Search

This study reports on the use of soluble biobased organic substances (SBO) with emulsifying properties in the production of oil-in-water emulsions for industrial consumption. One of the potentially interesting applications is in formulation of metalworking fluids, which typically consist of oil-in-water emulsions used in metal manufacturing industries. Soluble biobased substances were collected from urban food and gardening wastes in a waste management plant located in a densely populated area in North Italy. The biowastes were fermented under anaerobic and/or aerobic conditions and then treated chemically to yield four different SBO samples, which were characterized for chemical composition, solution behavior by water surface tension measurements, and ability to form stable 10% oil-in-water (O/W) emulsions. Experiments were carried out to evaluate the hydrophilic–lipophilic balance of emulsions with surfactant concentrations in the 2–8% (w/w) range. Stable emulsions were obtained with at least 3% (w/w) s...

As previous work proposed commercial expectations for soluble bio-organic substances (SBO) isolated from compost of urban food, gardening and park trimming residues as chemical auxiliaries, nine urban bio-wastes (BW) treated by aerobic and anaerobic digestion for 0-360 days were used to extract SBO and investigate source variability effects on product chemical composition and properties. The bio-wastes were collected over a 13732 km(2) area populated by 2.9 millions from 565 municipalities. The SBO were characterized by their content of different C types and functional groups and by their distribution coefficient (K(PEGW)) between polyethylene glycol and water. A significant linear correlation was found between KPEGW and the lipophilic/hydrophilic C ratio. The investigated SBO exhibited up to sixfold change of K(PEGW) demonstrating that BW available from densely populated urban areas are an interesting exploitable source of a wide variety of potential products for the chemical market. (C) 2010 Elsevier Ltd. All rights reserved.

In this paper, the effect of β-cyclodextrin as an additive in the dyeing of polyester with disperse dyes, as a substitute for a commercial surfactant commonly used, was explored with the aim of reducing the environmental impact of the exhausted baths. Using a chemometric approach, a small group of dyes was selected as a ‘training set’ to be representative of a larger series of dyes with a similar structure. The selected dyes were synthesised and applied to the dyeing of polyester fibres under various conditions. The technological properties of the dyed samples were measured. The results showed that β-cyclodextrin can satisfactorarily be used as an additive in dyebaths for polyester without the addition of other auxiliaries, with a positive environmental impact. Solubility isotherms evidenced dye–β-cyclodextrin interactions. The formation of inclusion complexes did not produce negative effects on the dyeing performance. Light fastness values were modelled as a function of the structure by the chemometric partial least squares method and the established model was used to predict the fastness of dyes of analogous structure, not yet explored.

Raman spectroscopy has been successfully employed in order to investigate the formation of β-cyclodextrin host–guest inclusion molecular complexes with several different azo-dye structures. The Raman pattern of the carbohydrate framework results negligible when neared to the magnificent intensity of the highly polarisable guest systems and a complete and feasible comparison of the spectral features between the free and the complexed situation of the guest molecule is allowed. In general, with respect to the free guest state, it was found within the complex that a hampering of Raman intensity displays, accompanied by a levelling directed variation of the relative peak intensities, and peculiar Raman peak broadening with shifts occur, relatable to the host–guest settling of inclusive intermolecular interactions. Supportively to the other commonly established characterising methods, or in valid alternative, Raman technique has proved astoundingly useful under the perspective of the diagnostic evaluation of cyclodextrin host–guest molecular inclusion for azo-dyes and, more generally, for a highly polarisable guest structure. It features sample non-destructivity, handiness, fastness and sensitive reproducibility, occasionally providing useful suggestions about the complexation topology.

