CA2701995A1

CA2701995A1 - Dust and odour control materials and processes

Info

Publication number: CA2701995A1
Application number: CA 2701995
Authority: CA
Inventors: Paul Jollez
Original assignee: LES PROCEDES SERVI-SAND CANADA Inc
Current assignee: LES PROCEDES SERVI-SAND CANADA Inc
Priority date: 2010-04-29
Filing date: 2010-04-29
Publication date: 2011-10-29
Also published as: WO2011134074A1; CA2797634A1; CA2797634C

Description

DUST AND ODOUR CONTROL MATERIALS AND PROCESSES
FIELD OF THE INVENTION

The present invention generally relates to the field of odour and dust control, and in particular to dust and odour control of materials such as particulate domestic animal litter.

BACKGROUND
Dust and odour are problematic phenomena that occur particularly in connection with particulate materials such as animal litter. When urine is released into litter, it contains a variety of compounds including ammonium, uric acid and urea. Ammonia, which is a relatively volatile odorous compound, can be released from the urine and over time urea is broken down into carbon dioxide and ammonia, resulting in disruptive odours emanating from the litter immediately and overtime.

In addition, materials such as animal litter often have a tendency to allow particles to "dust"
and become suspended in the air, which reduces air quality and in some cases can be a health hazard depending on the material and quantity of dust in the air. For materials that are disrupted, scooped, poured and displaced on a regular basis, dusting can be a particularly acute problem. It is a challenge to provide materials such as animal litter that has effective dust control.

Some substances are known for attempting to control odours, in a variety of different fields. In some cases, perfumes are used but they tend to mask rather than control odours. Urease inhibitors have been used in some industries for controlling urine odours by inhibiting the hydrolysis of urea into carbon dioxide and ammonia. Other known substances have proved ineffective, inefficient, costly, or difficult to apply to certain materials, Indeed, there is a present need in for techniques and products that respond to the disadvantages of what is known to enable effective dust and odour control of materials.

SUMMARY OF THE INVENTION

The present invention provides a dust and odour control material comprising:

2 a substrate;

an odour-neutralising and dust-control agent associated with the substrate;
and an odour-retardant agent associated with the substrate.

In an optional aspect, the substrate comprises a clay-based substance. In one preferred aspect, the substrate substantially comprises bentonite clay.

In another optional aspect, the odour-neutralising and dust-control agent is an alkaline-earth or alkaline metal chloride. In one preferred aspect, the odour-neutralising and dust-control agent is MgCI2.

In another optional aspect, the odour retardant agent is a urease inhibitor.
The urease inhibitor may be selected from N(n-butyl) thiophosphoric triamide (nBTPT), cyclohexyl thiophosphoric triamide (CHTPT), N-(N-butyl) phosphoric triamide (NBPT), cyclohexyl phosphoric triamide (CHPT), N-aliphatic and N,N-aliphatic phosphoric triamide, phosphorotriammides, 4-aminophenyl suiphonyl amino phenyl phosphorodiamidates, and N-(diaminophosphinyl)arylcarboxamines. The urease inhibitor may be a polysulfide or thiosulphate or the like.

In a further optional aspect, the odour-neutralising and dust-control agent and the odour-retardant agent are associated with the substrate substantially in the form of a coating.
Depending on the application method, there may be a solvent for each or both of the two agents.

The present invention also provides a process of making a dust and odour control material, comprising:

providing a substrate;

introducing an odour-neutralising and dust-control agent to the substrate; and introducing odour-retardant agent to the substrate.

In one optional aspect, the odour-neutralising and dust-control agent and the odour-retardant agent are applied onto the substrate as a coating. The two agents may be added sequentially

3 or simultaneously. In one aspect, the odour-neutralising and dust-control agent is sprayed onto the substrate first and the odour-retardant agent is sprayed on second.
In other aspects, the odour-neutralising and dust-control agent and the odour-retardant agent may be introduced during spray-drying, during extrusion into an appropriate substrate, during Impregnation, during compression, or during pellet or granule growth methods such as tumbling. The agents may be provided on the exterior of the substrate as a coating; or within the substrate such that the substrate coats a core made of the agents; or mixed together with the substrate to form a mixed material that can have even distribution of the agents within the substrate volume or not.

