Increasing the durability of trimming dies used to clean anodes is a very important goal in order to reduce the costs involved in obtaining aluminum. The research focused both on choosing an optimal material for the execution of trimming... more
Increasing the durability of trimming dies used to clean anodes is a very important goal in order to reduce the costs involved in obtaining aluminum. The research focused both on choosing an optimal material for the execution of trimming dies and on the application of technologies for plating active areas and, at the same time, on optimizing the geometric shape of the active area of the trimming die. In order to choose an optimal material from which to make the trimming dies, it was taken into account that they are usually made of X210Cr12 steel. In the stage of choosing an optimal material for the execution of the trimming dies, five steels were taken into account, namely: K105, K107, K110, K360, and K460. Analyses of the metallographic structure of the passage area were performed between the metal deposited by welding and the base material, demonstrating the fact that hot welding plating allows obtaining a more homogeneous metallographic structure compared to cold welding plating....
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The main objectives of this present paper were to indicate the immobilization of nano zerovalent iron (nZVI) onto a polymeric material (Purolite A400) and the synthesis of the polymeric material (A400-nZVI) through sodium borohydride... more
The main objectives of this present paper were to indicate the immobilization of nano zerovalent iron (nZVI) onto a polymeric material (Purolite A400) and the synthesis of the polymeric material (A400-nZVI) through sodium borohydride (NaBH4) reduction. The obtained polymeric material (A400-nZVI) was used for the nitrate ions removal from a simulated groundwater at different conditions. The polymeric materials, without and with nano zerovalent iron (A400 and A400-nZVI), were characterized trough the FTIR, SEM-EDAX, XRD, and TGA analysis. The analysis confirmed the presence of nano zerovalent iron (nZVI) onto the polymeric material (A400). The adsorption capacity of A400-nZVI, used as polymeric adsorbent, was evaluated by kinetic and thermodynamic studies. The obtained experimental results indicated that the nitrate ions reduction was fitted well by models: pseudo-second-order kinetic and Freundlich isotherm. According to the kinetic model results, a reaction mechanism could exist in ...
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Despite the publication of a high number of articles, mainly edited compilations, on both fire ecology in general and, more specifically, fire ecology in the temperate zone; it remains difficult to obtain accessible overviews of many... more
Despite the publication of a high number of articles, mainly edited compilations, on both fire ecology in general and, more specifically, fire ecology in the temperate zone; it remains difficult to obtain accessible overviews of many aspects of the subject. As a source of atmospheric carbon, biomass burning emissions associated with deforestation in the Romania are globally significant. These lands deforested and transformed in grasslands continue to be sources of substantial burning emissions for many years due to their burning. The present work discusses the burning and combustion of the forest biomass, and the factors that concur to the appearance and increase of the phenomena. There are presented the combustion, burning and spreading conditions of the fire. We suggest some preventing measures of forest fires and diminishing factors of its spreading.
By schist (shale) we mean a mixture of organic mass and various rocks existing in the environment, in which the inorganic mass is predominant. Usually, schists occur when magmatic rocks come in contact with the sedimentary ones. Classical... more
By schist (shale) we mean a mixture of organic mass and various rocks existing in the environment, in which the inorganic mass is predominant. Usually, schists occur when magmatic rocks come in contact with the sedimentary ones. Classical analyses give erroneous results due to thermal changes suffered by the accompanying rocks. This paper presents new methods that can differentiate humic shale from bituminous shale by extraction with solvents and by differential thermal analysis (DTA). The paper tries to demonstrate that exploitation of such schists directly into the reservoir (underground gasification and other new methods) may lead to environmental pollution. In this context, we suggest that the schist exploitation should take place by utilizing it where both the organic and inorganic mass are simultaneously exploited.
