous phase chemistry in IEPOX SOA production.

Abstract  A three-dimensional (3D) direct numerical simulation (DNS) of an experimental turbulent premixed jet flame at high Karlovitz number was studied. The DNS resolution adequately resolves both the flame and turbulence structures. A reduced chemical mechanism for premixed CH4/air flames with NOx based on GRI-Mech3.0 was used, including 268 elementary reactions, and 28 transported species. Consistent post-processing methods were applied to both the DNS and experimental data to evaluate turbulent burning velocity-related statistics, namely the flame surface density (FSD), and the flame curvature. Good agreement was achieved for the 2D comparisons. The DNS data were further analysed and provide 3D statistics unattainable from the experiment. The ratio of the 3D and 2D flame surface densities was estimated. The results are comparable with other values reported for various experimental flames. The 3D and 2D flame curvatures were also compared and their distributions are shown to be quite different owing to the round on-average geometry. Instantaneous images of the heat release surrogate, [CH2O][OH], between the DNS and experiment agreed qualitatively. Various other experimentally obtainable surrogates for heat release rate including [CH2O][H], [CH2O][O], [HCO], and [CH] are also evaluated and compared using the DNS. The inner structure of the flame was compared between the DNS and experiment in terms of the joint PDFs of OH concentration and temperature. Generally good agreement was obtained; discrepancies may be due to the inconsistency of assumed equilibrium levels of OH concentration in the co-flow. (C) 2016 by The Combustion Institute. Published by Elsevier Inc.

Abstract  Ultrasound (US) was shown to activate persulfate (PS) providing an alternative activation method to base or heat as an in situ chemical oxidation (ISCO) method. The kinetics and mechanism of ultrasonic activation of PS were examined in aqueous solution using an in situ electron paramagnetic resonance (EPR) spin trapping technique and radical trapping with probe compounds. Using the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), hydroxyl radical ((•)OH) and sulfate radical anion (SO4(•-)) were measured from ultrasonic activation of persulfate (US-PS). The yield of (•)OH was up to 1 order of magnitude greater than that of SO4(•-). The comparatively high (•)OH yield was attributed to the hydrolysis of SO4(•-) in the warm interfacial region of cavitation bubbles formed from US. Using steady-state approximations, the dissociation rate of PS in cavitating bubble systems was determined to be 3 orders of magnitude greater than control experiments without sonication at ambient temperature. From calculations of the interfacial volume surrounding cavitation bubbles and using the Arrhenius equation, an effective mean temperature of 340 K at the bubble-water interface was estimated. Comparative studies using the probe compounds tert-butyl alcohol and nitrobenzene verified the bubble-water interface as the location for PS activation by high temperature with (•)OH contributing a minor role in activating PS to SO4(•-). The mechanisms unveiled in this study provide a basis for optimizing US-PS as an ISCO technology.

Abstract  In order to assess the potential change in ambient concentrations of ozone and its precursors that may arise from the construction of large industrial facilities in the Terrace-Kitimat valley (TKV), we conducted a study using the WRF, SMOKE and CAMx models for two periods in 2010. We developed and applied control and test cases for each period, the former for model evaluation and the latter to assess pollutant change. Model evaluation showed that CAMx is able to emulate O-3 peaks in an adjacent valley (where monitoring occurred) for both the spring and summer periods. Results for the spring period suggest that the addition of NOX from industrial sources may lead to modest O-3 production outside of the main plume trajectory and on valley walls during afternoon hours as well as overnight O-3 titration along low elevations of the TKV upwards of 80 km downwind of sources. Results from the summer period suggest that the addition of O-3 precursors may at times contribute to a greater than 100 % increase in O-3 production under certain meteorological conditions up to 50 km downwind of sources.

