WO2007039019A1 - Filtre moule et processus pour sa fabrication - Google Patents

Filtre moule et processus pour sa fabrication Download PDF

Info

Publication number
WO2007039019A1
WO2007039019A1 PCT/EP2006/008207 EP2006008207W WO2007039019A1 WO 2007039019 A1 WO2007039019 A1 WO 2007039019A1 EP 2006008207 W EP2006008207 W EP 2006008207W WO 2007039019 A1 WO2007039019 A1 WO 2007039019A1
Authority
WO
WIPO (PCT)
Prior art keywords
filter
moulded
binder
filter medium
process according
Prior art date
Application number
PCT/EP2006/008207
Other languages
English (en)
Inventor
Swati Agarwal
Jaideep Chatterjee
Bhupesh Sadanand Desale
Samiran Mahapatra
Original Assignee
Unilever N.V.
Unilever Plc
Hindustan Lever Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Unilever N.V., Unilever Plc, Hindustan Lever Limited filed Critical Unilever N.V.
Publication of WO2007039019A1 publication Critical patent/WO2007039019A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • B01D39/2055—Carbonaceous material
    • B01D39/2058—Carbonaceous material the material being particulate
    • B01D39/2062—Bonded, e.g. activated carbon blocks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/08—Special characteristics of binders
    • B01D2239/086—Binders between particles or fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/10—Filtering material manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/12—Special parameters characterising the filtering material
    • B01D2239/125—Size distribution