A compost isolated humic acid-like (cHAL) material was pointed out in previous work for its potential as auxiliary in chemical technology. Its potential is based on its relatively low 0.4gL(-1) critical micellar concentration (cmc) in water, which enables cHAL to enhance the water solubility of hydrophobic substances, like phenanthrene, when used at higher concentrations than 0.4gL(-1). This material could be obtained from a 1:1 v/v mixture of municipal solid and lignocellulosic wastes composted for 15 days. The compost, containing 69.3% volatile solids, 39.6% total organic C and 21C/N ratio, was extracted for 24h at 65 degrees C under N2 with aqueous 0.1molL(-1) NaOH and 0.1molL(-1) Na4P2O7, and the solution was acidified to separate the precipitated cHAL in 12% yield from soluble carbohydrates and other humic and non-humic substances. In this work two typical applications of surfactants, i.e., textile dyeing (TD) and soil remediation by washing (SW), were chosen as grounds for testing the performance of the cHAL biosurfactant against the one of sodium dodecylsulfate (SDS), which is a well established commercial synthetic surfactant. The TD trials were carried out with nylon 6 microfiber and a water insoluble dye, while the SW tests were performed with two soils contaminated by polycyclic aromatic hydrocarbons (PAH) for several decades. Performances were rated in the TD experiments based on the fabric colour intensity (DeltaE) and uniformity (sigmaDeltaE), and in the SW experiments based on the total hydrocarbons concentration (CWPAH) and on the residual surfactant (Cre) concentrations in the washing solution equilibrated with the contaminated soils. The results show that both cHAL and SDS exhibit enhanced performance when applied above their cmc values. However, while in the TD case a significant performance effect was observed at the surfactants cmc value, in the SW case the required surfactants concentration values were equivalent to 25-125xcmc for cHAL and to 4-22xcmc for SDS. The vis-a-vis comparison of the two surfactants gave the following results: in the TD case the cHAL biosurfactant at 0.4gL(-1) yields good colour intensity and equal colour uniformity as SDS at 5gL(-1), in the SW case cHAL was found to enhance CWPAH by a factor of 2-4 relative to SDS with one soil, whereas with the other soil the two surfactants behaved similarly. The Cre data, however, showed that both soils absorbed by far more SDS (68-95%) than cHAL (12-54%). The results point out intriguing technological and environmental perspectives deriving from the use of compost isolated biosurfactants in the place of synthetic surfactants.

A selected series of 2-(4-methylpyridin-2-yl)-1H-benzimidazole derivatives, bases and cyclic mono- and bis-salts, were synthesized. Complete '1H nmr characterization is reported. Ambiguous assignments were solved using 1H-1H NOESY analysis. Significant ir and 1H nmr data are presented concerning: i) tautomeric equilibrium of imidazole hydrogen; ii) hydrogen bonds; iii) conformational inversion of partially saturated rings.

A series of azo disperse dyes with variable hydrophobic chain length and hydrophilic (hydroxy or glucosyl group) head were synthesised. 1 H and 13 C NMR spectra indicated that the glucosyl moiety was linked to the azo structure with a β anomeric bond. The dyeing properties on polyamide fibres were assessed with dyeing isotherms and Linitest experiments. The positive effects of additives, as ternary systems (SDS, Brij 35 and octanol) or cyclodextrins, on the dyeing uniformity were shown by tristimulus colorimetry.

Novel azobenzene dyes containing a glucopyranoside moiety were applied to polyethylene terephtalate and cellulose diacetate fibres. Isothermal rate-of-dyeing curves at different temperatures, calculations of the apparent activation energies, light and dry heating colourfastness are reported for polyester. For the cellulose diacetate fibres, bath exhaustions at equilibrium are considered. The data suggest that while the hydrophilic β- d -glucopyranose ring decreases toxicity, it also reduces the substantivity towards hydrophobic fibres. The analogue with an acetylated β- d -glucopyranose ring has dyeing properties comparable to traditional disperse dyes, and, in effluent treatment, is easily converted by hydrolysis of acetate groups to a non-toxic dye.

The voltammetric properties, measured at a dropping mercury electrode, have been studied for a series of 18 pyridyl-substituted heterocyclic bases [benzimidazoles, benzoxazoles and benzothiazoles]. The corresponding quarternary salts, obtained by reaction with methyl iodide, were also studied. The reduction potential was found to be dependent on the nature of the benzimidazole, benzoxazole or benzothiazole moiety and on its position on the pyridine ring as well as on the presence of a positive charge. The reversibility of the voltammetric waves was found to be function of the system structure. The effects of proton donors on the voltammetric behaviour of the bases was also investigated.