Abstract  Currently, there is a lack of knowledge about GHG emissions, specifically N2O and CH4, in subtropical coastal freshwater wetland and mangroves in the southern hemisphere. In this study, we quantified the gas fluxes and substrate availability in a subtropical coastal wetland off the coast of southeast Queensland, Australia over a complete wet-dry seasonal cycle. Sites were selected along a salinity gradient ranging from marine (34 psu) in a mangrove forest to freshwater (0.05 psu) wetland, encompassing the range of tidal influence. Fluxes were quantified for CH4 (range -0.4-483 mg C-CH4 h(-1) m(-2)) and N2O (-5.5-126.4 mu g N-N2O h(-1) m(-2)), with the system acting as an overall source for CH4 and N2O (mean N2O and CH4 fluxes: 52.8 mu g N-N2O h(-1) m(-2) and 48.7 mg C-CH4 h(-1) m(-2), respectively). Significantly higher N2O fluxes were measured during the summer months (summer mean 64.2 +/- 22.2 mu g N-N2O h(-1) m(-2); winter mean 33.1 +/- 24.4 A mu g N-N2O h(-1) m(-2)) but not CH4 fluxes (summer mean 30.2 +/- 81.1 mg C-CH4 h(-1) m(-2); winter mean 37.4 +/- 79.6 mg C-CH4 h(-1) m(-2)). The changes with season are primarily driven by temperature and precipitation controls on the dissolved inorganic nitrogen (DIN) concentration. A significant spatial pattern was observed based on location within the study site, with highest fluxes observed in the freshwater tidal wetland and decreasing through the mangrove forest. The dissolved organic carbon (DOC) varied throughout the landscape and was correlated with higher CH4 fluxes, but this was a nonlinear trend. DIN availability was dominated by N-NH4 and correlated to changes in N2O fluxes throughout the landscape. Overall, we did not observe linear relationships between CH4 and N2O fluxes and salinity, oxygen or substrate availability along the fresh-marine continuum, suggesting that this ecosystem is a mosaic of processes and responses to environmental changes.

Abstract  Leached cinnamon soil is the main agricultural soil distributed in the North China Plain. In this research, leached cinnamon soil samples were collected in the upper basin of Miyun Reservoir (northeast of Beijing, China). The BaPS method (Barometric Process Separation) was applied to measure nitrification, denitrification and respiration rates. The rates of nitrification, denitrification and respiration were 0-120.35 μg N/kg SDW h, 0-246.86 μg N/kg SDW h and 0.17-225.85 μg C/kg SDW h (Soil Dry Weight, SDW), respectively. The emission rates of CO2 and NxOy through nitrification, denitrification and respiration were 1.00-547.80 and 6.00-4850.65 μmol/h, respectively. The analysis of relationships between nitrification, denitrification and respiration rates indicated that these three microbial processes were interacted, which posed impacts on soil nitrogen availability. As indicated by the results, C:N ratio coupled with content could be taken as the indicators of content, which is usually the predominant form of N available to plants growing in soil. Results showed that content was the highest (i.e., >62.4 mg/kg) when C:N ratio was 5.30-8.40, meanwhile content was 3.71-4.39 mg/kg. Nevertheless, content was the lowest (i.e., <6.40 mg/kg) when C:N ratio was 9.2-12.10, meanwhile content was 3.41-4.35 mg/kg.

Abstract  This paper presents a study undertaken on a naturally aspirated, direct injection diesel engine investigating the combustion and emission characteristics of CH4-CO2 and CH4-CO2-H-2 mixtures. These aspirated gas mixtures were pilot-ignited by diesel fuel, while the engine load was varied between 0 and 7 bar IMEP by only adjusting the flow rate of the aspirated mixtures. The in-cylinder gas composition was also investigated when combusting CH4-CO2 and CH4-CO2-H-2 mixtures at different engine loads, with in cylinder samples collected using two different sampling arrangements.

The results showed a longer ignition delay period and lower peak heat release rates when the proportion of CO2 was increased in the aspirated mixture. Exhaust CO2 emissions were observed to be higher for 60CH(4):40CO(2) mixture, but lower for the 80CH(4):20CO(2) mixture as compared to diesel fuel only combustion at all engine loads. Both exhaust and in-cylinder NOx levels were observed to decrease when the proportion of CO2 was increased; NOx levels increased when the proportion of H-2 was increased in the aspirated mixture. In-cylinder NOx levels were observed to be higher in the region between the sprays as compared to within the spray core, attributable to higher gas temperatures reached, post ignition, in that region. (C) 2017 The Authors. Published by Elsevier Ltd.