The chemical and metallurgical industries are the main producers of metal-bearing liquid effluents that due to the toxic character of many of the metals contained in them need to be treated before the final discharge. The removal of Cr 6+... more
The chemical and metallurgical industries are the main producers of metal-bearing liquid effluents that due to the toxic character of many of the metals contained in them need to be treated before the final discharge. The removal of Cr 6+ from aqueous solution by an ion-exchange resin is described. Ion-exchange resins Purolite A 500 shows a remarkable increase in sorption capacity for Cr 6+ , compared to other resins. The sorption process, which is pH dependent shows the maximum removal of Cr 6+ in the pH range 1–5 for an initial Cr 6+ concentration of 1 g/L. The sorption of Cr 6+ on these cation exchange resins follows first-order reversible kinetics and pseudo-first-order kinetics.
Abstract In this paper, the performances and efficiency of some novel polymer membranes doped with fumed silica powder were investigated. The membranes obtained using a laboratory electrodialysis system was involved in zinc ions removal... more
Abstract In this paper, the performances and efficiency of some novel polymer membranes doped with fumed silica powder were investigated. The membranes obtained using a laboratory electrodialysis system was involved in zinc ions removal from model wastewater system. The experiments were carried out using three concentrations of zinc ions: 500, 1000 and 1500 ppm, respectively; an applied voltage of 5, 10 and 20 V; flow rate: 13 mL/min; time for each experiment: 2 h. The removal ratio (R) and mass flow (J) of zinc ions and also water content (% wt.) were determined. Membranes were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The results indicated that the membranes doped with fumed silica powder significantly influenced the zinc ions removal process from wastewater, this fact being proved by a strong enhancement of the removal ratio from 27.56 ± 0.38% to 96.30 ± 0.11% and by the increase of the mass flow from 8.79 ± 0.12 g/m 2 h to 92.33 ± 0.10 g/m 2 h. The FTIR-ATR spectra showed the existence of a peak located at ∼1079 cm −1 indicating the presence of silica. The TGA results indicated an improvement of the fouling resistance of the membranes doped with incorporated fumed silica powder. Other properties are also enhanced by the addition of fumed silica, namely the membrane hydrophilicity and the ionic conductivity. The highest ionic conductivity was 0.8937 mS/cm at 20 V.
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The sorption is one of the most important chemical processes in the soils that affect the transport of nutritive elements in soil. The quantification of the nutrient concentration in the soil and in the soil solution is an important stage... more
The sorption is one of the most important chemical processes in the soils that affect the transport of nutritive elements in soil. The quantification of the nutrient concentration in the soil and in the soil solution is an important stage in modelling the transport. The soil contamination ...
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This work aims to attain an efficient removal of the organic compounds from residual effluents derived from the manufacture of Ranitidine and Loperamide, evaluating the possibilities of removing them by means of photo-assisted techniques.... more
This work aims to attain an efficient removal of the organic compounds from residual effluents derived from the manufacture of Ranitidine and Loperamide, evaluating the possibilities of removing them by means of photo-assisted techniques. The experimental plan was developed taking in consideration a number of influencing factors: reaction time, catalyst concentration, pH, structure and concentration of the initial chemical compound, type of process applied. The experimental data allowed to comparatively evaluate the degradation of the pharmaceutical effluents and to determine the efficiency of their degradation by means of photo-assisted techniques. The optimal operating conditions were established. The presence of many organic contaminants in wastewaters, surface waters and ground waters may result from contaminated soil, agricultural runoff, industrial wastewaters and leakage of hazardous compounds storage. The presence of these organic compounds in water poses a serious threat to...
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Levels of nitrates in groundwater in some instances are above the safe levels proposed by the EPA and thus pose a threat to human health. Passive groundwater remediation using permeable reactive barriers (PRBs) is a new and innovative... more
Levels of nitrates in groundwater in some instances are above the safe levels proposed by the EPA and thus pose a threat to human health. Passive groundwater remediation using permeable reactive barriers (PRBs) is a new and innovative technology for the removal of pollutants ...
