Abstract
A diffusiophoretic water filter has improved inlet, outlet and membrane structures. A support is also disclosed as are method for manufacturing and assembling the diffusiophoretic water filter.
Claims
1-59. (canceled)
60. A gas-driven diffusiophoretic filter comprising: a first membrane support having a longitudinally-extending first hollow interior; a gas-permeable first membrane covering the first hollow interior; a gas-permeable second membrane; a second membrane support supporting the gas-permeable second membrane, the first and second supports being positionable so that the first and second membrane define at least one diffusiophoretic water channel having an inlet end for accepting a colloid; and an inlet manifold extending over the first and second membrane supports to seal the inlet.
61. The gas-driven diffusiophoretic filter as recited in claim 60 wherein the first membrane support has a closed inlet end, a hollow interior, and an open side supporting the first membrane.
62. The gas-driven diffusiophoretic filter as recited in claim 61 wherein the membrane support has a hole for a CO2 supply tube.
63. The gas-driven diffusiophoretic filter as recited in claim 61 wherein the open side has cross supports.
64. The gas-driven diffusiophoretic filter as recited in claim 61 wherein the first membrane support is a molded part.
65. The gas-driven diffusiophoretic filter as recited in claim 61 wherein the open side has cross supports.
66. The gas-driven diffusiophoretic filter as recited in claim 60 further comprising a splitter between first and second membranes.
67. The gas-driven diffusiophoretic filter as recited in claim 66 wherein the at least one diffusiophoretic water channel includes a plurality of diffusiophoretic water channels and the splitter extends across the plurality of diffusiophoretic water channels.
68. The gas-driven diffusiophoretic filter as recited in claim 66 wherein the splitter is made of metal.
69. The gas-driven diffusiophoretic filter as recited in claim 66 wherein the inlet manifold includes a plastic tube stretched over ends of the first and second membrane supports.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0073] Some preferred embodiments are disclosed below:
[0074] FIG. 1 shows a schematic cross-sectional lengthwise view of a first embodiment;
[0075] FIG. 2 shows a schematic view through A-A of FIG. 1,
[0076] FIG. 3 shows a schematic cross sectional widthwise view within compressing device 270, which is not shown on FIG. 3;
[0077] FIG. 4 shows a widthwise schematic cross sectional view of modular components of the present invention held in a ground support;
[0078] FIG. 5 shows a lengthwise view of the embodiment of FIG. 4;
[0079] FIG. 6 shows an outlet splitter for connecting to an outlet end of a component;
[0080] FIG. 7 shows schematically the sealed inlet end of the FIG. 5 embodiment;
[0081] FIG. 8 shows an outlet end of the FIG. 5 embodiment;
[0082] FIG. 9 shows a membrane support schematically;
[0083] FIGS. 10 and 11 show further embodiments of the membrane support;
[0084] FIGS. 12 and 13 show a separate membrane cross support for sitting on the membrane support of FIG. 9;
[0085] FIGS. 14 and 15 show a second embodiment of an outlet splitter;
[0086] FIGS. 16, 17, 18, 19 and 20 show schematically a vertically and horizontally stacked embodiment; and
[0087] FIGS. 21, 22, 23, 24, 25, 26, and 27 are used to illustrate a manufacturing method for the above embodiments and/or further embodiments of the present invention; and
[0088] FIG. 28 shows membranes 24, 26 with an air release and CO2 channels (shown schematically much larger than actual for clarity) opposite the colloid channels on an opposite surface of the membranes.
[0089] Additional FIGS. 29 to 35 show further embodiments.
[0090] FIGS. 36 to 46 show a further embodiment of a DWF with an intergral outlet splitter and a method for manufacturing a DWF.
