TREATING VINYL AROMATIC RESIN

Abstract

Provided is a method of treating a vinyl aromatic resin (I) comprising (a) bringing the vinyl aromatic resin (I) into contact with an alcohol, and maintaining the contact between the vinyl aromatic resin (I) and the alcohol for 10 minutes or more, and (b) bringing the vinyl aromatic resin into contact with a base. wherein the vinyl aromatic resin (I), prior to steps (a) and (b), has benzyl chloride groups,
benzyl alcohol groups, and methylene bridge groups.

Claims

1. A method of treating a vinyl aromatic resin (I) comprising (a) bringing the vinyl aromatic resin (I) into contact with an alcohol, and maintaining the contact between the vinyl aromatic resin (I) and the alcohol for 10 minutes or more, and (b) bringing the vinyl aromatic resin into contact with a base. wherein the vinyl aromatic resin (I), prior to steps (a) and (b), has benzyl chloride groups, benzyl alcohol groups, and methylene bridge groups.

2. The method of claim 1, wherein the alcohol is an alkyl alcohol having 1 to 4 carbon atoms.

3. The method of claim 1, wherein the base is an alkali metal hydroxide.

4. The method of claim 1, wherein step (a) is performed before step (b).

Description

EXAMPLE 1: TREATED RESIN-I

[0070] The procedure for treating Resin-I was as follows. 300 mL of wet Resin-I was added to a round bottom flask equipped with a temperature probe, reflux condenser, and overhead stirrer. 300 mL of methanol was added and stirred for a Methanol Soak Time of 1-8 hours at room temperature (approximately 23 C.) open to the atmosphere. The methanol was decanted and 300 mL of 10% aq. NaOH was added and heated to 90 to 95 C. over 1 hours and held at reflux for a Caustic Reflux Time of 4-8 hours. The reaction was cooled to room temperature (approximately 23 C.) and the resin was isolated.

[0071] The chlorine content of resins was measured by neutron activation analysis (NAA) before and after the treatment process. The NAA method used was as follows.

[0072] Before treatment, Samples were prepared by transferring approximately 4 grams of the resin into pre-cleaned 2-dram polyethylene vials. Standard aliquots of Cl were prepared by transferring appropriate amounts of a NIST-traceable chlorine standard solution into similar vials. The standards were diluted to the same volume as the samples using pure water. A blank sample, containing the pure water only, was also prepared. The vials were heat-sealed. The samples, standards and the blank were then analyzed for chlorine by neutron activation analysis (NAA), as follows. The samples were irradiated for 10 minutes at 3 kW of reactor power. After a waiting time of 10 minutes, the gamma spectroscopy was done for 400 seconds each. These spectra were used to analyze for chlorine. The elemental concentrations were calculated using these spectra, the Canberra software and the standard comparative technique.

[0073] After treatment, samples were prepared by transferring approximately 7 grams of the water sample into pre-cleaned 2-dram polyethylene vials. Standard aliquots of Cl were prepared by transferring appropriate amounts of a NIST-traceable chlorine standard solution into similar vials. The standards were diluted to the same volume as the samples using pure water. A blank sample, containing the pure water only, was also prepared. The vials were heat-sealed. The samples, standards and the blank were then analyzed for Cl by NAA as follows. The samples were irradiated for 40 minutes at 250 kW of reactor power. After a waiting time of 10 minutes, the samples were transferred into un-irradiated vials and the gamma spectroscopy was done for 400 seconds each. These spectra were used to analyze for chlorine. The elemental concentrations were calculated using Canberra software and standard comparative technique.

[0074] Eight different batches of Resin-I were treated as described above. Chlorine content was determined before and after treatment (Tmt). Results were as follows:

TABLE-US-00001 Chlorine Content (ppm by weight based on resin weight) Chlorine Methanol Caustic Treated Before Soak Reflux Chlorine Resin Tmt (ppm). Time (hr) Time (hr) After Tmt (ppm) Resin-e 12550 8 4 1980 Resin-f 55550 1 7 2280 Resin-g 43000 1 7 2320 Resin-h 43000 8 4 2650 Resin-a 43000 8 7 3250 Resin-b 43000 0.sup.(1) 7 5600 Resin-i 15250 1 7 8689 Resin-d 12550 1 4 9407 Note .sup.(1)methanol was decanted immediately after resin and methanol were brought together and then stirred.

