A simple and efficient procedure for the synthesis of 2-arylquinazolin-4（3H）-ones has been developed through cyclocondensation of 2-aminobenzamide with aromatic aldehydes using tetrabutylammonium bromide（TBAB） as ...A simple and efficient procedure for the synthesis of 2-arylquinazolin-4（3H）-ones has been developed through cyclocondensation of 2-aminobenzamide with aromatic aldehydes using tetrabutylammonium bromide（TBAB） as novel neutral ionic liquid catalyst in the presence of copper（Ⅱ） chloride（CuCl;） as oxidizing agent under solvent-free conditions at 100℃.In the absence of CuCl;and under a nitrogen atmosphere,the unoxidized intermediates,2-aryl-2,3-dihydroquinazolin-4（1H）-ones,were isolated. Treatment of these intermediates with CuCl;in TBAB media gave the oxidized products 2-arylquinazolin-4（3H）-ones.On the other hand,cyclocondensation of 2-aminobenzamide with aromatic aldehydes in TBAB under microwave irradiation directly gave 2- arylquinazolin-4（3H）-ones.展开更多
A novel, efficient, and environmentally friendly method for the synthesis of polyhydroquinoline derivatives by a one‐pot, four‐component unsymmetrical Hantzsch condensation of dimedone, aldehydes, ethyl acetoacetate...A novel, efficient, and environmentally friendly method for the synthesis of polyhydroquinoline derivatives by a one‐pot, four‐component unsymmetrical Hantzsch condensation of dimedone, aldehydes, ethyl acetoacetate, and ammonium acetate in the presence of a catalytic amount of tetrabutylammonium hexatungstate [TBA]2[W6O19] under solvent‐free conditions has been developed. The results showed that this heterogeneous catalyst has high catalytic activity and the desired products were obtained in good to high yields. Moreover, the catalyst was found to be reusable and considerable catalytic activity was still achieved after the fifth run.展开更多
Eugenol is extensively utilized in chemical industry.In actual production,it is mainly separated from clove essential oils(EOs)through acid-base solutions.In this work,a simple,rapid and effective extraction process w...Eugenol is extensively utilized in chemical industry.In actual production,it is mainly separated from clove essential oils(EOs)through acid-base solutions.In this work,a simple,rapid and effective extraction process was developed for the extraction of eugenol from EOs samples by directly forming deep eutectic solvents(DESs)without using acid-base solutions.The proposed process is designed to dissolve EOs in n-hexane and eugenol was highly selective extracted into DESs with tetrabutylammonium chloride(TBAC).Hydrogen bonds in DESs can be broken by addition of water,resulting in a separation of the two phases,thus obtaining a hydrophobic yellowish eugenol in the upper layer.The quaternary ammonium salt in the lower aqueous solution can be reused after recovery.The most determining influence factors such as the structure of quaternary ammonium salt,the mole ratio of quaternary ammonium salt to eugenol and the amount of n-hexane were investigated.The forming conditions of DESs were studied by Box-Behnken design(BBD).Experiment was carried out under the optimal conditions and good experimental result was demonstrated by the developed process,a high extraction recovery of 92.51% and the purity was about 98.50%,which verifies the excellent performance for the proposed process.展开更多
A simple and environmentally friendly method is described for the efficient conversion of alkyl halide to alkyl thiocyanate using tetrabutylammonium bromide （TBAB） as a phase transfer catalyst. The reactions occur i...A simple and environmentally friendly method is described for the efficient conversion of alkyl halide to alkyl thiocyanate using tetrabutylammonium bromide （TBAB） as a phase transfer catalyst. The reactions occur in water and furnish the corresponding alkyl thiocyanate in high yields. No evidence for the formation of isothiocyanates as by-product of the reaction was observed and the products were obtained in pure form without further purification.展开更多
In this letter,a mild and efficient procedure for synthesis of phenacyl derivatives under homogenous catalysis in the presence of tetrabutylammonium bromide in aqueous media is described.The nucleophilic substitution ...In this letter,a mild and efficient procedure for synthesis of phenacyl derivatives under homogenous catalysis in the presence of tetrabutylammonium bromide in aqueous media is described.The nucleophilic substitution reactions were performed under ecofriendly conditions and gave the corresponding products in high yields and short reaction times.展开更多
