WO2013153531A1 - Nanoporous, aluminium-supported alumina membrane, method for producing same and use thereof - Google Patents

Nanoporous, aluminium-supported alumina membrane, method for producing same and use thereof Download PDF

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Publication number
WO2013153531A1
WO2013153531A1 PCT/IB2013/052889 IB2013052889W WO2013153531A1 WO 2013153531 A1 WO2013153531 A1 WO 2013153531A1 IB 2013052889 W IB2013052889 W IB 2013052889W WO 2013153531 A1 WO2013153531 A1 WO 2013153531A1
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membrane
phosphorus
aluminum
membrane according
pores
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PCT/IB2013/052889
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French (fr)
Portuguese (pt)
Inventor
António José GUERREIRO BRITO
Daniel RIBEIRO
Gilberto MARTINS
Cláudia DA ROCHA VALENTE SIL MONTEIRO
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Universidade Do Minho
Ion - Environment & Business Consulting, Lda.
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Publication of WO2013153531A1 publication Critical patent/WO2013153531A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0039—Inorganic membrane manufacture
    • B01D67/0053—Inorganic membrane manufacture by inducing porosity into non porous precursor membranes
    • B01D67/006—Inorganic membrane manufacture by inducing porosity into non porous precursor membranes by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods
    • B01D67/0065—Inorganic membrane manufacture by inducing porosity into non porous precursor membranes by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods by anodic oxidation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/024—Oxides
    • B01D71/025—Aluminium oxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B01J20/08—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04 comprising aluminium oxide or hydroxide; comprising bauxite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28033—Membrane, sheet, cloth, pad, lamellar or mat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28033—Membrane, sheet, cloth, pad, lamellar or mat
    • B01J20/28035—Membrane, sheet, cloth, pad, lamellar or mat with more than one layer, e.g. laminates, separated sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28078—Pore diameter
    • B01J20/2808—Pore diameter being less than 2 nm, i.e. micropores or nanopores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28078—Pore diameter
    • B01J20/28083—Pore diameter being in the range 2-50 nm, i.e. mesopores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28095—Shape or type of pores, voids, channels, ducts
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/288—Treatment of water, waste water, or sewage by sorption using composite sorbents, e.g. coated, impregnated, multi-layered
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/105—Phosphorus compounds

Definitions

  • the present invention discloses a membrane comprising a sturdy metal frame comprised of an inner aluminum layer and an outer layer composed of nanoporosity aluminum oxide structures having an interporum distance of 50 to 100 nm and a pore diameter of 35 to and 50 nm and zero pore tortuosity to effect high efficiency retention of dissolved phosphorus in aquatic media. Its application in eutrophic and wastewater allows the capture of phosphorus and subsequent regeneration of the material with subsequent reuse of the material. This system integrates phosphorus removal and recovery, and transforms the traditional concept of water treatment - whether from eutrophic water sources, drinking water, or domestic and industrial wastewater - based on removal to a new paradigm, recovery.
  • the present invention relates to the water treatment area, more specifically to the phosphorus removal area in water bodies.
  • the invention is an aluminum-supported nanoporous alumina membrane which, when inserted into the waterbed, promotes phosphorus removal.
  • Phosphorus is an essential chemical element for food agricultural production and is essential for maintenance of vital functions (Elser, 2012). In addition to not having a substitute as a fertilizer, all its applications tend to increase, with an estimated global demand growth of around 2.5% / year. Phosphorus reserves are asymmetrically geodistributed and about 90% of the world's phosphorus reserves are in Morocco and Western Sahara, China, USA, and Russia, and can be expected to last between 35-40 and 350-400 years, depending on consumption and calculation assumptions (van Kauwenbergh, 2010; Cordell et al., 2011). Phosphorus mining and processing costs are rising and their price increased by 800% in 2009, but fell sharply in 2010 with the global economic crisis. Currently, the value is again rising moderately as indicated in US Geological Survey, Mineral Commodity Summaries, January 2012.