Definitions

  • the present invention relates to moulded filters, for use in gravity water filtration devices and a process for making such moulded filters.
  • Water to be used for drinking may already be polluted at the source or become polluted during transportation to consumers' homes through leaking pipelines. Thus, boiling or purifying treatments may be necessary before water is to be consumed.
  • Pollutants may include particulate material, chemical contaminants and microorganisms such as bacteria, viruses and protozoa. The latter are known to cause most of the water-borne diseases.
  • Water filtration devices can be classified based on whether water to be treated flows under pressure or under the influence of gravity alone.
  • the former method is generally referred to as online method, while the latter one is called batch method.
  • batch filtration usually used in domestic water purification devices, the filtration rate is largely dependent on the efficiency of the filter medium.
  • input water quality is bad, i.e. it contains high levels of particulate contaminants or dissolved chemical impurities that form precipitates during filtration; it is generally observed that the filtration rate drops considerably over time, due to clogging of the filter medium. This necessitates replacement and/or regular cleaning of the filter medium.
  • innovators in this field of technology have been constantly trying to develop filters, which can provide higher and consistent filtration rates, without clogging over time, while ensuring the removal of particulate contaminants and microorganisms.
  • a domestic (batch type) gravity-fed water filtration device has two chambers, an upper one and a lower one.
  • a filter element is positioned between the two.
  • Water to be filtered is poured at regular intervals into the top chamber, and purified water flows into the lower one from where it can be dispensed through a tap.
  • carbon based filter elements are often used.
  • filters are either cartridge type containing loose granular carbon in a container or the sintered (moulded) type where carbon particles are bound together with a suitable binder to form a solid filter element.
  • Carbon based moulded filters and various processes for preparing the same are well known in the art .
  • a wet process for preparing carbon filters has been described in US3,611,678 (Filtrona Corporation, 1971) using carbon particles in the range of 80 to 325 mesh along with 50-90 parts thermoplastic or thermosetting binder.
  • the method includes mixing the dry ingredients and sufficient water, charging to a mould, applying sufficient pressure, and curing the resulting filter.
  • the filter has voids in a sufficient amount to provide a pressure drop.
  • US5017318 discloses a dry process for preparing double-shell carbon filters.
  • CA2,396,510 (TYK Corp. 2003) describes a process for preparing carbon filters using particles of size 35-200 ⁇ m with 50% or more ceramic binder, wherein water is sprayed onto this mixture before it is sintered.
  • air filters and water treatment filters have different properties and different requirements.
  • the present invention provides moulded filters having uniform distribution of binder and filter medium throughout the filter thereby providing proper binding of filter medium with the binder and uniform and consistent flow rate over time.
  • the invention also provides a novel process for producing such filters.
  • Yet another object of the present invention is to provide a moulded filter that is capable of giving 3 -log reduction of cysts .
  • Yet further object of the present invention is to provide a process for preparing a moulded filter having uniform distribution of filter medium and binder.
  • the present invention relates to a moulded filter for use in gravity water-filters comprising, a) 50 to 95% by weight filter medium having particle size such that not more than 5% by weight of medium passes through a sieve of 150 mesh (lOO ⁇ m) and not more than 5% is retained on a sieve of 12 mesh (1680 ⁇ m) b) 5 to 50% by weight polymeric binder having a Melt Flow Rate less than 5 grams/10 minutes wherein the variation in the amount of binder present in each cm 3 cell unit is not more than 3% by weight of the total filter mass in that cell unit.
  • the range of weight percent values of said binder as measured in every unit cell of 1 cm 3 of said moulded filter is not more than 3%.
  • the range of weight percent values of said binder as measured per unit cell of 0.5 cm 3 and more preferably per unit cell of 0.1 cm 3 of said moulded filter is not more than 3%.
  • the filter medium particle size is preferably chosen such that not more than 5% by weight of filter medium passes through a sieve of 75 mesh (195 ⁇ m) and not more than 5% by weight is retained on a sieve of 30 mesh (595 ⁇ m) . It is particularly preferred that less than 1% filter medium passes through a sieve of 200 mesh (74 ⁇ m) .
  • the filter medium according to the invention is preferably selected from the group consisting of diatomaceous earth, glass bead, polystyrene resin bead, and activated carbon, more preferably the filter medium is activated carbon.
  • Activated carbon is preferably selected from one or more of bituminous coal, coconut shell, wood and petroleum tar.
  • Surface area of the activated carbon preferably exceeds 500 m 2 /g, more preferably exceeds 1000 m 2 /g.
  • the activated carbon has a size uniformity co-efficient of less than 2, more preferably less than 1.5.
  • the carbon preferably has a Carbon Tetrachloride (CCl 4 ) number exceeding 50%, more preferably exceeding 60%.
  • the activated carbon preferably has an Iodine number greater than 800, more preferably greater than 1000.
  • polymeric binder according to the invention is a binder having melt flow rate (MFR) less than 5 g/ 10 minutes, preferably less than 2 g/ 10 minutes, more preferably less then 1 g/10 minutes.
  • MFR melt flow rate