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The aim of the study was to assess the groundwater quality in a rural area affected by the abandoned pyrite ash waste dumps. The abundance of major ions in groundwater depends largely on the nature of the rocks, climatic conditions, and... more
The aim of the study was to assess the groundwater quality in a rural area affected by the abandoned pyrite ash waste dumps. The abundance of major ions in groundwater depends largely on the nature of the rocks, climatic conditions, and mobility. To evaluate geochemical processes, 30 groundwater samples collected from Valea Calugareasca, Prahova County, Romania, were analyzed for the major anions (NO3−, SO42−, Cl−, HCO3−, and F−) and cations (Ca2+, Mg2+, Na+, and K+), which are naturally highly variable due to climatic and geographical location conditions. Ca2+, Na+, Mg2+, and K+ varied between 118 and 275 mg/L, 32 and 160 mg/L, 12.2 and 78.4 mg/L, and 0.21 and 4.48 mg/L, respectively. NO3− levels exceeding the World Health Organization (WHO) limit of 50 mg/L were identified in 17% of the groundwater samples, mainly as result of fertilizers applied to agricultural activities. The hydrogeochemical study identified dolomite dissolution and halite precipitation as natural sources of io...
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Magnesium–aluminum (Mg-Al) and magnesium–aluminum–nickel (Mg-Al-Ni) layered double hydroxides (LDHs) were synthesized by the co-precipitation method. The adsorption process of Mn2+ from synthetic wastewater was investigated. Formation of... more
Magnesium–aluminum (Mg-Al) and magnesium–aluminum–nickel (Mg-Al-Ni) layered double hydroxides (LDHs) were synthesized by the co-precipitation method. The adsorption process of Mn2+ from synthetic wastewater was investigated. Formation of the layered double hydroxides and adsorption of Mn2+ on both Mg-Al and Mg-Ni-Al LDHs were observed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDX) analysis. XRD patterns for prepared LDHs presented sharp and symmetrical peaks. SEM studies revealed that Mg-Al LDH and Mg-Al-Ni LDH exhibit a non-porous structure. EDX analysis showed that the prepared LDHs present uniformly spread elements. The adsorption equilibrium on these LDHs was investigated at different experimental conditions such as: Shaking time, initial Mn2+ concentration, and temperatures (10 and 20 °C). The parameters were controlled and optimized to remove the Mn2+ from synthetic wastewater. Adsorption isotherms of Mn2+ were fitted by...
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The aim of this paper was to study the restraint kinetic of N-NO3 on a sandy soil sampled from Caracal-Olt area. The kinetic study aimed to establish the interdependences between ion exchange-sorption global process and the main factors... more
The aim of this paper was to study the restraint kinetic of N-NO3 on a sandy soil sampled from Caracal-Olt area. The kinetic study aimed to establish the interdependences between ion exchange-sorption global process and the main factors that influence the retention process on sandy soil granule level, N- NO3 concentration and N- NO3 soil load. Theoretical studies present in the speciality literature lead to various kinetic models able to give a satisfactory answer for samples regarding dependence between rate determinative stage of ion exchange process and process parameters. The problem becomes complicate when it is necessary to describe mathematically mutual influence of different elementary stages, solving this kind of problems being impossible with the existing models. In this paper it was presented a methodology by which ion exchange process rate is expressed only based on experimental results, that aren’t influenced by changes of ion exchange mechanism during process. The pres...