In this paper,we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide（CO2） using quaternary ammonium heteropolyphosphatotungstate–quaternary a...In this paper,we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide（CO2） using quaternary ammonium heteropolyphosphatotungstate–quaternary ammonium halide catalytic system with anhydrous hydrogen peroxide as an oxidant through one-pot two-step process.The effects of the amount of tetrabutylammonium bromide（TBAB）,the concentration of hydrogen peroxide and other reaction conditions were investigated.The catalyst system gave an optimum propylene oxide yield（91%） at75°C in oxidation step and the highest propylene carbonate yield（99%） at 140°C and 3.0 MPa in cycloaddition step.Based on the results,a reaction mechanism has been proposed.展开更多
A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NB...A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.展开更多
A facile and convenient one-pot synthesis method of substituted cyclopropanes in water has been developed. A series of 1,1-disubstituted cyclopropanes 3 were synthesized from the reaction of β-dicarbonyl compounds 1 ...A facile and convenient one-pot synthesis method of substituted cyclopropanes in water has been developed. A series of 1,1-disubstituted cyclopropanes 3 were synthesized from the reaction of β-dicarbonyl compounds 1 with 1,2-dibromoethane 2, in very high yields catalyzed by tetrabutylammonium bromide（TBAB） at 50 ℃ in the presence of K2CO3 in water. The catalyst TBAB in the aqueous phase can be reused after the separation of organic products.展开更多
The electrochemical behaviors of Ta in tetrabutylammonium hydrogen sulfate（TBAHS） ethanol solutions were studied using potentiodynamic polarization,cyclic voltammetry,potentiostatic current time transient and impeda...The electrochemical behaviors of Ta in tetrabutylammonium hydrogen sulfate（TBAHS） ethanol solutions were studied using potentiodynamic polarization,cyclic voltammetry,potentiostatic current time transient and impedance techniques.The results revealed that no active-passive transition is presented in the cyclic voltammogram,and the anodic current density increases with the increase of solution temperature,TBAHS concentration,potential scan rate and water content.The apparent activation energy is about 43.389 kJ/mol and the dissolution process is diffusion-controlled.Potentiostatic measurements showed that the current density gradually decays to a steady value when the potential is low;however,when the potential is higher than a certain value,the current density initially declines to a minimum value and then increases gradually.The resistance of passive film decreases with increasing potential,and inductive loops are presented when the potential is higher than 2.0 V.展开更多
The title heteropoly blue, (Bu_4N)_6H_(10)[PMo_(11)~ⅥMo~ⅤO_(40)]_4·H_2Ohas been photochemically synthesized and characterized with elemental analysis, solid diffusionreflectance electronic spectra, CV, ESR, XPS...The title heteropoly blue, (Bu_4N)_6H_(10)[PMo_(11)~ⅥMo~ⅤO_(40)]_4·H_2Ohas been photochemically synthesized and characterized with elemental analysis, solid diffusionreflectance electronic spectra, CV, ESR, XPS, IR spectra, conductivity measurement and X-ray singlecrystal analysis. The crystallographic data for C_(96)H_(218)Mo_(48)N_6O_(169)P_4 are as follows:M_r = 8889.76, triclinic, P_1, a = 1.4142(3) nm, b = 2.6027(5) nm, c = 2.6403(5) nm, α=113.96(3)°, β = 90.05(3)°, γ= 105.71(3)°, V = 8.481(3) nm^3, Z = 1, D_c = 1.741 g/cm^3, F(000)= 4264, μ= 1.798 mm^(-1). The X-ray crystal structure analysis reveals that there is oneindependent molecule in the unit cell of the title heteropoly blue which contains four mixed-valenceheteropoly anions, six tetrabutylammonium cations and one water molecule. Its molecular structurepossesses a centrosymmetrical arrangement in the unit cell. The phosphorus atom is in thecrystallographic inversion center of the heteropoly anion and the eight oxygen atoms surroundingcentral phosphorus atom comprise of a distorted hexahedron. Heteropoly anion has two equal sets ofPO_4 tetrahedron. The PO_4 tetrahedron and the MoO_6 octahedron in the polyanion are greatlydistorted.展开更多
