In situ aerosol acidity measurements using a UV–Visible micro-spectrometer and its application to the ambient air

Abstract

An in situ analytical method was demonstrated to measure the proton concentration ([H⁺]_C-RUV) of an aerosol particle by using colorimetry integrated with a Reflectance UV-Visible spectrometer (C-RUV). Acidic particles comprising ammonium, sulfate, and water were generated in a flow tube under varying humidity and employed to calibrate the method using the inorganic thermodynamic models (i.e., E-AIM and ISORROPIA). The predictive [H⁺]_C-RUV equation derived using strongly acidic compositions was then extended to ammonia-rich aerosols, which were lacking in the database of the thermodynamic models. The predictive [H⁺]_C-RUV equation was also expanded to aerosols composed of sodium, ammonium, and sulfate. [H⁺]_C-RUV generally agrees with both E-AIM predicted [H⁺] and ISORROPIA predicted [H⁺] for highly acidic aerosols, or aerosols at high humidity. For ammonia-rich aerosols under low humidity, [H⁺]_C-RUV disagrees with that predicted from inorganic thermodynamic models. C-RUV was feasible for ambient aerosols because colorimetry is specific to aerosol acidity. Most aerosols collected at the University of Florida between 2018 and 2019 were acidic. Sodium ions appeared during the spring and summer, as coastal sea breezes traveled inland. The concentrations of ammonium and nitrate were high in the winter due to the phase partitioning of nitric acid and ammonia gases. The fraction of non-electrolytic dialkyl-organosulfate (diOS) to total sulfate is estimated by comparing the actual particle [H⁺] measured by C-RUV to the [H⁺] predicted using the inorganic composition and the inorganic thermodynamic models. The diOS fraction varied from 0% to 60% and was higher in the summer months when [H⁺] is high.

Copyright © 2020 American Association for Aerosol Research     

Hydrolysis of Benzopyrylium Dyes – An Application of the Concept of Chemical Hardness

A systematic study on the relationship between the substitution pattern, the pK_a values, and spectral properties of flavylium cations and the respective–(CH₂)₂–bridged analoga (5,6-dihydrobenzo[c]xanthylium cations) is given in order to find rules concerning their spectral behaviour and their chemical reactivity. Our results show that the concept of chemical hardness can explain the different reactivity of 4′- and 7-substituted flavylium ions against HO⁻. The pK_a values of these species, which can act as a measure of reactivity with respect to a nucleophile, correlate linearly with the absolute hardness calculated from half the energy gap between the frontier orbitals. Since the longest-wavelength UV/VIS absorption maximum is mainly determined by the HOMO-LUMO transition, an analogous linear correlation is obtained between the spectral 0–0 transition and the pK_a value. Deviations from these correlations are assumed to be due to steric effects.     

Synthesis of star-shaped poly(vinyl ether)s by living cationic polymerization: Pathway for formation of star-shaped polymers via polymer linking reactions

Summary: Star-shaped polymers of isobutyl vinyl ether (IBVE) with a microgel core of an aliphatic divinyl ether (2) were synthesized in high yield on the basis of the living cationic polymerization with the HCl/ZnCl₂ initiating system. GPC analysis demonstrated that linear coupling products ("two-armed" polymers) and three-armed star polymers formed during the early stages of the linking reaction, and that subsequent coupling reactions between such low molecular weight star polymers gave star-shaped polymers with more arms. The number of arms ranged from 5 to 22, which increased with increasing [2]₀/[P^*] ratio and/or shortening the arm chain. Received: 11 April 2000/Accepted: 24 April 2000     

Wechselwirkungen in Kristallen. 96. Darstellung und Strukturen von Salzen [RnN⊕H…︁NRn][B⊖(C6H5)4] mit Prototyp-Wasserstoffbrücken N⊕H…︁N

