Adsorption of pyridine from aqueous solutions by polymeric adsorbents MN 200 and MN 500. Part 1: Adsorption performance and PFG-NMR studies

The removal of pyridine from aqueous solutions was carried out using Macronet polymeric adsorbents MN 200 and MN 500. The optimal pyridine uptakes were in approximately neutral solutions as a result of optimal effect of π -π hydrophobic and attractive electrostatic interactions between pyridine and the adsorbents. These adsorbents showed superior pyridine uptake capacities than some apatite and activated carbons in isotherm studies. Thermodynamic analysis showed that pyridine adsorption is exothermic on MN 200 and endothermic on MN 500, implying that the adsorption on MN 500 is an activated process, which is attributed to the presence of sulfonic acid groups. Pseudo-first and second order rate models were used to fit the adsorption kinetics for the adsorbents. Translational dynamics of guest molecules within the porous polymers was analysed by PFG-NMR diffusion technique and the diffusion behaviour was characterised by two distinctive diffusion regions. PFG-NMR derived self-diffusion coefficients of pyridine in MN 500 were much slower than the expected diffusion coefficients based on a purely geometrical confinement effect, which suggests the interaction of pyridine with the sulfonic acid groups on MN 500 and their stronger effect on diffusivity also enhances the adsorption performance of this adsorbent. These studies reveal new insights into adsorption properties of pyridine in porous polymers in relation to the structural and surface properties probed by PFG-NMR and account for the effectiveness of these adsorbents in the treatment of waste water containing the aromatic N-heterocyclic compound.Carmine D’Agostino would like to acknowledge Wolfson College, Cambridge, for supporting his research activities.This is the author accepted manuscript. The final version is available from Elsevier at http://dx.doi.org/10.1016/j.cej.2016.07.039

Inhibitory effect of oxygenated heterocyclic compounds in mesoporous catalytic materials: A pulsed-field gradient NMR diffusion study

Oxygenated heterocyclic compounds are often used as solvents in liquid-phase catalytic reactions, such as hydrogenation and oxidation over porous oxide-based catalysts. It has often been reported that such compounds inhibit catalyst activity relative to the use of hydrocarbons as the solvent media. In this work we use $^{1}$H pulsed-field gradient (PFG) NMR diffusion studies to study diffusion properties of binary mixtures 1,4-dioxane/cyclohexane in mesoporous TiO$_{2}$ over the whole composition range in order to understand the effect of the solid surface on molecular transport and molecular interactions within the pore space. The results reveal that whilst the diffusion of the hydrocarbon is only affected by geometrical restrictions, the diffusion profile of 1,4-dioxane is highly influenced by interactions within the catalyst pore, which is thought to be due to the presence of lone electron pairs on the oxygen atoms of 1,4-dioxane, allowing the molecule to act as a Lewis base when in contact with the solid surface. This agrees with findings on the inhibitory capacity of oxygenated heterocyclic compounds when used either as solvent in catalysis or present as impurities in some chemical feedstocks. The work shows that it is possible to use $^{1}$H PFG NMR in order to characterise the effect of surfaces on molecular transport and hence understand catalytic behaviour in liquid-phase catalytic reactions.Carmine D’Agostino would like to acknowledge Wolfson College, Cambridge, for supporting his research. The authors would also like to acknowledge the EPSRC (EP/G011397/1) for funding

Assessing the use of NMR chemical shifts for prediction of VLE in non-ideal binary liquid mixtures