[0091] FIGS. 47 to 54 show yet further embodiments of a DWF in which
[0092] FIG. 47 shows diffusiophoretic water filter of an embodiment;
[0093] FIG. 48 shows a diffusiophoretic water filter of a further embodiment;
[0094] FIGS. 49 and 50 show schematically an outlet of the FIG. 47 embodiment;
[0095] FIG. 51 shows schematically an inlet of the FIG. 48 embodiment; and FIG. 52 an outlet of the FIG. 48 embodiment;
[0096] FIG. 52 shows an embodiment of a removable outlet structure; and
[0097] FIG. 53 shows a three outlet removable outlet structure of another embodiment.
DETAILED DESCRIPTION
[0098] FIG. 1 shows a schematic cross-sectional lengthwise view of a first embodiment of a diffusiophoretic water filter of the present invention. Water flows from an inlet manifold with a heat shrunk supply tube 12 connected to the water filter at an inlet end of the water filter. The other end of the supply tube can be connected to a pressure regulator for example a height tube or pump for providing a colloid to be filtered. Two gas-permeable membranes 24, 26, for example PDMS 30 micrometers thick or thicker, define a channel, and are supported respectively on membrane supports 14, 16. Holes 34 can be used in this embodiment to allow gas to escape to atmosphere. Rubber bands 270, 280 or other compressive devices can press side walls of the membranes 24, 26 (or tapes on the membranes) together to help seal the sides of the colloidal channels. An outlet splitter 260 can fit over the end of one of the supports and be held between the side walls, and split the stream into a filtered water stream 240 and waste water stream 250 for example.
[0099] FIG. 2 shows a schematic view through A-A of FIG. 1, with tapes 20A, 20B defining side walls of the colloidal channel. Membrane 24, membrane support 14 and tapes 20A thus define a mating component 4 and membrane 26, membrane support 16 and tapes 20B a mating components 6.
[0100] FIG. 3 shows a schematic cross sectional widthwise view at the end with compressive device 270, which is not shown on FIG. 3. Outlet splitter 260 has a splitter support 261 that fits over the end of component 4 and supports a blade or thin section, for example 30 micrometers thick or thicker that fits over the tapes 20A and between tapes 20A and 20B. The channels thus can be split into waste water stream 250 and filtered water stream 240, although the waste water and filtered water streams can be switched depending on the type of particles (negative or positive) being filtered or by switching the components so that component 4 delivers gas and component 6 is open to atmosphere. Tapes 20A and 20b thus set a clean a water/waste water splitting ratio and can be the same thickness for a 50/50 split or different thicknesses.
[0101] FIG. 4 shows a widthwise schematic cross sectional view of modular components of the present invention held in a ground support 400 with legs 402, and a top 410 (that can have openings or a grate that permits access to atmosphere for holes or slots in component 4). Top 410 can be a weight that presses down on component 4.
[0102] FIG. 5 shows a lengthwise view of the embodiment of FIG. 4, with clean filtered water collected from streams 240 over the width shown in FIG. 4 in a perpendicularly extending sloped gutter 241, which can collect the water. The ends or bottoms of the outlet splitter 260 can collect waste water for example in a connected tube so the waste water can be further processed or disposed of.
[0103] FIG. 6 shows an outlet splitter 260 for connecting to an outlet end of a component 6, and can have a steel blade 262 held by tapes to the ends of a U-shaped wall t1 thick of splitter support 261. Inner distance t1 can match the outer support 14 width, and t3 an inner width of slots of ground support 400;
[0104] FIG. 7 shows schematically the sealed inlet end of the FIG. 5 embodiment, with inlet manifold 12 surrounding the ground support front end, and thus a sealed face is presented with only openings for the channels.
[0105] FIG. 8 shows an outlet end of the FIG. 5 embodiment showing how the splitter supports have space on the cantilevered ends of the support 14. The distance t4 can be twice t1.
[0106] FIG. 9 shows a membrane support 16 schematically but without the holes shown in FIG. 1 and instead having a slot 600. Membrane support 16 has a closed inlet end, a hollow interior, slot 606 on one longitudinally extending side and an open side opposite the side with slot 606 (the open top) for supporting membrane 26. A downstream end can have a hole for a connection for a CO2 supply tube 608. Slot 606 is sealed when support 16 is used as gas supply support, and open and not connected to a gas supply tube so that the support can function as support 14 supporting membrane 24 so that the support is open to atmosphere via slot 606 (and the hole for the CO2 connection). The hole also used for example to create vacuum pressure via a vacuum tube connection to aid in diffusiophoretic action.