Determinations of the adsorption at both solid-liquid and water-air interfaces of 1-alkyl-4-methylpyridinium salts have been performed. At the water-air interface, measurements of the surface tension as a function of the bulk concentration of 1-dodecyl-4-methylpyridinium chloride were performed. Mathematical treatment of the resulting isotherm allowed the size of the adsorbed molecule and the CMC to be obtained. The solid adsorbent was a titanium dioxide sample prepared in the laborato Adsorption isotherms of 1-dodecyl-4-methylpyridinium chloride and 1-butyl-4-methylpyridinium chloride were obtained at the same pH and ionic strength. For the shorter-chain surfactant, a second isotherm at a higher base electrolyte concentration was obtained. The experimental isotherms are discussed in the light of literature results and analyzed on the basis of the Frumkin-Fowler-Guggenheim adsorption equation. X-ray photoelectron spectroscopic analyses were performed both on the bare adsorbent and in the presence of the adsorbates. The binding energy of the surfactant elements (both nitrogen and carbon) was observed to undergo significant modifications when the compound was in the adsorbed state. The features of the adsorption of the two organic ions are discussed in light of the different experimental results.

Fifteen new difluorinated phosphonic and sulfophosphonic acids have been synthesized and characterized by 1H, 13C, 31P and 19F n.m.r. spectroscopy. The results are discussed in relation to previous work on monofluorinated acids.

Microemulsions, or their precursors, are proposed for improving the quality of dyed fabrics. The investigated substrates are polyamide (nylon 6 and 6.6) polyester, and a secondary cellulose acetate-nylon 6 blend. Besides conventional fibers, also nylon 6 and polyester microfibers are studied. It has been possible to ascertain that suitable organized systems allowed to obtain a better uniformity of coloration without depressing dyebaths exhaustion. Furthermore, in some cases, satisfactory results have been obtained at halved liquor ratios with consequent energy saving during the tinctorial cycles.

Tast polarography, differential pulse polarography and cyclic voltammetry were applied to the examination of 7 derivatives of 3-carboxy-4-hydroxy-6-acetylaminoazobenzene with H, CH3, OCH3, Cl, COCH3, NO2 and NHCOCH3 substituents in position 4'. A general reduction mechanism was suggested for the substances. The half-wave potentials obtained from tast polarographic measurements were correlated with the Hammett σ constants of the substituents in the para-position. The plot of this dependence is linear, which suggests that the reduction mechanism is identical within the entire series. The optimum conditions for quantitation of the substances were found within the concentration regions of 1 .10-4 to 1 .10-6 mol l-1 for tast polarography and 1 .10-4 to 1 .10-7 mol l-1 for differential pulse polarography.

A chemometric strategy tor the design of acid dyes for silk is reported. A small set of representative dyes was selected by the technique of fractional factorial design, using the principal properties of the substituents as design variables. The selected dyes were synthesised and fastness properties on silk were measured. Wash fastness and light fastness values were related to the chemical structure by the partial least squares (PLS) method. The models were used to predict the fastness of new dyes of the same class and to optimise the structure.

The absorption and fluorescence characteristics of 2(4-aminophenyl)pyrido[3,2-d]oxazole (1), of its thiazole 2 and imidazole 3 analogues, as well as of the corresponding pyrido[3,4-d]imidazole 4 have been examined. S 1 is a planar ππ * ICT state, similarly to p-electron-withdrawing substituted anilines. In the protonated form, the chromophore is the heterocyclic moiety. With compounds 3 and 4 in alcohols, hydrogen bonding depending on proton donating and accepting properties of the medium determines the fluorescence. In this case, a red-shifted emission attributed to a twisted TICT state is also observed

