WO2019068575A1

WO2019068575A1 - Clarification composition

Info

Publication number: WO2019068575A1
Application number: PCT/EP2018/076421
Authority: WO
Inventors: Aniruddh Singh JAMMORIA; Gurpreet Singh Kohli
Original assignee: Unilever N.V.; Unilever Plc; Conopco, Inc., D/B/A Unilever
Priority date: 2017-10-04
Filing date: 2018-09-28
Publication date: 2019-04-11
Also published as: CN111201203A; PH12020550123A1; BR112020006829A2

Abstract

The present invention relates to a clarification composition and to the use of the clarification composition for treating water used for laundering fabrics. The invention particularly relates to a clarification composition comprising an inorganic coagulant and an anionic polymeric flocculant. It is an object of the present invention to provide a packaged product having a particulate clarification composition contained in a package for clarifying turbid water, which composition is also storage stable. It is yet another object of the invention that the clarification is achieved in less than 15 minutes, more preferably less than 10 minutes, still more preferably less than 5 minutes, and ideally in 2 to 3 minutes.

Description

Clarification composition

Field of the invention

The present invention relates to a clarification composition and to the use of the clarification composition for treating water used for laundering fabrics. The invention particularly relates to a clarification composition comprising an inorganic coagulant and an anionic polymeric flocculant.

Background of the invention

There is an increasing need to provide efficient and cost-effective means to improve the quality of water at the point of use. In some areas around the world, natural water sources such as lakes, water streams or ground water are the major source of water. These natural water sources usually deliver water that is low in organic compounds, but may be soiled, i.e. high in suspended solids, such as clay or ash solids. The suspended solids provide a turbid appearance to the soiled water. Turbid water having suspended particles is less suitable for laundering fabrics, the cleaning efficacy of detergent compositions decreases in such water. One way of reducing turbidity in water is by precipitating suspended solids in water using a flocculant like alum (potassium aluminum sulfate dodecahydrate or aluminium sulphate). When turbid water is treated with a flocculant such as alum, the electrostatic repellent forces keeping the solids suspended is neutralised and the solids

agglomerate to form larger particles known as 'floes' which settle down slowly to the bottom. Disadvantage of using alum as flocculant is that the performance is

substantially affected at lower temperatures and there is poorer efficiency towards attracting organic suspended solids. A relatively large dose becomes necessary.

Adding excess coagulant beyond charge-neutralization results in the formation of metal coagulant precipitates and is termed sweep flocculation. Sweep flocculation

encompasses metal coagulants, such as Al-based or Fe-based salts, which are added in sufficient amount so that they form amorphous particles, e.g. amorphous AI(OH)3 particles. These amorphous particles entrap suspended solids leading to clarification of water. AI(OH)3 or Fe(OH)3 particles with entrapped suspended solids called sweep floes, have a size in the range of 100 μηι or below. At this size the sweep floes are still difficult to separate from the water by, e.g. filtration or decantation. Moreover, the kinetics of settling down of the sweep floes is very slow. Although ferric chloride is good at attracting inorganic solids, a lower efficiency for organic solids is observed.

Consumers prefer a clarification method that achieves floe formation within a few minutes. It is known in the art to improve the kinetics of settling down by adding a polymer flocculant, such as polyacrylamides (including acrylamide-acrylate

copolymers). This type of flocculation encompasses the addition of a polymer flocculant with a molecular weight of at least 100 kDa. These polymers are believed to adsorb on the sweep floes and thereby bring the sweep floes together to form bigger and stronger floes. This phenomenon is known as "bridging flocculation". This bridging mechanism helps in increasing the settling velocity of the floes and contributes therefore to faster clarification of water.

WO 2012/084621 A1 (Unilever) discloses a water purification composition having a flocculant, coagulant, filler and cationic surfactant to provide effective water clarification and purification. The polymer coagulant is described to be a neutral and/or anionically modified adsorbing polymer that is preferably polyacrylamide.

FR2870229 A1 (Acideka SA, 2005) discloses a stable composition for providing as coagulating and/or flocculating agents in solid-liquid separation process where the homogenous mixture of the metal coagulant and the organic flocculant is stabilised using a surfactant system such that the composition is stable and shows no phase separation or appearance of precipitates.