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CRISTINA MODROGAN1*, ALEXANDRA RALUCA MIRON1, IRINA PINCOVSCHI2, CRISTINA COSTACHE1, FIRAS HASHIM KAMAR3 1University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, Departament of Analytical Chemistry and... more
CRISTINA MODROGAN1*, ALEXANDRA RALUCA MIRON1, IRINA PINCOVSCHI2, CRISTINA COSTACHE1, FIRAS HASHIM KAMAR3 1University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, Departament of Analytical Chemistry and Environmental Engineering, 1-7 Polizu Str., 011061, Bucharest, Romania 2 University Politehnica from Bucharest, Department of Hydraulics, Hydraulic Machinery and Environmental Engineering, 313 Splaiul Independentei, 060042, Bucharest, Romania
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This study focuses on the preparation and efficient application of natural extract – doped membranes in the removal of nickel ions from synthetically prepared solutions. The experiments were carried out using a laboratory electrochemical... more
This study focuses on the preparation and efficient application of natural extract – doped membranes in the removal of nickel ions from synthetically prepared solutions. The experiments were carried out using a laboratory electrochemical system. The performance of the system was evaluated in terms of Demineralization Rate (DR %), removal efficiency of nickel (R %) and Energy Consumption (EC). The highest values of DR (> 62%) and R (> 67%) occurred for membrane doped with natural extract. The physical and chemical properties of the obtained functional membranes were investigated by FTIR, SEM and TGA. The efficient dispersion of natural extract would provide more accessible active sites, which facilitates the removal of nickel ions from synthetic wastewater. Also, the presence of natural extract minimized thermal degradation of polymer membrane and improved thermal stability of membrane.
Wastewater from fertilizer production contains a considerable amount of nitrogen in the ammonia and NO 3 form. It also contains a certain amount of fluorides, NO 3 - , phosphates, silica and suspended matters [1]. Recent results obtained... more
Wastewater from fertilizer production contains a considerable amount of nitrogen in the ammonia and NO 3 form. It also contains a certain amount of fluorides, NO 3 - , phosphates, silica and suspended matters [1]. Recent results obtained by some investigators refer to the mechanism of NO 2 - enzymatic reduction of the nitrogen oxides. One of the common processes in wastewater treatment, recently used, is the ion exchange [2, 3]. The ion exchange process has been satisfactorily used for municipal water treatment. [4]. As proven by data contained in the specialized literature the ion exchange is a very effective process which can be used in removing NO 3 - from water. This removal procedure can be used in a lot of concentrations. The increased NO 3 - concentration in public water supplies presents a potential health hazard due to the nitrites reduction in the gastrointestinal tract. In its turn, NO 3 - is a potential health hazard to infants [5, 6] and pregnant women due to NO 3 - red...
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The arsenic ions are very toxic and must be extracted from acid waters before their neutralization or recyclation. The depollution of residual waters containing arsenic ions is using, tributylphosphate (TBP) as extractant has been studied... more
The arsenic ions are very toxic and must be extracted from acid waters before their neutralization or recyclation. The depollution of residual waters containing arsenic ions is using, tributylphosphate (TBP) as extractant has been studied at different sulphuric acid concentration in the extractin solutions. The obtained results put in evidence the increase of the extraction degree with the sulphuric acid concentration. The increasing of sulphuric acid concentration determines the increase of the distribution coefficient.
The capacity of ion exchange resins, MN 500 and C100 H, for the removal of copper ions from aqueous solution has been investigated under different conditions, namely: initial solution pH, initial metal-ion concentration and contact time.... more
The capacity of ion exchange resins, MN 500 and C100 H, for the removal of copper ions from aqueous solution has been investigated under different conditions, namely: initial solution pH, initial metal-ion concentration and contact time. The adsorption of Cu(II) on these resins follows the first-order reversible kinetic. The film diffusion of Cu (II) in these ion exchange resins was shown to be the main rate limiting step. The studies showed that these cation exchange resins can be used as efficient adsorbent material for the removal of Cu (II) from aqueous solutions. The adsorption process, which is pH dependent, shows maximum removal of copper in the pH range 2-7 for an initial copper concentration of 10 mg/L. The adsorption rate constants for all these kinetic models have been calculated. Results showed that the intraparticle diffusion and initial Cu(II) sorption into resins was the main rate limiting step. The uptake of copper by the ion exchange resins is reversible and thus ha...