Acid soluble biopolymeric substances (SBP) were isolated from different urban biowastes comprised of a range of materials available from metropolitan areas. These biowastes provided products with a chemical nature and solubility properties changing over a wide range and, thus, allowed to assess the effect of the variability of the chemical nature on molecular conformation and surface activity in water solution. For this scope, the SBP were characterized for chemical composition and molecular weight (MW) by microanalysis, potentiometric titration, 13 C NMR spectroscopy, and size exclusion chromatography (SEC) coupled with an online multiangle light scattering (MALS) detector. These materials were found to have 67―463 kg mol 1 MW and 6―53 polydispersity index and to contain carboxylic acid and phenol groups bonded to aromatic and aliphatic C chains. An empirical parameter (LH) was calculated for use as an index of the lipophilic/hydrophilic C atoms ratio. The products solubility properties in solvents of different polarity, surface activity, power to enhance the water solubility of hydrophobic compounds, and particle size in water solution were also investigated by measurements of the products partition coefficient between polyethylene glycol and water (K PEGW ) and of air—water surface tension (γ), water—hexane interfacial tension (IFT), disperse red orange dye solubility (DS), and dynamic light scattering (DLS) versus added SBP concentration (Cs). The results indicate that LH correlates well with K PEGW and with the products surface activity properties. Both γ and DS are shown to depend on Cs, although in opposite ways, that is, higher Cs values yield lower γ and higher DS values. Both DS—Cs and γ―Cs plots showed a significant slope change at approximately the same 1.8―2.5 g L ―1 Cs value. This suggested a change of molecular conformation taking place at the above Cs values. Hydrodynamic diameter values for SBP in solution at Cs ≤ 10 g L ―1 were found to range from 130 to 300 nm, consistent with their macromolecular nature. The DLS coupled to the γ data were consistent with molecules at the water—air interphase and in the bulk water phase having different conformations, but not significantly different molecular sizes. Molecular aggregates more likely form at 50—100 g L ' Cs. The results confirm that urban biowastes are a sustainable source of biobased products that may have real commercial perspectives.

Heterocyclic azodyes of the pyridylazonaphthol and pyridylazoresorcinol series containing tuned hydrophobic chains have been prepared. Due to their chelating properties, the dyes are suitable candidates for preconcentration and selective separation of transition metal ions. After a discussion on the choice of the best synthetic pathway, physical and spectral uv/visible properties are presented and correlated with the structural features. A detailed analysis of nmr spectra allowed the clarification of currently unresolved signal assignments.

To promote biobased products for industry, six biosurfactants (BS) isolated from green and food urban residues aged under aerobic digestion for 0–60 days were investigated for their chemical composition, surface activity properties and detergent performance in fabric washing in comparison with commercial anionic and nonionic surfactants (CS). The BS exhibited a range of chemical composition and surface activity properties presumably related to their different biomass sources. Surface tension data for these substances correlated meaningfully with performance data in fabric washing. It was found that BS have similar performances as CS when used neat, but the 1:1 w/w BS–CS mixes are characterized by significant synergy. High sensitivity to water hardness and fabric yellowing were found to be the main deficiencies for the BS. However, both effects are minimized or are not critically evident when the BS are used together with CS and/or in common detergents formulations. The results indicate that when used above critical micellar concentration, no significant or critical performance differences are evident within the whole group of BS or between BS and CS. These facts encourage expectations for industrial production and real commercialization of BS as components of detergents formulations.

Acid polymers, −[N=P(OC6H5)2−x(OC6H4SO3H)x]n (II), having an entirely inorganic chain of fifth-group elements, with acid equivalent values between 2.90 and 5.19 mEq/g and molecular weights (Mw) of 105−106 (205≤n≤3582), have been obtained from −[N=P(OC6H5)2]−n (I), 4325≤n ≤ 20,300, in very strong acid medium (SO3/−P=N −=1.15−3.10 mol/mol). Sulfonation of the pendant substituents occurs first in the meta position and successively at the para carbons, presumably due to reduced conformational mobility as the degree of substitution (x) in II increases.

Nitro derivatives and amines containing X-azolo[4,5-c]pyridine moieties were prepared choosing more favourable synthetic pathways. Their physical and spectroscopic data were discussed in correlation with those of previously studied systems. The heteroaromatic amines were shown to be suitable precursors for the synthesis of disperse dyes and of their cationic counterparts.