The present invention also provides a use of a combination for dust and odour control of a substrate material, the combination comprising an odour-neutralising and dust-control agent and an odour-retardant agent both provided on the substrate material.

The present invention also provides a kit for dust and odour control of a substrate material, the kit including an odour-neutralising and dust-control agent and an odour-retardant agent provided on the substrate material.

The present invention also provides a method of dust and odour control of a odorous substrate material, comprising providing an odour-neutralising and dust-control agent onto the odorous substrate material and providing an odour-retardant agent onto the odorous substrate material.

DETAILED DESCRIPTION OF EMBODIMENTS AND ASPECTS

In an optional embodiment, the dust and odour control particulate material is a domestic animal litter preferably for use in a litter box. The particulate material is preferably used for controlling the odour when a bodily fluid, such as urine, is released into it.
The particulate material may also be a material onto which the agents are provided for neutralising its existing odours and retarding further odour development and release.

The particulate material may include a substrate composed of one or more materials. In some preferred aspects, the substrate may be a typical animal or pet litter, such as a cat litter, which are typically mixtures of absorbent materials, odour controlling agents, clumping agents, and other functional or cosmetic enhancing additives. Such substrates cover a wide

4 range of materials and can include recycled newsprint, recycled paper, paper sludge, corn cob granules, rice hulls, peanut hulls, alfalfa, sawdust, cedar sawdust, calcareous matter, ground cereals such as wheat, corn, gums, starches and various clays such as calcium and sodium montmorillonites (including sodium and calcium bentonite), attapulgites, kaolins, and opal clay mixtures, Clay-based litters which provide a clumping property allowing removal of liquid waste from the litter container without excessively contaminating the remaining litter have become popular. Clumps are created when the composition of the swells during the absorption of pet urine, creating a localized rigid clump. Typical additives for litter which provide this swelling and urine absorption property include montmorillonite clays.

In one aspect, the substrate is made of clay-based material which may be clumping or non-clumping. The substrate may also be composed of other appropriate materials for use as animal litter and similar applications wherein a potentially odorous liquid is released into the particulate material and may remain there for some time. In one preferred aspect, particularly for the embodiment of animal litter, the substrate comprises a clay-based substance, preferably bentonite clay, and still preferably sodium bentonite.

The particulate material includes an odour-neutralising and dust-control agent and an odour-retardant agent. The combination of the two agents enables advantageous functionality for dust and odour control in response to an odorous fluid, such as urine, that is released into the particulate material- The agents may be provided via a solution or in dry or solid form.

Consider the case of urine in further detail. Urine contains ammonium, uric acid and urea.
When urine is released into the particulate material, the first agent neutralises ammonia that is already present in the fluid and controls dusting and its negative and exacerbating effect on odour and air quality. Thus, the first agent has a rapid effect on the immediate odour-causing compound of ammonia. Though the initial amount of ammonia is neutralised, the urea present in the fluid has the potential to break down and form additional ammonia which cannot be neutralised by the first agent. The second agent retards the formation of additional ammonia that results from the hydrolysis of urea, preferably by blocking or retarding urease.
In one optional aspect, the agents are selected according to their action on particular compounds. For instance, the odour-neutralising and dust-control agent may be selected to neutralise a volatile odorous compound, while the odour-retardant agent may be selected to retard the formation of that same volatile compound by, for example, blocking an enzyme or reaction that would transform a less-odorous compound into the volatile odorous compound.
The agents thus provide a complementary and advantageous functionality.

