WO2016159801A1

WO2016159801A1 - Polymer inclusion membrane and method of preparation thereof

Info

Publication number: WO2016159801A1
Application number: PCT/PL2015/000081
Authority: WO
Inventors: Krystian EITNER; Elzbieta RADZYMINSKA-LENARCIK; WIodzimierz URBANlAK; Katarzyna WITT
Original assignee: Uniwersytet Technologiczno-Przyrodniczy
Priority date: 2015-03-31
Filing date: 2015-05-19
Publication date: 2016-10-06
Also published as: PL231714B1; EP3277413A1; PL411839A1

Abstract

The subject of the invention is polymer inclusion membrane and method of preparation thereof, wherein solution containing polymer is poured on the surface and after which the solvent is removed. Polymer inclusion membrane characterised in that, it consists of poly(vinyl chloride) modified with diketone groups, where up to 80% of chloride group is substituted with β-diketone groups, optionally containing 20-60% wt., preferably 25-40% wt. of plasticizer, especially from groups of higher organic esters. Method of preparation of polymer inclusion membrane, where solution containing polymer is poured on the surface, after which solvent is removed, characterised in that, a poly(vinyl chloride) is used as a polymer, in which 80% of chloride groups is substituted with β-diketone groups, and tetrahydrofuran as a solvent, wherein optionally 20-60% wt., preferably 25-40% wt. of plasticiser, especially from the group of higher organic esters, is added into the polymer solution.

Description

Polymer inclusion membrane and method of preparation thereof

The subject of the invention is polymer inclusion membrane and method of preparation thereof, wherein solution containing polymer is poured on the surface and after which the solvent is removed.

To extract and separate metal ions from aqueous solutions more frequently liquid membranes are utilized both in laboratory conditions as in industrial processes. Liquid membrane as a hydrophobic organic liquid separates two aqueous phases. Characteristic feature of liquid membranes is simultaneous presence of steps equivalent to extraction and reextraction, a result of which process is conducted continuously, wherein ions from feed solution are "translocated" to receiving solution [Chemical separation with liquid membranes, R. A. Bartsch, J. D. Way (Eds.), American Chemical Society, Washington, DC (1996)]. One of the types of liquid membranes are Supported Liquid Membranes (SLMs) and Polymer Inclusion Membranes (PIMs). Essential element of SLM type membrane is solid porous barrier saturated with solution of ion carriers and separating both aqueous phases. This barrier prevents mixing of aqueous solutions simultaneously enabling ion transport between aqueous phases. Synthetic materials such as: polypropylene, teflon, polyamides, polyvinyl chloride) and modified cellulose are materials for preparing this type of membranes. Thickness of synthetic material layer ranges from 10 to 150 pm and size of pores is restricted between 0.01 to 1 pm [R. W. Baker, Membrane technology and application, Wiley, 2012, Walkowiak W., Kozlowski C. (2009). Macrocycle carriers for separation of metal ions in liquid membrane processes - a review, Desalination, 240, 186-197].

Polymer inclusion membranes - PIMs, are membranes formed using method of solution pouring, which is a mixture of polymer and liquid organic phase. In this case highly plasticised polymer is utilized as a solvent [M. Sugiura, Coupled-ion transport through a solvent polymeric membrane, J. Colloid Interface Sci., 81 (1981 ) 385]. Polymer selection for polymer inclusion membrane (PIM) synthesis is more limited than in case of supported liquid membranes (SLMs), because polymers must be highly soluble in low boiling solvents and have high affinity to plasticisers, in which ion carriers are dissolved.

Most frequently, cellulose triacetate or polyvinyl chloride) described as PVC is utilized in inclusion membrane synthesis, wherein cellulose triacetate membrane has higher hydrophilic properties than PVC membrane. The vast majority of research in supported liquid membrane (SLM) and polymer inclusion membrane (PIM) field is focused on development of new ion carriers, substances specifically reacting with ion metals and reconstituted in plasticiser, wherein most frequently these are high molecular weight compounds, compounds with strong complexing properties, such as crown ethers, acyclic polyethers, organophosphorus compounds, amines, imidazoles etc.

In case of PVC, as a plasticizers typical plasticizers for processing of this polymer, for example esters of phthalic acid, esters of phosphoric acid, nitrophenyl alkyl ethers, adipates are used.

