GB2550936A

GB2550936A - Discharge solidifier and malodour control

Info

Publication number: GB2550936A
Application number: GB1609575.4A
Authority: GB
Inventors: Lee Stewart
Original assignee: Trio Healthcare Ltd
Current assignee: Trio Healthcare Ltd
Priority date: 2016-06-01
Filing date: 2016-06-01
Publication date: 2017-12-06
Anticipated expiration: 2036-06-01
Also published as: GB2550936B; GB201609575D0

Abstract

An ostomy bag insert 104 with a liquid and odour absorbing material 203 comprising a polyacrylate superabsorbent, a mesoporous polysaccharide and a silicate adsorbent. The insert is designed to absorb fluid excreted from the body and suppress odour. It is desirable that the insert should not draken in colour and should be environmentally benign upon disposal. A combination of pores in a mesoporous and microporous size distribution range is intended to improve the odour absorption of the polysaccharide. The mesoporous volume may be greater than 0.2 cm3g-1 and the ratio of mesoporous to microporous volume may be greater than 10. The insert may be a sachet containing the polyacrylate superabsorbent, a mesoporous polysaccharide and a silicate adsorbent. The sachet may be formed from carboxymethylcellulose and wood pulp. The insert may form part of an ostomy appliance (100, Fig. 1) which may have a flange or gasket attachable to the skin at the stoma site.

Description

Discharge Solidifier and Malodour Control

Field of invention

The present invention relates to a superabsorbent and malodour control composition and in particular, although not exclusively, to a superabsorbent composition configured to absorb liquid excreted by the body and to control odour associated with the excreted matter.

Background art

Ostomy patients typically wear an ostomy bag into which body waste is excreted. Ostomy patients fall into three categories, each category necessitating the patient wearing an ostomy bag. Firstly, urostomy patients typically have had their bladders removed. Accordingly in this case, urine is passed through the stoma and into the ostomy bag. Secondly, colostomy patients have undergone surgery to remove all or part of the colon necessitating an ostomy bag to collect both liquid and solid excreted matter. Thirdly, ileostomy patients similarly rely upon an ostomy bag to collect excreted matter which is redirected through the abdominal wall.

Generally an ostomy bag comprises an opening which is sealed against the patient’s skin around the surgically created body orifice, termed a stoma. When body waste is excreted into the ostomy bag it continues to release malodours which are unpleasant and can cause embarrassment to the patient. Also, where the excreted matter is in liquid form, leakage from the ostomy bag is a potential risk which would also cause embarrassment to the patient. A number of additives have been proposed for ostomy bags designed to solidify excreted fluid matter and reduce unpleasant malodours. US 2002/0055594 discloses a superabsorbent tablet configured to thicken body excretions. The tablet comprises a superabsorbent polymer in the form of cross linked sodium or calcium polyacrylate designed to provide quick gelling of the ostomy bag contents following excretion. US 6,852,100 also discloses an ostomy pouch configured to reduce unpleasant odours. Superabsorbent fibres are used in combination with a malodour counteractant selected from various different categories of odour controlling (masking and neutralising) agents including for example hydrogen peroxide and bacterial growth inhibiters such as sodium nitrate and benzyl alkonium chloride. GB 2329339 discloses a superabsorbent for an ostomy bag comprising granules of a superabsorbent formed into a stick or rod and housed within a water soluble outer sleeve. Odour counteractants, disinfectants and preservatives are also incorporated within the ostomy bag insert. US 5,860,959 discloses a hydroscopic composition to reduce malodours from an ostomy bag. Water absorbing materials such as starch or alkaline metal polyacrylates are employed as superabsorbents in combination with odour counteractants such as volcanic clays and activated carbon granules.

However, there exists a need for an ostomy bag insert configured to effectively solidify or gel excreted matter and control unwanted malodours.

