Papers by Keyword: Nanofiltration

Abstract: The aim of this research is to investigate the removal behavior of iron and manganese that naturally exist as divalent ions in groundwater by using nanofiltration membranes. The main focus of this study is to better understand the effect of applied pressures during the rejection of these metallic ions from synthetic groundwater in order to achieve drinking water standard. Polyamide and polypiperazine amide nanofiltration membranes denoted as PA-NF and PPA-NF were selected to investigate the iron and manganese rejection at low applied pressures (1-5 bar). In single solute solution with feed concentration at 10 mg/L and initial pH of 6.8 ± 0.5, the rejection of iron was ≥96% by PA-NF membrane at applied pressure of 2 bar. However, the rejection percentage by PPA-NF was 86.6% whereby this membrane unable to remove iron to the allowable drinking water standard. The rejection of manganese with single solute at concentration of 1 mg/L with initial pH of 6.8 ± 0.5 by using the PA-NF membrane was ≥98% and almost all of dissolved manganese were rejected at 5 bar. However, manganese removal by PPA-NF membrane was found less than 70% for all of the applied pressures. Findings from this work showed that the removal of iron and manganese were dependent on the applied pressures. PA-NF membrane able to remove both metallic ions that comply with the drinking water standard. The increased of applied pressure contributed to concentration polarization effect on the membrane surfaces leading to a decrease in solute rejection by decreasing the charge effect mainly for the iron removal from synthetic groundwater.

Abstract: Composite membranes were prepared for nanofiltration of aromatic solvents. Cross-linking with AlCl₃ was used to improve the stability of the PIM-1 selective layer in aromatic solvents like toluene, benzene and xylene. Nanofiltration performances of obtained membranes were tested with 4 different aromatic hydrocarbons and with 3 solvents from other classes of solvents. Obtained permeability for aromatic hydrocarbons was above 8,5 kg/m²·h·bar and retention of Remazol brilliant blue R dye with molecular mass 626 was up to 96 %. It was shown that permeability results correlated with Hansen solubility parameter and distance parameter between polymer and solvent. PIM-1 has higher permeability for non-polar hydrocarbons due to higher affinity between polymer and solvent.

Abstract: One of the modern methods of water demineralization and softening for domestic and drinking purposes as well as for its preparation in industrial production is a reverse osmosis. This demineralization method is peculiar for its concentrates that are formed due to reverse osmosis membranes and nanofiltration technologies, the utilization of which continues to be an unresolved problem. The article deals with the solution of such problem to utilize those concentrates, which are obtained using reverse osmosis and nanofiltration units. In this regard, it seems promising to reduce the volume of technological concentrate at the first stage by its repeated concentration according to nanofiltration - reverse osmosis scheme. After that, the nanofiltration concentrate containing predominantly divalent Са²⁺, Mg²⁺ and SO₄^2- ions is subjected to reagent treatment in the following sequence: first stage with barium compounds and second stage with carbonate and sodium hydroxide. Such sequence allows separating from the solution at the first stage practically insoluble BaSO₄ with its precipitation in the 1^st stage vortex reactor and, further precipitation of slightly soluble in alkaline medium CaCO₃ and Mg (OH)₂ in the ІІ stage reactor. These insoluble BaSO₄, CaCO₃ and Mg (OH)₂ salts thrown off the mass balance are finally dehydrated using a filter press and subjected to subsequent sale as a market product or raw material. The obtained solution of sodium chloride is concentrated by 3-stage reverse osmosis resulting in a 0.8-1.0% aqueous solution (8-10 g/l) of sodium chloride solution, a high-grade raw material for the production of electrolytic sodium hypochlorite with 4-6 g/l concentration by chlorine equivalent.

Abstract: Interfacial polymerization of a thin film composite (TFC) layer on top of a miroporous support membrane or other porous substrate is one of adequate method to form nanofiltration membrane in order to remove humic acid. Ultrafiltration (UF) polyethersulfone (PES) was used as membrane base support. Reaction occurred on the surface of membrane between two phase which are triethanolamine (TEOA) and trimesoyl chloride (TMC) as aqueous solution and organic solution respectively. Membrane that produced characterized by permeability, charged solutes rejection including salt solutions (NaCl and Na₂SO₄₎ and humic acid removal. Properties of membrane can be attributed with the changes of monomer concentration and reaction time. Pure water flux J_w for membranes calculated as a function of applied pressure to membrane ΔP. Thus, flux increased linearly with operating pressure is applied to membrane where meets Hagen-Poiseuille equation and gradient of every straight line give pure water permeability data. The variation of reaction time (15, 25 and 35 min) at 8% (w/v) monomer concentrations can affect the properties of the membrane produced and decreasing water permeabilities. The rejection order of the membrane changed from 0.001 M Na₂SO₄ > 0.1M Na₂SO₄> 0.001M NaCl > 0.1M NaCl. Humic acid removal resulted almost fully rejection showed that nanofiltration membrane is one of the best methods in water treatment technology.