WO 2015/062881 A1 (Unilever NV) discloses a composition for purification of water comprising arsenic having a compound of iron and a compound of aluminium with specific ratio between the total iron to total aluminium content and where the aluminium has a basicity of at least 40%. A common difficultly observed by the present inventors with such clarification composition having an inorganic coagulant and polymeric flocculant is that the composition is hygroscopic and has a tendency to absorb moisture and form lumps when stored over extended periods, specifically under hot and humid conditions. Lumping is not desirable, as the consumer believe such products to be of inferior quality. Moreover, in presence of higher moisture levels the inorganic coagulant and polymeric flocculant may interact negatively and may reduce the efficiency of the composition in use. The present inventors investigated ways of improving the kinetics of settling down of floes and, in particular, into including an anionic polymeric flocculant in a clarification composition having inorganic coagulant. However, the present inventors have found that incorporating an anionic polymeric flocculant has adverse effects on the storage stability of the clarification composition having inorganic coagulant.

The present inventors have thus sought to provide a clarification composition including an anionic polymeric flocculant and inorganic coagulant with improved storage stability. It is thus an object of the present invention to provide a free-flowing clarification composition.

It is yet another object of the present invention to provide a single clarification composition that provides, easy dosing and does not require the consumer to dose different compositions and/or dose different components in a specific order.

It is a further object of the present invention to provide a packaged product having a clarification composition contained in a package for clarifying turbid water, which composition is also storage stable.

It is yet another object of the invention that the clarification is achieved in less than 15 minutes, more preferably less than 10 minutes, still more preferably less than 5 minutes, and ideally in 2 to 3 minutes. Summary of the invention

The present inventors have surprisingly found that in a solid clarification composition having an inorganic coagulant, the addition of an anionic polymeric flocculant can improve the kinetics of formation and settling down of floes while also providing improved storage stability and protection against lump formation, and loss of activity in presence of moisture under extended hot and humid storage conditions, when the anionicity of the anionic polymeric flocculant is from 5 mole% to 25 mole%.

Accordingly, in a first aspect the invention provides a solid clarification composition for removing suspended solids from turbid water, said clarification composition comprising:

(i) an inorganic coagulant selected from polyaluminium coagulant, poly-iron

coagulant or combinations thereof;

(ii) an anionic polymer flocculant wherein the anionic polymer flocculant has an anionicity ranging from 5 mole% to 25 mole% and,

(iii) 0wt% to 15wt% water.

In a second aspect, the invention provides a process for clarifying turbid water comprising suspended solids, said process comprising the steps of:

(i) dosing the solid clarification composition, according to the first aspect, in a dose of 0.2 to 10 grams per litre of turbid water to obtain a mixture of the turbid water and the clarification composition;

(ii) stirring said mixture to induce the formation of floes; and,

(iii) separating the floes from the water to obtain clarified water. Preferably the clarified water is to be used in laundering fabrics.

In a third aspect, the invention provides use of an anionic polymeric flocculant wherein the anionic polymer flocculant has an anionicity ranging from 5 mole% to 25 mole% in a clarification composition according to the first aspect for clarifying water intended for use in laundering fabrics, in less than 3 minutes. In a fourth aspect, the invention provides a water clarification kit having a clarification composition of the first aspect and instructions for use instructing users to dose the clarification composition to water to obtain water suitable for laundry washing. These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilized in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of" or "composed of." In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about".

Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

Detailed description of the invention

The term 'flocculation' as used herein refers to a process of contact and adhesion whereby the particles of a dispersion form larger-size clusters.

The term "turbidity" as used herein refers to the cloudiness or haziness of a liquid caused by a large number of individual suspended particles. The unit "NTU" as used herein refers to Nephelometric Turbidity Units (NTU), as measured by the nephelometer, Turbiquant® 2100T, manufactured by Merck. The nephelometer preferably is calibrated using the standard formazin solutions as recommended by the instrument manufacturer. The nephelometer measures the propensity of particles to scatter a light beam focused on them.