Interactions in Crystals. 96. Preparation and Structures of Salts [R_nN^⊕H…︁NR_n][B^⊖(C₆H₅)₄] with Prototype Hydrogen Bridges N^⊕H…︁N Straightforward crystallization of ammonium salts [R_nN^⊕H] X^⊖ added lithium tetraphenylborate, and amine R_nN from acetone solution yields salts [R_nN^⊕H…︁NR_n][B^⊖(C₆H₅)₄] with the (under the conditions) unprotonated anions and the cations with prototype hydrogen bridges N^⊕H…︁N. The structures of both identically substituted R_nN (methylamine, trimethylamine, quinuclidine, diazabicyclooctane, and pyridine) as well as two-component cation species (quinuclidine…︁pyridine and diazabicyclooctane…︁pyridine) are reported and discussed. A Cambridge Structural Database search defines the area of charged N^⊕H…︁N interactions which can be correlated with both pK values and PM3 formation enthalpies. Additional information is provided by PM3 calculations based on the experimental structure coordinates. The charge distribution within the hydrogen bridges N^⊕H…︁N varies considerably with the individual proton donors N⁺H and proton acceptors N: Positive charges are highest at protonated quinuclidine and diazabicyclooctane centers and lowest at pyridine N acceptor centers.     

Ion Exchange of the Organometallic Aqua‐Ion fac‐[99mTc(CO)3(H2O)3]+ from Aqueous Solutions

Dynamic (column) studies on the ion exchange of triaquatricarbonyltechnetium(I) cation, fac‐[^99mTc(CO)₃(H₂O)₃]⁺ (1), in the system: amphoteric ion exchange resin (Purolite S‐950) ‐ aqueous HNO₃ solutions (0.05–2 M) corroborate the +1 charge of 1. Stability constants of fac‐[^99mTc(CO)₃(H₂O)_3?nCl_n]^1?n complexes, determined from the distribution coefficients in the system anion exchanger (Dowex 1X4) ‐ aqueous HCl solutions (0.1–12 M) differ from the literature values determined at a constant ionic strength. This difference, resulting from the decrease in the activity of water with increasing HCl concentration, may be a measure of the effect of non‐constant ionic strength on ion‐exchange equilibria. Weak acidic properties of 1 in aqueous solution at n.c.a. (no carrier added) level (pK_a ?9) have been demonstrated by paper electrophoresis.     

EXTRACTION OF PALLADIUM(II) AND PLATINUM(IV) AS CHLOROCOMPLEX ACIDS INTO BASIC ORGANIC SOLVENTS

Solvent extraction of platinum(IV) and palladium(II) with tri-n-octylamine(TOA) in o-xylene from 4.0M (Na,H)(Cl, HSO₄) has been investigated at 298K in order to compare with similar extraction by trioctylphosphine oxide(TOPO). The dependence of the distribution ratio of platinum(IV) and pal 1adium(II) on TOA, hydrogen ion and chloride ion concentrations suggests the dominant extracted species of these metals would be 2:1 for proto-nated amine : chlorocomplex anion and the extraction should be essentially anion exchange reaction. The extraction constants (Kex = D[H⁺(T0A)C1 ] ²[C1 ]²), were evaluated as 10^6-3 and 10^5.8 for platinum(IV) and pal ladium(II), respectively. The anion exchange with protonated TOPO salt represented by H(T0P0)₂ ⁺C1  is less than that with protonated TOA salt by a factor of one order.     

Halogen-free polyisobutylene by in situ methylation of living polyisobutylene using dimethylzinc

Summary Halogen-free polyisobutylene (PIB) was synthesized by in situ methylation of living PIB using dimethylzinc. Quantitative methylation of living PIB was achieved within 60 min using a ratio of [(CH₃)₂Zn]/[TiCl₄]₀= 1 without any side reactions. Under similar conditions, living PIB capped with 1,1-diphenylethylene (PIB-DPE⁺) yielded close to 1:1 mixture of methoxy- and methyl-functionality. By using the ratio of [(CH₃)₂Zn]/[TiCl₄]₀≥ 3, however, quantitative methylation of PIB-DPE⁺ could be achieved in 120 min without any side reactions as confirmed by spectroscopic and chromatographic analyses. Received: 1 February 2000/Revised version: 23 April 2000/Accepted: 23 April 2000     

