EDA Interaction Research Articles

Microwave-assisted preparation of nitrogen-doped biochars by ammonium acetate activation for adsorption of acid red 18

Abstract Nitrogen-doped biochars derived from Phragmites australis (PA) were prepared using ammonium chloride (AC) and ammonium acetate (AA) as nitrogen sources by phosphoric acid activation via microwave assisted treatment. Their physicochemical properties, acid red 18 (AR18) adsorption performance and possible mechanisms were systematically evaluated. Nitrogen was successfully doped onto the biochar’s surface in the formation of pyrrole-N, pyridine-N and oxidized-N with pyridine-N being the major component (64%). The pH iep and basic foundational groups of the biochars increased consequently however their surface areas slightly decreased. The adsorption kinetic data were best fit to the pseudo-second order model and the equilibrium data were well simulated by Freundlich model for all biochars, indicating the important role of chemical interactions. The maximum AR18 adsorption capacities of PAB-AA and PAB-AC were 1.41 and 1.18 times higher compared with the non N-doped biochar, which were mainly attributed to the π-π EDA interaction between the pyridine-N and AR18 as revealed by the comparison of XPS analyses before and after AR18 adsorption. Meanwhile, other mechanisms such as pore filling effect, Lewis acid-base interaction, electrostatic attraction and hydrogen bonding also existed as demonstrated by BET, XPS and FTIR analyses.

Sorption of sulfamethazine to biochars as affected by dissolved organic matters of different origin

Sorption characteristic of sulfamethazine (SMT) to straw biochars pyrolyzed at 300°C (BC300) and 600°C (BC600), and the effect of ubiquitous DOM were investigated. Results showed that physisorption (partition) and weak chemical binding (π-π EDA interaction) dominated the sorption of SMT to BC300 and BC600, respectively. Graphene sheets in biochar played important roles in the sorption of SMT, leading to higher sorption capacity (Kf) on BC600 (1.77mg1−nLng−1) than BC300 (0.11mg1−nLng−1). Sorption amount of SMT to BC300 was not affected by polysaccharide and malic acid, while it was slightly promoted by citric acid, but dramatically increased 1.25 times by methacrylic acid through decreasing solution pH and providing new sorption sites. Humic acid and bovine serum albumin restrained the sorption of SMT to BC600, but enhanced SMT− adsorption to BC300. The chemical nature of DOM, biochar properties and antibiotic species co-determined the impact of DOM on antibiotics adsorption.

Roles of polar groups and aromatic structures of biochar in 1-methyl-3-octylimidazolium chloride ionic liquid adsorption: pH effect and thermodynamics study.

Adsorption mechanisms of 1-methyl-3-octylimidazolium chloride ([OMIM]Cl) on rice straw-derived biochars produced at 400, 500, and 700°C (referred as RB400, RB500, and RB700, respectively) were evaluated. Adsorption affinity followed the order of RB700>RB400>RB500. Electrostatic attraction and hydrogen bond controlled adsorption of [OMIM]Cl on RB400, while π-π EDA interaction between [OMIM]Cl and the aromatic rings of biochar dominated adsorption of RB500 and RB700. With increasing solution pH, -COOH and -OH on biochar became deprotonated. Consequently, [OMIM]Cl binding to these sites changed from hydrogen bond to electrostatic attraction. Adsorption capacity of [OMIM]Cl increased with increasing pH during the adsorption process. Solid concentration induced by -OH of [OMIM]Cl was higher than that of -COOH. Thermodynamics study indicated that adsorption process was spontaneous and endothermic. ∆H 0 values indicated that [OMIM]Cl adsorption on biochars was a physisorption.

From Lignin to Three-Dimensional Interconnected Hierarchically Porous Carbon with High Surface Area for Fast and Superhigh-Efficiency Adsorption of Sulfamethazine

A novel three-dimensional lignin-based interconnected hierarchical porous carbon (3DLHPC) with very high specific surface areas (2784 m2 g–1) and large pore volumes (1.382 cm3 g–1) was prepared using sodium lignin sulfonate as carbon precursor, via confinement carbonization, etching silica-template, and in situ alkali activation, for fast and super highly efficient removal of sulfamethazine (SMZ) antibiotics from water. By batch adsorption experiments test, 3DLHPC showed a strong adsorption affinity for SMZ with the maximum monolayer adsorption capacity of 869.6 mg g–1 at 308 K. Owing to this well-defined 3D interconnected hierarchical porous structure, the adsorption equilibrium could be reached within 30 min at 298 K. The adsorption mechanism might be involved in van der Waals force, π–π EDA interaction, electronic interaction, and hydrophobic interaction, as well as hydrogen bonding interaction. Meanwhile, it was demonstrated that 3DLHPC exhibited excellent regeneration ability, showing the potential p...