The term "basicity" of a polyaluminium compound as used herein is defined by the equation B^*100/3; where the degree of neutralization of a pre-hydrolysed polyaluminum compound is represented by B value which is a molar ratio of OH content to Al content of the polyaluminium compound that is represented by the formula: B = [OH] / [Al]

Similarly, the term "basicity" of a poly-iron compound as used herein is defined by the equation B^*100/3; where the degree of neutralization of a pre-hydrolysed poly-iron compound is represented by B value which is a molar ratio of OH content to Fe content of the poly-iron compound that is represented by the formula: B = [OH] / [Fe]

The term "aluminium chlorohydrate" as used herein refers to compounds having the general formula (Al_nCI(3n-m)(OH)_m), wherein the basicity of said compounds is from 45 % to 85%.

The term "anionicity" in the meaning of the present invention refers to the relative amount of anionic monomeric units comprised in the anionic polymer flocculant.

Clarification composition

The solid clarification composition according to the invention comprises an inorganic coagulant and an anionic polymeric flocculant.

The clarification composition is preferably in a solid form, preferably a powder composition; it may also be in the particulate form or a granulated form. Preferably, the powder clarification composition is free flowing. Inorganic coagulant:

The inorganic coagulant of the present invention is selected from polyaluminium coagulant, poly-iron coagulant or combinations thereof. The inorganic coagulant in the clarification composition is preferably a polyaluminium coagulant.

The polyaluminium coagulant in the clarification composition is preferably selected from polyaluminium chloride, polyaluminium chlorosulfate, aluminium chlorohydrate compound and combinations thereof. The aluminium chlorohydrate compound in the clarification composition is preferably selected from aluminium chlorohydrate, aluminium chlorohydrate sulfate and combinations thereof. Most preferably, the aluminium chlorohydrate compound is aluminium chlorohydrate.

The clarification composition according to the present invention preferably comprises 10 to 70 wt.% calculated by weight of dry matter, of the inorganic coagulant.

Preferably the amount of inorganic coagulant in the clarification composition is at least 1 1wt%, still preferably at least 12wt%, further preferably at least 13wt% and most preferably at least 14wt%, but typically not more than 60wt%, still preferably not more than 55 wt% and most preferably not more than 45wt%. Most preferably, the clarification composition comprises 12 to 20 wt. % calculated by weight of dry matter, of the inorganic coagulant. The basicity of the inorganic coagulant in the clarification composition selected from polyaluminium flocculant, poly-iron flocculant and combinations thereof, is preferably in the range of 45% to 85%, more preferably in the range of 55% to 85% and most preferably in the range of 60% to 85%. The composition preferably further contains a metal salt coagulant selected from aluminum sulfate, aluminum chloride, ferric sulfate, ferrous sulfate, ferric chloride and combinations thereof.

In the context of the present invention, the inorganic coagulant achieves coagulation by decreasing or neutralizing the negative charge or negative zeta potential of insoluble particles by interaction with the coagulant, so that the insoluble particles display an initial aggregation, thereby forming microflocs. This process is reversible, so that microflocs exist in a dynamic equilibrium with the surrounding water, which limits their size depending on the conditions. Microflocs have a very loose consistency, which is such that they cannot themselves be isolated from the solution.

Anionic polymer flocculant:

The anionic polymer flocculant of the present invention has anionicity ranging from 5 mole% to 25 mole%.

In the context of the present invention, the anionic polymer flocculant achieves flocculation, by a process of bringing together microflocs under its influence to form large agglomerates. Thus, the anionic polymer flocculant adsorbs microflocs. The agglomerate of microflocs absorbed to a flocculant is called a floe in the present context. Although floes might break, the formation of floes is in principle not reversible. In contrast to microflocs, floes can be isolated from the solution. Preferably the anionicity of the anionic polymeric flocculant is at least 8 mole%, still preferably at least 10 mole%, further preferably at least 12 mole% and most preferably at least 13 mole%, but typically not more than 24 mole%, still preferably not more than 22 mole% and most preferably not more than 23 mole%. Most preferably, the anionic polymeric flocculant has an anionicity of from 10 to 15 mole%.