A method of estimating vapour liquid equilibrium (VLE) using NMR chemical shift data has been proposed by Xu et al. (2012). This method is based on the concept that the average local composition around each species is determined by the thermodynamics of the system, and also determines the screening of the NMR active groups within that molecule, and so their NMR chemical shifts. Xu et al.‘s method has been replicated and verified; results are confirmed to be accurate for alcohol + hydrocarbon mixtures, giving VLE predictions of comparable accuracy to the UNIFAC, generally considered the best predictive activity coefficient model available. However, for more strongly non-ideal mixtures, the method becomes less reliable, giving significantly less accurate predictions of total pressure than UNIFAC. Several causes for this are identified. The model proposed by Xu et al. (2012) is unable to fit minima or maxima in chemical shifts, which are observed experimentally in some binary mixtures. Different NMR resonances within the same molecule lead to different predictions of VLE, clearly an un-physical result. The thermodynamics of strongly non-ideal mixtures are determined by more complex interactions than a simple description of average local composition around each component in the mixtures, for example strong and directional hydrogen bonds. Different groups within the same molecule may have different local compositions in their immediate vicinity; for example in the case of alcohol + water mixtures, one would expect a clustering of water molecules around the hydroxyl group but not the aliphatic group. Hence, the concept of a simple local composition model is not valid for these more complex cases, and it is therefore not surprising that a model based on this simple concept is often not effective in predicting VLE.C. D’Agostino would like to acknowledge Wolfson College, Cambridge, for supporting his research activities.This is the accepted manuscript. The final version is available from Elsevier at http://www.sciencedirect.com/science/article/pii/S0009250914004461

Assessing the effect of reducing agents on the selective catalytic reduction of NO<inf>x</inf> over Ag/Al<inf>2</inf>O<inf>3</inf> catalysts

The selective catalytic reduction (SCR) of NOx in the presence of different reducing agents over Ag/Al2O3 prepared by wet impregnation was investigated by probing catalyst activity and using NMR relaxation time analysis.We gratefully acknowledge funding for this work from the EPSRC CASTech grant (EP/G012156/1). Carmine D’Agostino would like to acknowledge Wolfson College, Cambridge, for supporting his research activities. The authors would also like to thank Dr Jonathan Mitchell for useful discussions.This is the final version of the article. It first appeared from RSC via http://dx.doi.org/10.1039/C5CY01508

Prediction of mutual diffusion coefficients in binary liquid systems with one self-associating component from viscosity data and intra-diffusion coefficients at infinite dilution

© 2016 Elsevier Ltd. A new model for prediction of mutual diffusion coefficients is proposed over the whole composition range for binary liquid systems of one self-associating component and one non-polar component. The model is based on the Darken equation with the knowledge of intra-diffusion coefficients at infinite dilution of both species and viscosity data for the system, and takes into account the cluster diffusion approach with a scaling power on the thermodynamic correction factor. The model was validated to show good concurrence with the experimental mutual diffusion data. Following the analysis that the mutual diffusion coefficients at infinite dilution can be identified with the molecular intra-diffusion coefficient of the species (i.e., the intra-diffusion coefficient at infinite dilution in the absence of self-association), the proposed equation was extended to binary liquid systems without significant association. The accuracy of prediction for systems of cross associating species is expected to be limited. The model relies on the knowledge of the viscosity of the mixture over the whole composition range and may be used as a valid alternative to models based on measuring intra-diffusion coefficients as a function of composition. Indeed, such data are not always available or are more difficult to obtain whereas viscosity measurements can be readily available and more easily measured.C. D’Agostino would like to acknowledge Wolfson College, Cambridge, for supporting his research activities

Do group 1 metal salts form deep eutectic solvents?

Mixtures of metal salts such as ZnCl2, AlCl3 and CrCl3·6H2O form eutectic mixtures with complexing agents, such as urea. The aim of this research was to see if alkali metal salts also formed eutectics in the same way. It is shown that only a limited number of sodium salts form homogeneous liquids at ambient temperatures and then only with glycerol. None of these mixtures showed eutectic behaviour but the liquids showed the physical properties similar to the group of mixtures classified as deep eutectic solvents. This study focussed on four sodium salts: NaBr, NaOAc, NaOAc·3H2O and Na2B4O7·10H2O. The ionic conductivity and viscosity of these salts with glycerol were studied, and it was found that unlike previous studies of quaternary ammonium salts with glycerol, where the salt decreased the viscosity, most of the sodium salts increased the viscosity. This suggests that sodium salts have a structure making effect on glycerol. This phenomenon is probably due to the high charge density of Na+, which coordinates to the glycerol. 1H and 23Na NMR diffusion and relaxation methods have been used to understand the molecular dynamics in the glycerol-salt mixtures, and probe the effect of water on some of these systems. The results reveal a complex dynamic behaviour of the different species within these liquids. Generally, the translational dynamics of the 1H species, probed by means of PFG NMR diffusion coefficients, is in line with the viscosity of these liquids. However, 1H and 23Na T1 relaxation measurements suggest that the Na-containing species also play a crucial role in the structure of the liquids.A. P. Abbott would like to thank the Royal Society for funding the work through the Brian Mercer Award. C. D’Agostino would like to acknowledge Wolfson College, Cambridge, for supporting his research activities. S. Davis thanks EPSRC for funding a PhD studentship.This is the author accepted manuscript. The final version is available from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C6CP05880