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The goal of the present paper was to synthesize, characterize, and evaluate the performance of the modified composite based on magnetite (Fe3O4) and polyvinyl alcohol (PVA). The obtained composite was used to degrade Methyl Orange dye... more
The goal of the present paper was to synthesize, characterize, and evaluate the performance of the modified composite based on magnetite (Fe3O4) and polyvinyl alcohol (PVA). The obtained composite was used to degrade Methyl Orange dye from synthetic wastewater by a laboratory photocatalytic reactor. Various parameters of the photodegradation process were tested: composite dosage, amount of hydrogen peroxide (H2O2), and pH. The composite was characterized by Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The degradation experiments indicated that the complete dye decolorization depended on the amount of H2O2. In addition, the H2O2 could accelerate Methyl Orange degradation to more highly oxidized intermediates in the presence of UV light (99.35%). The results suggested that the obtained modified composite could be used to treat wastewater containing various types of dyes.
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The main goal of the present paper was to synthesize the polyvinyl alcohol-SiO2 nanoparticles polymeric membrane by wet-phase inversion method. The efficiency of prepared membranes (without and with SiO2) was investigated using a... more
The main goal of the present paper was to synthesize the polyvinyl alcohol-SiO2 nanoparticles polymeric membrane by wet-phase inversion method. The efficiency of prepared membranes (without and with SiO2) was investigated using a versatile laboratory electrodialysis system filled with simulated wastewaters that contain zinc ions. All experiments were performed at following conditions: the applied voltage at electrodes of 5, 10 and 15 V, a concentration of zinc ions solution of 2 g L−1, time for each test of 1 h and at room temperature. The demineralization rate, extraction percentage of zinc ions, current efficiency and energy consumption were determined. The polymeric membranes were characterized by Fourier Transforms Infrared Spectroscopy-Attenuated Total Reflection (FTIR-ATR), Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS). The higher value of percentage removal of zinc ions (over 65%) was obtained for the polymeric membrane with SiO2 nanopart...
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The aim of this work was to investigate the corrosion inhibition effect of natural seaweeds in seawater on carbon steel. The corrosion efficiency of carbon steel in the absence and the presence of natural seaweeds in seawater was... more
The aim of this work was to investigate the corrosion inhibition effect of natural seaweeds in seawater on carbon steel. The corrosion efficiency of carbon steel in the absence and the presence of natural seaweeds in seawater was evaluated by the gravimetric method at room temperature and calculating the corrosion rate and protection degree. The experimental results showed that the corrosion rate on carbon steel decreased when the seaweeds were used. In addition, the value of protection degree (P) was greater than 60% when seaweeds were used. Natural seaweeds reduce the corrosion rate and can be considered an ecofriendly corrosion inhibitor for carbon steel.
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Electro coagulation represents a good alternative to the conventional treatment techniques for dye containing wastewaters. In this paper, electrochemical coagulation efficiency (expressed in terms of colour removal degree) with aluminum... more
Electro coagulation represents a good alternative to the conventional treatment techniques for dye containing wastewaters. In this paper, electrochemical coagulation efficiency (expressed in terms of colour removal degree) with aluminum and iron sacrificial anodes has been ...
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The chemical behavior of groundwater is one of the most dynamic areas of environmental research. In the present study, groundwater sampling from different locations in the central and south-eastern parts of Romania was performed to assess... more
The chemical behavior of groundwater is one of the most dynamic areas of environmental research. In the present study, groundwater sampling from different locations in the central and south-eastern parts of Romania was performed to assess groundwater chemistry and to compare water types using distribution maps. Groundwater chemistry has been evaluated and natural processes are identified as control factors for hydrochemistry. The Piper diagram was created to compare the results of water types. Chemical analysis of groundwater was used to calculate the values of the water quality index. Romanian drinking water Law EPA 458-2002 and WHO standards were taken into account when calculating the WQI. The SAR index was used to evaluate groundwater samples, taken from in the study area, and used for irrigation purposes. The classification of water types based on water quality (WQI) values for each groundwater sample shows that 80% of the analyzed samples can be used as drinking water resource...