According to the invention, polymer inclusion membrane consists of polyvinyl chloride) modified with diketone groups, where up to 80% of chloride group is substituted with β-diketone groups, optionally containing 20-60% wt., preferably 25-40% wt. of plasticiser, especially from groups of higher organic esters.

Essence of the invention is also method for preparation of polymer inclusion membrane, in which solution containing polymer is poured on the surface and next solvent is removed. It is based on the usage of polyvinyl chloride) as a polymer, in which 80% of chloride groups is substituted with β- diketone groups and tetrahydrofuran as a solvent, wherein optionally 20-60% wt. preferably 25-40% wt. of plasticiser, especially from the group of higher organic esters, is added into the polymer solution.

Polyvinyl chloride) utilized in the invention, in which 80% of chloride groups is substituted with β-diketone groups, is prepared by replacement of chloride atoms by iodine atoms in suspensive polyvinyl chloride) in a powder form with 0.05-0.25 mm, preferably 0.08-0.18 mm granulation with a known method. Subsequently, according to the invention iodinated polyvinyl chloride) is suspended in low boiling ketone, preferably in acetone or methyl-ethyl ketone, after which sodium or potassium acetylacetonate is added. Reaction is conducted in temperature of about 25°C with continuous stirring for at least 24 h, after which product is filtered and washed with distilled water in order to remove soluble iodides.

In second variant polyvinyl chloride), where up to 80% of chloride groups is substituted with β-diketone groups, is prepared by stirring and heating with reflux in 20°C up to 50°C, preferably 40°C, for 1 to 24 hours, preferably 2 hours, of mixture consisting of suspensive polyvinyl chloride) in form of powder with resin size of 0.05-0.25 mm, preferably 0.08-0.18 mm, sodium or potassium iodide and low-boiling ketone, preferably acetone or methyl-ethyl ketone. Subsequently, to solution sodium or potassium acetyloacetonate in acetone or methyl-ethyl ketone is added and heated in temperature 20°C up to 50°C, preferably 40°C with continuous stirring, for 1 to 24 hours, preferably for 4 hours, after which product is filtered and washed with distilled water in order to remove soluble iodides.

Essential feature of modified polymer used in the invention is that the vast majority of β-diketone groups is connected to the polymer chain via methylene group of β-diketone (C-substitution), and not via oxygen of carbonyl group (O-substitution), thus giving to the membrane according to the present invention metal ion complexing (chelating) properties. Up to now no polymers prepared by PVC modification containing chelating diketone groups were described. Membrane used in the invention is characterised by strong sorption properties. Can be used for capturing of metal ions, especially zinc and copper. Method of preparing membrane according to the present invention also influences the complexing properties of the membrane.

After dissolving of PVC modified according to the invention in tetrahydrofuran (THF), and subsequent pouring into open vessel and evaporation of solvent, a thin membrane is obtained, which shows properties of complexing metal ions from solution and especially strong alkaline ammonium solutions. Addition of plasticizer from group of organic esters, preferably bis(2- ethylhexyl) adipate to the polymer solution in amount of 20-60% wt., preferably 25-40% wt., and further evaporation of solvent, leads to the preparation of elastic, thin membrane, with highly increased properties of metal ion capturing from the solution, especially zinc and copper ions, with highly preferable separation coefficients S Cu(ll)/Zn(ll) - circa 7.3.

Ion complexing reaction is reversible, i.e. metal ions are washed out of the membrane by acidic solutions, what enables usage of prepared membranes in membrane processes.

The invention is illustrated by following examples.

Example I

Into 750 cm³ volume round-bottomed flask equipped with a magnetic stirrer 10 g of suspensive polyvinyl chloride) (POLANVIL) in form of powder of 0.08-0.18 mm beads size and 250 cm³ of acetone was introduced. 36 g of sodium iodide solution in 250 cm³ of acetone was added to the obtained suspension and kept in temperature of circa 25°C for 24 hours. Subsequently, 200 mL of water was added to the reaction mixture, flask content was filtered and precipitate was washed with 500 mL of water. Washed precipitate was air- dried for at least 24 hours. For slightly flesh-coloured obtained product it was found using XRF method, that a significant part (over 80%) of chlorine atoms was substituted with iodine.

Then, prepared iodinated polymer was suspended in 400 mL of acetone and 30 g of sodium acetylacetonate was added with stirring in temperature of circa 25°C for 24 h. Product was filtered and washed with distilled water in order to remove sodium iodide.