The clarification composition according to the present invention preferably comprises 0.1 to 15 wt.% calculated by weight of dry matter, of the anionic polymer flocculant. Preferably the amount of anionic polymer flocculant in the clarification composition is at least 0.5wt%, still preferably at least 2wt%, further preferably at least 3wt% and most preferably at least 4wt%, but typically not more than 12wt%, still preferably not more than 10 wt.% and most preferably not more than 8wt%. Most preferably, the

clarification composition comprises 4 to 10 wt.% calculated by weight of dry matter, of the anionic polymer flocculant. The anionicity is the degree of anionic monomeric units present in the anionic polymer flocculant. The anionic polymeric flocculant preferably contains randomly repeating monomer units containing chemical functionality which when dissolved in water become anionically charged, such as carboxylate groups, acrylate group, sulfonate grous, phosphonate group, and the like or a combination thereof.

The anionic polymer flocculant preferably includes anionic monomer units selected from the group consisting of carboxylic acid, acrylic acid, methacrylic acid, 2- acrylamido-2-methylpropane sulphonic acid, sulphonates, phosphonates, and water- soluble salts thereof. The anionic monomer units may also be selected from a combination of two or more such units. More preferably the anionic monomer unit is acrylic acid or sodium acrylate.

Non-limiting examples of an anionic polymer flocculant includes copolymers made by the polymerization of (meth)acryamide, N-vinyl pyrrolidone, N-vinyl formamide, N,N dimethylacrylamide, N-vinyl acetamide, N-vinylpyridine, N-vinylimidazole, isopropyl acrylamide and polyethylene glycol methacrylate, polyacrylamide and one or more anionic monomer(s) such as acrylic acid, methacrylic acid, 2-acrylamido-2- methylpropane sulphonic acid (ATBS) and salts thereof. The anionic polymer flocculant employed in accordance with the present invention is preferably selected from anionic polyacrylamide or a copolymer thereof, anionic polyacrylate and combinations thereof. Most preferably, the anionic polymer flocculant is an anionic polyacrylamide. The anionic polymer flocculant is preferably a copolymer of acrylamide and anionic monomer units selected from acrylic acid, methacrylic acid, 2-acrylamido-2- methylpropane sulphonic acid and salts thereof. A preferred anionic polymer flocculant is a copolymer of sodium acrylate and polyacrylamide having 5 mole% to 25 mole% of sodium acrylate units.

Preferably the anionic polymeric flocculant has a weight average molecular weight of more than 100 kDa. More preferably, the molecular weight of the flocculant is at least 250 kDa, even more preferably at least 500 kDa and most preferably at least 1000 kDa. It is preferred that the weight average molecular weight of the anionic polymeric flocculant does not exceed 20 million Da. Highly preferred anionic polymer flocculant has a weight of 15 million Da. For avoidance of doubt, the unit Da (Dalton) as used herein refers to atomic mass unit (amu, the less commonly used SI unit). Preferably the anionic polymeric flocculant of the present invention is in solid form, preferably powder form. Preferably the anionic polymeric flocculant has a moisture content from 0 to 12%, still preferably from 0 to 10%, further preferably from 0 to 5% by weight of the anionic polymer flocculant.

Inorganic Filler:

The inorganic filler of the present invention is preferably an inert particulate filler.

Preferably the filler is inert to the other ingredients present in the clarification composition. The filler is preferably a solid with a high density. The density of the inorganic filler is preferably at least 1.5 kg/dm³. More preferably the density of the inorganic filler is between 1.75 to 3.5 kg/dm³ and most preferably the density of the inorganic filler is between 2 to 2.5 kg/dm³.

The clarification composition according to the present invention preferably comprises 20% to 90 % by weight of the inorganic filler, calculated by weight of dry matter. More preferably the clarification composition comprises 25% to 85 % by weight of the inorganic filler, most preferably the purification composition comprises 30% to 50 % by weight of the inorganic filler, calculated by weight of dry matter. The inorganic filler is preferably selected from feldspar, clay, alumina, aluminium hydroxides, magnesium hydroxides, iron hydroxides, calcite, and combinations thereof. More preferably the inorganic filler is selected from feldspar, clay and combinations thereof. Even more preferably the inorganic filler is selected from feldspar, bentonite and combinations thereof. Most preferably the inorganic filler is feldspar.