Functionalization of Graphene Oxide with 9-aminoanthracene for the Adsorptive Removal of Persistent Aromatic Pollutants from Aqueous Solution.

A novel modified graphene oxide nanocomposite was fabricated via a facial procedure, aiming to removal of the aromatic pollutants from aqueous solution. The graphene oxide (GO) was functionalized with 9-aminoanthracene and produced graphene oxide-9-aminoanthracene (GO-9-AA). FTIR, XRD, TGA, TEM and Raman spectroscopy techniques were used for characterization of the adsorbents. Adsorption of naphthalene (NAP), acenaphthylene (ACN), and phenanthrene (PHN) as a model of polycyclic aromatic hydrocarbons (PAHs) was investigated by GO-9-AA. The adsorbent showed excellent removal efficiency towards PAHs from aqueous solution. Equilibrium data of the adsorption process were successfully fitted with Freundlich model from single solute system, and the maximum adsorption capacities followed the order of NAP > ACN >PHN. The kinetic analysis revealed that the overall adsorption process was fast and successfully fitted with the pseudo-second-order kinetic model. The anthracene ring makes GO-9-AA π-electron rich, thus facilitating π-π EDA interaction between NAP, ACN and PHN with GO-9-AA.

Contribution of hydrophobic effect to the sorption of phenanthrene, 9-phenanthrol and 9, 10-phenanthrenequinone on carbon nanotubes

Polycyclic aromatic hydrocarbons (PAHs), with diverse sources and acute toxicity, are categorized as priority pollutants. Previous studies have stated that the hydrophobic effect controls PAH sorption, but no study has been conducted to quantify the exact contribution of the hydrophobic effect. Considering the well-defined structure of carbon nanotubes and their stable chemical composition in organic solvents, three multi-walled carbon nanotubes (MWCNTs) were selected as a model adsorbent. Phenanthrene (PHE) and its degradation intermediates 9-phenanthrol (PTR) and 9, 10-phenanthrenequinone (PQN) were used as model adsorbates. To quantify the contribution of the hydrophobic effect for these three chemicals, the effect of organic solvent (methanol and hexadecane) was investigated. Adsorption isotherms for PHE, PTR and PQN were well fitted by the Freundlich isotherm model. A positive relationship between adsorption affinities of these three chemicals and specific surface area (SSA) was observed in hexadecane but not in water or methanol. Other factors should be included other than SSA. Adsorption of PQN on MWCNTs with oxygen functional groups was higher than that on pristine MWCNTs due to π-π EDA interactions. The contribution of hydrophobic effect was 50%–85% for PHE, suggesting that hydrophobic effect was the predominant mechanism. This contribution was lower than 30% for PTR/PQN on functionalized MWCNTs. Hydrogen bonds control the adsorption of PTR, and π-π bonding interactions control PQN sorption after screening out the hydrophobic effect in hexadecane. Hydrophobic effect is the control mechanism for nonpolar chemicals, while functional groups of CNTs and solvent types control the adsorption of polar compounds. Extended work on quantifying the relationship between chemical structure and the contribution of the hydrophobic effect will provide a useful technique for PAH fate modeling.

Application of goethite modified biochar for tylosin removal from aqueous solution

Abstract Recent investigations have shown frequent detection of pharmaceuticals in soils and waters posing potential risks to human and ecological health. Here, we report the enhanced removal of tylosin (TYL) from water by a novel goethite biochar (BCF) composite. Characterization by scanning electron microscopy (SEM) images showed good dispersion of goethite nanoparticles on the biochar surface. The coating was constructed by well-crystallized cubic phase goethite nanoparticles as examined by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. To evaluate the feasibility of BCF composite as a potential adsorbent for antibiotic removal, batch sorption experiments were conducted using TYL as the model antibiotic molecule. The results showed that this adsorbent showed rapid and high sorption of TYL. According to the Henry and Freundlich model, the maximum capacities of TYL on BCF were 8132.89 L/kg and 5386.76 (μg/g)/(mg/L) n respectively. Besides, the sorption capacity of TYL on BCF was obviously affected by pH and ionic strength. The sorption mechanisms of TYL on BCF were contributed to hydrophobic, electrostatic, H-bonding, cation exchange and π-π EDA interaction. The present work suggests that BCF composite, owing to their simple preparation procedures, high sorption capacity, low cost, and environmentally benign nature, have great potential as the next-generation adsorbent in the removal of antibiotics and other emerging contaminants.

