IT202200000005A1 - INNOVATIVE SOLUTION FOR WATER SOFTENING - Google Patents

Description

Description of the industrial invention entitled:

?Innovative solution for water softening?

TECHNICAL FIELD OF THE INVENTION

The present invention falls into the field of water softening, i.e. the reduction of their hardness. In particular, the present invention is relating to a system and device for softening water. In detail, the present invention is relating to a system and device for quantity reduction? or percentage of metal ions contained in water. Even more? in detail, the present invention is relating to a system and device for quantity reduction? or percentage of calcium and magnesium ions contained in water, the device and system according to the present invention being suitable for softening both water for domestic use and water for industrial use.

STATE OF THE PRIOR ART

The problem of reducing water hardness is currently addressed using solutions that vary depending on the type of systems and/or processes that require softened water.

Among the systems that require water softening, for example, we can mention those whose functionality? can? be compromised by the formation of limescale (e.g. washing machines, boilers, etc.).

Other systems include washing systems in which the high hardness of the water negatively affects the efficiency and/or effectiveness of the detergents (e.g. dishwashers, washing machines, etc.);

Finally, water softening is necessary in systems where the properties organoleptic characteristics of the water are negatively influenced by the hardness of the water itself (e.g. food industry, coffee production systems, etc.).

Among the solutions still most used today in the various systems mentioned above for water softening, the one that involves the use of ion exchange resins certainly deserves to be mentioned.

This solution ? in fact one of the most widespread for the removal of calcium and magnesium ions from water.

Ion exchange resins are made up of polymeric beads that allow ion exchange, whereas according to one of their most embodiments? widespread, the said resins adsorb calcium and magnesium from the water, releasing sodium ions twice and thus allowing the exchange of cations, and where therefore following the ion exchange, the water leaving the system has a lower hardness than that entering the system .

Ion exchange resins, although usually very efficient from the softening point of view, nevertheless often present non-negligible disadvantages which the applicant intended to overcome or at least reduce through the present invention; said problems and/or disadvantages include, but are not limited to:

the decrease in the pH of the outgoing solution (of the treated water), where in turn the acidification of the treated water can determine the onset of various problems, including corrosion;

the necessity? to size a system containing ion exchange resins considering: i) the quantity? of water to be treated, ii) the quantity? of calcium and magnesium ions to be removed, and iii) the hardness of the incoming water);

being typically formed in the form of pellet beads, ion exchange resins require solutions suitable for their contingency, as they are not capable of self-sustaining. The water to be treated must then be forced through the system; ion exchange resins, in some of their configurations, can be regenerated using chemical agents that are corrosive or dangerous to health (e.g. hydrochloric acid), as prolonged contact times (between chemical agents and resins) are also required (e.g. from 2 to 6 hours );

the regeneration of the resins negatively affects their performance, where more? regenerations are performed and more? resins lose adsorption efficiency over time.

Specific task of the present invention? therefore that of making available a solution which allows at least in part to overcome the problems described above found in known and still unresolved softening systems. As part of this task, ? particular purpose of the present invention is to provide a system and/or device for the softening of water which allows:

to model the shape of the filter system depending on the shape of the system used to limit the flow of water;

to obtain, on equal terms? of flow conditions, an improvement in the exchange of matter between the fluid to be treated and the system and/or device, thanks in particular to the intrinsic tortuosity? of the system itself, in the absence of load losses;

an increase in the possible configurations to be used, taking advantage of the possibility? to obtain relative movement between adsorbent material and fluid;

to introduce properties into the system? bacteriostatic/bactericidal, and therefore can also be used in immersion or stagnation conditions;

to be characterized by low (or zero) pressure drops;

the implementation of constructive solutions that provide the possibility? to have stagnant fluids, without the formation of biofilm thanks also to the properties? bacteriostatic/bactericidal, and at the same time maintain properties? adsorbents; to obtain adsorption of metal ions without causing a lowering of the pH; the creation of a robust and almost insensitive to the hardness of the incoming water, where therefore the softening efficiency is not influenced by the quantity? of calcium and/or magnesium ions entering the system; to carry out the regeneration operations in mild conditions (e.g. 0.1% wt sodium chloride aqueous solution) and without the use of harmful or dangerous substances, the operating conditions of the regeneration phase being therefore sustainable, both from the point of environmental and procedural view, compared to those necessary for the regeneration of ion exchange resins, also preventing? the decay of performance in the face of consecutive regenerations;

to operate the regeneration also in-situ, directly flowing the regeneration solution through the system, the fluid dynamic conditions for the regeneration being completely similar to those of operation, and significantly more? mild compared to the regeneration of systems representing the state of the art (e.g. ion exchange resins), both in terms of times and in terms of volumes used. Note: In this patent application, the term ?'absorption? indicates the phenomenon whereby there is the transfer of a chemical species (i.e. an exchange of matter) from a solution onto the surface of a solid (adsorption) or across the separation interface between two phases (absorption).