The Reaction of Ozone with Bisulfide (HS−) in Aqueous Solution – Mechanistic Aspects

The ozone demand to oxidize HS^?/H₂S [pK_a(H₂S) = 6.9, k(HS^? + O₃) = 3 × 10⁹ M^?1 s^?1, k(H₂S + O₃) = 3 × 10⁴ M^?1 s^?1] to SO₄ ^2? is only 2.4 mol ozone per mol SO₄ ^2? formed, much lower than stoichiometric 4.0 mol/mol if a series of O-transfer reactions would occur. As primary step, the formation of an ozone adduct to HS^?, HSOOO^–, is suggested that decomposes into HSO^– and singlet oxygen (16%) or rearranges into peroxysulfinate ion, HS(O)OO^– (84%). Potential reactions of the above intermediates are discussed. Some of these can account for the low ozone demand.     

SPECTROSCOPIC STUDY OF THE EXTRACTION OF NICKEL BY 2-HYDROXY-5-NONYLBENZOPHENONE OXIME (LIX 65N) AND 5,8-DIETHYL-7-HYDROXYDODECANE-6-ONE OXIME (LIX 63).

ABSTRACT

A novel method for determination of solvent extraction equilibria and kinetics using Infrared attenuated total reflectance spectroscopy (ATR) is described. The method allows complete, quantitative kinetic studies using a total of one gram of extractant. Solvent extraction of aqueous Ni²⁺ into 0.5 - 1.0 μm films of Apiezon M (ApM, aliphatic hydrocarbon) containing the title reagents was examined. In contrast with LIX 65N extraction which proceeds solely through the LIX 65N anion, extraction of Ni²⁺ by LIX 63 proceeds through both neutral and anionic forms of LIX 63. This results in a kinetic rate law having two terms, each exhibiting first order dependence on both [Ni²⁺] and [LIX 63]₀. For mixtures of LIX 65N and LIX 63 (LIX 63:LIX 65N ≤ 0.12) In the ApH films, the rate law has only one term, of orders [LIX 65N]₀ ¹, [LIX 63] ₀ ¹, [Ni²⁺]¹, and [H⁺]^?1. While the equilibrium constants favor Ni(LIX 65N)₂, the relatively large rate of reaction of the neutral LIX 63 leads to a catalysis of the overall LIX 65N extraction.     

Ionic liquid-based extraction and separation trends of bioactive compounds from plant biomass

Ionic liquids have been projected as the best solvent for extraction and separation of bioactive compounds from various origins. This review offers a collection of the published results, using ionic liquids for the extraction and purification of biomolecules. Ionic liquids have been studied as solvents, co-solvents and supported materials for separation of bioactive compounds. The ionic liquids-based extraction procedures were previously reported, such as ionic liquids-based solid-liquid extraction, liquid-liquid extraction and ionic liquids-modified materials are reviewed and compared to their performance. In this review, the main activities and future challenges are discussed, with major gaps identified using ionic liquids in extraction procedures and by advancing few steps to overcome these drawbacks.