Abstract  Flat Na2S2O8@PVDF-g-PDMAEMA/PVDF inorganic-organic composite membrane was prepared by sequential use of atom transfer radical polymerization (ATRP), non-solvent induced phase inversion separation (NIPS) and post-dipping treatment. The membrane was tested in a membrane chemical reactor (MCR) system for concurrent advanced oxidation and ultrafiltration of ofloxacin (OFLX) under UV irradiation. Results indicated that the production of sulfate radicals (SO4) from persulfate can achieve 54% removal efficiency of OFLX, outperforming single advanced oxidation processes (AOPs) or ultrafiltration treatment. The best performance, was secondary to the combination of high redox potential of the SO4, hydrophilicity of N,N-dimethylaminoethyl methacrylate (DMAEMA) and molecular cutoff of polyvinylidene fluoride (PVDF) ultrafiltration membrane. This study also identified factors related to successfully preparing composite membranes with concurrent positive charges and hydrophilicity. Characterization using XRD, FTIR and EDS showed that introducing PDMAEMA into the polymer mixture and post dipping were both required to obtain a multifunctional membrane, Which can electrostatically attract negative S20i- species. Judging from SEM results, the formation mechanisms of the composite membrane structure were derived from instantaneous liquid-liquid demixing. (C) 2017 Elsevier B.V. All rights reserved.

Abstract  NOx emissions and their intermediate species NO, HCN, and NH3 have been investigated in an industrial waste-to-energy plant for the first time. Therefore, an innovative gas probe was designed accordingly to meet the challenging requirements of HCN and NH3 measurement. The N intermediates were measured in three different sample positions close to the grate. The highest concentrations were detected on the front side of the grate where the lowest local excess air ratio occurs. The NOx reduction potential, which is defined as the ratio of HCN and NH3 to NO, was above 1 during most of the relevant position sampling; hence, the selective high-temperature reduction does not seem to be a suitable technology for a further reduction of NOx emissions. The operating points investigated were conventional operation, flue gas recirculation (VLN-GM), air staging, and air staging with improved mixing. Conventional operation leads to emissions of about 450 mg/m(3), which could be reduced to 200 mg/m(3) by VLN-GM. Since the emissions are strongly dependent on the primary air ratio lambda(1), they show an almost linear correlation. The pretreatment of waste by shredding stabilizes the combustion and simplifies NOx control. The lowest emissions (around 100 mg/m(3)) were achieved during air-staged operation with additional air injection, due to improved mixing and the additional staging.

Abstract  A SACM/CT study of the CF2(OH)CF2OO + NO2 -> CF2(OH)CF2OONO2 and CF3CF2OO + NO2 CF3CF2OONO2 recombination reactions and their reverse unimolecular decomposition process was performed. The electronic energy along the reaction pathways was calculated at the G4(MP2) level. High-pressure rate coefficients of 1.53 x 10(-12) (T/300)(0.37) cm(3) molecule (-1) s(-1) and 1.79 x 10(16) (T/300)(0.40) exp (-24.4 kcal mo(-1)/RT) s(-1) were derived at 200-300 K for the direct and backward reactions of CF2(OH) CF2OONO2, while for CF3CF2OONO2, the expressions 1.01 x 10(-12)(T/300)(0.39) cm(3) molecule(-1) s(-1) and 1.05 x 10(16)(T/300)(0.44) exp(-23.0 kcal mot(-1)/RT) s(-1) were obtained. A decomposition lifetime profile was derived for CF2(OH)CF2OONO2, indicating that it could act as transport and reservoir of CF2(OH) CF2OO and NO2 in the stratosphere. (C) 2017 Elsevier.B.V. All rights reserved.

Abstract  The surfactant sodium lauryl ether sulfate (SLES) is widely used in the composition of detergents and frequently ends up in wastewater treatment plants (WWTPs). While aerobic SLES degradation is well studied, little is known about the fate of this compound in anoxic environments, such as denitrification tanks of WWTPs, nor about the bacteria involved in the anoxic biodegradation. Here, we used SLES as sole carbon and energy source, at concentrations ranging from 50 to 1000 mg L(-1), to enrich and isolate nitrate-reducing bacteria from activated sludge of a WWTP with the anaerobic-anoxic-oxic (A(2)/O) concept. In the 50 mg L(-1) enrichment, Comamonas (50%), Pseudomonas (24%), and Alicycliphilus (12%) were present at higher relative abundance, while Pseudomonas (53%) became dominant in the 1000 mg L(-1) enrichment. Aeromonas hydrophila strain S7, Pseudomonas stutzeri strain S8, and Pseudomonas nitroreducens strain S11 were isolated from the enriched cultures. Under denitrifying conditions, strains S8 and S11 degraded 500 mg L(-1) SLES in less than 1 day, while strain S7 required more than 6 days. Strains S8 and S11 also showed a remarkable resistance to SLES, being able to grow and reduce nitrate with SLES concentrations up to 40 g L(-1). Strain S11 turned out to be the best anoxic SLES degrader, degrading up to 41% of 500 mg L(-1). The comparison between SLES anoxic and oxic degradation by strain S11 revealed differences in SLES cleavage, degradation, and sulfate accumulation; both ester and ether cleavage were probably employed in SLES anoxic degradation by strain S11.

