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
The main focus in this review is showing how to use the developed buffer theory for assessing and predicting the long-term phenomena of attenuation and natural remediation of ionic pollutants in contaminated aquatic e...The main focus in this review is showing how to use the developed buffer theory for assessing and predicting the long-term phenomena of attenuation and natural remediation of ionic pollutants in contaminated aquatic ecosystems,as well as for analyzing the way by which metals move and transform within the environment,the distribution of metals in ecosystems,their deposition and cycling in the terrestrial environment.The buffer theory is based on the rigorous thermodynamic analysis of complex chemical equilibria under environmental conditions in aquatic ecosystems,as natural waters and soils.It has been established that both homogeneous and heterogeneous systems manifest a buffer action towards all their components.The buffer properties in relation to the solid phase components are amplified with an increase of solubility due to protolytic or complex formation equilibria in saturated solutions.It has been established that the buffer capacities of components are mutually proportional,whereas for heterogeneous systems these relationships depend on the stoichiometric composition of solid phases.The use of the developed buffer approach may yield extended knowledge and a deeper understanding of the processes that control the concentrations of components.A number of the important conclusions concerning the investigated buffer systems have been made.The obtained results are indented to provide researchers with a tool needed to help them to set reliable limits of ion(metal)levels in the environment.展开更多
Introduction:The copper content in natural waters usually range from 0.2 to 30μg/L.The higher concentrations are habitually found in industrial effluents and other contaminated waters.Methods:This work develops the s...Introduction:The copper content in natural waters usually range from 0.2 to 30μg/L.The higher concentrations are habitually found in industrial effluents and other contaminated waters.Methods:This work develops the spectrophotometric method of determination of copper(II)microgram amounts with a new reagent-sodium salt of 4-phenylsemicarbazone 1,2-naphthoquinone-4-sulfonic acid(L),used as a ligand for a new coordination compound of copper(II).The complex formation is accompanied by color change,allowing use of this property for quantitative determination of copper(II)ions in various objects such as:alloys,superconducting ceramics and tap water.The determination of copper(II)ions has been carried out by voltammetric and spectrophotometric methods.Results:The complex of composition CuL is stable within the pH range from 5.74 to 6.51.Its stability constant is logβ=4.53.The molar absorption coefficient of the complex has been found.Both methods give the same concentration of about 0.0400 mg/L of copper(II)in tap water,ceramics,and alloys.The detection limit of the spectrophotometric determination of copper(II)ions in the presence of the main metal ions in tap water is 0.012 mg/mL.Conclusions:The advantages of this method are the simplicity of the synthesis of reagent,its ease of recrystallization from water-ethanol solution,and stability in the crystalline state.展开更多
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.
文摘The main focus in this review is showing how to use the developed buffer theory for assessing and predicting the long-term phenomena of attenuation and natural remediation of ionic pollutants in contaminated aquatic ecosystems,as well as for analyzing the way by which metals move and transform within the environment,the distribution of metals in ecosystems,their deposition and cycling in the terrestrial environment.The buffer theory is based on the rigorous thermodynamic analysis of complex chemical equilibria under environmental conditions in aquatic ecosystems,as natural waters and soils.It has been established that both homogeneous and heterogeneous systems manifest a buffer action towards all their components.The buffer properties in relation to the solid phase components are amplified with an increase of solubility due to protolytic or complex formation equilibria in saturated solutions.It has been established that the buffer capacities of components are mutually proportional,whereas for heterogeneous systems these relationships depend on the stoichiometric composition of solid phases.The use of the developed buffer approach may yield extended knowledge and a deeper understanding of the processes that control the concentrations of components.A number of the important conclusions concerning the investigated buffer systems have been made.The obtained results are indented to provide researchers with a tool needed to help them to set reliable limits of ion(metal)levels in the environment.
文摘Introduction:The copper content in natural waters usually range from 0.2 to 30μg/L.The higher concentrations are habitually found in industrial effluents and other contaminated waters.Methods:This work develops the spectrophotometric method of determination of copper(II)microgram amounts with a new reagent-sodium salt of 4-phenylsemicarbazone 1,2-naphthoquinone-4-sulfonic acid(L),used as a ligand for a new coordination compound of copper(II).The complex formation is accompanied by color change,allowing use of this property for quantitative determination of copper(II)ions in various objects such as:alloys,superconducting ceramics and tap water.The determination of copper(II)ions has been carried out by voltammetric and spectrophotometric methods.Results:The complex of composition CuL is stable within the pH range from 5.74 to 6.51.Its stability constant is logβ=4.53.The molar absorption coefficient of the complex has been found.Both methods give the same concentration of about 0.0400 mg/L of copper(II)in tap water,ceramics,and alloys.The detection limit of the spectrophotometric determination of copper(II)ions in the presence of the main metal ions in tap water is 0.012 mg/mL.Conclusions:The advantages of this method are the simplicity of the synthesis of reagent,its ease of recrystallization from water-ethanol solution,and stability in the crystalline state.