Summary of the Invention

It is an objective of the present invention to provide a superabsorbent and malodour control composition suitable to form an insert for an ostomy appliance and in particular an ostomy bag so as to solidify or gel matter excreted by a patient and to control and in particular suppress undesirable odours associated with the excreted matter.

It is a further specific objective to provide a superabsorbent and malodour control insert that does not darken in colour (to an undesirable extent), the excreted matter. It is a specific objective to provide superabsorbent and malodour control characteristics via a superabsorbent composition that is relatively 1neutral' in colour such that the solidified or gelled matter comprises a colouration or appearance that is not masked appreciably (or to an undesirable extent) by the superabsorbent and malodour adsorbent components.

It is a further specific objective to provide a superabsorbent and malodour control composition that is environmentally benign so as to be capable of being processed according to conventional sewerage treatment applications typically associated with conventional domestic sewerage management practices.

The objectives are achieved by providing a superabsorbent and malodour control composition configured specifically to solidify or gel body excreted liquids and high moisture content solids and to control (by adsorption) undesirable odours associated with such liquids and high moisture content solids. In particular, and according to a first aspect of the present invention there is provided an ostomy bag insert comprising: a polyacrylate superabsorbent; a mesoporous polysaccharide; and a silicate adsorbent.

Reference within this specification to ‘mesoporous ’ and ‘microporous’ are in accordance with standards of the International Union of Pure and Applied Chemistry (IUPAC). Mesoporosity includes pore size distributions typically between 2 to 50 nm (20 to 500 A). Microporosity includes pore size distributions typically being smaller than 2 nm (20 A). Within this specification, the mesoporous polysaccharide includes a polysaccharide exhibiting mesoporosity optionally in combination with microporosity with such pores configured to adsorb compounds associated with unpleasant odours.

The mesoporous polysaccharide used within the subject invention are powdered compositions having a porosity with a high degree of mesoporosity. Such mesoporous polysaccharide may be produced from high surface area forms of polysaccharide derived porous materials that are thermally treated. It is to be noted that the thermally treated mesoporous materials have surface structures which, to varying degrees, resemble those of the parent polysaccharide derived porous material or are more carbon-like, the relative proportion being determined by, for example, the treatment temperature (100 - 700°C or more).

Suitable methods for preparing ‘expanded’ or high surface area starches are described in W02005/011836 and US 5,958,589 the disclosures of which are hereby incorporated by reference. The described methods are, in general terms, applicable also to the preparation of high surface area polysaccharides. Polysaccharides treated by these methods are referred to herein as ‘polysaccharide derived porous materials’ or ‘expanded polysaccharides'.

Generally, suitable preparation methods involve the steps of (i) thermally assisted hydration of a polysaccharide to yield a polysaccharide/water gel or colloidal suspension, (ii) allowing the polysaccharide to recrystallize and (iii) exchanging the water in the recrystallised polysaccharide with a water miscible non-solvent for the polysaccharide which has a lower surface tension than water. A suitable non-solvent is ethanol. The method can involve a series of solvents to remove the water and can involve final drying of the high surface area polysaccharide by evaporation, or can involve the use of supercritical drying including the use of liquid or supercritical carbon dioxide. The high surface area polysaccharide derived porous material can be stored as a solid material or kept as slurry in a non-solvent.

Functionalisation of the expanded polysaccharide may also be performed prior to any thermal treatment step for carbonisation. In one particularly significant method, oxidation of the polysaccharide may be effected to introduce carboxylic acid groups. A particularly suitable method of oxidation uses H2O2 in the presence of an iron phthalocyanine catalyst. The method is generally as describe by Kachkarova-Sorokina et al in Chem Commun, 2004 2844-2845.