Iodine was not observed in XRF spectrum. In IR spectrum with bands characteristic for PVC there were also observed bands characteristic for carbonyl group (1723 cm^"1) and OH group (1770 cm^"1) of enol form of diketone indicating, that iodide atoms were substituted with diketone group.

Example II

In 750 cm³ volume round-bottomed flask equipped with a magnetic stirrer 10 g of suspensive polyvinyl chloride) (POLANVIL) in form of powder of 0.08- 0.18 mm beads size and 400 cm³ of methyl-ethyl ketone (MEK) and 45 g of potassium iodide (Kl) were introduced. Mixture was heated under reflux in temperature of 40°C for 2 hours, and subsequently suspension of 35 g potassium acetylacetonate in 100 cm³ MEK was added and heated in temperature of 45°C under reflux for 4 hours. After completing the reaction precipitate was filtered, washed with water and dried analogously as in example I. Slightly flesh-coloured obtained product, in which it was found using XRF method, that circa 60% of chloride groups was substituted, no iodine presence was observed and in IR spectrum characteristic bands for diketone groups were observed.

Example III

0.12 g of modified PVC according to the example I was dissolved in 10 cm³ of tetrahydrofuran (THF) and such prepared homogeneous, clear solution was poured on levelled 10 cm diameter Petri dish. After solvent evaporation clear, quite rigid membrane was formed. From obtained membrane fragment with mass of 0.01 g was excised and covered with solution of zinc copper. After 24 hours amount of metals in solution was determined and it was calculated that 1 g of membrane binds 2,1 5x10^"5g of Zn and trace amounts of Cu.

Example IV

Analogously as in example III membrane was prepared using 0.12 g of polymer from example II and 0.05 g of plasticizer - ADO, bis(2-ethylhexyl) adipate. From obtained elastic membrane fragment with mass of 0.03 g was excised and covered with 2 cm³ solution of zinc copper as in example III. After 24 hours amount of metals in solution was determined and it was calculated that 1 g of membrane binds 5.852x10^" g of Cu and 7.729x10^"4 Zn.

Claims

1. Polymer inclusion membrane characterised in that, it consists of polyvinyl chloride) modified with diketone groups, where up to 80% of chloride group is substituted with β-diketone groups, optionally containing 20-60% wt, preferably 25-40% wt. of plasticizer, especially from groups of higher organic esters.

2. Method of preparation of polymer inclusion membrane, where solution containing polymer is poured on the surface, after which solvent is removed, characterised in that, a polyvinyl chloride) is used as a polymer, in which 80% of chloride groups is substituted with β-diketone groups, and tetrahydrofuran as a solvent, wherein optionally 20-60% wt., preferably 25-40% wt. of plasticiser, especially from the group of higher organic esters, is added into the polymer solution.

3. Method according to the claim 2, characterised in that the polyvinyl chloride), in which up to 80% of chloride groups is substituted with β- diketone groups, is prepared by known method of chloride atom substitution for iodide atoms in suspensive polyvinyl chloride) in form of powder with 0.05-0.25 mm, preferably 0.08-0. 8 mm granulation, after what obtained iodinated polyvinyl chloride) is suspended in low-boiling ketone, preferably acetone or methyl-ethyl ketone, then sodium or potassium acetylacetonate is added and reaction is conducted in 25°C with continuous stirring for at least 24 h, after what product is filtered and washed with distilled water in order to remove soluble iodides.

4. Method according to the claim 2 characterised in that, polyvinyl chloride), in which up to 80% of chloride groups is substituted with β- diketone groups, is prepared by mixing and heating with reflux in temperature of 20°C up to 50°C, preferably, 40°C, for 1 to 24 h, preferably 2 hours, of mixture consisting of suspensive polyvinyl chloride) in form of powder of 0.05-0.25 mm, preferably 0.08-0. 8 mm beads size, sodium or potassium iodide, low-boiling ketone preferably acetone or methyl-ethyl ketone, preferably from group of higher organic esters, next sodium or potassium acetylacetonate is added to the mixture and during continuous mixing is heated in temperature of 20°C up to 50°C, preferably 40°C, for 1 to 24 hours, preferably for 4 hours, and then the product is filtered and washed with distilled water in order to remove soluble iodides.