In this article tetrabutylammonium bromide （TBAB） was first added in buffer to compose a convenient and environmentally friendly system, and enzymatic polymerization of phenol catalyzed by horseradish peroxidase （...In this article tetrabutylammonium bromide （TBAB） was first added in buffer to compose a convenient and environmentally friendly system, and enzymatic polymerization of phenol catalyzed by horseradish peroxidase （HRP） could proceed efficiently in this system. When TBAB was added, the most conversion of phenol could reach 99.1%. The phenol polymer was considered to consist of a mixture of phenylene （Ph） and oxyphenylene （Ox） units by IR analysis, and the ratio of phenylene to oxyphenylene units （Ph/Ox） was measured by titration. Moreover, the effects of the dosage of horseradish peroxidase （HRP） and pH value on the conversion of phenol were investigated. The reaction performed very effectively in this novel system when the addition of HRP was only 0.2 mg. In all cases, the weight-average molecular weight calculated by GPC-SLS was in a range from 12000 Da to 30000 Da. The phenol polymer prepared in the present research possessed good thermal stability shown by TG analysis.展开更多
Two polymorphs of the inclusion compound [（n-C4H9）4N]＋＇（C13H903）H2O have been prepared and characterized by X-ray crystallography. Polymorph 1： triclinic P1, a = 13.4982（2）, b = 13.5743（2）, c = 17.1996（2）...Two polymorphs of the inclusion compound [（n-C4H9）4N]＋＇（C13H903）H2O have been prepared and characterized by X-ray crystallography. Polymorph 1： triclinic P1, a = 13.4982（2）, b = 13.5743（2）, c = 17.1996（2） A, at = 67.045（1）,β = 77.845（1）, γ= 88.762（1）°, V = 2830.43（7） A3, Z = 4, R = 0.0491, wR= 0.1276; Polymorph 2： tetragonal P43, a = b = 13.53690（1） A, c = 30.8491（8） A, V = 5653.02（16） A3, Z = 8, R = 0.0448, wR = 0.0984. In these two crystal structures, the hydrogen-bonded ribbons built of 4,4＇-dihydroxybenzophenone （DHBP, C13H1003） anions and water molecules are orderly arranged to generate two-dimensional host layers, with tetrabutylammonium cations contained between the layers to form the sandwich-like inclusion compounds. The structures of 1 and 2, which exist as two polymorphs, both display the similar packing pattern and hydrogen-bond linking model.展开更多
A novel supported liquid phase film catalyst: Supported PdCl2-(n-C4H9),N+Cl- molten salts was found to be an effective catalyst with good stability for selective hydrodechlorination of CCl2F2 (CFC-12) to its alternati...A novel supported liquid phase film catalyst: Supported PdCl2-(n-C4H9),N+Cl- molten salts was found to be an effective catalyst with good stability for selective hydrodechlorination of CCl2F2 (CFC-12) to its alternatives CH2F2 and CHClF2. Addition of CoCl2, GaCl3 and CuCl2 to PdCl2-(n-C4H9),N+Cl- modifies the catalytic performance of supported molten salts.展开更多
Introduction:The influence of the interaction of calcium carbonate(CaCO3)and surface-active substances(SAS;surfactants)with different chain lengths and cationic and anionic hydrophilic centers has been analyzed.Result...Introduction:The influence of the interaction of calcium carbonate(CaCO3)and surface-active substances(SAS;surfactants)with different chain lengths and cationic and anionic hydrophilic centers has been analyzed.Results:Laboratory simulations indicate reduced negative influences on cationic SAS nitrification/self-purification processes in the presence of anionic species.This suggests the role of complex ionic formation[anionic SAS*cationic SAS]as a cause of this effect.UV-Vis spectra of lauryl sulfate(LS)and of cetyltrimethylammonium(CTMA),as well as of their mixtures in ratios of 2:1 and 1:1,treated by fine particles of CaCO3,display decreased amounts of SAS in analyzed solutions and their presence on the surface of CaCO3 nanoparticles.UV-Vis spectra reveal the decomposition of the complex[anionic SAS(SAS-An)*cationic SAS(SAS-Ct)]in solutions when CaCO3 is added.CTMA can be bonded by LS through hydrophobic chains,on the surface of CaCO3 particles.Therefore,CaCO3 modifies the nature of LS and CTMA interactions.This leads to an increased degree of toxicity of cationic SAS in aquatic environment.The amounts of CTMA in aqueous solutions are diminished in the presence of ammonium ion NH4+(2 mg/L).In the presence of two orders higher concentration of ammonium ion,this effect strongly increases,making the association obvious.The structure of cationic SAS does not influence this effect.The obtained results have been confirmed both by timed natural aquatic sample analysis and laboratory simulations using water from Moldovan small rivers(Isnovat,Raut,and Bic).Conclusions:UV-Vis spectra and laboratory simulations demonstrate the change due to the addition of calcium carbonate.Simulations and laboratory tests of water samples from Isnovat,Bic,and Raut Rivers,establish the cationic SAS negative influence on treatment and self-purification processes.展开更多