[0075] In each resin, the treatment significantly reduced the chlorine content. Also, all the untreated resins had chlorine content above 10,000 ppm, while after treatment all the resins had chlorine content of below 10,000 ppm.

[0076] Comparison of resins a, b, g, and h, which all had 43,000 ppm of chlorine at the outset, shows that methanol soak time of 0 had the least effectiveness at removing chlorine.

[0077] The amounts of various chemical groups were studied by nuclear magnetic resonance (NMR) spectroscopy. .sup.13C NMR spectra were obtained at ambient temperature on a Bruker Avance III 400WB spectrometer operating at 100.6 MHz with a 4.0 mm MAS triple resonance broadband probe. The resins were spun at 14.0 kHz in a 4.0 mm zirconia rotor with a Kel-F cap. .sup.13C chemical shifts were externally referenced to adamantane. Cross polarization magic angle spinning (CP-MAS) spectra were acquired with a .sup.1H 90 pulse length of 2.3 s, 2 ms contact time, 3.0 s recycle delay, and approximately 1500-7500 transients. The acquisition time was 20.5 ms with a spectral width of 50 kHz. CP-MAS spectra were processed with 25 or 50 Hz exponential line broadening. The resins were placed under vacuum (approximately 10 Torr) for 24 hours prior to analysis. Resins are characterized as being tested either before or after treatment. Results were as follows:

TABLE-US-00002 TABLE 1 Functional Group Ratios Resin Treatment ratio REB.sup.(2) ratio RAB.sup.(3) Resin-a after 0.0165:1 0.0166:1 Resin-b after 0.0125:1 0.0271:1 Resin-c after 0.0124:1 0.0292:1 Resin-d after 0.0094:1 0.0221:1 Resin-I.sup.(4) before 0:1 0.0666:1 Note .sup.(2)mole ratio of benzyl ether groups to methylene bridge groups Note .sup.(3)mole ratio of benzyl alcohol groups to methylene bridge groups Note .sup.(4)Reference Example

[0078] The treated resins all had significant amount of benzyl ether groups, while the untreated reference resin had no benzyl ether groups.

EXAMPLE 2: PERFORMANCE OF RESINS

[0079] Cobalt oxide nanopowder was 1720HT from Nanostructured and Porous Materials, Co.sub.3O.sub.4 powder, 99% purity, particle size 50-80 nm.

[0080] For the mixed bed of ion exchange resins, the following were used: [0081] AMBERLITE IRN78 resin=strong base gel type polystyrene anion exchange resin, supplied by Dow Chemical Company [0082] AMBERLITE IRN99 resin=strong acid gel type polystyrene cation exchange resin, supplied by Dow Chemical Company
The mixed bed was prepared by mixing 66% by weight AMBERLITE 78 with 34% by weight AMBERLITE 99. The mixed bed was placed in a glass column, 15 mm ID and 75 cm length. The height of the mixed bed was approximately 33 cm.

[0083] On top of the mixed bed in the column, an overlay was placed. Various resins were used for the overlay. Height of the overlay was approximately 23 cm.

[0084] Surrogate solutions were prepared in 20 ppm, 1.5 L batches in deionized water and ultrasonicated at 30 W with an immersion probe for 3 minutes in order to ensure good mixing of the solutions. The sonication was continued for the duration of the testing. The sonication resulted in a temperature rise of approximately 10 C. of the feed solution over the duration of the resin testing. Particle size analysis (Particle Technology Laboratories) of the surrogate solutions indicated that the nanopowders agglomerated upon contact with water, thus the immersion probe was also utilized to break up, to the extent possible, the nanoparticles in the feed solutions. The Co solution appeared to respond well to ultrasonication (although particulates did accumulate at the bottom of the beaker if allowed to settle).