Adsorption of sulfonamides on reduced graphene oxides as affected by pH and dissolved organic matter

With the significant increase in use and application of graphene and the frequent presence of sulfonamides (SAs) in water environments, their interactions have attracted extensive attention. In this study, adsorption of two selected SAs (sulfapyridine and sulfathiazole) by two reduced graphene oxides (rGO1 and rGO2) was examined as affected by pH and dissolved organic matter (DOM). Adsorption of SAs by rGOs was highly pH-dependent, and adsorption affinity of different SAs species followed the order of SA0 > SA+ > SA−. The contribution of SA0 to the overall adsorption was greater than its species fraction, implying the importance of the neutral species to adsorption. SAs adsorption isotherms at three selected pHs were in the order of pH 5.0 > pH 1.0 > pH 11.0, which was in accordance with the variation of site energy distribution analysis. Hydrophobic interaction, π–π EDA interaction and electrostatic interaction were the main mechanisms responsible for SAs adsorption by rGOs. Three representative natural DOMs including humic acid (HA), bovine serum albumin (BSA), and sodium alginate together with sodium dodecylbenzenesulfonate (SDBS) as a synthetic DOM were used to investigate their effect on SAs adsorption. The inhibition impact of DOM on SAs adsorption was lower for rGOs compared with carbon nanotubes and graphite, which might be attributed to the higher oxygen contents of rGOs. Also, the suppression effect of DOM generally followed an order of SDBS > HA ≥ BSA > alginate, indicating the importance role of DOM compositions. These results should be important for assessing the fate and transport of graphene and antibiotics in the environment.

Preparation and retention mechanism exploration of mesostructured cellular foam silica as stationary phase for high performance liquid chromatography

Siliceous mesostructured cellular foam (MCF) with highly interconnected porous structure, ultralarge pore size and relatively uniform particle size (3–5μm) was prepared to achieve the mixed-mode and efficient separation of intact proteins. And molecular sieving effect for the first time played an important role in protein separation using mesoporous silica materials as HPLC stationary phase. The spherical silica particles were synthesized via hydrothermal method and the pore size was easily regulated by adding NH4F as well as altering the aging time. After aminopropyl derivatization, the chromatographic performance of functionalized mesoporous silica particles was investigated in comparison with those without modification and commercial NH2 column, and their mixed-mode retention mechanisms were investigated in detail. The superior separation performance for the retention of proteins was obtained on our home-made column in comparison with commercial NH2 column. The influences of aminopropyl derivatization and mobile phase composition on the column property were also investigated. Moreover, the home-made column showed similar performance for separation of polar anilines and neutral PAHs with the commercial column, owing to mixed-mode retention mechanisms including p–π stacking, electron interaction, hydrophobic effect, π–π EDA interaction and hydrogen bonding. All these results indicated that the aminopropyl modified MCF would be promising in the mixed-mode and efficient separation of biomolecules in addition with small molecules.

Water-enhanced Removal of Ciprofloxacin from Water by Porous Graphene Hydrogel.

An environmentally benign and efficient hydrothermal reduction method was applied for the preparation of three-dimensional (3D) porous graphene hydrogel (GH) adsorbents. The physicochemical properties of GH granules were systematically characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectra and Brunauer-Emmett-Teller (BET) method. GH granules showed an excellent adsorption capacity (235.6 mg/g) for ciprofloxacin via combined adsorption interaction mechanisms (e.g. π-π EDA interaction, hydrogen bonding, and hydrophobic interaction). Moreover, reducing the size of the hydrogels can significantly accelerate the adsorption process and enhance the removal efficiency of pollutants from aqueous solution. Water (more than 99 wt%) within hydrogels played a key role in enhancing adsorption performance. The GO hydrogels exhibited an excellent adaptability to environmental factors. These findings demonstrate that GH granules are promising adsorbents for the removal of antibiotic pollutants from aqueous solutions.