文摘A simple and efficient procedure for the synthesis of 2-arylquinazolin-4（3H）-ones has been developed through cyclocondensation of 2-aminobenzamide with aromatic aldehydes using tetrabutylammonium bromide（TBAB） as novel neutral ionic liquid catalyst in the presence of copper（Ⅱ） chloride（CuCl;） as oxidizing agent under solvent-free conditions at 100℃.In the absence of CuCl;and under a nitrogen atmosphere,the unoxidized intermediates,2-aryl-2,3-dihydroquinazolin-4（1H）-ones,were isolated. Treatment of these intermediates with CuCl;in TBAB media gave the oxidized products 2-arylquinazolin-4（3H）-ones.On the other hand,cyclocondensation of 2-aminobenzamide with aromatic aldehydes in TBAB under microwave irradiation directly gave 2- arylquinazolin-4（3H）-ones.
基金supported by Islamic Azad University, Mashhad Branch, Iran
文摘A novel, efficient, and environmentally friendly method for the synthesis of polyhydroquinoline derivatives by a one‐pot, four‐component unsymmetrical Hantzsch condensation of dimedone, aldehydes, ethyl acetoacetate, and ammonium acetate in the presence of a catalytic amount of tetrabutylammonium hexatungstate [TBA]2[W6O19] under solvent‐free conditions has been developed. The results showed that this heterogeneous catalyst has high catalytic activity and the desired products were obtained in good to high yields. Moreover, the catalyst was found to be reusable and considerable catalytic activity was still achieved after the fifth run.
基金financially supported by National Natural Science Foundation of China(22174129,22206171)the Natural Science Foundation of Zhejiang Province(LZY21E030001)the Xin-Miao Talents Program of Zhejiang Province(2023R403067).
文摘Eugenol is extensively utilized in chemical industry.In actual production,it is mainly separated from clove essential oils(EOs)through acid-base solutions.In this work,a simple,rapid and effective extraction process was developed for the extraction of eugenol from EOs samples by directly forming deep eutectic solvents(DESs)without using acid-base solutions.The proposed process is designed to dissolve EOs in n-hexane and eugenol was highly selective extracted into DESs with tetrabutylammonium chloride(TBAC).Hydrogen bonds in DESs can be broken by addition of water,resulting in a separation of the two phases,thus obtaining a hydrophobic yellowish eugenol in the upper layer.The quaternary ammonium salt in the lower aqueous solution can be reused after recovery.The most determining influence factors such as the structure of quaternary ammonium salt,the mole ratio of quaternary ammonium salt to eugenol and the amount of n-hexane were investigated.The forming conditions of DESs were studied by Box-Behnken design(BBD).Experiment was carried out under the optimal conditions and good experimental result was demonstrated by the developed process,a high extraction recovery of 92.51% and the purity was about 98.50%,which verifies the excellent performance for the proposed process.
基金Partial support for this work by Chamran University Research Council is gratefully acknowledged.
文摘A simple and environmentally friendly method is described for the efficient conversion of alkyl halide to alkyl thiocyanate using tetrabutylammonium bromide （TBAB） as a phase transfer catalyst. The reactions occur in water and furnish the corresponding alkyl thiocyanate in high yields. No evidence for the formation of isothiocyanates as by-product of the reaction was observed and the products were obtained in pure form without further purification.
基金Partial support for this work by Islamic Azad University,Mahshahr branch research council
文摘In this letter,a mild and efficient procedure for synthesis of phenacyl derivatives under homogenous catalysis in the presence of tetrabutylammonium bromide in aqueous media is described.The nucleophilic substitution reactions were performed under ecofriendly conditions and gave the corresponding products in high yields and short reaction times.