In another optional aspect, the odour-neutralising and dust-control agent is an alkaline-earth

5 or alkaline metal chloride. In one preferred aspect, the odour-neutralising and dust-control agent comjprises at least one of CaC12 or MgCl2, still preferably MgCI2. The MgC12 may be provided in diluted solution form such as a 30 wt% solution. Regarding the action of MgCl2, in addition to its strong dust control properties, it conserves its water of crystallisation even above 50 C. It also remains active over time and even in high temperature environments.
Solutions of MgC12 and ammonia form a stabilised ionic system which inhibits the liberation of ammonia into the atmosphere and displays a certain absorptive capacity evidenced by the absence of characteristic ammonia odours. In addition, Mg2+ ions have some degree of inhibiting action on urease, which also retards the formation of ammonia during the transformation of urea.

In another optional aspect, particularly for the embodiment of animal litter, the odour-retardant agent is a urease inhibitor. The urease inhibitor may be selected from N-(n-butyl thiophosphoric triamide (nBTPT), cyclohexyl thiophosphonc triamide (CHTPT), N-(N-butyl) phosphoric triamide (NBPT), cyclohexyl phosphoric triamide (CHPT), N-aliphatic and N,N-aliphatic phosphoric triamide, phosphorotnamides, 4-Aminophenyl sulphonyl amino phenyl phosphorodiamidates, and N-(diaminophosphinyl) arylcarboxamines. The urease inhibitor may also be a polysulftde, or thiosulphate. When he odour-retardant agent has an odour of its own, it may be preferred to associate it with the substrate so as to minimize or eliminate such odour, for example by impregnating the material with it or by providing in a non-exposed layer or in a certain form. Molecule such as the triamides and other products, while effective as retardants of the transformation of urea by urease, do not have an effect on the ammonia already present in the medium.

In a further optional aspect, the odour-neutralising and dust-control agent and the odour-retardant agent are associated with the substrate substantially in the form of a coating.
Depending on the application method, there may be a solvent for each or both of the two agents. Depending in the chemical nature and properties of the selected agents, there may be one common solvent for a single spray application of the coating.
Alternatively, there may

6 be a different solvent for each agent when applied separately. The two agents may also be added sequentially or simultaneously. In one aspect, the odour-neutralising and dust-control agent is sprayed onto the substrate first and the odour-retardant agent is sprayed on second.
The present invention also provides a process of making a dust and odour control particulate material, comprising:

providing a substrate;

introducing an odour-neutralising and dust-control agent to the substrate; and introducing odour-retardant agent to the substrate.

In other aspects, the odour-neutralising and dust-control agent and the odour-retardant agent may be introduced by extrusion into an appropriate substrate, by compression, or by pellet or granule growth methods such as tumbling. The odour-neutralising and dust-control agent is preferably provided as a coating or otherwise available to rapidly neutralise odours already present in the fluid when released into the particulate material. The odour-retardant agent is provided so as to be available over a longer period of time for retarding the generation of highly odorous substances such as ammonia. Accordingly, the odour-retardant agent may be associated with the substrate to enable a long-lasting effect and thus may be partially embedded or distributed within the particles of the material. The odour-retardant agent may access the fluid due to the fluid's infiltrating around or into the particulate material.

In another aspect, there is provided a use of a combination of compounds for dust and odour control of a substrate material. The combination includes the odour-neutralising and dust-control agent and the odour-retardant agent as described above. The agents are provided on the substrate material, preferably particulate materials such as materials that are clay-based, limestone-based, silica-based, cellulose-based, cellulose derivatives-based, agricultural waste-based, soil-based, in natural or synthetic form, or any number of substrates. The agents may be pre-applied on the particulate substrate material to make a product such as animal litter, hygiene products, or the like; or may be applied on an odorous municipal or industrial material such as solid or semi-solid waste, filtrates, residues, tailings, or the like; or may be other like materials that may benefit from dust and odour control. The combination

7 mentioned above may be provided in the form of a chemical kit comprising the two agents in dry form or in separate solvents.