A Molecular Electrostatic Potential Analysis of Hydrogen, Halogen, and Dihydrogen Bonds

Hydrogen, halogen, and dihydrogen bonds in weak, medium and strong regimes (<1 to ∼ 60 kcal/mol) have been investigated for several intermolecular donor-acceptor (D-A) complexes at ab initio MP4//MP2 method coupled with atoms-in-molecules and molecular electrostatic potential (MESP) approaches. Electron density ρ at bond critical point correlates well with interaction energy (Enb) for each homogeneous sample of complexes, but its applicability to the entire set of complexes is not satisfactory. Analysis of MESP minimum (V(min)) and MESP at the nuclei (Vn) shows that in all D-A complexes, MESP of A becomes more negative and that of D becomes less negative suggesting donation of electrons from D to A leading to electron donor-acceptor (eDA) interaction between A and D. MESP based parameter ΔΔVn measures donor-acceptor strength of the eDA interactions as it shows a good linear correlation with Enb for all D-A complexes (R(2) = 0.976) except the strongly bound bridged structures. The bridged structures are classified as donor-acceptor-donor complexes. MESP provides a clear evidence for hydrogen, halogen, and dihydrogen bond formation and defines them as eDA interactions in which hydrogen acts as electron acceptor in hydrogen and dihydrogen bonds while halogen acts as electron acceptor in halogen bonds.

Adsorption of roxarsone from aqueous solution by multi-walled carbon nanotubes

Roxarsone, an organoarsenic compound serving as a common feeding additive in poultry industry, brings about potential risk of the toxic inorganic arsenate contamination in ambient environment. Current understanding in the dynamics of roxarsone removal and the determining environmental processes remains unclear, thus restricts the progress in roxarsone-contaminated wastewater treatment. In this study, the adsorption of roxarsone on multi-walled carbon nanotubes (MWCNTs) was investigated. The adsorption of roxarsone on MWCNTs decreased dramatically with increasing pH from 2.0 to 11.7 and decreased significantly with increasing ionic strength from 0 to 1.0mol/L KCl. It was found that the sorption isotherms of roxarsone on MWCNTs were nonlinear, which can be well described according to the Freundlich and Polanyi–Manes models. Thermodynamic analysis indicates that the adsorption of roxarsone on MWCNTs is an exothermic and spontaneous process. Sorption site energy analysis reveals a distribution of sorption energy and the heterogeneous adsorption sites of roxarsone on MWCNTs. The dynamic adsorption with column shows the potential of the practical application for the roxarsone-contaminated wastewater treatment by MWCNTs. The FTIR analysis indicates that EDA interaction and electrostatic repulsion might be the dominant mechanisms for the adsorption of roxarsone on MWCNTs.

Speciation of the Ionizable Antibiotic Sulfamethazine on Black Carbon (Biochar)

Adsorption of ionizable compounds by black carbon is poorly characterized. Adsorption of the veterinary antibiotic sulfamethazine (SMT; a.k.a., sulfadimidine; pK(a1) = 2.28, pK(a2) = 7.42) on a charcoal was determined as a function of concentration, pH, inorganic ions, and organic ions and molecules. SMT displayed unconventional adsorption behavior. Despite its hydrophilic nature (log K(ow) = 0.27), the distribution ratio K(d) at pH 5, where SMT(0) prevails, was as high as 10(6) L kg(-1), up to 10(4) times greater than literature reported K(oc). The K(d) decreases at high and low pH but not commensurate with the decline in K(ow) of the ionized forms. At pH 1, where SMT(+) is predominant and the surface is positive, a major driving force is π-π electron donor-acceptor interaction of the protonated aniline ring with the π-electron rich graphene surface, referred to as π(+)-π EDA, rather than ordinary electrostatic cation exchange. In the alkaline region, where SMT(-) prevails and the surface is negative, adsorption is accompanied by near-stoichiometric proton exchange with water, leading to the release of OH(-) and formation of an exceptionally strong H-bond between SMT(0) and a surface carboxylate or phenolate, classified as a negative charge-assisted H-bond, (-)CAHB. At pH 5, SMT(0) adsorption is accompanied by partial proton release and is competitive with trimethylphenylammonium ion, signifying contributions from SMT(+) and/or the zwitterion, SMT(±), which take advantage of π(+)-π EDA interaction and Coulombic attraction to deprotonated surface groups. In essence, both pK(a1) and pK(a2) increase, and SMT(±) is stabilized, in the adsorbed relative to the dissolved state.