文摘In this paper,we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide（CO2） using quaternary ammonium heteropolyphosphatotungstate–quaternary ammonium halide catalytic system with anhydrous hydrogen peroxide as an oxidant through one-pot two-step process.The effects of the amount of tetrabutylammonium bromide（TBAB）,the concentration of hydrogen peroxide and other reaction conditions were investigated.The catalyst system gave an optimum propylene oxide yield（91%） at75°C in oxidation step and the highest propylene carbonate yield（99%） at 140°C and 3.0 MPa in cycloaddition step.Based on the results,a reaction mechanism has been proposed.
文摘A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.
基金Supported by the National Natural Science Foundation of China(Nos.20572013, 20711130229)the Ministry of Educa-tion of China(No.105061).
文摘A facile and convenient one-pot synthesis method of substituted cyclopropanes in water has been developed. A series of 1,1-disubstituted cyclopropanes 3 were synthesized from the reaction of β-dicarbonyl compounds 1 with 1,2-dibromoethane 2, in very high yields catalyzed by tetrabutylammonium bromide（TBAB） at 50 ℃ in the presence of K2CO3 in water. The catalyst TBAB in the aqueous phase can be reused after the separation of organic products.
基金Project(2007AA03Z425)supported by the Hi-tech Research and Development Program of ChinaProject(50404011)supported by the National Natural Science Foundation of China
文摘The electrochemical behaviors of Ta in tetrabutylammonium hydrogen sulfate（TBAHS） ethanol solutions were studied using potentiodynamic polarization,cyclic voltammetry,potentiostatic current time transient and impedance techniques.The results revealed that no active-passive transition is presented in the cyclic voltammogram,and the anodic current density increases with the increase of solution temperature,TBAHS concentration,potential scan rate and water content.The apparent activation energy is about 43.389 kJ/mol and the dissolution process is diffusion-controlled.Potentiostatic measurements showed that the current density gradually decays to a steady value when the potential is low;however,when the potential is higher than a certain value,the current density initially declines to a minimum value and then increases gradually.The resistance of passive film decreases with increasing potential,and inductive loops are presented when the potential is higher than 2.0 V.
文摘The title heteropoly blue, (Bu_4N)_6H_(10)[PMo_(11)~ⅥMo~ⅤO_(40)]_4·H_2Ohas been photochemically synthesized and characterized with elemental analysis, solid diffusionreflectance electronic spectra, CV, ESR, XPS, IR spectra, conductivity measurement and X-ray singlecrystal analysis. The crystallographic data for C_(96)H_(218)Mo_(48)N_6O_(169)P_4 are as follows:M_r = 8889.76, triclinic, P_1, a = 1.4142(3) nm, b = 2.6027(5) nm, c = 2.6403(5) nm, α=113.96(3)°, β = 90.05(3)°, γ= 105.71(3)°, V = 8.481(3) nm^3, Z = 1, D_c = 1.741 g/cm^3, F(000)= 4264, μ= 1.798 mm^(-1). The X-ray crystal structure analysis reveals that there is oneindependent molecule in the unit cell of the title heteropoly blue which contains four mixed-valenceheteropoly anions, six tetrabutylammonium cations and one water molecule. Its molecular structurepossesses a centrosymmetrical arrangement in the unit cell. The phosphorus atom is in thecrystallographic inversion center of the heteropoly anion and the eight oxygen atoms surroundingcentral phosphorus atom comprise of a distorted hexahedron. Heteropoly anion has two equal sets ofPO_4 tetrahedron. The PO_4 tetrahedron and the MoO_6 octahedron in the polyanion are greatlydistorted.
基金financially supported by the Natural Science Foundation of Henan Province(No.132300410147)
文摘In this article tetrabutylammonium bromide （TBAB） was first added in buffer to compose a convenient and environmentally friendly system, and enzymatic polymerization of phenol catalyzed by horseradish peroxidase （HRP） could proceed efficiently in this system. When TBAB was added, the most conversion of phenol could reach 99.1%. The phenol polymer was considered to consist of a mixture of phenylene （Ph） and oxyphenylene （Ox） units by IR analysis, and the ratio of phenylene to oxyphenylene units （Ph/Ox） was measured by titration. Moreover, the effects of the dosage of horseradish peroxidase （HRP） and pH value on the conversion of phenol were investigated. The reaction performed very effectively in this novel system when the addition of HRP was only 0.2 mg. In all cases, the weight-average molecular weight calculated by GPC-SLS was in a range from 12000 Da to 30000 Da. The phenol polymer prepared in the present research possessed good thermal stability shown by TG analysis.