The high surface area polysaccharide derived porous material can be converted directly into a carbonised mesoporous or thermally modified material by heating in suitable conditions. The heating may be carried out at any temperature or other conditions at which suitable modification of the expanded polysaccharide occurs including in particular, partial carbonisation, substantially complete carbonisation or complete carbonisation. Suitable conditions are preferably non-oxidative and desirably include vacuum conditions, or an inert atmosphere such as a nitrogen atmosphere. In some aspects the heating conditions may include the use of microwave heating. Also, in some aspects processing conditions may also involve use of a catalyst (such an acid catalyst) to promote the desired thermal modification (carbonisation). The amount of acid catalyst and its identity may be varied in order to vary the subsequent processing and material properties.

The expanded polysaccharide already contains acid functional groups (e.g. where the polysaccharide is expanded alginic acid). The acid-containing expanded polysaccharide may be heated to about 100°C or higher in either a vacuum or an inert atmosphere, in the absence of an acid catalyst to achieve the desired thermally modified (carbonised) material.

Self-carbonising behaviour of expanded polysaccharides with innate acid functionally (e.g. expanded alginic acid and pectin) is advantageous not only with regard to decreasing the number of process steps, but selection of such polysaccharides may facilitate a reduction in the micropore content in the resulting materials. Thus, the materials derived from acidic polysaccharides display even lower micropore content than those prepared from polysaccharides which do not have acid functionality (and which normally require the use of an acid catalyst) at the same temperatures. Porosimetry and surface areas can be measured, for example using automated BET measuring devices based, for example, on nitrogen adsorption. Techniques such as electron microscopy and spectroscopic probing can be used to study the surface structure, energy and chemistry.

Preferably, the components of the insert are powdered. Preferably, the powdered components are a blended powder mixture.

The co-existence of micro, meso and macro pores of the silicate and the polysaccharide gives a spectrum of adsorbent activity such that these two adsorbents act synergistically to give a range of molecular capture/adsorbent mechanisms. Such adsorbent characteristics may be due, in part, to van-der-Waals or other electrostatic interactions, other types of entrapment and/or chemical bonding between the odorous compounds and the present adsorbents.

Preferably, the superabsorbent and powdered adsorbents is housed within a water soluble paper sachet. The sachet may comprise sodium carboxymethylcellulose and wood pulp. The edges of the sachet may be sealed so as to trap the powders within an envelope formed by the soluble paper.

Optionally, the active blend may be enclosed within a water soluble film (e.g. a PVA film); a gel cap, or may be formed as a tablet. Moreover, the insert may comprise a plurality of separate units (e.g. tablet, gel cap, sachet). These units may then be inserted separately into the ostomy bag.

Preferably, the mesoporous polysaccharide comprises pores in a mesoporous and a microporous size distribution range.

Preferably, the mesoporous polysaccharide comprises a mesoporous volume (Vmeso) that is greater than 0.2 cm3g"', or in the range 0.2 to 3 cm3g·’ or more preferably 0.5 to 2 cm3g''.

Optionally, the mesoporous polysaccharide comprises pores in which a ratio of the mesoporous volume (Vmeso) to a microporous volume (Vmicro) is greater than 10, or may be in a range 10 to 500.

Preferably, the mesoporous polysaccharide comprises a surface area (Sbet) greater than 100 mV1· Preferably, the mesoporous polysaccharide comprises a total pore volume of 0.3 to 1.0 cm3g"’ or more preferably 0.4 to 0.8 cm3g''. Preferably, the silicate adsorbent comprises a surface area (Sbet) of greater than 400 mV or in a range 400 to 600 m2g‘1, 450 to 580 mV or more preferably 480 to 550 m2g'1.

Preferably, the silicate adsorbent comprises a total pore volume of greater than 0.4 cm3g'', or in a range 0.4 to 1.0 cmV, 0.7 to 0.9 cmV or more preferably 0.74 to 0.84 cm3g'1.