Marengo, E., Carpignano, R., Savarino, P. and Viscardi, G., 1992. Comparative study of different structural descriptors and variable selection approaches using partial least squares in quantitative structure-activity relationships. Chemometrics and Intelligent Laboratory Systems , 14: 225–233. A technical property, namely fastness to light, of a series of mono-azo dyes is modelled by the partial least squares (PLS) method, using different kinds of structure descriptors: molecular descriptors calculated on the basis of partial equalization of orbital electronegativities, 13 C NMR and 1 H NMR experimental data, and tabulated substituent physico-chemical parameters. Two variable selection approaches in PLS are compared with traditional PLS: a backward variable elimination and a stepwise selection procedure, respectively. For this set of compounds, the best descriptors appear to be the experimental NMR data and the calculated molecular descriptors. The last ones are advantageous since previous synthesis of the compounds is not needed to obtain the value of the descriptors in order to apply the statistical model for prediction purposes. As far as the statistical approach is concerned, both the stepwise and the backward refinements appear to improve the predictive ability of PLS.

To promote biobased products for the industry, six biosurfactants isolated from green and food urban residues aged under aerobic digestion for 0-60 days were investigated for their potential to perform as auxiliaries for dyeing cellulose acetate fabric with water-insoluble dyes. The experimental plan included investigation of the chemical nature, surface activity, and power to enhance dye solubility in water, as well as dyeing test performed under a variety of experimental conditions presenting a range of challenge levels. For comparison, the same investigation was performed on commercial synthetic surfactants. The investigated biosurfactants exhibited chemical composition and surface activity properties presumably related to their different biomass sources. However, no significant performance differences in textile dyeing were evident among the biosurfactants and between biosurfactants and synthetic surfactants. The results encourage product and process development for exploitation of biomass residues as a source of chemicals to recycle to the industry.

From waste came forth surfactants: Humic acid like substances isolated from 0-60 day-old compost display excellent surface activity and solvent properties. These biosurfactants were used to solubilize a dye in water below and above their critical micellar concentration. The biosurfactant unimers appear to have higher dye-solubilizing power than the corresponding micelles.Humic acid like substances isolated from compost show potential as chemical auxiliaries. In the present study, three surfactant samples were obtained from green waste composted for 0-60 days to assess aging effects of the source on the properties of the products. The surface activity, dye solubility enhancement, and chemical nature of these substances were compared. No differences in performance were established among the samples. They lower water surface tension and enhance the dye solubility upon increasing their concentration. However, the ratio of soluble dye to added surfactant is higher in the premicellar than in the postmicellar concentration region. Structural investigations indicated the humic acid like substances to be amphiphiles with molecular weights in the range of 1-3 x 10(5) g mol(-1). The surfactant samples were also compared to sodium dodecylbenzenesulfonate, polyacrylic acid, and soil and water humic substances. The results encourage the application of compost as a source of low-cost biosurfactant.

Enthalpies of dilution at 25° C of potassium 4-((hexylcarbonyl)amino)-2-hydroxybenzoate (KPAS-C 7 ) have been measured as a function of the pH and of the ionic strength using an LKB 2107 flow microcalorimeter. From the experimental data, apparent and partial molar relative enthalpies as a function of the molality of the surfactant have been derived. Enthalpic properties are strongly dependent on the pH, probably because the dissociation of the salicylic OH affects the hydrophilic-lipophilic balance of the molecule. Around a surfactant concentration of 0.13 mol kg −1 , the plot of apparent and partial molar enthalpies of the solutions in KOH (0.02 mol kg −1 ) shows an abrupt change in slope: this is attributed to a transition in the micelle structure. The presence of maxima in the partial molar enthalpy versus molality curves at the highest KOH concentrations could confirm this hypothesis. An increase in the ionic strength in the KOH solutions (0.02 mol kg −1 ) causes the transition to shift to a lower concentration, without a strong effect on the overall trend of the enthalpic curves. The thermodynamic functions of micellisation have been evaluated on the basis of the pseudo-phase-transition model by graphical extrapolation: in the limits of experimental error, they vary almost linearly with pH.