  • Bulk density of the binder used as per the invention is preferably less than or equal to 0.6 g/cm 3 , more preferably less than or equal to 0.5 g/cm 3 , and most preferably less than or equal to 0.25 g/cm 3 .
  • melt-flow rate is measured using ASTM D 1238 (ISO 1133) test.
  • the test measures the flow of a molten polymer through an extrusion plastometer under specific temperature and load conditions.
  • the extrusion plastometer consists of a vertical cylinder with a small die of 2 mm at the bottom and a removable piston at the top. A charge of material is placed in the cylinder and preheated for several minutes. The piston is placed on top of the molten polymer and its weight forces the polymer through the die and on to a collecting plate.
  • the temperature for testing the present polymeric binder material is chosen at at 190 0 C and the load at 15kg.
  • the amount of polymer collected after a specific time interval is weighed and normalized to the number of grams that would have been extruded in 10 minutes: melt flow rate is thus expressed in grams per 10 minutes.
  • the binder is preferably a thermoplastic polymer having the low MFR values above described. Suitable examples include ultra high molecular weight polymer preferably polyethylene, polypropylene and combinations thereof, which have these low MFR values. The molecular weight is preferably in the range of 10 6 to 10 9 g/mole. Binders of this class are commercially available under the trade names HOSTALEN from Tycona GMBH, GUR, Sunfine (from Asahi, Japan) , Hizex (from Mitsubishi) and from Brasken Corp (Brazil) . Other suitable binders include LDPE sold as Lupolen (from Basel Polyolefins) and LLDPE from Qunos (Australia) . The weight ratio of filter medium to binder is preferably in the range of 2:1 to 10:1.
  • the moulded filter of the invention provides for removal of chemical contaminants and more importantly provides for effective removal of at least 3 -log i.e. 99.9% of cysts such as Giardia lamblia, Cryptospordirium parvum and Entamoeba histolica. Thus, if the input water contains 1000 cysts, the output water will contain at the most only 1 cyst.
  • the moulded filter of the present invention does not require frequent washing and reverse flow flushing at regular intervals to ensure reusability.
  • reverse flushing can be done under tap water or by reversing the carbon block within the gravity filter device. Back flushing can help in increasing the flow rate.
  • Moulded filters of prior art in which the final product contains particles of filter medium (primarily activated carbon) interspersed with binder particles suffer from a problem of differential distribution of these two particulate materials. That is, some areas have a high local concentration of carbon particles, while others have a high local concentration of binder particles. This leads to improper binding. As a result, the filter chokes faster.
  • the present invention provides a moulded filter wherein the range of weight percent values of the polymeric binder as measured in every unit cell of one cubic centimetre, preferably 0.5 cubic centimetres and more preferably 0.1 cubic centimetre of said moulded filter is not more than 3% .
  • range means “statistical range”, which is defined for a set of data as the difference between the highest and lowest values in the set .
  • range means the numerical difference between the largest value and the smallest value of the binder content as measured in every unit cell of one cubic centimetre of the moulded filter.
  • the range of 3% can be evenly or unevenly distributed around the average binder content .
  • the measured binder content could be any value in the range of 28.5% to 31.5% or 29% to 32%.
  • the binder content can be measured by any known method and is preferably measured by thermo-gravimetric analysis.
  • the present invention relates to a process for preparing a moulded filter according to the invention.
  • the moulded filters obtained by the process are substantially identical with respect to the distribution of filter medium and binder throughout the filter. This overcomes the problem of prior art processes wherein reproducibility of the process is not high; i.e. the process leads to filters having high variation in the local concentration of filter medium or binder.
  • the process for making a moulded filter comprises the steps of: a) mixing 1 part by weight polymeric binder having Melt Flow Rate less than 5 g/10 minutes, with 1 to 20 parts by weight filter medium in presence of a fluid wherein the amount of said fluid is not more than 4 times the amount of said filter medium by weight; b) moulding the mix obtained in step (a) ; c) optionally, compressing said mould; d) heating said mould to a temperature in the range of
  • one part by weight polymeric binder is mixed with 2 to 10 parts by weight filter medium.
  • the fluid is preferably not more than 3 times, more preferably from 0.5 to 1.5 times the amount of the filter medium.
  • Mixing is preferably done in vessels which include an agitator, mixer with dulled impeller blades, ribbon blender, rotary mixer, sigma mixer or any other low shear mixer that does not significantly alter the particle size distribution.
  • the mixing is carried out to prepare a uniform mix of the filter medium. It is essential, according to the invention that this step of mixing is carried out in the presence of a fluid.
  • the term "fluid" for the purpose of this invention includes solvents preferably selected from the group consisting of water, ethyl alcohol and mixtures thereof. According to the most preferred aspect, the fluid is water.
  • the fluid used is not more that 4 times the amount of filter medium by weight, and preferably not more than 3 times, most preferably from 0.5 tol .5 times.
  • the binder is then added to the above mixture and is further mixed. Mixing is preferably carried out for at least 15 minutes, more preferably 20 to 60 minutes.
  • the most preferred mixer is a sigma mixer.