Abstract  At the centre of all air quality regulation stands the right of humans to an environment that is not harmful to health and well-being. In many developing countries, including South Africa, coal-fired power station emissions are managed both from an ambient air quality and minimum emissions standpoint. Ambient air quality standards and minimum emissions standards (MES) are often in conflict with one another, as power stations in which vicinity ambient air quality standards are met still have to comply with a blanket set of MES. In developing countries this often leads to the unnecessary incurrence of already constrained financial resources. This study proposes an alternative emissions management strategy where potential human health exposure is used as a decision-making basis on which power station emissions control is founded. The potential human health exposure of population groups to primary particulate matter with a diameter of 10 mu m or less (PM10), secondary sulphurous and nitrous particulate matter (PM), sulphur dioxide (SO2) and oxides of nitrogen (NOx) emissions are calculated and compared for 13 power stations in the highveld of South Africa. It was found that the potential human health exposure to individual power stations differ substantially. It is suggested that it makes more sense both from both a human health and fiscal perspective that emissions from coal-fired power stations be managed on an individual power station basis, especially in developing countries.

Abstract  Revisiting aggregation of extractant molecules into water-poor mixed reverse micelles, we propose in this paper to identify the thermodynamic origins of synergy in solvent extraction. Considering that synergistic extraction properties of a mixture of extractants is related to synergistic aggregation of this mixture, we identify here the elements at the origin of synergy by independently investigating the effect of water, acid, and extracted cations. Thermodynamic equations are proposed to describe synergistic aggregation in the peculiar case of synergistic solvent extraction by evaluating critical aggregation concentration (CAC) as well as specific interactions between extractants due to the presence of water, acid and cations. Distribution of two extractant molecules in the free extractants and in reverse micelles was assessed, leading to an estimation of the in-plane interaction parameter between extractants in the aggregates as introduced by Bergström and Eriksson ( Bergström, M.; Eriksson, J. C. A Theoretical Analysis of Synergistic Effects in Mixed Surfactant Systems . Langmuir 2000 , 16 , 7173 - 7181 ). Based on this model, we study the N,N'-dimethyl-N,N'-dioctylhexylethoxymalonamide (DMDOHEMA) and di(2-ethylexyl) phosphoric acid (HDEHP) mixture and show that adding nitric acid enhances synergistic aggregation at the equimolar ratio of the two extractants and that this configuration can be related to a favored enthalpy of mixing.

Abstract  In this research, degradation of P-Nitrophenol (PNP) as a model nitro-aromatic compound was carried out by photocatalytic process using magnetic Titania nano particles (MTNPs). The recyclable MTNPs were synthesized with average diameter of 22nm and a narrow size distribution. The process was modeled and optimized by a second order reduced polynomial model. Based on the model prediction, the process can be degraded PNP up to 90% under the optimum conditions of the initial pH=4, [PNP]=15mgL(-1), [MTNPs]=85mgL(-1), and T=25°C. PNP mineralization was obtained 69%, at the optimum condition after 120min of the process. The process kinetic was well fitted by pseudo first order kinetic model and electrical energy consumption of the process was obtained about 177.8kWh/m(3). Furthermore, the effect of sodium sulfite, sodium sulfate and sodium nitrite on the photocatalytic degradation process was assessed. The results showed that sulfite or sulfate ions decrease and nitrite ions increase the process efficiency. Also, a sample of redwater as a nitro-aromatic effluent was treated.