Densities, heat capacities and enthalpies of dilution at 25°C and osmotic coefficients at 37°C were measured for N-octyl- and N-dodecylnicotinamide chlorides in water over an extended concentration region. Partial molar volumes, heat capacities, relative enthalpies and nonideal free energies and entropies at 25°C were derived as a function of the surfactant concentration. For both surfactants, plots of volumes, enthalpies and free energies vs. concentration are regular whereas those of heat capacities and entropies present anomalies at about 0.8 and 0.1m for the octyl and dodecyl compounds, respectively. Changes in the slope of a plot of osmotic coefficients times molality vs. molality were also observed at these same concentrations. These peculiarities are ascribed to micelle structural transitions. The nonideal free energies do not seem to depend on the alkyl chain length when they are plotted vs. m/Ccmc. Also, a plot of the nonideal free energy vs. logm/Ccmc is roughly independent of the nature of the surfactant because of the constant activity of surfactants in micellar solutions. Nonideal free energies, enthalpies and entropies have been calculated at 15 and 35°C. At each concentration the nonideal free energy is temperature independent as a result of a compensatory effect between enthalpy and entropy. The thermodynamic functions of micellization were graphically evaluated on the basis of the pseudo-phase transition model. These data suggest that the nicotinamide group possesses less hydrophilic character than the ammonium group.

Starting from 2-methyl-6-alkylamidoquinolines containing alkyl chains in the range C 1 –C 15 , a series of styryl and symmetrical polymethine dyes was synthesized. Besides the characterization and a short discussion on physical and spectroscopic constants of dyes and of their intermediates, attention has been focussed on the aggregation of dyes in solution and on their interaction with amphiphilic systems. The dyes in water showed a marked tendency to form aggregates (even in the presence of fairly short alkyl chains) and the addition of anionic, cationic and nonionic surfactants (below, at and above their c.m.c.) did not afford satisfactory deaggregation. Preliminary, encouraging results were attained by resorting to oil-in-water microemulsions.

The osmotic coefficients of N-nonyl and N-decyl nicotinamide chlorides, synthesized in our laboratory, have been determined by means of a OSMOMAT vapor pressure osometer. In the precision limits of the method used, they agree as a trend with those previously measured for octyl and dodecyl compounds. If interpreted by means of a pseudo-phase transition model, they could suggest the presence of a phase transition involving a change in the number of particles present in solution, as was already supposed in the case of octyl and dodecyl compounds from measurements of heat capacities vs concentration. — The experimental trends can be fitted by using different theoretical approaches, allowing for the determination of the ionic interaction parameters. — The determination of osmotic coefficients allows the evaluation of the excess free energies of the surfactant solutions and of the entropic contributions once the enthalpic ones are known. Analyzing the behavior of the excess free energies for the homologous series of alkyl-nicotinamide surfactants, a group contribution for each −CH2 group of −2.9 kJ mol−1 can be evaluated in the postmicellar region.

BACKGROUND: In the context of the modern concern regarding rapid consumption and low availability of fossil sources of energy and chemicals, urban and agro-industrial sources of chemicals represent interesting environmentally friendly alternatives. A recent paper has shown that a humic acid-like material extracted from urban and green wastes compost exhibits very good surfactant properties. A large number of technological applications could possibly use this material as a chemical auxiliary. This paper reports on the performance of the material as a chemical auxiliary in textile dyeing. RESULTS: The compost-isolated humic acid-like bio-surfactant is shown to perform in nylon 6 microfiber dyeing by water soluble and insoluble dyes as well as and more conveniently than commercial sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS). With both types of dye the bio-surfactant allows the same quality of dyed product as the synthetic surfactants do, but at lower additive concentration. From process cost and environmental impact points of view, the bio-surfactant has the advantages of operating at much lower additive concentrations and should be available at significantly lower cost than the synthetic surfactants. CONCLUSION: The results suggest that biomass wastes may be a low cost renewable source of chemicals with friendly environmental impact. Such a perspective implies economic and environmental benefits deriving from a new waste management technology that considers biomass waste as a source of chemicals, and from lower oil consumption in the manufacture of synthetic surfactants. Copyright © 2007 Society of Chemical Industry

A disperse and a disperse/reactive azo-dyes were prepared and characterised with spectroscopic methods. The complexes with β-cyclodextrin were prepared by a dry milling method. The characterisation of the complexes in solid state was performed by 13C CP MAS NMR, FT-IR, Raman spectroscopies and TGA–DTA analysis. The presence of the complexes in solution was evidenced with ESI-MS experiments. The products were used to dye synthetic (nylon, PET), natural (cotton) and cotton-PET blend fibres. Colour intensity and uniformity were evaluated by means of tristimulous colorimetry. β-Cyclodextrin, used as additive in dyeing baths, enhanced the colour intensity and uniformity of dyed samples. The complexes gave rise to a generalised good result. The disperse/reactive dye showed better fastness to washing properties on nylon 6 and cotton fibres. β-Cyclodextrin easily substituted the surface active agents, normally used in industrially dyeing processes, without loss in dyeing quality as dyeing uniformity, intensity and washing fastness.