Abbreviation: [(HSO₃)C₄MIM]⁺: 1-(4-sulfonylbutyl)-3-methylimidazolium; [(C₆H₃OCH₂)₂im]⁺: 1,3-dihexyloxymethylimidazolium; [C_nC₁MIM]⁺: 1-alkyl-2,3-dimethylimidazolium; [C_nMIM]^{+; [Cn, 2, 3, 4, 6, 8, 10, 12]}: 1-alkyl-3-methylimidazolium; [C_nC₁pyr]⁺: 1-alkyl-3-methylpyridinium; [C_nim]⁺: 1-alkylimidazolium; [C_npyr]⁺: 1-alkylpyridinium; [aC_nim]⁺: 1-allyl-3-alkylimidazolium; [C₇H₇MIM]⁺: 1-benzyl-3-methylimidazolium; [C₄(C₁C₁C₁Si)im]⁺: 1-butyl-3-trimethylsilylimidazolium; [(HOOC)C₂MIM]⁺: 1-carboxyethyl-3-methylimidazolium; [(OH)C_nMIM]⁺: 1-hydroxyalkyl-3-methylimidazolium; [(C₂H₅O)₃SiC₃MIM]⁺: 1-methyl-3-(triethoxy)silypropyl imidazolium; [(NH₂)C₃MIM]⁺: 1-propylamine-3-methylimidazolium; [C_wH_xN_yO_z]⁺: Chirally functionalized methylimidazolium; [P_{10(3OH)(3OH)(3OH)}]⁺: Decyltris(3-hydrox- ypropyl) phosphonium; [N_111(2OH)]⁺: N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium (cholinium); [N_00nn]⁺: N,N-dialkylammonium; [N_0nn(2OH)]⁺: N,N-dialkyl-N-(2-hydroxyethyl) ammonium; [C₁₀C₁₀C₁gluc]⁺: N,N-didecyl-N-methyl-d-glucaminium; [N_11(2(O)1)0]⁺: N,N-dimethyl(2-methoxyethyl) ammonium; [N_{11(2OH)(C7H7)}]⁺: N-benzyl-N,N-dimethyl-N-(2-hydroxyethyl) ammonium; [P₆₆₆₁₄]⁺: Trihexyltetradecylph- osphonium; [P_i(444)1]⁺: Triisobutyl (methyl) phosphonium; P.minus: Polygonum minus; NPs: Nanoparticle; ZnO : Zinc oxide nanoparticles ; Ni NPs: Nickel nanoparticles; MO: Methyl orange; UAE: Ultrasonic-assisted extraction; LLE: Liquid-liquid extraction; ABS: Aqueous biphasic system ; [Ace]^?: Acesulfamate; [Ala]^?: alalinate; [TMPP]^?: bis(2,4,4-trimethylpentyl)phosphinate; : ; [NTf₂]^?: bis(trifluoromethylsulfonyl)imide; [[Br]^–]: [Br]omide; [Calc]: calkanoate; [Cl]^–: chloride; [Bz]^?: benzoate; [PF₆]^?: hexafluorophosphate; [HSO₄]^?: hydrogenosulfate; [OH]^?: hydroxide; I^–: iodide; [Lac]^?: lactate; [NO₃]^?: nitrate; [[Cl]O₄]^?: perchlorate; [Phe]^?: phenilalaninate; [BF₄]^?: tetrafluoroborate; [SCN]^?: thiocyanate; [C(CN)₃]^?: tricyanomethanide; [CF₃CO₂]^?: trifluoroacetate; [CF₃SO₃]^?: trifluoromethanesulfonate; [FAP]^?: tris(pentafluoroethyl)trifluorophosphate; ILs: Ionic liquids; Ag NPs: Silver nanoparticle; Cu NPs: Copper nanoparticle; MB: Methylene blue; MR: Methyl red ; MAE: Microwave-assisted extraction; SLE: solid-liquid extraction.     

Highly symmetrical 24-membered macrocyclic organoantimony(V) complexes constructed from Schiff base ligands possessing two terminal carboxyl groups

Two novel organoantimony(V) complexes [Ph₃SbL^a]₂ (1) and [Ph₃SbL^b]₂ (2) (H₂L^a = 5-{[(2-carboxyphenyl)methylene]amino}-4-chlorobenzoic acid, and H₂L^b = 5-{[(2-carboxyphenyl)methylene]amino}-2-chlorobenzoic acid) have been synthesized by the reaction of triphenylantimony dichloride and Schiff base ligands with the ratio of 1:1, and characterized by elemental analysis, IR, ¹H and ¹³C NMR spectroscopy. X-ray single-crystal diffraction analyses reveal that two highly symmetrical 24-membered macrocyclic organoantimony derivatives were found unprecedentedly, in which two antimony atoms are bridged by four terminal carboxyl groups of the Schiff base ligands, and antimony atoms exhibit typical five-coordinated trigonal-bipyramid geometry with two carboxyl oxygen atoms occupying the axial positions. In complexes 1 and 2, there exist several types of secondary interactions (C–H…π, C–Cl…π and C-H…Cl), which contribute to the formation of a 1D infinite chain in 1 and a 2D supramolecular network structure in 2 in their crystal structures, respectively.     