文摘Two polymorphs of the inclusion compound [（n-C4H9）4N]＋＇（C13H903）H2O have been prepared and characterized by X-ray crystallography. Polymorph 1： triclinic P1, a = 13.4982（2）, b = 13.5743（2）, c = 17.1996（2） A, at = 67.045（1）,β = 77.845（1）, γ= 88.762（1）°, V = 2830.43（7） A3, Z = 4, R = 0.0491, wR= 0.1276; Polymorph 2： tetragonal P43, a = b = 13.53690（1） A, c = 30.8491（8） A, V = 5653.02（16） A3, Z = 8, R = 0.0448, wR = 0.0984. In these two crystal structures, the hydrogen-bonded ribbons built of 4,4＇-dihydroxybenzophenone （DHBP, C13H1003） anions and water molecules are orderly arranged to generate two-dimensional host layers, with tetrabutylammonium cations contained between the layers to form the sandwich-like inclusion compounds. The structures of 1 and 2, which exist as two polymorphs, both display the similar packing pattern and hydrogen-bond linking model.
文摘A novel supported liquid phase film catalyst: Supported PdCl2-(n-C4H9),N+Cl- molten salts was found to be an effective catalyst with good stability for selective hydrodechlorination of CCl2F2 (CFC-12) to its alternatives CH2F2 and CHClF2. Addition of CoCl2, GaCl3 and CuCl2 to PdCl2-(n-C4H9),N+Cl- modifies the catalytic performance of supported molten salts.
基金The study is produced as part of the Diaspora Professional Return Program,which is a part of the Diaspora Engagement Hub,implemented by the Diaspora Relations Bureau of the State Chancellery of the Republic of Moldova in partnership with the International Organization for Migration,Mission to Moldova,in the framework of the“Consolidating Moldova’s Migration and Development Institutional Framework”project,funded by the Swiss Agency for Development and Cooperation.Also,this research was supported,in part,under National Science Foundation Grants CNS-0958379 and CNS-0855217 and the City University of New York High Performance Computing Center at the College of Staten Island and by the National Science Foundation through TeraGrid resources provided by the TeraGrid Science Gateways program under grants CHE090082 and CHE0000036.
文摘Introduction:The influence of the interaction of calcium carbonate(CaCO3)and surface-active substances(SAS;surfactants)with different chain lengths and cationic and anionic hydrophilic centers has been analyzed.Results:Laboratory simulations indicate reduced negative influences on cationic SAS nitrification/self-purification processes in the presence of anionic species.This suggests the role of complex ionic formation[anionic SAS*cationic SAS]as a cause of this effect.UV-Vis spectra of lauryl sulfate(LS)and of cetyltrimethylammonium(CTMA),as well as of their mixtures in ratios of 2:1 and 1:1,treated by fine particles of CaCO3,display decreased amounts of SAS in analyzed solutions and their presence on the surface of CaCO3 nanoparticles.UV-Vis spectra reveal the decomposition of the complex[anionic SAS(SAS-An)*cationic SAS(SAS-Ct)]in solutions when CaCO3 is added.CTMA can be bonded by LS through hydrophobic chains,on the surface of CaCO3 particles.Therefore,CaCO3 modifies the nature of LS and CTMA interactions.This leads to an increased degree of toxicity of cationic SAS in aquatic environment.The amounts of CTMA in aqueous solutions are diminished in the presence of ammonium ion NH4+(2 mg/L).In the presence of two orders higher concentration of ammonium ion,this effect strongly increases,making the association obvious.The structure of cationic SAS does not influence this effect.The obtained results have been confirmed both by timed natural aquatic sample analysis and laboratory simulations using water from Moldovan small rivers(Isnovat,Raut,and Bic).Conclusions:UV-Vis spectra and laboratory simulations demonstrate the change due to the addition of calcium carbonate.Simulations and laboratory tests of water samples from Isnovat,Bic,and Raut Rivers,establish the cationic SAS negative influence on treatment and self-purification processes.