[0085] The surrogate solutions are considered to mimic the behavior of colloidal particles found in the cooling water systems of nuclear power plants.

[0086] Resins used for overlays were as follows: [0087] Resin-j=a repeat of Resin-e defined above (a batch of Resin-I treated with 8 hours methanol soak time and 1 hour caustic reflux). [0088] Resin-k=a repeat of Resin-e defined above (a batch of Resin-I treated with 1 hour methanol soak time and 7 hours caustic reflux). [0089] DOWEX MP725-OH resin=macroporous strong base anion exchange resin from Dow Chemical Company, styrene/DVB copolymer, quaternary ammonium functional groups; has no methylene bridges

[0090] The resin column was packed by rinsing it with deionized water downflow at a rate of approximately 130 mL/min. Column shrinkage of approximately 2 cm was observed as a result of the packing. Packing water was drained from the column prior to feed of the surrogate solution to 0.3 cm0.1 cm above the resin. This drainage procedure was followed to minimize dilution of the feed solution and to avoid air contact with the wetted test resin. Feed solution was pumped through the resin at a flow rate of 0.5 bed volumes per minute (BV/min), and an effluent sample was collected at 1, 3, 5, 7 and 10 bed volumes (BV). The samples were assessed for Co by Inductively coupled plasma mass spectrometry (ICP-MS) or inductively couple plasma atomic emission spectroscopy (ICP-AES), and chloride (Cl) by Ion chromatography (IC).

[0091] A sample of the feed to the top of the column was collected once or twice during the testing (generally once). This was typically performed at 8 BV by disconnecting the column from the top insert (to avoid the possibility of solution hang-up in a sampling line). This sample was collected in order to ascertain how much of the surrogate solution was reaching the top of the column.

[0092] Two different portions of Resin-2 were tested in duplicate experiments. Similarly, two different portions of Resin-3 were tested in duplicate experiments. Results were as follows:

TABLE-US-00003 Resin-2 Overlay-first experiment time (min) BV Location Co (ppm) Chloride (ppm) 0 0 feed 12.9 2 1 outlet 0.006 <0.01 6 3 outlet 0.006 <0.01 10 5 outlet 0.005 <0.01 14 7 outlet <0.005 <0.01 16 8 top of column 11 20 10 outlet <0.005 <0.01

TABLE-US-00004 Resin-2 Overlay-second experiment time (min) BV Location Co (ppm) Chloride (ppm) 0 0 feed 19.0 2 1 outlet 0.014 <0.01 6 3 outlet 0.009 <0.01 10 5 outlet 0.007 <0.01 14 7 outlet <0.005 <0.01 16 8 top of column 13.0 20 10 outlet <0.005 <0.01

TABLE-US-00005 Resin-3 Overlay-first experiment time (min) BV Location Co (ppm) Chloride (ppm) 0 0 feed 19.0 2 1 outlet 0.018 <0.01 6 3 outlet 0.024 <0.01 10 5 outlet 0.022 <0.01 14 7 outlet 0.025 <0.01 16 8 top of column 11.8 20 10 outlet 0.015 <0.01

TABLE-US-00006 Resin-3 Overlay-second experiment time (min) BV Location Co (ppm) Chloride (ppm) 0 0 feed 17.7 2 1 outlet 0.048 <0.01 6 3 outlet 0.060 <0.01 10 5 outlet 0.066 <0.01 14 7 outlet 0.071 <0.01 16 8 top of column 11.2 20 10 outlet 0.067 <0.01

TABLE-US-00007 MP-725AOH Overlay-comparative experiment time (min) BV Location Co (ppm) Chloride (ppm) 0 0 feed 18.5 2 1 outlet 0.770 <0.01 6 3 outlet 0.584 <0.01 10 5 outlet 0.560 <0.01 14 7 outlet 0.561 <0.01 16 8 top of column 10.5 20 10 outlet 0.557 <0.01

[0093] The inventive examples using Resin-2 and Resin-3 showed that Resin-2 and Resin-3 both removed almost all the cobalt and did not release chloride into the water.