Study of phenol removal using fluidized-bed Fenton process

In this paper, the removal of phenol from simulated wastewater was studied using gas–liquid fluidized bed with the Fenton reagent. The factors that affect the removal rate of phenol were investigated, including the initial concentrations of hydrogen peroxide [H₂O₂] and [Fe²⁺], the molar ratio of [Fe²⁺]/[H₂O₂], pH value, temperatures, reaction time, and the ventilation volume. It was found that the optimal operating conditions existed as: [H₂O₂] = 12 mmol/L, [H₂O₂]/[Fe²⁺] = 4:1, pH = 4, T = 60 °C, reaction time of 30 min, and a ventilation volume of 0.12 m³/h. Under these conditions, the phenol removal rate of about 96% was obtained.     

Proton-Ionizable Crown Compounds: Transport of Alkali and Alkaline Earth Cations Using Proton-Ionizable Triazolo Macrocycles

Abstract

The macrocycle-mediated flaxes of the alkali and alkaline earth metal cations have been determined in a H₂O-CH₂Cl₂-H₂O bulk liquid membrane system. Water-insoluble proton-ionizable macrocycles of the triazolo type were used. The proton-ionizable feature allows the coupling of cation transport to reverse H⁺ transport. This feature offers promise for the effective separation and/or concentration of alkali metal ions with the metal transport being driven by a pH gradient. A counter anion in the source phase is not co-transported. Transport of the alkali cations only occurred when the source phase pH was greater than the aqueous pK_a value for the carriers. Transport increased regularly with increasing source phase pH. Transport of alkaline earth cations from neutral pH source phases was minimal. The alkali cation selectivity order was K⁺ > Rb⁺ > Cs⁺ > Na⁺ > Li⁺ for the l8-crown-6 sized macrocycles, while little selectivity was observed with the 15-crown-5 sized macro-cycle.     

Synthesis, characterization, and catalytic application of copper(I) nitrile cations with perfluorinated weakly coordinating anions

Complexes of the type [Cu(CH₃CN)₄]⁺[A]^– ([A]^– = [B(C₆F₅)₄]^– (1), [B{C₆H₃(CF₃)₂}]^– (2), [(C₆F₅)₃B–C₃H₄N₂–B(C₆F₅)₃]^– (3)) are synthesized and characterized. Their utilization as catalysts in cyclopropanation and aziridination reactions of olefins, forming three membered rings is explored. The compounds are found to catalyze both reactions in moderate to good yields being the best results obtained with compound 1. The more weakly the nitrile ligands are coordinated to the metal center, the better is the catalytic performance of the catalyst.     

One-Dimensional Hydrogen-Bonded Polymer from Hexaazamacrotetracyclic Nickel(II) Complex and trans-1,4-Cyclohexanedicarboxylate Ligand

The reaction of [Ni(L)](ClO₄)₂·2H₂O (L) = 1,3,10,12,16,19-hexaazatetracyclo[17,3,1,1^12.16,0^4.9]tetracosane) with trans-1,4-cyclohexanedicarboxylic acid (H₂-chdc) produces a 1D hydrogen-bonded polymer with formula [Ni(L)(H-chdc⁻)₂] (1). This polymer complex has been characterized by X-ray crystallography, spectroscopy and magnetic susceptibility. The crystal structure of 1 shows a distorted octahedral coordination geometry about Ni with two secondary and two tertiary amines of the macrocycle and two oxygen atoms of the H-chdc⁻ ligand at the trans position. Electronic spectrum of 1 exhibits a high-spin octahedral environment. The magnetic behavior of 1 reveals a very weak antiferromagnetic interaction with J values of −0.66(2) cm⁻¹ .     