Association of USF1 and APOA5 polymorphisms with familial combined hyperlipidemia in an Italian population.

Familial combined hyperlipidemia (FCH) is a polygenic and multifactorial disease characterized by a variable phenotype showing increased levels of triglycerides and/or cholesterol. The aim of this study was to identify single nucleotides (SNPs) in lipid-related genes associated with FCH. METHODS AND RESULTS: Twenty SNPs in lipid-related genes were studied in 142 control subjects and 165 FCH patients after excluding patients with mutations in the LDLR gene and patients with the E2/E2 genotype of APOE. In particular, we studied the 9996G > A (rs2073658) and 11235C > T (rs3737787) variants in the Upstream Stimulatory Factor 1 gene (USF1), and the -1131T > C (rs662799) and S19W (rs3135506) variants in the Apolipoprotein A-V gene (APOA5). We found that the frequencies of these variants differed between patients and controls and that are associated with different lipid profiles. At multivariate logistic regression SNP S19W in APOA5 remained significantly associated with FCH independently of age, sex, BMI, cholesterol and triglycerides. CONCLUSIONS: Our results show that the USF1 and APOA5 polymorphisms are associated with FCH and that the S19W SNP in the APOA5 gene is associated to the disease independently of total cholesterol, triglycerides and BMI. However, more extensive studies including other SNPs such as rs2516839 in USF1, are required

An improved method on stimulated T-lymphocytes to functionally characterize novel and known LDLR mutations.

The main causes of familial hypercholesterolemia (FH) are mutations in LDL receptor (LDLR) gene. Functional studies are necessary to demonstrate the LDLR function impairment caused by mutations and would be useful as a diagnostic tool if they allow discrimination between FH patients and controls. In order to identify the best method to detect LDLR activity, we compared continuous Epstein-Barr virus (EBV)-transformed B-lymphocytes and mitogen stimulated T-lymphocytes. In addition, we characterized both novel and known mutations in the LDLR gene. T-lymphocytes and EBV-transformed B-lymphocytes were obtained from peripheral blood of 24 FH patients and 24 control subjects. Functional assays were performed by incubation with fluorescent LDL followed by flow cytometry analysis. Residual LDLR activity was calculated normalizing fluorescence for the mean fluorescence of controls. With stimulated T-lymphocytes we obtained a better discrimination capacity between controls and FH patients compared with EBV-transformed B-lymphocytes as demonstrated by receiver operating characteristic (ROC) curve analysis (the areas under the curve are 1.000 and 0.984 respectively; P < 0.0001 both). The characterization of LDLR activity through T-lymphocytes is more simple and faster than the use of EBV-transformed B-lymphocytes and allows a complete discrimination between controls and FH patients. Therefore the evaluation of residual LDLR activity could be helpful not only for mutation characterization but also for diagnostic purposes

Solvent inhibition in the liquid-phase catalytic oxidation of 1,4-butanediol: Understanding the catalyst behaviour from NMR relaxation time measurements

Solvent inhibition over surfaces affects behaviour and performances of heterogeneous catalysts.Johnson Matthey, EvonikDegussa, Technology Strategy Board (Grant ID: TP/7/ZEE/6/I/N0262B), Engineering and Physical Sciences Research Council and CASTech consortium (Grant ID: EP/G011397/1), Wolfson College Cambridg