Preferably, the insert comprises at least 80 wt% sodium polyacrylate; 0.5 to 10 wt% mesoporous polysaccharide and 0.5 to 10 wt% silicate adsorbent. More preferably, the polyacrylate superabsorbent is included at 85 to 95 wt%; the mesoporous polysaccharide is included at 2 to 6 wt% and the silicate adsorbent is included at 2 to 6 wt%. Optionally, the mesoporous polysaccharide and silicate adsorbent are included in combination in a range 1 to 20 wt%. Preferably, any remaining wt% is sodium polyacrylate. Within this specification, the relative concentrations of the components refers to the powdered components and does not include the weight of the containing sachet. Optionally, the nominal weight of the sachet material is in a range 0.3 to 0.4 g. Preferably, the polyacrylate superabsorbent, the mesoporous polysaccharide and silicate adsorbent are contained within the sachet. Optionally, the sachet comprises a cellulose based material and/or wood pulp.

According to a further aspect of the present invention there is provided an ostomy appliance comprising an insert as claimed herein. Optionally, the insert comprises a flange or gasket attachable to mammalian skin; and a bag connected or connectable to the flange or gasket, the bag comprising the insert as claimed herein.

Brief description of drawings A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Figure 1 illustrates an ostomy bag comprising an insert configured to solidify liquid and/or high moisture containing matter within the ostomy bag and control and reduce malodours according to a specific implementation of the present invention; and

Figure 2 illustrates a partial cut-away view of the ostomy bag insert of figure 1 formed as a sachet containing a granular and powdered material.

Detailed description of preferred embodiment of the invention

The inventors provide a material blend configured to solidify excreted matter within an ostomy bag and to reduce odours within the ostomy bag which would otherwise be released from the bag when it is emptied by a patient. A material blend is housed within a water soluble sachet which provides a convenient means by which the liquid and odour absorbing material blend may be stored and transported prior to use within the ostomy bag. The dissolvable sachet may be used in all manner of pouches or bags designed for collecting body excretions such as ostomy, drainage bags or other applications where body fluids require thickening or gelling and odour control (neutralisation/absorption).

Figure 1 illustrates an ostomy bag 100 comprising an internal chamber 105 and an inlet opening 101 surrounded by an annular adhesive pad 102. A drainage flap 103 is provided at a lower region 106 of bag 100. An odour controlling and liquid superabsorbent insert 104 is housed within internal chamber 105 and is dimensioned so as to pass through inlet opening 101 during initial insertion prior to attachment of bag 100 and through outlet opening 103 after empty and reuse of bag 100.

In use, ostomy bag 100 is secured to the skin of a patient at the abdominal region, via adhesive pad 102 such that inlet opening 101 is aligned with the stoma site formed in the patient. Accordingly, excreted matter passes through the stoma and into internal chamber 105 of ostomy bag 100 via inlet opening 101.

The excreted body fluid contacts insert 104 which acts to gel (partially solidify) the fluid matter and control malodours within internal chamber 105.

Following solidification of the excreted matter, the contents of the ostomy bag 100 may then be emptied via the flap arrangement 103 configured to dispense liquid and/or solid from internal chamber 105. Flap 103 may comprise any conventional tap or flap design configured to allow liquid and/or solid matter to be released from internal chamber 105. Following emptying of the bag, a new insert may then be inserted into internal chamber 105 via the flap 103 such that a user is not required to detach bag 100 from positioning around the stoma.

Referring to figures 2 and 3, insert 104 is formed as a sachet comprising a water soluble paper having an upper layer 200 and a lower opposed layer 204. The edges of the upper and lower layers 200, 204 are heat sealed 201 to define an internal cavity 202 sealed along all four edges of the rectangular sachet. Insert 104 comprises liquid and odour absorbing material blend 203. Material blend 203 comprises a polyacrylate superabsorbent, a mesoporous polysaccharide and a silicate adsorbent. In particular, the polyacrylate superabsorbent and silicate adsorbent are configured to absorb the excreted fluids whilst the mesoporous polysaccharide is configured to control the malodours associated with the excreted matter. The polysaccharide has been found to be especially effective in malodour control where the polysaccharide comprises a mesoporous structure in which the odours are capable of entering and being retained within the pores of the polysaccharide so as to suppress the undesirable odours. In particular, the inventors have identified a mesoporous polysaccharide comprising both mesoporous and microporous characteristics to be particularly advantageous for malodour control and suppression. Such a polysaccharide is advantageous as being compatible with a polyacrylate superabsorbent and silicate adsorbent that together provide an environmentally benign powdered blend specifically adapted for moisture and malodour management of excreted matter within an ostomy appliance.