DESCRIPTION OF THE PRESENT INVENTION

According to the present invention, the predetermined objectives are at least partially achieved and the disadvantages found in the known art at least partially overcome by means of a system according to claim 1, a device according to claim 10, and a method according to claim 14, as well as? through the embodiments of said system, device and method according to the dependent claims.

According to one embodiment, a softening system is proposed for reducing the hardness of water by reducing the quantity of water. or percentage of metal ions contained therein, in particular by reducing the quantity? or percentage of calcium and magnesium ions contained therein, said system comprising a solid porous substrate and therefore including a plurality? default cavity? per unit? in volume, said substrate being capable of being impregnated with water so that said cavities? are at least partially invaded by said water, where the surface of at least a percentage of said cavities? ? covered by a layer of graphene oxide, and therefore where the invasion of said percentage of cavities? by water translates into the capture by said graphene oxide layer of at least part of the calcium and magnesium ions contained therein and therefore in the reduction of the hardness of said water.

According to one embodiment, said substrate ? made of polymeric material, in particular polyurethane foam.

According to one embodiment, said substrate ? made of ceramic material.

According to one embodiment, said substrate ? Made of metal material.

According to one embodiment, in said substrate, the number of cavities? per linear inch (PPI) ? between 10 and 100.

According to one embodiment, in said substrate, the linear dimension of said cavities? ? between 0.5 and 5 mm.

According to one embodiment, in said substrate, the degree of vacuum, i.e. the overall volume of said cavities? ? between 80% and 95% of the total volume of said substrate.

According to one embodiment, the thickness of said graphene oxide layer is ? between 0.5 and 100 ?m.

According to one embodiment, in said substrate, the quantity? of graphene oxide GO ? between 7 and 15 mg/cm3.

This invention? also relating to a softening device for reducing the hardness of water by reducing the quantity? or percentage of metal ions contained therein, in particular by reducing the quantity? or percentage of calcium and magnesium ions contained therein, said device comprising a system including a porous solid substrate, said device comprising a system according to one of the embodiments of the present invention. According to one embodiment, said device comprises a container inside which there is a housed said system, wherein said container and said system have complementary shapes and dimensions.

According to one embodiment, said container includes a delivery opening and a drain opening for introducing water into it and respectively discharging water from inside it.

According to one embodiment, said delivery opening and exhaust opening are placed in fluid communication with a delivery duct and respectively an exhaust duct.

This invention? further relating to a method for the production of a system according to one of the embodiments of the present invention, wherein said method comprises the step of impregnating said substrate with an aqueous solution containing graphene oxide in a concentration between 2 and 20 mg/ml, in particular equal to 4 mg/ml.

According to one embodiment, said step of impregnating said substrate with said aqueous solution containing graphene oxide lasts between 2 and 60 seconds.

According to one embodiment, said method includes a phase subsequent to said phase of impregnating said substrate with said aqueous solution containing graphene oxide suitable for eliminating the excess solution, avoiding the occlusion of said cavities, ensuring the deposition of said layer of graphene oxide of essentially uniform thickness.

According to one embodiment, said phase is designed to eliminate the excess solution while avoiding the occlusion of said cavities. includes a squeeze phase during which the said substrate is squeezed.

According to one embodiment, said phase is designed to eliminate the excess solution while avoiding the occlusion of said cavities. includes a ?dip-spin coating? phase during which the said substrate is subjected to the action of centrifugal force.

According to one embodiment, during said ?dip-spin coating? said substrate is subjected to a speed? rotation between 1000 and 3000 rpm.

According to one embodiment, said method comprises a drying phase following said phase suitable for eliminating the excess solution by evaporating said aqueous solution from said substrate thus to allow the consolidation of the graphene oxide layer.

DESCRIPTION OF THE FIGURES

Will this invention come? further clarified by means of the following detailed description of the embodiments represented in the drawings, where in the drawings:

Figure 1 shows a schematic view of a system according to one embodiment;

Figure 2 shows an enlargement of a section of a system according to one embodiment;

figure 3 shows in schematic form the operation of a system according to one embodiment;

figure 4 shows a substrate not yet covered with graphene oxide (figure 4a) and respectively the same substrate covered with a layer of graphene oxide (figure 4b);

figure 5 shows one of the possible applications of the system according to an embodiment.