[0107] FIG. 10 shows with the open side 614 of a further embodiment of a membrane support 514, 516 having cross supports 616 for further supporting membrane 26. These cross supports may be made of PVC or other plastic and be part of the molded PVC part. FIG. 11 shows open side 714 with a cross hatching pattern of cross supports 716. The cross supports can keep the membrane 24, 26 from sagging or bulging and aid in placement and/or adhesion. The cross supports should be rather narrow, for example 1 mm or less to not interfere too much with CO2 or other gas diffusion. Honeycomb or other structures for the cross supports are also possible. Both slot 606 and hole 607 for a gas inlet are on a side opposite the open side as shown in FIG. 10 and as possible with the FIG. 11 embodiment. Hole 607 is in a cantilevered section of support 514, 516 out of a ground support so that a gas pipe can be attached. It also is far enough away from the outlet end that a splitter as in FIG. 14 does not cover the hole 607.
[0108] FIG. 12 shows schematically a separate membrane grated support, such as a cross support, 814 that can be adhered to a flat unstructured side 815 of membrane 24, 26, as shown in FIG. 13. Cross support 814 can be made of PVC, and can have side and end walls that match a thickness of the walls of membrane support 14 and 16 so that the cross support can be placed on the open side with the membrane.
[0109] FIG. 14 shows an outlet splitter 1260 that fits over both ends of membrane supports 514, 516 as shown in FIG. 15. In this way both waste water 250 and filtered water 240 can be collected via a closed structure and piping connected to holes in the outlet splitter 1260, as shown. Splitter blade 1262 can be made of PVC and narrow to a point of 10 micrometers for example and fit between membranes 24, 26 as shown.
[0110] FIG. 16 shows in cross section a ground support 1400 with four slots 1401 defined by support walls 1403. In this embodiment and as shown in FIG. 17 as well, mated pairs of membranes 24, 26 on supports 1014, 1016 respectively define a module 2000 with a channel or set of channels C1. Three sets of channel(s) also can extend vertically and four widthwise so that sets of channels C1 to C12 are possible, although hundreds in each direction are possible. Since each channel set may have hundreds of channels, thousands or tens of thousands of channels or more may be present.
[0111] Membrane supports 1014, 1016 can be similar to supports 514, 516 in FIG. 10, but are lower in height, for example with an interior height of 1 cm, so a total height with a 50 mm wall is 1.5 cm, and the width still 2.5 cm. An interior height of 0.5 cm is also possible, for 1 cm high supports. A spacer 914 can fit between modules 2000 and be of a length similar to the walls 1403, for example 60 cm. Spacer 914 can be open at both ends and be U-shape as shown in FIG. 20 and have a height of 1 cm as well. Spacer 914 permits the space above membrane 24 to be open to atmosphere via slot 606 and both an open front and downstream side of spacer 914 as shown in FIG. 19. Spacer 914 can also be clipped to walls 1402 on both ends to position spacer 914 longitudinally with respect to base 1400. Spacer 914 then has a protrusion 607, integral and made of PVC or plastic for example, that can seal slot 606 in membrane support 1016, which delivers CO2 to membrane 26. Protrusion 607 can be coated with an elastomer to aid sealing and also positions the membrane support 1016 longitudinally. Ground support 1400 at the bottom of each slot also has a protrusion 626 that can seal and longitudinally position first membrane support 1016, which also delivers gas.
[0112] FIG. 19 shows how the membrane supports 1014, 1016, which can be 80 cm in length, cantilever out the front and rear of ground support 1400. Water can be supplied to each channel C1 through C12 by individual water manifolds 1012 connected to a settable pump P that can set a common inlet colloid (water) pressure, for example 30 mbar. Waste water 250 can be collected on each row as can filtered water 240, and the water conveyed further via suction or gravity.