Example 1

The subject invention may be illustrated with reference to the following non-limiting example. Material blend 203 comprises 2.5 g sodium polyacrylate; 0.1 g mesoporous polysaccharide and 0.1 g silicate adsorbent. All three components are included as dry powders. The mesoporous polysaccharide is derived from a gelation and retro-gradation of naturally sourced alginic acid and comprises CAS no. 9005-32-7 as detailed below. The silicate adsorbent comprises silica gel powder CAS no. 63231-67-4. A method of preparing the mesoporous polysaccharide from alginic acid is in accordance with WO 2009/037354 including in particular the following preparation steps.

Part 1 - preparation ofpolysaccharide derived porous material

Expanded polysaccharide was prepared either by (a) thermal preparation or (b) microwave preparation (a) Thermal Preparation of Polysaccharide Derived Porous Material lOOg of alginic acid and 2L of deionised water was stirred at 700 rpm for ten minutes in a modified domestic pressure cooker prior to heating (Volume = 3L; Operating conditions 120°C/80 KPa). The lid component of the device was modified with an aluminium enclosure facilitating insertion of a thermocouple. The system was heated to 120°C (30 minutes) and held at this temperature for a further forty five minutes. Upon returning to atmospheric pressure, the lid was detached, and the resulting solution decanted into powder drying jars. The vessels were then sealed and the gels retrograded at 5°C. (b) Microwave Assisted Preparation of Polysaccharide Derived Porous Material 0.25g of alginic acid was mixed with 5.0ml of distilled water in a commercial microwave reactor vessel, placed in the reactor and the pressure sensor attached. The sample was then heated to the desired temperature (i.e. 90-C - 180°C, typically 130°C) over 150 seconds in a CEM Discover microwave reactor with computer controlled operation. Upon returning to atmospheric pressure, the vessel remained sealed and was placed in a refrigerator and left to recrystallize at 5°C for a desired time. The resulting gel was then solvent exchanged and dried.

Part 2- solvent exchange

Water was removed from the hydrates and recrystallized (expanded) polysaccharide by means of a solvent exchange procedure. An initialvolume of ethanol (10% v/v with water) was added and stirred for 2 hours. A second volume ofethanol (20% v/v) was then added followed by 2 hours stirring. This was followed by a further addition of ethanol (30% v/v) and another 2 hours stirring. A fourth volume of ethanol (50% v/v) was then added followed by another 2 hours of stirring. The resulting suspension was allowed to settle or was centrifuged. The excess solvent was decanted. A volume of ethanol was then added, equivalent to the volume of water used in the gelatinisation stage and stirred for a time period of from 2 hours to overnight. The suspension was then allowed to settle and the excess solvent was decanted. This process of adding ethanol, stirring and removing was repeated twice. The product was then filtered until partially dry. The resulting solid at this point was then dried via rotary evaporation, and then held overnight at 40°C in a vacuum oven. Alternatively, the residual ethanol can be removed by supercritical CO2 drying.

Part 3 - Thermal treatment for conversion of expanded polysaccharide into desired mesoporous material (“carbonisation ”)

Samples of dry mesoporous (that is, thermally hydrated, recrystallized and solvent exchanged) alginic acid were converted into the desired mesoporous materials by oven heating to the desired temperature (> 170°C) via a stepwise heating program in a nitrogen atmosphere (lOOmL N2/minute). Different treatment regimes were used of which the maximum temperatures for alginic acid were 180, 250, 450 or 600°C, while for pectin maximum temperatures of 200,400 or 600°C were used.