The clarification composition according to the present invention preferably has a water content of not more than 15 % by weight. More preferably the water content of the clarification composition is not more than 12 % by weight. Most preferably the water content of the clarification composition is within 5 to 10 % by weight. Preferably the water content of the clarification composition is from 0wt% to 15wt%, still preferably 0wt% to 12wt%, further preferably 0wt% to 10wt%, still further preferably 3 wt% to The clarification composition is preferably prepared according to the following steps. Preferably, the individual ingredients are weighed as per the proportion and mixed using an appropriate powder mixing apparatus or equipment known in the art. Method for clarifying turbid water

(iv) dosing the clarification composition, according to the first aspect, in a dose of 0.2 to 10 grams per litre of turbid water to obtain a mixture of the turbid water and the clarification composition;

(v) stirring said mixture to induce the formation of floes; and

(vi) separating the floes from the water to obtain clarified water.

The clarification composition is preferably dosed in a dose of 0.2 to 5 grams per litre of water and still preferably in a dose of 0.2 to 4 grams per litre water and most preferably 0.2 to 3 grams per litre water.

Dispersing of the clarification composition throughout the water to be clarified can be achieve, for instance, by stirring. Stirring in the process of the present invention is preferably performed for at least 10 seconds, more preferably performed for 15 to 60 seconds and most preferably the stirring of the mixture is performed for 15 to 50 seconds. Different patterns of stirring may be followed applied, e.g. stirring-pause- stirring or stirring-pause or variations thereof. The separation of the precipitated floes from the water is preferably performed by filtration, decantation and combinations thereof. More preferably the separation of the precipitate from the water is performed by filtration.

Preferably, the turbidity of the water to be clarified is reduced to less than 70 NTU, more preferably less than 60 NTU, still preferably less than 50 NTU and more preferably to less than 30 NTU, still preferably less than 20 NTU and most preferably less than 15NTU by the present process. Typically, the water to be clarified in the present process has an initial turbidity of 100 NTU or more, more preferably 200 NTU or more, still preferably 400 NTU or more.

In a third aspect, the invention provides use of an anionic polymer flocculant wherein the anionic polymer flocculant has an anionicity of 5 mole% to 25 mole% in a clarification composition according to the first aspect for clarifying water intended for use in laundering fabrics, in less than 3 minutes.

In a fourth aspect, the invention provides a water clarification kit having a clarification composition of the first aspect and instructions for use instructing users to dose the clarification composition to water to obtain water suitable for laundering fabrics.

Preferably the clarification composition is provided in a package, more suitably a flexible package or a container. The package may be made of any suitable material and form known in the art for enclosing a solid composition, particularly a powder, particulate or granular composition. The kit may preferably include a bucket and a separator plate configuration. The bucket may preferably include a water discharge means such as a faucet.

Preferably the water clarification kit includes an alkaline buffering agent selected from calcium oxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, magnesium oxide, magnesium hydroxide and combinations thereof.

The invention is further illustrated by the following non-limiting examples. Examples

Example 1 : Storage stability and performance of different clarification compositions Different clarification compositions were prepared according to the ingredients showed in table 1 . All the ingredients were weighed as per proportion and were dry mixed to form a homogeneous mixture. Several petridish were then taken and filled with the prepared compositions. The petridishes were then stored for 4 weeks at a temperature of 37°C and relative humidity of 70% in an open condition. Model turbid water was prepared by addition of model particulate soil to tap water and liquid detergent. The turbidity of this model dirty water was measured to be 150 NTU with a pH of 6.5 to 8. The clarification compositions shown in Table 1 were added to the aforementioned turbid water in an amount of 0.5 gram per litre while continuously stirring, for 30 seconds at 100 rpm. After 30 seconds of stirring the mixture was allowed to standstill for 1.5 minutes to allow the floes to separate from the clarified water. The turbidity of the samples was measured using a turbidometer. The calibration of the machine was done using standard protocol as per manual of the instrument. Similar experiments were also conducted after the storage of the compositions for 1 week, 2 weeks and 3 weeks and the results were recorded. A turbidity of 10 or below was considered acceptable, and the turbidity of samples were measured at the end of every week until the turbidity reported was above 10.