Abstract: This paper presents artificial neural network (ANN) predictions for a nanofiltration membrane used to treat wastewater of welding electrode manufacturing in a cross flow set up. The main parameters were time, feed flow rate, and transmembrane pressure (TMP). The experimental data were correlated and analyzed using ANN. ANN’s prediction of the permeate flux, turbidity, total dissolved solids (TDS), hardness for various TMPs, and flow rates are discussed. The effects of the training algorithm, neural network architectures, and transfer function on the ANN performance, as reflected by the percentage average absolute deviation, are discussed. A network with one input layer, 50-100 hidden layers, and one output layer is found to be adequate for mapping input–output relationships and providing a good interpolative tool. A good agreement has been obtained between the ANN predictions and the experimental data with a deviation below 2% for all cases considered.

Abstract: Nanofiltration membrane was prepared by static layer-by-layer (LBL) self-assembly of poly (ethyleneimine) (PEI) and poly (sodium 4-styrenesulfonate) (PSS) on the modified poly-arcylonitrile ultra-filtration membrane. Study on self-assembly of polyelectrolyte membranes with changing surface charges and wettability, rejection properties of nanofiltration membrane in different conditions and pH with respect to heavy metal ions, namely Ni²⁺ and Cd²⁺were investigated. The results show that the PEI/PSS membrane composed of 4 bilayers at operating pressure 0.4MPa, rejection of PAN-PEI/PSS nanofiltration membrane towards these 2 kind of heavy metal ions reached no less than 90%.

Abstract: The potential hazard effects of Endocrine Disruptors (EDCs) are drawing growing attention from the public,and the traditional sewage water treat process works in an unstable way in the removal of EDCs and can be influenced by many factors.The membrane technology shows good interception efficiency of EDCs,and the photocatalytic oxidation,with its wide application range of different types of polluted water,can thoroughly convert EDCs to inorganic materials.The combination process of nanofiltration and photocatalytic oxidation can easily extract EDCs from the water at first step,and decompose the EDCs in the concentrated polluted water and the back fluch water collected at the second step.The combination process is a reliable,practical and effective methods for EDCs removal.

Abstract: The objective of this work is to study the removal of acetate from succinate in an aqueous solution by dead-end nanofiltration. The effect of applied pressure under 40, 50 and 60 psi on the separation between both solutes was investigated. Experiments with a HL4040FM membrane were evaluated using various synthetic solutions, i.e. single-solute solutions of potassium acetate and potassium succinate and mixed-solute solutions containing both solutes. In single-solute solution, the retentions of acetate and succinate salts increase with increasing in applied pressures. At each applied pressure the retention of acetate salt decreases with time while the retention of succinate salt declines to a constant. In mixed-solute solutions, in presence of succinate anion, the retention of acetate anion is significantly lower than those observed in single-solute solution even showing negative value. The lower retention of acetate can be well described by the facilitated transport of the monovalent anion due to pumping effect and electroneutrality in the presence of a divalent anion. It was expected that removal of acetate by-product from succinate solution with HL4040FM in dead end filtration was possible.

Abstract: Adsorption is ubiquitous during nanofiltration filtering which leading to overestimation of retention with adsorption interpreted as some of the initial retention. The adsorption of four phthalates (PAEs) (dietyl (DEP), di-n-butyl (DBP), dicyclohexyl (DCHP) and di-2-ethylohexyle (DEHP)), in different water matrices (Milli-Q water, simulated water and river water) by nanofiltration (NF) was examined using two types of nanofiltration membranes (NF90 and NF70). PAEs was added to different water matrices with concentration of 100 μg/L. The adsorption removal was calculated through mass balance during laboratory-scale cross-flow NF membrane rig working. The results showed that adsorption of PAEs on membranes was related to membrane pore size, substance characteristics, and coexisting nature organic matter (NOM). No significant effect of the PAEs concentration was observed. The order of adsorption removal in all water matrices was DCHP > DEHP > DBP > DEP. In Milli-Q water, the adsorption of PAEs decreased with increase of pH. The humic acid (HA) added in the simulated water increased the adsorption of PAEs on NF90 but decreased that on NF70, and the ions (K⁺, Ca²⁺) added in the simulated water affected the adsorption by influencing membrane structure, HA structure and interaction between membrane and HA, and the same result was obtained in the river water.

Abstract: To date, membrane technology is of great concern while conventional processes are not able to fulfill prosperous separation. The presence of EDCs in the environment indicates that conventional treatment plants (CTPs) may have limited capability to remove these compounds. Membrane process such as membrane bioreactors (MBRs), nanofiltration (NF) and reverse osmosis (RO) can produce high quality effluents suitable for reuse applications. Membrane bioreactor (MBR) technology is a promising method for water and wastewater treatment because of its ability to produce high-quality effluent that meets water quality regulations. This paper aimed to provide a review of recent research on feasibility of membrane technology such as MBR, NF and RO and also their application to remove EDCs and PhACs from aqueous solution which are highly harmful and toxic. The major factors which exert influence on the separation of these organic micropollutants have been also studied.