  • the products used have been prepared from alumina (aluminum oxide), iron and calcium salts or industrial by-products, all of which are commercially available (eg: Phoslock TM, Plocher TM, Baraclear TM, AlgalBLOCK TM, Aqua-P TM ).
  • the essential purpose of these techniques is to cover the sediment surface, which is intended to prevent the internal recycling of phosphorus and, as such, does not have any reusability of the captured phosphorus.
  • Another equally important issue is not addressed by these systems except at the time of application throughout sedimentation: the need to also reduce the concentration value of phosphorus available in the body of water (not just sediment).
  • nanoporous alumina membranes have been applied as molds to form nanostructured materials, namely nanoconductors, and these parts are totally porous membranes in all their thickness (Shingubara, 2003).
  • alumina adsorption capacity is known (Hano et al., 1997; Xie et al., 2005; JP62014984)
  • the ability to combine the nanoporous alumina layer and the rigid support in one piece. of aluminum for phosphorus adsorption in natural and built aquatic ecosystems has never been developed.
  • the present invention is a new advance and is based on the creation of aluminum supported aluminum oxide nanostructures and allows for faster and more efficient removal of phosphorus and further recovery of phosphorus by an aqueous solution.
  • the technology is based on a process of physical separation by nanotechnology that uses alumina structures produced under specific and unique technical conditions that allow inducing nanoporosities of appropriate configuration to effect a phosphorus recovery with high efficiency. Its application in water treatment allows phosphorus capture and material regeneration.
  • Nanoporous alumina can be electrochemically manufactured by anodic oxidation of aluminum by self-organizing aluminum atoms, producing highly orderly arranged pore arrangements.
  • the membrane has pores with a straight structure.
  • the membrane has a pore distance of 50 - 100 nm. In a preferred embodiment of the invention, the membrane has a pore length of 120 times its width value.
  • the membrane has circular pores and the pore diameter is between 35-50 nm.
  • the membrane has a membrane area / thickness ratio of 42 mg / (m 2. Ym).
  • the membrane is used to remove the phosphate anion.
  • the membrane has a phosphate adsorption rate under reference conditions of distilled water at a temperature of 20 ° C, described by equation
  • CP (t) maximum CP / [2b * (t + c)]
  • CP represents the concentration of phosphorus in solution as a function of time (t)
  • ebec are kinetic constants with b equal to 2,5 and c equal to 0 , 2 for an initial phosphorus concentration below 70 mg / L.
  • the membrane comprises an inner aluminum layer having a thickness of not more than 20 mm.
  • the membrane comprises an outer layer having a thickness not exceeding 60 nm. It is a further object of the present invention to describe a membrane production method comprising the following steps: dissolving aluminum foils in an electrolyte comprising sulfuric acid preferably at a concentration of 190 g / l;
  • the membrane production method features used aluminum sheets which are previously extruded from 6060 or 6063 alloys.
  • the membrane production method has a geometry of aluminum blades with dimensions up to 6.00 x 0.12 m and thickness up to 0.02 m.
  • the invention is intended for the recovery of a non-renewable resource, phosphorus which at the same time constitutes the limiting element of mass eutrophication processes. and key to its restoration, while minimizing the risk to public health from recurrent episodes of cyanotoxin release.
  • a non-renewable resource phosphorus which at the same time constitutes the limiting element of mass eutrophication processes. and key to its restoration, while minimizing the risk to public health from recurrent episodes of cyanotoxin release.
  • wastewater can have a positive impact on the community, restoring functions and creating value.
  • the regenerative vision is widespread and broadened for the protection of water resources, ie for the mining of apparently dissipated resources, to which is added the context of protection of public health present in many of these environmental problems.
  • the technology is based on a nanotechnological process of molecular separation based on aluminum oxide (alumina) structures produced under specific conditions to induce appropriate zero tortuosity nanoporosities to effect high phosphorus recovery.