The stepwise heating programs followed in the examples herein were (RT indicates room temperature): (i) For samples prepared at 180°C: RT - 140°C - ΙΟΚ/min (Isothermal: 30 minutes) 140 - 150°C 2K/min (Isothermal: 30 minutes) 150 - 180°C - 1 K/min. Samples were held at the final temperature of 180°C for 30 minutes and allowed to cool for about 1 hour; (ii) For samples prepared at 200°C: RT - 140°C - ΙΟΚ/min (Isothermal: 30 minutes) 140 - 150°C - 2K/min (Isothermal: 30 minutes) 150-180°C -1 K/min (Isothermal: 30 minutes) 180 - 200°C: 1 K/min. Samples were held at the final temperature of 200°C for 30 minutes and allowed to cool for about 1 hour 5; (iii) For samples prepared at 250°C: RT - 140°C - ΙΟΚ/min (Isothermal: 30 minutes) 140 - 150°C - 2K/min (Isothermal: 30 minutes) 150-180°C -1 K/min (Isothermal: 30 minutes) 180 - 230°C: 1 K/min (Isothermal: 30 minutes) 230 -250°C -1 K/min (Isothermal: 30 minutes). Samples were held at the final temperature of 250°C for 30 minutes and allowed to cool for about 1 hour; (iv) For samples prepared at 320°C: RT - 140°C - lOK/min (Isothermal: 30 minutes) 140 -150°C - 2K/min (Isothermal: 30 minutes) 150 - 180°C - 2K/min (Isothermal: 30 minutes) 180-230°C: 1 K/min (Isothermal: 30 minutes) 230-250°C -1 K/min (Isothermal: 30 minutes) 250-280°C-1 K/min (Isothermal: 30 minutes) 280-300°C-1 K/min (Isothermal: 30 minutes) 300-320°C -1 K/min (Isothermal: 30 minutes). Samples were held at the final temperature of 320°C for 30 minutes and allowed to cool for About 2.5 hour; (v) For samples prepared at 400°C: RT - 140°C - lOK/min (Isothermal: 30 minutes) 140 - 170°C -2K/min (Isothermal: 30 minutes) 170 - 190°C - 2K/min (Isothermal: 30 minutes) 190 - 230°C: 1 K/min (Isothermal: 30 minutes) 230-260°C -1 K/min (Isothermal: 30 minutes) 260-280°C -1 K/min (Isothermal: 30 minutes) 280-300°C -1 K/min (Isothermal: 30 minutes) 300 - 350°C - 2K/min (Isothermal: 30 minutes) 350 -400°C - 5K/min (Isothermal: 30 minutes). Samples were held at the final temperature of 400°C for 30 minutes and allowed to cool for about 3 hours; (vi) For samples prepared at 450°C: RT - 140°C - lOK/min (Isothermal: 30 minutes) 140 - 170°C -2K/min (Isothermal: 30 minutes) 170 - 190°C - 2K/min (Isothermal: 30 minutes) 190-230°C: lK/min (Isothermal: 30 minutes) 230 - 260°C -1 K/min (Isothermal: 30 minutes) 260-280°C -1 K/min (Isothermal: 30 minutes) 280-300°C -1 K/min (Isothermal: 30 minutes) 300 -350°C - 2K/min (Isothermal: 30 minutes) 350 - 400°C - 5K/min 400 - 450°C - lOK/min. Samples were held at the final temperature of 450°C for 30 minutes and allowed to cool for about 3.5 hours; (vii) For samples prepared at 600°C: RT -140 °C - lOK/min (Isothermal: 30 minutes) 140 - 170°C - 2K/min (isothermal: 30 minutes) 170 - 190°C - 2K/min (Isothermal: 30 minutes) 190 - 230°C: 1 K/min (Isothermal: 30 minutes) 230-260°C -1 K/min (Isothermal: 30 minutes) 260-280°C-1 K/min (Isothermal: 30 minutes) 280-300°C -1 K/min (Isothermal: 30 minutes) 300 - 350 °C - 2K/min (Isothermal: 30 minutes) 350 - 400°C - 5K/min 400 - 600°C - lOK/min (Isothermal: 30 minutes). Samples were held at the final temperature of 600°C for 30 minutes and allowed to cool for about 4.5 hours.