A series of 12 dyes were synthesised and used for the dyeing of nylon 6 and 6,6. β-Cyclodextrin was tested as a low environmental impact additive in dyeing processes. Interactions between dyes and β-cyclodextrin were studied by means of solubility isotherms, TGA and DTA analysis. β-Cyclodextrin showed good levelling properties in the dyeing of polyamide fibres. The observed effect can be due to the formation of complexes between β-cyclodextrin and dyes.

The insoluble organic fraction (humin-like material, HLM) from rice hull–dairy cattle compost is well converted into water soluble HLM-sulphonate by reaction in liquid SO 3 . Microanalytical, potentiometric, molecular weight, and NMR data are consistent with a highly homogeneous polymeric arylsulphonate having 4000 Da MW, 1.3 sulphonic groups per aromatic ring and significant content of carboxylic and phenolic groups. By comparison with structure–property relationships for commercial lignosulphonates derived from the pulp and paper industry, the above arylsulphonate is likely to be a candidate at a variety of applications in the chemical industry and in agriculture. Therefore, sulphonation is a means for upgrading composts HLM to the same uses as for commercial lignosulphonates.

The photocatalytic degradation of the anthraquinonic dye Acid Blue 80 in aqueous solutions containing TiO2 dispersions has been investigated. The process has been monitored by following either the disappearance of the dye (via HPLC) and the formation of its end-products (via IC, GC, and TOC analysis). Although a relatively fast decolorization of the solutions has been observed, the mineralization is slower, and the presence of residual organic compounds was evidenced even after long term irradiation, confirming the relevant stability of anthraquinone derivatives. The identification of various unstable intermedi ates formed after low irradiation times was performed by HPLC-MS, allowing us to give insight into the early steps of the degradation process which mainly involve C−N bonds breaking and substrate hydroxylation. Complete and relatively fast mineralization of the substrate was achieved by irradiating the semiconductor dispersions in the presence of added K2S2O8.

A series of surfactants with tuned polarity were prepared, including a new class of compounds: gluco-pyridinium surfactants. Pure anomers were obtained by chromatographic separation. The conductivity and surface tension of surfactant solutions in water were measured, and provided interesting information regarding their aggregation behavior. Peculiarities were observed in the premicellar range. Tensidic parameters correlated with antimicrobial activity. A few parameters, mainly the hydrophobicity of the headgroup, may play a role in finding more efficient antimicrobial structures.

A series of surfactants with tuned polarity were prepared, including a new class of compounds: gluco-pyridinium surfactants. Pure anomers were obtained by chromatographic separation. The conductivity and surface tension of surfactant solutions in water were measured, and provided interesting information regarding their aggregation behavior. Peculiarities were observed in the premicellar range. Tensidic parameters correlated with antimicrobial activity. A few parameters, mainly the hydrophobicity of the headgroup, may play a role in finding more efficient antimicrobial structures.

Chelating aggregates consisting of Triton X100 host micelles and hydrophobic derivatives of PAN have been examined as suitable candidates for preconcentration and selective separation of transition metal ions through micellar-enhanced ultrafiltration. The effective accumulation in the surfactant-rich retentate of nickel(II), copper(II), cobalt(II), manganese(II) and zinc(II), present at trace levels in aqueous samples, has been achieved by operating at pH ca. 6 with a ligand having a binding constant to the host micelles higher than 2000 l./mol. The efficient separation of micelle-bound metal chelates from unreactive ions has been assessed, together with the feasibility of selective enrichment and purification of the investigated metal ions present in mixtures through a multistage process.