  • the above mixture is optionally vibrated for a short period, e.g. for 3-10 minutes to compact the mixture before moulding.
  • the vibratory compaction is preferably carried out in a vibrator having a frequency in the range of 30-100Hz. This process step is preferably carried out for a period of at least one minute, more preferably for 3 to 10 minutes.
  • the mass, whether or not compacted by vibration, is then placed in a mould of pre-selected size and shape and subjected to a pressure of not more than 12 Kg/cm 2 , preferably from 3 to 10 Kg/cm 2 and most preferably from 4 to 8 Kg/cm 2 .
  • the pressure is preferably applied using either a hydraulic press or a pneumatic press, more preferably a hydraulic press.
  • the mould is made of aluminum, cast iron, steel or any material capable of withstanding temperatures exceeding 400 0 C.
  • a mould release agent is preferably coated on the inside surface of the mould.
  • the mould release agent is preferably selected from silicone oil, aluminum foil, or the mould can be coated with suitable materials like Teflon or any other commercially available mould release agent that has little or no adsorption onto the filter medium.
  • the mould is then heated to a temperature of 150 0 C to 350 0 C, preferably in the range of 200 0 C to 300 0 C.
  • the mould is kept heated for more than 60 minutes, preferably 90 to 300 minutes.
  • the mould is preferably heated in a non-convection, forced air or forced inert-gas convection oven.
  • the mould is then cooled and the moulded filter released from the mould.
  • the invention relates to a water filtration device, which comprises the moulded filter of the invention.
  • the device comprises a sediment filter that is washable and removable and is preferably made of a woven or non-woven fabric, more preferably a non-woven fabric having micro porous structure.
  • This sediment filter ensures filtration and retention of particles generally above 3 microns.
  • the sediment filter can be washed and rinsed under flowing tap water or by using a small amount (0.1-10 g/L) of fabric wash detergent in water. This facilitates wide and extensive application of the moulded filter of the invention.
  • the carbon block filter media are adhered to a base plate with an orifice for the water exit and additionally comprises a detachable cover.
  • the base plate can be made of polypropylene, polyethylene, or copolymers like Acrylonitrile-Butadiene- Styrene and Styrene-Acrylonitrile .
  • the detachable cover is preferably made of: polypropylene, polyethylene, or copolymers like Acrylonitrile-Butadiene-Styrene and Styrene- Acrylonitrile .
  • the moulded filter can be of any desired shape depending on the end application or use. Suitable shapes include flat circular discs of low thickness, square discs of low thickness, low height tapered flat discs, cylindrical, solid conical, hollow hemispherical and hollow conical shapes.
  • the inclusion of the granular adsorbent particles in the water filter enables filtration of a significantly higher amount of input water over extended time period thereby ensuring more efficient utilization of the carbon block filter media of the invention. Additionally, the granular adsorbent particles in the water filter enables effective filtration of highly contaminated water containing high amounts of fine particles like dust and dissolved impurities like iron and aluminum salts.
  • a moulded carbon filter according to the invention (Example Ia) was prepared by using 10Kg activated carbon, supplied by- Active Carbon (India) and 2Kg ultra high molecular weight polyethylene with MFR - Og/10 minutes, and having bulk density of 0.22 g/cm 3 from Asahi Corporation (Japan) .
  • the activated carbon had 5% of the particles passing through 150 mesh.
  • 1OL water was added to carbon particles followed by the binder.
  • the composite was mixed in a sigma mixer for 30 minutes and 23Og was transferred to a mould. The mould was then subjected to a hydraulic pressure of 3 kg/cm 2 followed by heating to 250 0 C for 150 minutes and cooling for 1 hour.
  • a conventional moulded carbon filter was prepared (Example Ib) according to the process as described without water.
  • the two filters so prepared were used to compare the binder content, which was measured using a thermo-gravimetric analyzer (TGA) .
  • a set of 6-7 different cubes of 1 cubic centimeter of the carbon block under example Ia and Ib were cut into 8 equal smaller cubes and transferred to the sample holder of the TGA. Analysis was performed holding the sample at 100 0 C for 10 minutes and then heated to 700 0 C under nitrogen at the rate of 10°C/min. The weight loss was calculated between 400- 600 0 C as under these conditions nearly 100% of the binder gets burnt, whereas less than 2% of the carbon gets affected. Therefore the weight loss determined is equal to the weight of the binder.
  • Table-1 gives the range of wt% values of the binder as measured by TGA for various lcm 3 cubes of the filters prepared as in Examples Ia and Ib.
  • Performance of moulded carbon filters made by conventional process against the process of the present invention for cyst exclusion was evaluated by determining its ability to remove cysts/oocysts from the spiked water passed through it. This was determined by passing test water spiked with targeted level of live/irradiated oocysts through the moulded filters and enumerating them in the output samples. Cyst removal was determined as the difference in number of cysts analysed in the input and output water samples and is expressed as percent reduction or reduction log 10 number. Table-2
  • the invention thus provides for a carbon block filter media, a process for preparing the same and water filters which can be prepared using such carbon blocks which provide for vastly improved filtration efficiency of water under gravity flow conditions while providing the desired high flow rate.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Filtering Materials (AREA)
  • Water Treatment By Sorption (AREA)