One-Dimensional Coordination Polymer Assembled by Tetraaza Macrocyclic Nickel(II) Complex and trans-1,4-Cyclohexanedicarboxylate ligand

The reaction of [Ni(L)]Cl₂·2H₂O (L = 3.14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) with trans-1,4-cyclohexanedicarboxylic acid (H₂chdc) generates a 1D coordination and 2D hydrogen-bonded polymer {[Ni(L)(chdc)₂]·2H₂O}_n (1). The polymer complex was characterized by X-ray crystallography, spectroscopy and magnetic susceptibility. Each nickel(II) ion has a distorted octahedral coordination environment with the four secondary amines of the macrocycle in which two trans carboxylate anions of the chdc²⁻ ligand have assembled around each nickel center. The electronic spectrum of 1 in the solid state exhibits a high-spin octahedral environment. The magnetic behavior of 1 reveals a weak intramolecular antiferromagnetic interaction with J values of −1.15(2) cm⁻¹.     

Kinetics of Solvent Extraction of Iron(III) from Sulfate Medium by Purified Cyanex 272 using a Lewis Cell

Abstract

The kinetics of the forward and backward extraction of the title process have been investigated using a Lewis cell operated at 3 Hz and flux or (F) – method of data treatment. The dependences of (F) in the forward extraction on [Fe³⁺], [H₂A₂]_(o), pH, and [HSO₄ ^?] are 1, 0.5, 1, and ?1, respectively. The value of the forward extraction rate constant (k _f ) has been estimated to be 10^?7.37 kmol^3/2 m^?7/2 s^?1. The analysis of the experimentally found flux equation gives the following simple equation: F _f =10^0.13 [FeHSO₄ ²⁺] [A^?], on considering the monomeric model of BTMPPA and the stability constants of Fe(III)‐HSO₄ ^? complexes. This indicates the following elementary reaction occurring in the aqueous film of the interface as rate determining: [FeHSO₄]²⁺+A^?→[FeHSO₄.A]⁺. The very high activation energy of 91 kJ mol^?1 supports this chemical reaction step as rate-determining. The negative value of the entropy change of activation (?94 J mol^?1 K^?1) indicates that the slow chemical reaction step occurs via the S_N2 mechanism.

The backward extraction rate can be expressed by the equation: F _b =10^?5.13 [[FeHSO₄A₂]]_(o) [H⁺] [H₂A₂]_(o) ^?0.5. An analysis of this equation leads to the following chemical reaction step as rate-determining: [FeHSO₄A₂]_(int)→[FeHSO₄A]+A_(i) ^?. However, the activation energy of 24 kJ mol^?1 suggests that the backward extraction process is intermediate controlled with greater contribution of the diffusion of one or the other species as a slow process. The equilibrium constant obtained from the rate study matches well with that obtained from the equilibrium study.     

Regioselective synthesis and pharmacological activities of spirodibenzo[a,d]cycloheptene-5,2′-[1,3,4]thiadiazole derivatives

Some new 3^′,5^′-substituted-5H,3^′ H-spirodibenzo[a, d]cycloheptene-5,2^′-[1,3,4]thiadiazole and 10,11-dihydro-5H,3^′ H-spirodibenzo[a, d]cycloheptene-5,2^′-[1,3,4]thiadiazole derivatives 3a–n were regioselectively synthesized under 1,3-dipolar cycloaddition of 5-thiooxo-5H-dibenzo[a, d]cyclo-heptene and 5-thiooxo-10,11-dihydro-5H-dibenzo[a, d]cycloheptene with a variety of nitrilimines (generated in situ via dehydrohalogenation of the corresponding hydrazonoyl chlorides in the presence of triethylamine). The new products were tested for antiinflammatory, analgesic, and ulcerogenic score activities comparable to Indomethacin. Compounds 3i–l showed significant activity compared to Indomethacin.