The present paper synthesized, characterized, and evaluated the performance of the novel biopolymeric membrane enriched with cellulose acetate and chitosan (CHI)-silver (Ag) ions in order to remove iron ion from the synthetic wastewater... more
The present paper synthesized, characterized, and evaluated the performance of the novel biopolymeric membrane enriched with cellulose acetate and chitosan (CHI)-silver (Ag) ions in order to remove iron ion from the synthetic wastewater using a new electrodialysis system. The prepared membranes were characterized by Fourier Transforms Infrared Spectroscopy-Attenuated Total Reflection (FTIR-ATR), Thermal Gravimetric Analysis (TGA) and Differential Thermal Analysis (DSC), contact angle measurements, microscopy studies, and electrochemical impedance spectroscopy (EIS). The electrodialysis experiments were performed at the different applied voltages (5, 10, and 15 V) for one hour, at room temperature. The treatment rate (TE) of iron ions, current efficiency (IE), and energy consumption (Wc) were calculated. FTIR-ATR spectra evidenced that incorporation of CHI-Ag ions into the polymer mixture led to a polymer-metal ion complex formation within the membrane. The TGA-DSC analysis for the o...
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The realization of some composite materials that allow the best removal of H2S from syngas was the main objective of this work. Thus, the optimization of the technological parameters for obtaining composites based on Zn-Ti was achieved.... more
The realization of some composite materials that allow the best removal of H2S from syngas was the main objective of this work. Thus, the optimization of the technological parameters for obtaining composites based on Zn-Ti was achieved. The paper studies the influence of calcination temperature on the characteristics of the binary ZnO-TiO2 system used to synthesize a composite material with suitable properties to be used subsequently for syngas treatment. The mineralogical and structural analyzes showed that starting with the calcination temperature of 700 °C the material synthetized is composed mainly of zinc orthotitanate which possess the corresponding characteristics to be finally used in the treatment of the syngas for its desulfurization. At this calcination temperature the material has a compact structure most likely due to sintering of the formed titanates. These composites have a texture that places them rather in the category of non-porous materials, the pore volume and th...
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A novel hydrogel composite based on gellan gum and graphene oxide (GG/GO) was synthesized, characterized and tested for sorption capacity in this work. The microstructural, thermogravimetric and spectroscopic analysis confirmed the... more
A novel hydrogel composite based on gellan gum and graphene oxide (GG/GO) was synthesized, characterized and tested for sorption capacity in this work. The microstructural, thermogravimetric and spectroscopic analysis confirmed the formation of the GG/GO composite. Comparative batch sorption experiments revealed a sorption capacity of the GG/GO composite for Zn (II) ions of approximately 2.3 higher than that of pure GG. The GG/GO composite exhibits a maximum sorption capacity of 272.57 mg/g at a pH of Zn (II) initial solution of 6. Generally, the sorption capacity of the sorbents is approximately 1.5 higher in slightly acidic conditions (pH 6) comparative with that for strong acidic conditions (pH 3). The sorption isotherms revealed that the sorption followed a monolayer/homogenous behavior. The sorption kinetic data were well fitted by the pseudo-second-order kinetic model, and were consistent with those derived from sorption isotherms. The intraparticle diffusion was considered to...
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The aim of this work is the study of te adsorption process of some heavy metals like lead, copper, chrome and nickel in agricultural argilaceous soil in order to put in evidence the influence of adsorption conditions on adsoption process.... more
The aim of this work is the study of te adsorption process of some heavy metals like lead, copper, chrome and nickel in agricultural argilaceous soil in order to put in evidence the influence of adsorption conditions on adsoption process. The adsorption isotherms, Langmuir and Freundlich, have been used to describe the adsorption equilibrium. The experimental data put in evidence that the adsoption capacity of heavy metals increases in order Ni2+ (about 110 micromol/g), Pb2+ (about 150 micromol/g), Cr3+ (about 300 micromol/g) and Cu2+(about 350 micromol/g). In all cases, the Langmuir isotherm reflects more exactly the adsorption process, being recomended for thermodynamic parameters determination.