Abstract

La présente invention concerne des filtres moulés, destinés à une utilisation dans des dispositifs de filtration d'eau par gravité et un processus pour la fabrication de tels filtres moulés. L'un des objets de l'invention consiste à mettre à disposition des milieux filtrants donnant des débits élevés et réguliers dans les dispositifs de purification d'eau alimentés par gravité tout en assurant une élimination efficace des contaminants particulaires. L'invention concerne un processus de production desdits filtres comportant les étapes consistant à : mélanger 1 partie en poids de liant polymérique doté d'un indice de fluidité inférieur à 5 g/10 minutes, avec 1 à 20 parties en poids d'un milieu filtrant en présence d'un fluide, la quantité dudit fluide ne dépassant pas 4 fois la quantité dudit milieu filtrant, mouler le mélange obtenu à l'étape précédente, éventuellement comprimer ledit moule, chauffer ledit moule à une température dans la plage de 150°C à 350°C et démouler le filtre moulé. L'invention concerne également des filtres moulés destinés à une utilisation dans des filtres à eau par gravité.
PCT/EP2006/008207 2005-09-19 2006-08-21 Filtre moule et processus pour sa fabrication WO2007039019A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN1131MU2005 2005-09-19
IN1131/MUM/2005 2005-09-19

Publications (1)

Publication Number Publication Date
WO2007039019A1 true WO2007039019A1 (fr) 2007-04-12

Family

ID=37016117

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2006/008207 WO2007039019A1 (fr) 2005-09-19 2006-08-21 Filtre moule et processus pour sa fabrication

Country Status (1)

Country Link
WO (1) WO2007039019A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010020513A1 (fr) * 2008-08-22 2010-02-25 Unilever Nv Filtre à particules
EP2627203A4 (fr) * 2010-10-15 2018-04-04 Celanese Acetate LLC Appareils, systèmes et procédés associés pour former des masses poreuses pour un filtre à fumée

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5017318A (en) * 1986-04-07 1991-05-21 Amway Corporation Method of making a water filter
JP2000342918A (ja) * 1999-06-03 2000-12-12 Mitsubishi Rayon Co Ltd 濾過フィルタおよび浄水器
EP1247572A1 (fr) * 2001-04-03 2002-10-09 MSA Auer GmbH Procédé de préparation d'un corps de filtre
US20040195180A1 (en) * 2003-04-04 2004-10-07 The Clorox Company Microorganism-removing filter medium having high isoelectric material and low melt index binder
US20050004299A1 (en) * 1998-09-25 2005-01-06 Ticona Gmbh Activated carbon filter
WO2005056151A2 (fr) * 2003-12-04 2005-06-23 Access Business Group International Llc Filtre a liquide bacteriostatique

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5017318A (en) * 1986-04-07 1991-05-21 Amway Corporation Method of making a water filter
US20050004299A1 (en) * 1998-09-25 2005-01-06 Ticona Gmbh Activated carbon filter
JP2000342918A (ja) * 1999-06-03 2000-12-12 Mitsubishi Rayon Co Ltd 濾過フィルタおよび浄水器
EP1247572A1 (fr) * 2001-04-03 2002-10-09 MSA Auer GmbH Procédé de préparation d'un corps de filtre
US20040195180A1 (en) * 2003-04-04 2004-10-07 The Clorox Company Microorganism-removing filter medium having high isoelectric material and low melt index binder
WO2005056151A2 (fr) * 2003-12-04 2005-06-23 Access Business Group International Llc Filtre a liquide bacteriostatique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 2000, no. 15 6 April 2001 (2001-04-06) *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010020513A1 (fr) * 2008-08-22 2010-02-25 Unilever Nv Filtre à particules
EP2161067A1 (fr) * 2008-08-22 2010-03-10 Unilever N.V. Filtre à particules
EA017592B1 (ru) * 2008-08-22 2013-01-30 Юнилевер Н.В. Фильтр тонкой очистки
CN105056634A (zh) * 2008-08-22 2015-11-18 荷兰联合利华有限公司 微粒过滤器
EP2627203A4 (fr) * 2010-10-15 2018-04-04 Celanese Acetate LLC Appareils, systèmes et procédés associés pour former des masses poreuses pour un filtre à fumée

Similar Documents

Publication Publication Date Title
US6770736B1 (en) Activated carbon filter
RU2437706C2 (ru) Фильтр и способ его изготовления
EP2161067B1 (fr) Filtre à particules
CA2396356C (fr) Filtre a eau a bloc de charbon
WO2007003383A1 (fr) Filtre et procede de filtrage de liquides
WO2005094966A1 (fr) Milieux filtrants
EP2914550B1 (fr) Milieu filtrant contenant des fibres
WO2007039019A1 (fr) Filtre moule et processus pour sa fabrication
EP1948346B8 (fr) Cartouche filtrante pour épuration des eaux
WO2007003259A1 (fr) Cartouche filtrante
EP2635362B1 (fr) Procédé de fabrication d'un bloc de filtration comportant un filtre à sédiments
WO2007054196A1 (fr) Procede de regeneration de filtres au bloc de carbone
MXPA01003099A (en) Activated carbon filter
MXPA06010494A (en) Filter media
RU2006136371A (ru) Фильтрующие среды

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 06776994

Country of ref document: EP

Kind code of ref document: A1