The results of the turbidity measurements are presented in Table 1 .

Table 1

inorganic coagulant used was aluminium chlorohydrate with basicity 85 % * anionic polymeric flocculant used was a copolymer of acrylamide and sodium acrylate with specific mole% of sodium acrylate units.

• Flogel 3303 (obtained from SNF); Molecular weight >10,000 kDa; copolymer of sodium acrylate and acrylamide with anionicity 30 mole%

· Flogel 3233 (obtained from SNF); Molecular weight >10,000 kDa; copolymer of sodium acrylate and acrylamide with anionicity 23 mole%

• Flogel 3133 (obtained from SNF); Molecular weight >10,000 kDa; copolymer of sodium acrylate and acrylamide with anionicity 13 mole%

The table above shows that the desired reduction in turbidity is shown by the composition of Ex 1 and Ex 2 that has anionic polymer flocculant with anionicity according to the invention. The composition of Ex A which has an anionic polymer flocculant with anionicity outside the claimed ranges is not storage stable after 2 weeks of the study and does not provide the desired clarification and after 2 weeks of storage study the composition fails to flocculate turbid water.

Claims

1 A solid clarification composition for removing suspended solids from water, said clarification composition comprising:

(i) an inorganic coagulant selected from polyaluminium coagulant, poly-iron coagulant or combinations thereof,

(ii) an anionic polymer flocculant wherein the anionic polymer flocculant has an anionicity ranging from 5 mole% to 25 mole%. and,

(i i i ) 0 wt% to 15wt% water.

2 A composition according to claim 1 wherein the anionic polymeric flocculant has charged monomer units selected from the group consisting of carboxylic acid, acrylic acid, sulphonates, phosphonates respective salts thereof and their combinations.

3 A composition according to claim 1 or 2 wherein the anionic polymer flocculant is an anionic polyacrylamide or copolymer thereof.

4 A composition according to claim 3 wherein the anionic polymer flocculant is a copolymer of sodium acrylate and acrylamide having 5 mole% to 25 mole% of sodium acrylate units.

5 A composition according to any one of the preceding claims wherein the

inorganic coagulant has basicity ranging from 45% to 85%.

6 A composition according to any one of the preceding claims wherein the

inorganic coagulant is aluminium chlorohydrate.

7 A composition according to any of the preceding claims, wherein the composition comprises an inorganic filler, preferably an inorganic filler having a density of at least 1 .5 kg/dm³. A composition according to claim 7, wherein the inorganic filler is selected from feldspar, clay, alumina, aluminium hydroxides, magnesium hydroxides, iron hydroxides, calcite and combinations thereof. A composition according to claim 7 or claim 8, wherein the composition comprises 20% to 90%, calculated by weight of dry matter, of the inorganic filler. A composition according to any one of the preceding claims, wherein the composition comprises from 0.1 % to 15 wt.% calculated by weight of dry matter, of the anionic polymer flocculant. A composition according to any one of the preceding claims, wherein the composition comprises from 10% to 70 wt.%, calculated by weight of dry matter, of the inorganic coagulant. Process for clarifying turbid water comprising suspended solids, said process comprising the steps of:

(i) dosing the clarification composition, according to any one of the previous claims, in a dose of 0.2 to 10 grams per liter of water to obtain a mixture of the water and the clarification composition;

(ii) stirring said mixture to induce the formation of floes; and

(iii) separating the floes from the water to obtain clarified water. Use of a anionic polymer flocculant wherein the flocculant has an anionicity ranging from 5 mole% to 25 mole% in a clarifying composition according to any one of the previous claims for removing turbidity from a water intended for use in laundering fabrics, preferably in less than 5 minutes. A water clarification kit comprising:

(i) a package comprising a composition according to any one of claims 1 to 1 1 ; and,

(ii) instructions for use instructing users to dose the clarification composition to water to obtain water suitable for laundry washing. Water clarification kit according to claim 14, wherein the kit comprises an alkaline buffering agent selected from calcium oxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, magnesium oxide, magnesium hydroxide and combinations thereof.