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The Effect of Mineral Salt on Reactive Dye Removal from Aqueous Solutions by Ultrafiltration

Ahmed Arif Eftekhar, Majewska-Nowak Katarzyna, Grzegorzek Martyna, Szymanek Igor

Journal of Ecological Engineering

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2022

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Vol. 23, nr 10

239--247

EN

The effect of mineral salt on the reactive dye removal was evaluated by using flat ultrafiltration (UF) membranes made of polyethersulfone (PES) and regenerated cellulose (C). Five reactive dyes varied in molecular weight (Reactive Orange 16, Remazol Brilliant Blue R, Reactive Orange 20, Reactive Black 5, Reactive Read 120) were used in the UF experiments. The applied membranes were characterized by the cut-off value equal to 10 kDa. The ultrafiltration process was performed in a dead-end mode under the transmembrane pressure of 0.2 MPa. Dye concentration in model solutions was equal to 100 mg/dm3. Two various mineral salts (NaCl and Na2SO4) were chosen to simulate the composition of dye-house baths. The concentration of monovalent and divalent salt in model dye solutions amounted to 1–2 g/dm3. Transport and separation properties of the UF membranes towards reactive dyes and mineral salts were evaluated. It was found that the separation efficiency of all tested dyes was dependent on the mineral salt presence. The effect of mineral salt on dye retention was more pronounced for membrane made of regenerated cellulose (C) than for polyethersulfone membrane (PES). In the case of the C membrane the dye retention coefficients varied in the wide range – from 55 to 83%, whereas for PES membrane the degree of dye separation was less diverse and amounted to 81–96%. The presence of mineral salt in water and dye solutions generally worsen the membrane permeability due to osmotic pressure increase as well as enhancing adsorptive fouling of dye particles in membrane matrix.

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Removal of reactive dyes from aqueous solutions using ultrafiltration membranes

Ahmed Arif Eftekhar, Majewska-Nowak Katarzyna, Grzegorzek Martyna

Environment Protection Engineering

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2021

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Vol. 47, nr 3

109--120

EN

The removal of five reactive dyes varying in molecular weight (Reactive Orange 16, Remazol Brilliant Blue R, Reactive Orange 20, Reactive Black 5, Reactive Red 120) was evaluated by using flat ultrafiltration membranes made of polyethersulfone (PES) and regenerated cellulose (C) characterized by various cut-off values (5, 10, and 30 kDa). The ultrafiltration process was performed in a dead-end mode under the transmembrane pressure range of 0.05–0.2 MPa. Dye concentration in model solutions was equal to 100 mg/dm3. The separation efficiency of all tested dyes was strongly dependent on the membrane type and the membrane cut-off, as well as on the applied pressure. Unexpectedly, the molecular weight of the tested reactive dyes had a minor impact on the dye removal effectiveness. The ultrafiltration membranes made of polyethersulfone and regenerated cellulose can be used in reactive dye removal on the condition that the membrane cut-off is not higher than 10 kDa. The PES and C membranes enable the separation of reactive dyes by 80–97%, and 45–89%, respectively.

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Nanofiltration usage for fluoride removal in the sodium chloride presence

Grzegorzek Martyna

Archives of Environmental Protection

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2021

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Vol. 47, no. 4

98--108

EN

Fluorine and sodium chloride are common elements present in the water environment. According to WHO guidelines fluoride content in water cannot be not higher than 1.5 mF-/dm3. Elevated fluoride content was observed all over the world and it leads to many health issues. It can be removed with the usage of various methods (ion exchange, membrane processes, adsorption, precipitation). In this paper fluoride removal with nanofiltration usage was described. Tests were performed with the application of Amicon 86400 filtration cells. Two types of commercial nanofiltration membranes NP010P and NP030P (Microdyn Nadir) were used. Transmembrane pressure was established as 0.3 MPa. For lower fluoride concentrations (5 mgF-/dm3) NF process allowed to decrease fluoride content under level 1.5 mgF-/dm3. Removal efficiency decreased with increasing fluoride content. Membrane NP030P showed better separation properties. Sodium chloride influenced removal efficiency as well as fluoride adsorption on/in membranes during the process. According to obtained data, better hydraulic properties exhibited membrane NP010P. For both membranes decrease in permeate flux in comparison to pure water was noticed what was observed. Relative permeability was lowered even to 0.32.

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The effect of nitrate on fluoride removal by batch electrodialysis

Ahmed Arif Eftekhar, Grzegorzek Martyna, Majewska-Nowak Katarzyna

Environment Protection Engineering

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2019

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Vol. 45, nr 4

87--101

EN

Fluoride and nitrate are common pollutants in drinking water and their presence deteriorates the quality of drinking water. According to WHO guidelines, the fluoride content in drinking water cannot be higher than 1.5 mg F–/dm3. The purpose of this paper was to evaluate the efficiency of fluoride removal from model aqueous solutions under the presence of nitrate. The experiments were conducted with the use of laboratory installation PCCell BED-1 System at a constant current density (0.78, 1.72, and 2.34 mA/cm2) with the use of monovalent selective ion-exchange membranes. The influence of initial nitrate concentration (15, 30, 45 mg NO3 – /dm3) and initial fluoride concentration (5, 10, 15 mg F–/dm3) on the process performance was studied. The degree of desalination varied from 85 to 91.7% depending on the solution composition and the applied current density, whereas the fluoride removal was in the range of 70–90%. The presence of coexisting NO3 –ions in fluoride solutions improved process efficiency in view of fluoride removal by batch electrodialysis.