[0113] A top 1402 (FIG. 16) can supply a defined pressure to the stacks of modules in each slot to aid in sealing of the membranes 24, 26 at the side walls of the membranes.
[0114] A ground support 1400 can hold for example 50 modules vertically for a height around 1.5 meters, and have 2 cm thick walls so that 40 slots and modules horizontally is about 1.8 meters in width. With three channels per channel set C1 of 250 micrometers (125 micrometer half channels) and a width of 0.3 cm, at a pressure of 30 mbar flow is estimated as laminar with a Reynolds number of 11.8 and a velocity of 0.0256 m/s and a flow rate of 1.15 ml/min. A dwell time in the 80 cm long channel is 39 seconds giving time for many particles to move 200 micrometers via diffusiophoretic motion. A 50/50 split at 125 micrometers thus given a good filtering effect on the 250 micrometer wide stream, and clean water flow of 0.575 ml/min. With 200 channels sets and 600 channels, the device can produce 345 ml/min of clean water or 20.7 liters per hour. Higher throughputs with higher pressures are also possible and larger channel sizes are also possible.
[0115] FIG. 21 shows a possible channel structure for a membrane 24 backed on a tape 300. The membrane can be for example 250 micrometer thick at mt4 and have 125 micrometer deep channels as shown at mt4 that are 0.3 cm wide (schematically shown). A base thickness mt5 of 125 micrometers which can allow CO2 flow remains, although thinner base thicknesses are possible for better CO2 diffusion. Side walls of 0.5 cm width can be provided. A width W can be 2.5 cm and match a width of w as shown in FIG. 24, which shows transversely spaced adhesive applicators 400. The membrane 24 can be easily manufactured using a 250 micrometer thick PDMS continuous ribbon with the channels cut by CO2 lasers, which is an easy and inexpensive method, although milling, grinding and other possibilities exist. The tape backed ribbon can be rolled from a roll 350 as shown in FIG. 23. An adhesive applicator 400, which may have a brush or widthwise applicators, can apply an adhesive such as a silicone-based adhesive to membrane support 14 as shown in FIGS. 23 and 24, and thus adhesive applied to longitudinal supports 112 between gas or air holes 110. The adhesive can also be applied to cross supports 113, which are optional, if present. The amount and thickness of the adhesive is relatively unimportant, but the gas or air 112 holes should remain clear.
[0116] FIG. 22 shows rollers 200 moved by a conveyor CY used to move supports 14 through a manufacturing process. As shown in FIG. 23, the adhesive is applied by applicator 400, and the membrane 24 unrolled and the tape 300 removed. A cutter pair 410 (not showing a second cutter downstream near the nip of the tape roller) can operate near the nip of the tape rollers and cut section of the membrane widthwise. Pressing rollers 210, 211 can press the membrane against the support 24 for a good adhesion. FIG. 23 shows as well a CO2 laser array 700, transverse to the direction of movement, that can cut the channels into the PDMS membrane after adhesion, which may be preferable. In this case the roll 350 is simply of a sheet for example made of PDMS 250 micrometers thick. FIG. 25 shows the attached membrane 24 on longitudinal supports 112 and side walls of support 24 at a cross sectional location. The membrane 24 and support 24 can be for a length L, for example 80 cm long.
[0117] Length L, width W and all the other dimensions can be application and material specific. It may be for example that widths of 15 or 30 cm for the membrane supports 24, 26 and membranes 14, 16 are preferred, and many more channels provided widthwise. This can reduce the number of CO2 and colloid input connections and base support slot material, as well as providing more channels per unit width.
[0118] An oversized length of the membranes 24, 26 and precision of placement in the lengthwise direction advantageously has little impact on the functioning of the filter, and in fact extra length L2 can be used to stretch and place precut membranes 24, 26 on their respective supports as shown in FIG. 26 with a vertically moving applicator. As shown in FIG. 27 the inlet and outlet splitter functions remain unimpeded.