Energies of Charge Transfer for the Supramolecular Complexes of [60]- and [70]Fullerenes with a Series of meso-Tetraphenylporphyrins in the Solution State

Supramolecular complexes of [60]- and [70]fullerenes with various meso-tetraphenylporphyrins in toluene solutions have been studied by electronic absorption spectroscopy. Charge transfer (CT) absorption bands are observed in the visible region. Vertical ionization potentials (IDV) of the meso-tetraphenylporphyrins are reported from a study of EDA interaction of these porphyrins with a number of electron acceptors like o-chloranil, p-chloranil, 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) and vitamin K. The dependence of the CT transition energy on the donor ionization potential has been utilized to estimate the vertical electron affinities (EAV) of [60]- and [70]fullerenes in solution. The value of EAV for [60]fullerene is found to be 0.10 eV lower in magnitude than that of [70]fullerene. We have extracted degrees of CT, and oscillator and transition dipole strengths of the fullerenes/meso-tetraphenylporphyrins complexes. The experimental results show that the CT complexes studied here have a neutral character in their ground states. Electronic coupling elements have been determined for fullerene/meso-tetraphenylporphyrin complexes. Values of the solvent reorganization energy indicate that the electron transfer process takes place at a faster rate in the case of [70]fullerene/meso-tetraphenylporphyrin complexes.

Adsorption of Single-Ring Organic Compounds to Wood Charcoals Prepared under Different Thermochemical Conditions

Environmental black carbon (BC) is believed to be an important adsorbent of organic pollutants. In this study, we examined the effects of changes in surface properties and adsorbate structure. A series of apolar compounds (cyclohexane, 1,2-dichlorobenzene, 1,4-xylene, 1,2,3,5-tetramethylbenzene, 1,3,5-triethylbenzene) and a series of polar compounds (o-cresol, 4-nitrotoluene, 2,4-dinitrotoluene, and 2,4,6-trinitrotoluene) were sorbed from aqueous solution to maple wood char prepared under five thermochemical conditions. Two chars were prepared in air at 340 degrees C (C340) and 400 degrees C (C400). A subsample of C400 was treated with H2 in the presence of a supported Pt catalyst at 500 degrees C (C400-H) to remove surface O. Another was treated under N2 at 500 degrees C (C400-N) to serve as a control for C400-H. The reduced C400-H was further oxidized in air at 340 degrees C to reintroduce O (C400-H-A). The five chars vary in O content (26.1, 22.3, 4.2, 20.8, and 18.6 wt %, respectively) but show only minor differences in surface area and pore size distribution on the basis of N2 and CO2 adsorption analysis. These chars provide a basis for rationalizing sorption intensity as a function of sorbate molecular structure and surface chemistry. The following conclusions were drawn. (1) Polar interactions with surface O functional groups are not a significant driving force for adsorption. (2) When isotherms are adjusted for solute hydrophobicity (n-hexdecane-water partition coefficient), sorption intensity of the polar compounds is greater than that of the apolar compounds, possibly because of pi-pi EDA interactions of the polar compounds with the basal plane of the graphene sheets. (3) The largest test compounds show steric exclusion from a portion of the adsorption space available to the other compounds. (4) Removal of O functionality by hydrogenation enhances sorption intensity of polar and apolar compounds, alike by reducing competitive adsorption by water molecules.

Spectrophotometric study of complexation of benzoyl acetone with [60]- and [70]fullerenes and some other electron acceptors

To improve the understanding of the formation of electron donor–acceptor complexes of [60]- and [70]fullerenes, EDA interaction of [60]- and [70]fullerenes and some other electron acceptors with benzoyl acetone were studied in CHCl 3 medium using absorption spectrophotometry. An absorption band due to charge transfer (CT) transition is observed in the visible region. The vertical ionization potential ( I B v ) of the benzoyl acetone was determined from the CT transition energy. Oscillator and transition dipole strengths have also been calculated. Trends in the formation constant for the complexes [60]- and [70]fullerenes with benzoyl acetone were discussed in terms of enthalpies and entropies of formation.