DETAILED DESCRIPTION OF THIS INVENTION

Although the present invention is clarified by the following description of its embodiments depicted in the figures, the present invention is not limited to the embodiments described below and represented in the figures. On the contrary, all those variations of the embodiments described below and represented in the figures which will be obvious to the man of the trade or expert in the art fall within the scope of the present invention.

Figure 1 schematically shows the components of system S according to one embodiment, namely the solid (not necessarily rigid) porous support A and the related graphene oxide (GO) layer B.

As represented, the support or substrate A, can? be made of polymeric material (with advantages in terms of workability and low costs), or in another material, such as ceramic (with advantages in terms of chemical inertia, even in chemically extreme environments) or metallic (with advantages in terms of properties ? mechanical and thermal conductivity), depending on the characteristics that the filter system S will have? have.

Substrate A? however solid (as anticipated, not necessarily rigid) and porous, i.e. characterized by complex geometry defined by a plurality? of cavities? internal (C cells and/or P pores, see the following description) preferably communicating: could it? in particular have the shape of foams or 3D printed structures, such as POCS (open cellular matrix periodic structures) thus allowing? better customization of the final structure. Complex structures such as open cell foams allow for a high degree of vacuum and high surface area per unit? of volume.

According to one embodiment, the substrate A can be understood as a polyurethane foam including a plurality? of cavities? internal cells communicating with each other through pores and for this reason also defined as "open cells".

With reference to figure 2? in particular it is possible to appreciate the complex structure of the substrate A. In fact, in figure 2 we can recognize the open cells C delimited by filaments (struts) F and reciprocally connected by pores P, the filaments being reciprocally connected by nodes (Junction) N, which constitute the solid part of the substrate A.

More? precisely, the C cells are said to be open precisely because? are mutually interconnected through the P pores which therefore confer continuity? between one cell C and the others. The open C cell structure therefore facilitates the passage (flow) of water through the substrate A and therefore inside the C cells, whereas the structure of the substrate A can also be of the ?closed? C cell type (not or only partially communicating), in cases where even a slowed flow of water through substrate A allows you to obtain (although perhaps in longer times) a satisfactory softening of the water. In consideration of what has been specified, what will be done in the remainder of this description? possibly simply referring to ?cavit?) with this meaning both C cells (indifferently closed or open) and/or P pores.

For the purposes of the present invention the substrate A will have preferably a number of pores P per linear inch (PPI) in a range typically between 10 and 100, cell dimensions C between 0.2 ? 5 mm and vacuum level between 80% and 95%.

Regarding the graphene oxide coating layer B, does it cover the solid part of the substrate A, for example the struts and/or the internal surface of the cells C and/or the pores P,? consisting in particular of graphene oxide (graphene oxide), and/or derivatives thereof (reduced graphene oxide or modified graphene oxide), with typical thicknesses ranging from 0.5 to 100 ?m and quantities? 7 to 15 mg GO/cm<3 >of volume of support used.

The operation or use of the system S according to an embodiment ? schematized in figure 3; as represented, the system S (substrate A coating B of graphene oxide) is subjected to a flow of water so that the same invades and wets at least partially the cells C and/or the pores P and/or the filaments F, or in any case in a that the water comes into contact with layer B; in this regard, it should be noted that the open cell structure C facilitates the circulation of water within the substrate B and therefore the invasion of the C cells and/or the P pores.

As an alternative to the flow of water, the S system can? simply be immersed in water. Again as shown, the incoming water is ? charged with metal ions, in particular calcium and magnesium ions, where during the crossing of system S, the contact between water and layer B translates into the capture by layer B of said metal ions, the water exiting system S thus being sweetened compared to the incoming one, and that is? characterized by a quantity? negligible and in any case much lower than that of the incoming water of metal ions, in particular calcium and magnesium ions.

The S system according to one embodiment can be achieved by implementing the following method.

In case of using flexible B supports (such as foams or POCS) in polymeric material (such as polyurethane) the deposition strategy of the coating B on the substrate A will be of the ?dip-squeeze? type, followed by a drying process to fix the coating B on the support A. In particular, according to the procedure the substrate A is immersed in (or alternatively subjected to the flow of) a volume of aqueous solution containing graphene oxide at a concentration between 2 and 20 mg/ml (typically 4 mg/ml) for a few seconds. Thereby ? It is possible to guarantee that the solution penetrates inside the empty part (in the cells C and/or in the pores P) of support A, guaranteeing contact between all surfaces (internal and external) and the solution.