[0119] The thicknesses and channel sizes of the membranes 14, 16 also may be varied, particularly it may be desirable to have a thicker PDMS base with CO2 channels 805 cut into the side opposite the colloid channels C between PDMS material support on longitudinal supports 112, as shown in FIG. 28. These CO2 channels 805 can be directly opposite the colloid channels, and be the same or deeper, but need to be sealed at the ends either by the way they are imparted into the PDMS material, or by front and rear extensions of the supports 24, 26, and or by adhesive or other material closing the CO2 channel ends.
[0120] FIGS. 29 and 31 show a possible stacking of the FIG. 28 embodiment in a support 1400. Integrated CO2 and air spacers 116, with a bottom open end air area with an end entry for a CO2 pipe and a closed end CO2 chamber can be provided as shown in FIG. 30. FIG. 32 shows the inlet area for channels C of the FIG. 31 embodiment, and FIG. 33 an outlet area.
[0121] FIGS. 34 and 35 show an alternate engagement of the membrane 26 with a spacer or a CO2 chamber 816 where pegs 817 sit over slots 818 and fit in and support the membrane 26 between rigs at CO2 channels 805 (or air channels for a membrane 24)
[0122] FIGS. 36, 37 and 38 show a sheet 4010 of PDMS material that can for example be a 1 mm thick sheet and 80 cm wide at sheet width SW. A laser support LS with a plurality, for example 100, lasers LA, for example CO2 lasers spaced 1 mm apart in the unwinding direction U can move on a structure crosswise to the sheet 4010, which can stop after being unwound for example 1 m in direction U. The lasers then move crosswise in direction S and machine channels C, for example 100 channels C at a first power, and are focused and powered to cut the channels 200 micrometers deep at ct1, and at width W of for example 500 micrometers (250 micrometers on either side of each laser LA). The channels thus can be spaced 500 micrometers apart, and cover 50% of the 1 meter length on the sheet in direction U. After most of the channels C have been cut in direction S, the power can be reduced so that only a depth ct2 is machined, for example at 100 micrometers. A width w can remain the same. A second set of lasers behind or in front of lasers LA could also be used to machine the ct2 depth. Before the edge E, the laser machining can stop so no material is machined.
[0123] As shown in FIGS. 38, 39 and 40, a second laser or set of lasers L2 can machine in a direction U′ through the thickness ct3 to provide a channel outlet 4250, for example for waste water. The channel 4250 can have a depth for example of 90 micrometers and width of 500 micrometers and a length of Lo that can preferably be 1 cm or more. A high precision laser such as a YAG laser thus is desired, and one of more precision than the lasers used for channels C, which can be inexpensive CO2 lasers for example. A splitter 4270 of 10 micrometer thickness is thus can remain, although other sizes are possible.
[0124] The sheet 4010 can be unwound another meter and processed again so that a continuous sheet of perpendicularly extending channels, for example 100 meters long can be produced. A cutter C can cut the sheet to any desired location in direction U, which can then define the width of water filter, with SW generally defining the length.
[0125] As shown in FIGS. 40, 41 and 41a, and 42 the sheet 4010 thus produced can be placed on a water impermeable, gas permeable sheet 4012, with for example an air or gas permeable support 4110, 4112 for each. Air channels on the side opposite the water channels C can also be machined into sheet 4010 and gas channels into the side of sheet 4012. An outlet 4209 with one or more perpendicularly running collection channels can collect the waste water 4250 and the filtered water 4240 and fit in a slot 4312 to seal the outlet to the sheets 4010, 4012 or a support. The outlet can thus also clamp the sheets 4010/4012 together. Likewise, slots 4212, 4220 can be provided for a perpendicularly running inlet manifold 4600 which can have a tube with a slot into which the inlets of the channels C fit and are sealed. A height of the manifold above the outlets in a height tube HT can set the pressure and thus flow rate for the channels C, and may be for example between 10 and 100 cm.