  • This effect is achieved by placing the aluminum foils in an electrolyte prepared with 190 g / L sulfuric acid, and applying a potential difference (electrical voltage) between the aluminum foil (positive pole) and the cathode (negative pole). 18 to 20 V, obtaining an electrical density between 1.2 to 1.5 A / m2, with a ratio of cathode area to anode ratio of 2.5.
  • the alumina produced is in the amorphous state, but maintains a high chemical stability, which allows the phosphorus adsorption and desorption process to occur without altering the physical and chemical structure of the nanoporosity anodized aluminum oxide membrane.
  • the membrane has an interporum distance between 50 and 100 nm and pore diameter between 35 and 50 nm, with pore length 120 times the width and zero tortuosity. This set of dimensions and properties has been selected in order to improve the suitability between anodizing plant production times and to ensure adequate adsorption capacity for its performance in aquatic environments.
  • Said membrane is introduced into the water body by scientific methodologies supported by mathematical modeling of the water body and / or aquatic ecosystem.
  • the adsorption of phosphate to aluminum oxide may also occur by double bonding regardless of the adsorption kinetics and the sizing and implementation of the system is supported by mathematical balances for the concentration of dissolved phosphorus concentration in the water column. These include assessing the potential of phosphorus species present in the sediment to mobilize to the water column, thereby optimizing the benefits of product placement.
  • FIG. 1 SEM top-view nanoporous membrane depicting the porous structure of alumina viewed from the top by scanning electron microscopy (SEM).
  • FIG. 1 Nanoporous membrane - View of pores and non-tortuous structure by (SEM) where: 1. Horizontal plane (top view): Pores on membrane surface; 2. Vertical plane: view of the pores in section: The sectioned section allows to observe the linearity of the pores and their non macrotortuosity.
  • the photograph demonstrates the interface between the alumina layer and the aluminum alloy.
  • the graph shows rapid phosphate adsorption under reference conditions (90% adsorption).
  • Figure 5 Percentage of phosphorus removal in the solution to be treated as a function of time.
  • the present invention discloses a membrane comprising a sturdy metal structure comprised of an inner aluminum layer and an outer layer which comprises nanoporosity aluminum oxide (alumina) structures having an interporum distance between 50 and 100 nm and a pore diameter between 35 and 50 nm and tortuosity of void pores to effect high efficiency retention of dissolved phosphorus in aquatic media.
  • alumina nanoporosity aluminum oxide
  • the process for phosphorus adsorption comprises the manufacture of aluminum sheets from the commercial alloy 6060 or 6063, in a geometry that maximizes the surface area with maximum dimensions of 6.00x0.12m and thickness 0.02m, produced by extrusion.
  • the aluminum oxide (AI 2 O3) nanoporosities produced on both sides of the flat plate are produced by an anodizing process by electrochemical reaction of aluminum (Al) with oxygen (0 2 ) and optimized for phosphorus adsorption. This is done by placing the aluminum foils in an electrolyte prepared with sulfuric acid with a concentration of 190 g / l, and an electrical density of 1.2 to 1.5 A / m2 being applied, based on the area of the cathode to anode 2.5.
  • a layer of aluminum oxide on the aluminum structure is produced for phosphorus adsorption, which layer has a maximum thickness of 60 nm, with pores with an average diameter of 40 nm and an interporum distance of 50 nm.
  • surface-produced alumina completely covers aluminum, optimizing the relationship between factory production times, minimizing energy costs, but with the guarantee of phosphorus adsorption capacity, isolating it from the outside liquid environment, ie preventing contamination of water with dissolved aluminum.
  • the nanoporous structure is mechanically placed at the margin of the water body or transported by boat and placed at different locations and depths, depending on prior mathematical modeling of the natural ecosystem or constructed to be treated to optimize phosphorus adsorption efficiency along to sediments at times of phosphorus mobility at the water-sediment interface, or near surface water inlets to capture external loads, and can be applied in closed module reactors, baffles / coils, or suspended in the water body.