Microemulsions, or their precursors, are assuming increasing importance in dyeing processes. N,N-diethylaminoazo-benzene was tested, as a model dye, in quantitative studies on the dyeing of secondary cellulose-acetate rayon. The effects of surfactant, cosurfactants with tuned HLB values, and long-chain alcohols on both the spectral behaviour and the partition of the dye between the bath and the substrate, were investigated. Taking advantage from quantitative results, technical dyeing tests were carried out on a substituted azobenzene dye possessing very good fastness properties. The tests evidenced the important role of sonication and of the choice of the suitable cosurfactant. The presence of an oil component promoted excellent dye uptake, uniformity of coloration, saving chemicals and related environmental implications.

A series of bases containing X-azolopyridines (X = O, NH) and methylquinolines, assembled in different ways, was prepared by reaction of methylquinolinecarboxylic acids (or carboxamides) with diamino (or hydroxyamino) pyridines. The bases were quaternized with methyl iodide. The physical and spectroscopic data of both the bases and the salts were correlated and compared with those of [X-azolopyridine][pyridine] systems previously studied. The structure of the salts was markedly influenced by a balance of basicity-hindrance factors in the heteroaromatic substrates.

The synthesis and photophysical characterization of several complexes of Ru(II) containing 4,4′-di(carboxyphenyl)-2,2′-bipyridine (DCPB) and related bipyridine ligands are reported. In all complexes studied the lowest excited state is associated with Ru→DCPB charge transfer (CT) transition. The introduction of phenyl groups between the peripheral carboxyl group and the bipyridine framework caused a red-shifted, more intense absorption but the excited state properties (luminescence and transient absorption) remain nearly the same. The acid-base properties in the ground and excited state are different. With respect to 4,4′-carboxy-2,2′-bipyridine (dcbpy) derivative, the ground state pKa of Ru(DCPB)3 increases by about 2.5 pH units and a further extremely small increase in the pKa is observed upon visible light excitation. The results suggest that the charge density is largely localized in the diimine unit and does not carry through the phenyl group. This could account for inefficient sensitization (⩽8% monochromatic photon-to-current conversion efficiency) obtained on TiO2 electrodes. Possible implication of the present results on the design of photosensitizers is also discussed.

A series of aminophenyl-X-azolopyridines were diazotized and coupled to N,N-diethylaniline. The resulting disperse dyes showed a great versatility towards different fibres such as polyamide polyester and cellulose acetate. The disperse dyes were transformed into cationic dyes by reaction with methyl iodide. The quaternized dyes dyed polyacrylonitrile fibres with excellent uniformity without using a retarding agent. Physical and spectroscopic parameters fastness on dyed fabrics and colour data were correlated with the structure of the dyes. Two-dimensional proton-NMR NOESY experiments were useful for the assessment of particular structures.

N,N-Disubstituted aminoazobenzene dyes containing a 2-pyridyl substituent were prepared and used for the dyeing, as disperse dyes, of polyamide, polyester and cellulose acetate. The dyeings and the fastness tests gave very satisfactory results. Correlations of physico-chemical constants and spectroscopic parameters, as well as of colour parameters of dyed fabrics, with the structure of the present set of dyes and of previous ones were found. A detailed 1H and 13C nuclear magnetic resonance (NMR) analysis of dyes, including correlation techniques, was performed.

Voltammetric reduction on a hanging mercury electrode in aprotic and anhydrous medium was performed for a series of azobenzene dyes. The effects of substituent s on both the aromatic rings and the N,N-diethylamino chain have been investigated, thus yielding correlations of reduction potentials with absorption maxima of dyes and their 13 C nuclear magnetic resonance (NMR) chemical shifts.

A series of heterocyclic coupling agents having tuned hydrophobic chains, has been prepared by reaction of diamino or hydroxy-aminopyridines and p-aminosalicylic acid. The acetylation of amino group and hydroxyl in oxazole derivatives showed a selectivity depending on wheter acetic anhydride or acetyl chloride was used. Correlations between structure and spectroscopic data, including related compounds previously described, are reported.

The 1H NMR spectra of a series of disperse monoazo dyes in solution are reported and analysed in terms of electronic effects of the substituents, rotational isomerism and hydrogen bonding.