[0126] FIG. 43 shows how the side 4012a of the sheet 4012 and the water channels C can be structured with CO2 channels to thin the sheet of thickness ct4, for example 1 mm to thickness ct5, for example 50 micrometers, so that CO2 can permeate the sheet 4012 into channels C. As shown in FIG. 44, a cross wise pattern or any other pattern promoting CO2 diffusion can be machined or extruded into sheet 12. Grooves 4212, 4312 for the inlet manifold 600 and outlet 209 can also be machined in the unwind direction U as shown in FIG. 45
[0127] As similar manufacturing and construction can be used for sheets where the channels are simply cut all the way through to the second end by lasers LA (FIG. 36), and where a long removable splitter for example is used to fit between the two sheets at the outlet end. FIG. 46 shows the water filter with sheet 4012 on a support 4112 over a CO2 chamber. Support 4112 is gas permeable, for example a honeycomb structure, except at seal locations 41100 and 41111. Support 4110 for sheet 4010 is also air permeable except for a seal location 41110. In that case outlet 4209 can have a separate splitter 4460 as shown.
[0128] An easily manufactured and high output device thus can be provided, and can extend for example 100 meters or more in length easily.
[0129] FIG. 47 shows a diffusiophoretic water filter with a diffusiophoretic-inducing membrane 5022 and a cover 5024, clamped together via clamps 5200 and defining a plurality of longitudinally-extending channels.
[0130] FIG. 48 shows a diffusiophoretic-inducing membrane 5022 and a cover 5028, clamped together via clamps 5200 and defining a plurality of longitudinally-extending channels. Membrane 5022 and cover 5028 are spaced apart by tapes 5126, each with two tapes 5126A, 5126B laid over each other.
[0131] FIGS. 49 and 50 show schematically an outlet of the FIG. 47 embodiment. A stainless steel blade 5027, for example 2 cm in length l, cuts channels with a width w of for example 20 micrometers to 2 cm and height h of 50 to 1000 micrometers in half over length l. The blade 5027 may have a thickness t of 10 micrometers for example and define a waste outlet 5026 and a clean water outlet 5025. Blade 5027 advantageously can be slid into a soft material of the cover made of silicone (PDMS) for example. The method for manufacturing the outlet thus is easy, and also provides for easy manufacture of the channels in the PDMS material of cover 5028, for example by milling or laser cutting. Clean water outlet 5026 may be spaced a distance D, for example 1 cm, in the longitudinal direction so that water may exit by gravity. Waste water stream 5026 containing negatively-charged colloids pushed away from membrane 5022 exits further downstream and can be discarded for example.
[0132] FIG. 51 shows schematically an inlet of the FIG. 48 embodiment; and FIG. 52 an outlet of the FIG. 48 embodiment, where the splitter 5027 is between tapes 5126A and 5126B. The tapes 5126A, 5126B can run the whole length of the filter, or can be slit into the two tapes just at the outlet. The splitter can be made of plastic or metal, and may be the same as in the FIG. 49 embodiment, although the tapes permit usage of many types of splitters. The tapes 5126A, 5126B can be for example 125 micrometer thick PTFE tapes or made of other materials.
[0133] FIG. 53 shows a further embodiment of a removable outlet structure that fits between a diffusiophoretic-inducing membrane 5122 and a cover 5128 that may or may not have a channel structure. A support 5023, for example made of stainless steel 1 mm thick, can have tapes supporting a blade or sheet 5027. The membrane 5128 can hold the outlet structure in place against membrane 5122, or a separate clamp could be provided.
[0134] FIG. 54 shows a three outlet removable outlet structure of another embodiment in which three outlet streams 5025, 5026 and 5125 are provided by two splitters 5027, 5127 spaced apart by tapes and supported by a support 5123. Outlet stream 5125 can have negatively charged particles, outlet stream 5025 positively charged particles, and stream 5026 filtered water.