Abstract

The present invention describes a membrane for removing anions from liquid media, preferably phosphorus, comprising an aluminium metal structure containing: • an inner layer with two faces, made of non-anodized and non-porous aluminium; • an outer layer that coats the inner layer and contains anodized aluminium oxide with nanoporosities, the pores in the nanoporosities having an essentially rectilinear structure. Also described in this patent application are the method for producing said membrane and the use of the membrane.

Description

DESCRIÇÃO  DESCRIPTION
MEMBRANA DE ALUMINA NANOPOROSA SUPORTADA EM ALUMÍNIO, RESPECTIVO MÉTODO DE OBTENÇÃO E SUA UTILIZAÇÃO  NANOPOROUS ALUMIN MEMBRANE SUPPORTED IN ALUMINUM, THEIR METHOD OF OBSERVATION AND ITS USE
A presente invenção divulga uma membrana que compreende uma estrutura metálica resistente constituída por uma camada interna de alumínio e uma camada externa constituída por estruturas de óxido de alumínio (alumina) com nanoporosidade com distância interporo entre 50 e 100 nm e de diâmetro de poro entre 35 e 50 nm e tortuosidade de poros nula para efectuar uma retenção de alta eficácia de fósforo dissolvido em meios aquáticos. A sua aplicação em águas eutrofizadas e águas residuais permite a captura de fósforo e a subsequente regeneração do material com posterior reutilização do material. Este sistema integra a remoção e recuperação de fósforo e concretiza uma transformação do conceito tradicional de tratamento de águas - seja de origens de água eutrofizadas, água de abastecimento para consumo humano ou águas residuais domésticas e industriais - baseado na remoção para um novo paradigma, a recuperação. The present invention discloses a membrane comprising a sturdy metal frame comprised of an inner aluminum layer and an outer layer composed of nanoporosity aluminum oxide structures having an interporum distance of 50 to 100 nm and a pore diameter of 35 to and 50 nm and zero pore tortuosity to effect high efficiency retention of dissolved phosphorus in aquatic media. Its application in eutrophic and wastewater allows the capture of phosphorus and subsequent regeneration of the material with subsequent reuse of the material. This system integrates phosphorus removal and recovery, and transforms the traditional concept of water treatment - whether from eutrophic water sources, drinking water, or domestic and industrial wastewater - based on removal to a new paradigm, recovery.
Campo da invenção Field of the invention
A presente invenção insere-se na área de tratamento de águas, mais especificamente na área de remoção de fósforo em massas de água. A invenção consiste numa membrana de alumina nanoporosa suportada em alumínio que quando inserida no leito de água, promove a remoção de fósforo.  The present invention relates to the water treatment area, more specifically to the phosphorus removal area in water bodies. The invention is an aluminum-supported nanoporous alumina membrane which, when inserted into the waterbed, promotes phosphorus removal.
Antecedentes da invenção Background of the invention
O fósforo é um elemento químico essencial para a produção agrícola alimentar e, a par disso, é essencial para a manutenção de funções vitais (Elser, 2012) . Além de não ter substituto como fertilizante, todas as suas aplicações tendem a aumentar, estimando-se um crescimento global da procura na ordem dos 2.5%/ano. As reservas de fósforo estão assimetricamente geodistribuidas e cerca de 90% das reservas mundiais de fósforo estão em Marrocos e Saara Ocidental, China, USA, e Rússia, prevendo-se que possam ter uma duração entre 35-40 e 350-400 anos, dependendo dos consumos e dos pressupostos de cálculo (van Kauwenbergh, 2010; Cordell et al . , 2011). Os custos de mineração e processamento de fósforo são crescentes e o seu preço aumentou 800% em 2009, mas teve uma queda abrupta em 2010 com a crise económica mundial. Actualmente, o valor está novamente a subir, de forma moderada conforme indicado em U.S. Geological Survey, Mineral Commodity Summaries, January 2012. Phosphorus is an essential chemical element for food agricultural production and is essential for maintenance of vital functions (Elser, 2012). In addition to not having a substitute as a fertilizer, all its applications tend to increase, with an estimated global demand growth of around 2.5% / year. Phosphorus reserves are asymmetrically geodistributed and about 90% of the world's phosphorus reserves are in Morocco and Western Sahara, China, USA, and Russia, and can be expected to last between 35-40 and 350-400 years, depending on consumption and calculation assumptions (van Kauwenbergh, 2010; Cordell et al., 2011). Phosphorus mining and processing costs are rising and their price increased by 800% in 2009, but fell sharply in 2010 with the global economic crisis. Currently, the value is again rising moderately as indicated in US Geological Survey, Mineral Commodity Summaries, January 2012.