It should also be understood that, in some aspects and embodiments, the odour-neutralising and dust-control agent and the odour-retardant agent may be one and the same substance.
In addition, there may be one or more of each agent provided in a single material and they may be provided together or in separate layers or coatings. It should also be understood that the material may include a first portion of substrates that are provided with one agent and a second portion of the substrates that are provided with the other agent, the first and second portions being mixable together by a manufacturer prior to packaging or by a user just prior to use.

EXAMPLES
Example I

Cat litter material was prepared according to the following procedures:

A bentonite type absorbent substrate was prepared having a known granulometry.
A first aqueous solution (solution 1) containing 20-35 % wlw of MgCl2 was prepared to then be applied on a portion of the prepared litter absorbent at 1-1.3 % wfw. In parallel, a second aqueous solution (solution II) containing about 15-30 % wfw of N(n-butyl) thiophosphoric triamide BTPT was prepared, in the presence of surfactant or not, to be applied on another portion of the prepared litter substrate at 0.03-0.06 % wlw. Finally, the two solutions I and II
were applied one after the other on another portion of the prepared litter substrate in the same concentrations noted hereinabove.

The dosimetric responses regarding the detection of ammonia released for the three portions of solution-treated litter after adding 50 ml of ammonia at 4 % w/w, showed the following results:

Solution Released ammonia treatment Solution I 474 m after 24 hours Solution II 500 m after 1 hour Solution I & 2 480 m after 24 hours

8 Example 2 The same litter preparation at in Example I was separated into 3 portions of 400 grams that were exposed to an aqueous solution containing 7.5 grams of urea, 0.5 grams of urease in 50 grams of water. The results of released ammonia over time are as follows:

Solution Released ammonia treatment Solution I 21 m after 48 hours Solution 11 11 m after 48 hours Solution I & 2 8 ppLn after 48 hours Example 3 Regarding detection of volatile dust, the following results were obtained:
Solution Dust treatment Solution I I m i Solution 11 10 m Solution I & 2 1 m Example 4 In this example, the products were introduced at the last stage of an extrusion of a mixutre of exfoliated bentonite and starch. The conditions were as follows:

- Twin screw extruder was used.

- Starch and MgCl2 were introduced into the upstream part along with the exfoliated bentonite in suspension in water.

- The mixture was heated and then the product was cooled at the middle of the extruder and the odour control solution was introduced at a downstream end of the extruder.

- The end-products that were obtained were cut up, dried and tested in the presence of urea and urease.

9 The results show that only I to 2.5 ppm of ammonia is detected after 48 hours.

Knowing that a higher degree of dusting also favours odour dispersion, one can appreciate the importance of these low dust detection levels with the combination of the two agents on solutions I and II, as well as the combination's efficiency pertaining the detection levels of ammonia.

By associating the MgCI2 with the odour-retardants one observes complementary action and synergy that allow obtaining a product that is dust-reducing and that neutralises ammonia that may already be present in the medium and also retards the action of urease thus avoiding the formation of additional ammonia and, consequently, the occurrence of odours.
The above examples show these effects.

The MgCI2 may be used in an amount of about 0.5 % to about 2 % of a 20-35 wt%
MgCI2 solution, preferably in an amount of about 0.5 % to about 1.8 %.

A solution of N-(n-butyl) thiophosphoric triamide may be used for the odour-retardant agent.
The solution may be about 20 % to about 30 % of the N-(n-butyl) thiophosphoric triamide agent with a certain amount of solvent and/or solubilising compounds for providing it as a liquid. Their may also be other additives such as surfactants, dispersing agents, stabilisers, and the like. The N-(n-butyl) thiophosphoric triamide may be preferably used in an amount between about 0.01 % and about 1 %.

It should be understood that the embodiments, aspects and examples provided hereinabove are meant to be exemplary and should not be used to limit what has actually been invented.