Subsequently, during a so-called squeeze phase, the substrate B is squeezed in order to eliminate the excess solution, avoiding the occlusion of the C cells and/or the P pores and guaranteeing uniform thicknesses of the coating B.

Finally, substrate A is subjected to a drying phase during which the evaporation (more or less forced) of the water from the deposited wet layer allows the consolidation of the graphene oxide layer B on the surfaces of support A.

The above steps can be repeated to increase the quantity. of adsorbent material B on the surfaces (inside the cells C and/or the pores P) of the substrate A, until the desired material load is reached (for example, to reach the concentration of 7 mg/cm3 two passes are necessary) In case of use of rigid A supports (such as foams or metallic POCS, foams or ceramic POCS) the squeeze phase will be? replaced by one or more? ?dip-spin coating? phases, also followed by a drying phase. In particular, during this phase the substrate A, previously immersed in and extracted from a graphene oxide solution (with viscosities between 10<-3 > and 100 Pa*s in the shear rate range 10<-3 >- 10 <3 >s<-1>), is subjected to the action of centrifugal force. There? is obtained by rotating support A with speed? of rotation between 1000 and 3000 rpm, so? to eliminate the excess solution. Also in this case multiple steps can be performed so? to modulate the quantity? of adsorbent material B on the surfaces of substrate A.

System S composed of substrate A and coating B can? be used in different applications and in different ways? variable depending on circumstances and/or needs. For example, as represented in figure 5, the system S can? be used to create a softening device D including a container G in which there is? system S is housed. The said container G can? Furthermore, it must be equipped with a Gm delivery and a Gs drain for introducing the water to be softened inside it (thus forcing the water to be softened to invade the substrate S) and respectively for discharging the water from inside it , the container G (with substrate A both rigid and soft and/or elastic) and the system S preferably having corresponding shapes and dimensions.

Alternatively, system S (with substrate A being rigid, soft and/or elastic) can? be positioned directly in a T pipe in order to intercept and therefore soften the water in transit in said pipe.

Yes ? what? demonstrated by means of the previous detailed description of the embodiments of the system S according to the present invention represented in the drawing tables that the system S according to the present invention allows to obtain the desired results and to overcome the drawbacks found in softening systems according to the known art allows:

to model the shape of the filter system S depending on the shape of the system used to limit the flow of water, thanks to the intrinsic ease? processing of cellular A supports and, in particular, polymeric ones;

to obtain, on equal terms? of flow conditions, an improvement in the exchange of matter between the fluid to be treated and the graphene oxide layer B deposited on the geometric support A, thanks to the intrinsic tortuosity? of the S system, without disadvantages in terms of pressure drops.

an increase in the possible configurations to be used, taking advantage of the possibility? to obtain relative movement between adsorbent material B and fluid (water or aqueous solution);

to introduce properties into the S system? bacteriostatic/bactericidal, induced by the presence of graphene oxide (and therefore being able to operate even in immersion or stagnation conditions).

to have low pressure drops thanks to the high degree of vacuum of the cellular support A;

the implementation of constructive solutions that provide the possibility? to have stagnant fluids, without the formation of biofilm thanks also to the properties? bacteriostatic/bactericidal, and at the same time maintain properties? adsorbents; to obtain adsorption of metal ions without causing a lowering of the pH; the creation of a robust and almost insensitive to the hardness of the incoming water: the softening efficiency, in fact, is not influenced by the quantity? of calcium and magnesium ions entering system A;

to carry out the regeneration operations in mild conditions (e.g. aqueous solution 0.1 %wt of sodium chloride, solution volume/substrate volume S = 1) and without the use of harmful or dangerous substances. The operating conditions of the regeneration phase are therefore more sustainable, both from an environmental and procedural point of view, compared to what is typically done with ion exchange resins, also preventing the decay of performance in the face of consecutive regenerations.

to operate the regeneration also in-situ, directly flowing the regeneration solution through the S system. The fluid dynamic conditions for the regeneration are completely similar to those of operation, and significantly more? mild compared to the regeneration of systems representing the state of the art (e.g. ion exchange resins), both in terms of times and in terms of volumes used. Although the S system according to the present invention has been clarified by means of the previous detailed description of the embodiments represented in the drawing tables, numerous modifications may be made by the expert in the art to the embodiments described and represented in the drawing tables without thereby go outside the scope of protection of the present invention.