Contudo, o principal elemento a reter é que se trata de um recurso essencial mas não-renovável , pelo que, futuramente, é certo que se extinguirá (Cordell et al . , 2012) . Nos últimos cinquenta anos, a concentração de fósforo nas águas doces e ecossistemas terrestres aumentou mais de 75% excedendo, largamente, o consumo de fertilizantes fosfatados, estimado em cerca de 18 milhões de toneladas em 2007 (FAOStat 2009). Essa rejeição de efluentes domésticos e industriais ricos em fósforo nas massas de água é a principal causa do processo de eutrofização, o qual constitui um dos mais significativos problemas, ainda por resolver, a nivel da protecção dos recursos hídricos. Com efeito, na Europa, mais de 53% dos lagos estão em estado eutrófico e é a principal pressão responsável pelo fracasso na obtenção do bom estado das águas prescrito na Directiva- Quadro da Água (Gibbs e Õzkundakci, 2011) . Além disso, todos os 217 lagos incluídos na avaliação da Comissão Internacional de Lagos Internacionais mostraram um aumento do nível de eutrofização ao longo dos últimos 50 anos (UNEP, 2012) . A eutrofização tem fortes impactes ao nível da saúde pública (produção de cianotoxinas ) e da biodiversidade, com destruição de comunidades e eliminação de populações menos competitivas. However, the main element to keep in mind is that it is an essential but non-renewable resource, and it is certain that it will eventually become extinct (Cordell et al., 2012). Over the past fifty years, phosphorus concentration in freshwater and terrestrial ecosystems has increased by more than 75%, far exceeding the consumption of phosphate fertilizers, estimated at around 18 million tonnes in 2007 (FAOStat 2009). This rejection of phosphorus-rich domestic and industrial effluents in water bodies is the main cause of the eutrophication process, which is one of the most significant unresolved problems in the protection of water resources. Indeed, in Europe more than 53% of lakes are eutrophic and is the main pressure responsible for the failure to achieve good water status prescribed by the Water Framework Directive (Gibbs and Õzkundakci, 2011). Besides that, All 217 lakes included in the International Commission on International Lakes assessment have shown an increase in eutrophication over the past 50 years (UNEP, 2012). Eutrophication has strong impacts on public health (cyanotoxin production) and biodiversity, with the destruction of communities and the elimination of less competitive populations.
A segurança do abastecimento de fertilizantes agrícolas pode constituir uma vantagem competitiva para assegurar as necessidades da produção alimentar (Salviati, 2010) e uma futura recuperação local de fósforo das massas de água, para onde se dissipa a maior quantidade de fósforo, contribuirá para uma gestão eficiente do recurso (Cordell et al . , 2011) . Até hoje, no entanto, não existem sistemas em operação que efectuem a captação de fósforo dos sistemas aquáticos naturais para o exterior do sistema lagunar, mas já existem algumas unidades para esse efeito nas águas residuais . Securing the supply of agricultural fertilizers can be a competitive advantage in meeting the needs of food production (Salviati, 2010), and a future local recovery of phosphorus from water bodies, where the greatest amount of phosphorus dissipates, will contribute to the management of resource efficiency (Cordell et al., 2011). To date, however, there are no systems in place that capture phosphorus from natural aquatic systems outside the lagoon system, but there are already some units for this purpose in wastewater.