Understanding the absorption behaviour of sulphur dioxide in aqueous electrolyte solutions is of major interest for the design of flue gas desulphurization processes, as for example wet flue gas desulphurization of coal fired power plants... more
Understanding the absorption behaviour of sulphur dioxide in aqueous electrolyte solutions is of major interest for the design of flue gas desulphurization processes, as for example wet flue gas desulphurization of coal fired power plants or municipal solid waste incineration plants. In the present paper the influence of the water salinity on SO2 absorption is studied. The SO2 absortion was performed in equilibrium condition. The variation of marine solubility from 10 g/L to 40 g/L determines the variation of SO2 concentration in water from 2.6 mol/L to about 3.2 mol/L. In consequence, the variation of water salinity in these limits can detemine a quite big difference of water pollution.
This work is devoted to examine the effectiveness of the different commercial liquid additives for fish (sweet corn and molasses) on corrosion of mild steel in natural water by different methods (gravimetric and potentiostatic... more
This work is devoted to examine the effectiveness of the different commercial liquid additives for fish (sweet corn and molasses) on corrosion of mild steel in natural water by different methods (gravimetric and potentiostatic polarization) at room temperature. The corrosion tests were employed to evaluate corrosion rate (CR) and inhibition efficiency (IE %). The maximum inhibition efficiency was obtained for the inhibitor type molasses of 90.00% by gravimetric method for a period of 3 hours and over 31 % by potentiostatic polarization method. It was found that the commercial liquid additives acted as a good inhibitors for the tested environment. Furthermore, the corroded metal was observed by metallographic microscope.
The adsorption of cadmium and zinc ions from waste waters in agricultural argilaceaus soils have been studied, using a thermodynamic method in order to put in evidence the influence of adsorption conditions on adsorption degree. The... more
The adsorption of cadmium and zinc ions from waste waters in agricultural argilaceaus soils have been studied, using a thermodynamic method in order to put in evidence the influence of adsorption conditions on adsorption degree. The adsorption isotherms, Langmuir and Freundlich, have been used to describe the adsorption equilibrium. The experimental data put in evidence that Cd2+ ions are more adsorbable (about 300 mmol/g) than Zn2+ ones (about 200 mmol/g). The Langmuir isotherms reflect more exactly the adsorption process of both Cd2+and Zn2+ ions, being recommended for thermodynamic parameters determination.
In the present work, the mass transfer characteristics such as the lenght of mass transfer unit (LMTU), the break through time and column saturation time have been studied in the case of sulphur dioxide adsorption on 13 X zeolite. The... more
In the present work, the mass transfer characteristics such as the lenght of mass transfer unit (LMTU), the break through time and column saturation time have been studied in the case of sulphur dioxide adsorption on 13 X zeolite. The adsorption column was working in unsteady-state conditions. For these determinations a chromatographic method has been used, permiting the direct inregistration of breakthrough curves, whose shape depends on adsorption conditions (gas concentration, temperature, the size of adsorbent grains, gas velocity). The method is very sensitive, reflecting all changes of adsorption parameters.
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ABSTRACT In the present work depollution of residual acid waters containing cadmium ions is presented. For depollution the tributylphosphate (TBP) as extractant has been used. The cadmium ions are very toxic and must be extracted from... more
ABSTRACT In the present work depollution of residual acid waters containing cadmium ions is presented. For depollution the tributylphosphate (TBP) as extractant has been used. The cadmium ions are very toxic and must be extracted from acid waters before their neutralization or recyclation. Different parameters affecting the extraction of cadmium ions as hydrochloric acid concentration and water-extractant rate have been studied. The obtained results put in evidence the big influence of hydrochloric acid concentration on cadmium extraction degree. The increasing of the HCl concentration determines the increasing of distribution coefficient.