The scope of protection of the present invention is? therefore defined by the claims.

Claims (20)

1. Softener system (S) for reducing water hardness by reducing the quantity of water. or percentage of metal ions contained therein, in particular by reducing the quantity? or percentage of calcium and magnesium ions contained therein, said system (S) comprising a solid and porous substrate (A) and therefore including a plurality? default cavity? (C, P) per unit? in volume, said substrate (A) being capable of being impregnated with water so that said cavities? (C, P) are at least partially invaded by said water, said substrate (A) being characterized by the fact that the surface of at least a percentage of said cavities? (C, P) ? covered by a layer of graphene oxide (B), and therefore by the fact that the invasion of said percentage of cavities? (C, P) by water results in the capture by said graphene oxide layer (B) of at least part of the calcium and magnesium ions contained therein and therefore in the reduction of the hardness of said water. 2. System (S) according to previous claim 1, characterized in that said substrate (A) is made of polymeric material, in particular polyurethane foam. 3. System (S) according to claim 1, characterized in that said substrate (A) is made of ceramic material. 4. System (S) according to the previous claim 1, characterized in that said substrate (A) is Made of metal material. 5. System (S) according to one of claims 1 to 4, characterized in that, in said substrate (A), the number of cavities? (C, P) per linear inch (PPI) ? between 10 and 100. 6. System (S) according to one of claims 1 to 5, characterized in that, in said substrate (A), the linear dimension of said cavities? (C, P) ? between 0.2 and 5 mm. 7. System (S) according to one of claims 1 to 6, characterized in that, in said substrate (A), the degree of vacuum, i.e. the overall volume of said cavities? (C, P) ? between 80% and 95% of the total volume of said substrate (A). 8. System (S) according to one of claims 1 to 7, characterized in that the thickness of said graphene oxide layer (B) is? between 0.5 and 100 ?m. 9. System (S) according to one of claims 1 to 8, characterized in that, in said substrate (A), the quantity? of graphene oxide GO ? between 7 and 15 mg/cm<3>. 10. Softener device for reducing water hardness by reducing the quantity or percentage of metal ions contained therein, in particular by reducing the quantity? or percentage of calcium and magnesium ions contained therein, said device comprising a system including a solid porous substrate, said device being characterized by the fact that said system is? a system (S) according to one of claims 1 to 9. 11. Device according to claim 10, characterized by the fact of comprising a container inside which there is? housed said system (S), and by the fact that said container and said system (S) have complementary shapes and dimensions. 12. Device according to claim 11, characterized in that said container comprises a delivery opening and a drain opening for the introduction of water into it and respectively the discharge of water from its interior. 13. Device according to claim 12, characterized in that said delivery opening and exhaust opening are placed in fluid communication with a delivery duct and respectively an exhaust duct. 14. Method for the production of a system (S) according to one of claims 1 to 9, characterized in that said method comprises the step of impregnating said substrate (A) with an aqueous solution containing graphene oxide in a concentration between 2 and 20 mg/ml, in particular equal to 4 mg/ml). 15. Method according to claim 14, characterized in that said step of impregnating said substrate (A) with said aqueous solution containing graphene oxide lasts between 2 and 60 seconds. 16. Method according to one of the previous claims 14 and 15, characterized by the fact of comprising a phase subsequent to said phase of impregnating said substrate (A) with said aqueous solution containing graphene oxide suitable for eliminating the excess solution avoiding the occlusion of said cavity? (C, P), ensuring the deposition of said graphene oxide layer (B) of substantially uniform thickness. 17. Method according to claim 16, characterized in that said phase is suitable for eliminating the excess solution while avoiding the occlusion of said cavities? (C, P) includes a squeeze phase during which the said substrate (A) is squeezed. 18. Method according to claim 16, characterized by the fact that said phase is suitable for eliminating the excess solution while avoiding the occlusion of said cavities? (C, P) includes a ?spin coating? during which the said substrate (A) is subjected to the action of centrifugal force. 19. Method according to claim 18, characterized by the fact that during said ?spin coating? said substrate (A) is subjected to a speed? rotation between 1000 and 3000 rpm. 20. Method according to one of claims 16 to 19, characterized in that it comprises a drying phase subsequent to said phase suitable for eliminating the excess solution by evaporation of said aqueous solution from said substrate (A) thus? to allow the consolidation of the graphene oxide layer (B).