Vertical ionisation potentials of a number of crown ethers from charge transfer bands of their EDA complexes

Vertical ionisation potentials ( I D v) of a number of crown ethers, viz. dibenzo-30-crown-10 (Crown 1), benzo-15-crown-5 (Crown 2), dibenzo-24-crown-8 (Crown 3), dicyclohexano-24-crown-8 (Crown 4) and 4′-nitrobenzo-15-crown-5 (Crown 5) are being reported for the first time from a study of EDA interaction of these crown ethers with a number of electron acceptors like C 60, C 70, o-chloranil, p-chloranil, 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) and pyromellitic diimide (PMD). The study has been carried out in CCl 4 medium by electronic absorption spectroscopy. Charge transfer (CT) absorption bands in the 360–900 nm range have been found in each case (excepting the 60 fullerene–Crown 4 system). The vertical ionisation potentials ( I D v) of all the crown ethers thus determined show a good correlation with those calculated by the semiempirical AM1 method. Of the six acceptors under study the vertical electron affinity of PMD was not found in the literature. This has also been determined from an analysis of the present hν CT data.

OHO hydrogen bond and electrostatic interactions in a complex of pyridine betaine with phenylacetic acid studied by X-ray diffraction, FTIR spectroscopy and PM3, DFT calculations

Crystalline complex of pyridine betaine with phenylacetic acid (PBPHA) has been prepared and characterized by single-crystal X-ray analysis, FTIR spectroscopy, PM3 and DFT calculations. The crystals are monoclinic, space group P21/c, with a=15.902(2), b=6.2866(8), c=16.005(2)Å,β=119.18(1)° and with one complex molecule in the asymmetric unit. The molecule of phenylacetic acid is linked to pyridine betaine by a strong, asymmetric hydrogen bond (O⋯O 2.521(2)Å). A characteristic motif of the crystal packing is a tetrameric unit consisting of two inversion-related molecules of PBPHA. The tetrameric unit is stabilized by EDA interaction between the pyridine and phenyl rings and by C–H⋯O contacts. The FTIR spectrum shows a broad absorption in the 2800–800cm−1 range with a maximum at about 1300cm−1 due to the antisymmetric mode of hydrogen bond and a complex absorption in the carbonyl–carboxylate region. Both PM3 and DFT calculations predict a slightly longer hydrogen bond and different relative orientation of the aromatic rings than those in the crystal.

Conformational study of the higher [n.n]paracylophanes: evaluation as potential hosts for molecular halogens and benzenes

A fundamental study of the conformations of [7.7]-, [8.8]-, [9.9]-, [11.11]- and octamethyl[8.8]-paracyclophanes in the solid state shows that the [odd.odd] members of the series possess parallel, symmetrically disposed benzene rings. A new genre of inclusion phenomenon based on donor–halogen EDA interactions is also defined and the potential of cyclophanes to act as hosts both in this capacity and to benzenes is discussed.

Solvatochromism of anthraquinone and symmetrical dihydroxy derivatives. Local interactions

Abstract The solvent effects on the electronic absorption spectra of 9,10-anthraquinone (AQ) and its symmetric dihydroxy derivatives namely 1,5-dihydroxyanthraquinone (1,5-DHAQ) and 2,6-dihydroxyanthraquinone (2,6-DHAQ) have been studied in pure solvents and some binary solvent mixtures. The frequencies of the absorption for AQ and 2,6-DHAQ are quite solvent sensitive while those for 1,5-DHAQ are not. Due to the intramolecular hydrogen bond between the CO and OH groups, no influence of solvent hydrogen bond acceptors is observed in 1,5-DHAQ. This hydrogen bond gives a stable six member cycle which is not broken even by the strongest hydrogen bond acceptor solvents used in this work, such as DMSO and DMF. The Taft and Kamlet's solvatochromic comparison method was applied for AQ and 2,6-DHAQ. Aromatic solvents and aliphatic amines were not included in the correlations since they strongly deviate suggesting another type of interactions. All the π→π * bands of AQ and 2,6-DHAQ show strong influence of π * despite the fact that their dipole moment is zero. Although it would be reasonable to expect that in the absence of a solute dipole moment there is not significant orientation of solvent molecules around the solute molecules, in this case dipolar interactions between solute and solvent due to local effects might be expected. AQ may be considered as formed by two carbonyl groups weakly interacting with the benzene rings; that means that the carbonyl group can behave as an isolated dipole and independently of the other. To detect possible specific interactions between the AQ and aliphatic amines and aromatic hydrocarbons, preferential solvation in mixed solvent was investigated. It is concluded that EDA interactions are important in the solvation of AQ with these compounds as solvents.