Abstract  The potential of microalgae and cyanobacteria for bioremediation of wastewater by nutrient uptake combined with simultaneous biomass production is a well recognized perception of today's world. The present study illustrates the treatment of a highly polluted wastewater generated during parboiling of paddy in rice mill industries, widely operational in developing countries where rice is the staple food crop, with the help of microalgal and cyanobacterial isolates capable of growing at high rates in parboiled rice mill effluent (RME). This endeavor leads to comprehensive bioremediation of the said effluent and subsequent use of the harvested biomass as slow release phosphorus biofertilizers and the treated effluent for crop irrigation. The RME-acclimatized algal consortium demonstrated highest growth in terms of fresh weight and greatest remediation efficiency at the end of 36 days' treatment of RME, with 93.9% phosphorus and 100% ammonia-nitrogen removal, 98.7%, 91.6% and 93.5% reduction in biological oxygen demand, chemical oxygen demand and total dissolved solid, respectively, and an increment of 186 +/- 0.3 mg L-1 dissolved oxygen, bringing down the pollutants level well below the discharge limits suggested by Central Pollution Control Board, India. Additionally, microalgae in the consortium aggregated in clumps spontaneously in presence of the filaments of Phormidium sp. facilitating easy harvest. The RME-acclimatized algal consortium demonstrated highest accumulation of polyphosphate (poly-P) (0.76 +/- 0.01% of dry weight) as well as highest release of phosphorus in non-sterile soil emphasizing the essential role of soil phosphorus solubilizing organisms to leach soluble phosphorus from the insoluble poly-P present in the biomass. The rice seedlings watered with treated RME also showed improved growth effect on shoot height and leaf width. The study results establish the suitability of RME as an excellent growth media for microalgae and cyanobacteria. (C) 2016 Elsevier B.V. All rights reserved.

Abstract  A macrocyclic pseudopeptide 3 is described featuring three amide groups and three 1,4-disubstituted 1,2,3-triazole units along the ring. This pseudopeptide was designed such that the amide NH groups and the triazole CH groups converge toward the cavity, thus creating an environment well suited for anion recognition. Conformational studies in solution combined with X-ray crystallography confirmed this preorganisation. Solubility of 3 restricted binding studies to organic media such as 5 vol% DMSO/acetone or DMSO/water mixtures with a water content up to 5 vol%. These binding studies demonstrated that 3 binds to a variety of inorganic anions in DMSO/acetone including chloride, nitrate, sulfate, and dihydrogenphosphate anions. In the more competitive DMSO/water mixtures, only affinity to the more strongly coordinating oxoanions is retained. Quantitative binding studies showed that dihydrogen phosphate complexation in DMSO/water involves the dimer of the H2PO4(-) anion. By contrast, sulfate and hydrogenpyrophosphate complexation involves a stepwise process comprising formation of a 1 : 1 complex followed by a 2R : 1A complex in which two molecules of 3 (R) bind to a single anion (A). While the second binding equilibrium is associated with a much smaller stability constant in comparison with the first one in the case of sulfate complexation, the two binding constants are of similar magnitude in the case of the hydrogenpyrophosphate anion. Formation of the 2R : 1A complex was attributed to the fact that the cavity size and rigidity of 3 prevents saturation of all hydrogen acceptor sites on the anionic guests.

Abstract  Two sets of isostructural mononuclear compounds, [Ln(LOMe)2(H2O)2](PF6) [1, Ln = Er; 3, Ln = Gd; LOMe = CpCo{P(O)(O(CH3))2}3] and Ln(LOMe)2(NO3) (2, Ln = Er and 4, Ln = Gd), are synthesized by self-assembly of the respective lanthanide ions and tripodal chelate ligands. The Ln ions are encircled by two LOMe ligands, and two water molecules or one nitrate anion. Each octacoordinated Ln center adopts a distorted square antiprism geometry. The Er complex (2) chelated by a nitrate anion shows slow dynamics in magnetic relaxation, diagnostic of a single-ion magnet. Quantum tunneling in 2 is effectively blocked by application of an external field. Weak intermolecular magnetic interactions occur in 2, and are supported by the magnetic behavior of 4. Chemical dilution of Er with the diamagnetic Y ion can nullify magnetic interactions and suppress quantum tunneling. Generation of slow relaxation dynamics in the Er system is related to the anisotropic charge distribution supplied by the coordination of ligands with different charge densities, as observed in the Dy analogue. This suggests that magnetic anisotropy arises in a coordination system when an anisotropic lanthanide ion (Dy and Er) is surrounded by a ligand environment with anisotropic charge density, resulting in slow magnetic relaxation.

Abstract  This work demonstrates a new method for selective identification of low ppb concentrations of O-3. Atomic layer deposited thin film SnO2 was used as a sensing layer. SnO2 sensitized quartz crystal microbalances (QCM) demonstrate expected mass loading behavior as well as unique frequency domain response towards synthetic air, O-3, and NO2 at room temperature. Power spectral densities (PSD) of the response of each gas were calculated and contain peaks at different normalized frequencies. These PSD peaks are found to have significant differences in magnitude for each analyte and provide evidence of selective room temperature adsorption of gases on SnO2.