Enhancement of esterification conversion using pervaporation membrane reactor

AbstractIn the present study, the esterification reaction of propionic acid with isobutyl alcohol to produce isobutyl propionate and water was studied. The performance of esterification reaction was compared by using the batch process and the pervaporation assisted hybrid process which performs the reaction and separation simultaneously. A polyvinyl alcohol–polyethersulphone (PVA–PES) hydrophilic polymeric membrane was used in the study to separate water and also to shift the equilibrium. The influence of process parameters such as catalyst loading, molar ratio of acid to alcohol, reaction temperature and ratio of membrane area to initial reaction volume (S/V) was studied. The results showed that the pervaporation assisted esterification process gave more conversion than the batch process of esterification. The membrane showed high selectivity to the removal of water in the propionic acid, isobutyl alcohol, isobutyl propionate and water mixture. Moreover, the conversion of propionic acid was enhanced by enhancing the catalyst amount, molar ratio of acid to alcohol, reaction temperature and S/V ratio

Use of polyethylene glycol coatings for optical fibre humidity sensing

Humidity induced change in the refractive index and thickness of the polyethylene glycol (PEG) coatings are in situ investigated for a range from 10 to 95%, using an optical waveguide spectroscopic technique. It is experimentally demonstrated that, upon humidity change, the optical and swelling characteristics of the PEG coatings can be employed to build a plastic fibre optic humidity sensor. The sensing mechanism is based on the humidity induced change in the refractive index of the PEG film, which is directly coated onto a polished segment of a plastic optical fibre with dip-coating method. It is observed that PEG, which is a highly hydrophilic material, shows no monotonic linear response to humidity but gives different characteristics for various ranges of humidity levels both in index of refraction and in thickness. It undergoes a physical phase change from a semi-crystal line structure to a gel one at around 80% relative humidity. At this phase change point, a drastic decrease occurs in the index of refraction as well as a drastic increase in the swelling of the PEG film. In addition, PEG coatings are hydrogenated in a vacuum chamber. It is observed that the hydrogen has a preventing effect on the humidity induced phase change in PEG coatings. Finally, the possibility of using PEG coatings in construction of a real plastic fibre optic humidity sensor is discussed. (C) 2008 The Optical Society of Japan

Single precursor sonochemical synthesis of mesoporous hexagonal-shape zero-valent copper for effective nitrate reduction

This short communication reports an efficient protocol for green synthesis of three-dimensional hexagonal-like zero-valent Cu following a facile sonochemical route. The method involved the use of copper(II) acetate [Cu(CH3COO)2] as a precursor, and a mixture of ethylene glycol (C2H4(OH)2) and ethanol (1:1) as the solvent. The final products obtained were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, porosity analysis and UV–visible spectroscopy to investigate the reduction of nitrate from polluted waters. Surface activity of the prepared materials for the removal of nitrate was examined by ion chromatography. The results indicated that the prepared zero-valent copper has a hexagonal shape and is well crystallized with a specific surface area of 23 m2/g. High reactivity of products towards nitrate (>90% after 30 min) clearly demonstrated the efficiency of this novel, fast, facile, and green method for the synthesis of pure-phase copper zero-valent materials for environmental remediation.publishe

Morpholin-4-ium 4-meth­oxy­benzoate 4-meth­oxy­benzoic acid monohydrate

In the crystal structure of the title compound, C4H10NO+·C8H7O3 −·C8H8O3·H2O, cations, anions and neutral mol­ecules are linked by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds into chains running parallel to the c axis. The –CO2 groups make dihedral angles of 4.6 (3) and 5.7 (4)° with the attached ring in the 4-methoxybenzoic acid molecule and the 4-methoxybenzoate anion, respectively

Bis(nitrato-κO)[(S)-2-(pyrrolidin-2-yl)-1H-benzimidazole]cadmium(II)

The title compound, [Cd(NO3)2(C11H13N3)2], was synthesized by hydro­thermal reaction of Cd(NO3)2 and S-2-(pyrrolidin-2-yl)-1H-1,3-benzimidazole. The Cd atom lies on an inversion centre. The distorted octa­hedral Cd environment contains two planar trans-related N,N-chelating S-2-(pyrrolidin-2-yl)-1H-1,3-benzimidazole ligands in one plane and two monodentate nitrate ligands. N—H⋯O hydrogen bonds involving a nitrate O atom build up an infinite chain parallel to the a axis

2-(2-Pyrrolidinio)-1H-benzimidazol-3-ium dinitrate

In the title compound, C11H15N3 2+·2NO3 −, one of the imidazole N atoms and the N atom of the pyrrolidine ring are protonated. The pyrrolidine ring adopts an envelope conformation, with the C atom carrying the benzoimidazolium substituent as the flap atom. In the crystal structure, cations and anions are linked through N—H⋯O hydrogen bonds, forming chains that run parallel to the c axis

Dibromido[(S)-2-(pyrrolidin-2-yl)-1H-benzimidazole]zinc(II)

The title compound, [ZnBr2(C11H13N3)], was synthesized by hydro­thermal reaction of ZnBr2 and (S)-2-(pyrrolidin-2-yl)-1H-benzimidazole. The ZnII atom has a distorted tetra­hedral geometry and is coordinated by two N atoms from the chelating organic ligand and two terminal Br− anions. In the crystal structure, mol­ecules are linked into a chain along the [101] direction by N—H⋯Br and C—H⋯Br hydrogen bonds

(S)-2-(2-Pyrrolidinio)-1H-benzimidazol-3-ium dichloride monohydrate

In the title compound, C11H15N3 2+·2Cl−·H2O, one N atom of the imidazole ring and the N atom of the pyrrolidine ring are protonated. The crystal structure is stabilized by aromatic π–π inter­actions between the benzene rings of neighbouring benzimidazole systems [centroid–centroid duistance = 3.712 (2) Å]. The crystal structure is further stabilized by inter­molecular N—H⋯Cl, O—H⋯Cl and N—H⋯O hydrogen bonds

Sustainability of treatment technologies for industrial biowastes effluents

Despite the huge efforts to develop efficient technologies for the treatment of recalcitrant biowastes and other emerging pollutants, selecting the most sustainable method among the possible alternatives is still a formidable task. This is mainly because of the integration of technical, economic, environmental, and social criteria in decision-making process. Traditionally, various multi-criteria decision-making approaches have been adopted to integrate innumerable criteria for environmental applications. In this study, we have examined the fuzzy-Delphi approach to evaluate seventeen parameters for integrating technical, economic, environmental and social criteria in order to rank the nine treatment technologies divided in two categories (physico-chemical and biological processes). The results of this study indicated that although efficiency of treatment methods is the most important criterion, but contribution of other sustainability criteria should also be considered because they are of high importance for the selection of sustainable wastewater treatment methods. As per our proposed framework on membrane technologies (among the many other physico-chemical methods) and anaerobic sludge blanket technology (among the biological treatment methods) are the most promising approaches for the treatment of highly polluted emerging industrial pollutants. The findings of this study are fully supported by the consensus achieved by a group of fifty experts from nineteen different countries. Opportunities for the improvement of the methods as per data generated are discussed.publishe

4-Butyl­anilinium perchlorate

In the crystal structure of the title salt, C10H16N+·ClO4 −, the 4-butyl­anilinium cation is mirror symmetric, the butyl C atoms and anilinium N atom and 1,4-position C atoms of the benzene ring being located on the mirror plane; the perchlorate anion is also mirror symmetric, with two O atoms and one Cl atom lying on the mirror plane. Trifurcated N—H⋯O hydrogen bonding is observed between the cation and anion in the crystal structure