The powdered porous polysaccharide comprised a surface area expressed as a brunauer-ennitt-teller (BET) area (Sbet) in a range 100 m2g"' to 240 m2g_1. The silicate gel powder comprised a total pour volume in the range 0.7 to 0.9 cm3g'‘ and an Sbet in a range 400 to 600 m2g''. Additionally, the silicate adsorbent comprised a particle size in a range 230 to 400 mesh according to ASTM. The powdered blend was then incorporated with a water soluble sachet comprising sodium carboxymethylcellulose (CMC) and wood pulp formed as a dual layer structure with an internal cavity, with each layer having a thickness in a range 0.07 to 0.09 mm.

Claims

1. An ostomy bag insert comprising: a polyacrylate superabsorbent; a mesoporous polysaccharide; and a silicate adsorbent.

2. The insert as claimed in claim 1 wherein the mesoporous polysaccharide comprises pores in a mesoporous and a microporous size distribution range.

3. The insert as claimed in claim 1 or 2 wherein the mesoporous polysaccharide comprises a mesoporous volume (Vmeso) that is greater than 0.2 cm3g_1.

4. The insert as claimed in claim 3 wherein Vmeso is in a range 0.2 to 3 cm3g"'.

5. The insert as claimed in claim 3 wherein Vmeso is in a range 0.5 to 2 cm3g''.

6. The insert as claimed in any preceding claim wherein the mesoporous polysaccharide comprises pores in which a ratio of the mesoporous volume (Vmeso) to a microporous volume (Vmicro) is greater than 10.

7. The insert as claimed in any preceding claim wherein a ratio of the mesoporous volume (Vmeso) to microporous volume (Vmicro) is in a range 10 to 500.

8. The insert as claimed in any preceding claim wherein the mesoporous polysaccharide comprises a surface area (Sbet) greater than 100 m2g"'.

9. The insert as claimed in any preceding claim wherein the silicate adsorbent comprises a surface area (Sbet) greater than 400 m2g"‘.

10. The insert as claimed in any preceding claim wherein the silicate adsorbent comprises a surface area (Sbet) in a range 400 to 600 m2g'!.

11. The insert as claimed in any preceding claim wherein the silicate adsorbent comprises a total pore volume of greater than 0.4 cnrig"1.

12. The insert as claimed in any preceding claim wherein the silicate adsorbent comprises a total pore volume in a range 0.4 to 1.0 cm3g*!.

13. The insert as claimed in any preceding claim comprising: sodium polyacrylate at least 80 wt%; mesoporous polysaccharide in the range 0.5 to 10 wt% and silicate adsorbent in the range 0.5 to 10 wt%.

14. The insert as claimed in any preceding claim wherein the polyacrylate superabsorbent is included at 85 to 95 wt%; the mesoporous polysaccharide is included at 2 to 6 wt% and the silicate adsorbent is included at 2 to 6 wt%.

15. The insert as claimed in any preceding claim wherein the insert comprises a sachet and wherein the polyacrylate superabsorbent, the mesoporous polysaccharide and the silicate adsorbent are contained within the sachet.

16. The insert as claimed in claim 15 wherein the sachet comprises a cellulose based material.

17. The insert as claimed in claimed in 15 or 16 wherein the sachet comprises carboxymethylcellulose and wood pulp.

18. An ostomy appliance comprising an insert as claimed in any preceding claim.

19. The appliance as claimed in claim 18 comprising: a flange or gasket attachable to mammalian skin; and a bag connected or connectable to the flange or gasket, the bag comprising the insert as claimed herein.