No domínio da engenharia das águas residuais várias tecnologias podem ser, alegadamente, utilizadas para a remoção de fosfatos, mas são mais direccionadas para a reciclagem e poucas para a recuperação. A remoção de fosfatos por via da acumulação nas lamas biológicas não constitui uma tecnologia que vise a recuperação do fósforo, mas sim a sua reutilização, através da aplicação das lamas no solo com uso agrícola. No caso dos processos de recuperação do fósforo presente na fase líquida dos sistemas de tratamento de águas residuais incidem em quatro grupos principais, a saber: precipitação a partir de uma fase liquida em reactores perfeitamente agitados conforme indicado nos documento de patente W09427915A1 e JP10118687, cristalização em grânulos em reactores de leito fluidizado conforme indicado nos pedidos de patente EP0355886A1 e WO2011143775A1, permuta iónica e posterior precipitação de estruvite conforme indicado no pedido de patente US4477355 com esparsas tentativas experimentais com outras metodologias, designadamente processos membranares (Blocher et al . , 2012) . Verifica-se que a formação de estruvite, ou fosfato de magnésio-amónio, é a principal estratégia de precipitação e, como a sua solubilidade é dependente do pH, exige a adição de reagentes químicos (ajuste de pH, adição de magnésio) (Jaffer et al., 2002) . Além disso, a maioria dos processos referenciados são apropriados apenas acoplados a sistemas de tratamento de águas residuais, não para uma aplicação em massas de água naturais. No caso das massas de água, os processos tradicionais de adsorção para redução da disponibilidade de fósforo nas massas de água assentam na aplicação e dispersão de compostos químicos na superfície da água, em muitos casos com efeitos conjuntos de coagulação de outras substâncias que também se encontram presentes na coluna de água, passando, após sedimentação, a integrar definitivamente os sedimentos do fundo. Os produtos utilizados têm sido preparados à base de alumina (óxido de alumínio) , sais de ferro e cálcio ou subprodutos industriais, sendo que todos estão comercialmente disponíveis (e.g.: Phoslock™, Plocher™, Baraclear™, AlgalBLOCK™, Aqua-P™) . O objectivo essencial destas técnicas é esse recobrimento da superfície dos sedimentos, com a qual se pretende impedir a reciclagem interna de fósforo e, por isso, não apresentam qualquer capacidade de reutilização do fósforo capturado. Uma outra questão igualmente importante não é enfrentada por estes sistemas, excepto no momento de aplicação ao longo da sedimentação: a necessidade de também se reduzir o valor da concentração de fósforo disponível na massa de água (não apenas nos sedimentos) . Com efeito, dado que existindo nutrientes na massa de água é o aumento de luminosidade que estimula a ocorrência de blooms algais que se mantêm até ao esgotamento de ortofosfatos , a forma de prevenir esses episódios é conseguir que a competição entre o sistema biológico e o sistema químico de adsorção presente na massa de água seja ganho por este último, tornando o fósforoIn the field of wastewater engineering a number of technologies may allegedly be used for phosphate removal, but they are more directed towards recycling and few towards recovery. The removal of phosphates by accumulation in biological sludge is not a technology aimed at the recovery of phosphorus, but its reuse through the application of sludge in soil for agricultural use. In the case of phosphorus recovery processes in the liquid phase of wastewater treatment systems fall into four main groups, namely: precipitation from a liquid phase in perfectly stirred reactors as indicated in patent documents W09427915A1 and JP10118687, pellet crystallization in fluidized bed reactors as indicated in EP0355886A1 and WO2011143775A1, ion exchange and subsequent struvite precipitation as indicated in US4477355 with sparse experimental attempts with other methodologies, namely membrane processes (Blocher et al., 2012 ). Formation of struvite or magnesium ammonium phosphate is found to be the main precipitation strategy and, as its solubility is pH dependent, requires the addition of chemical reagents (pH adjustment, magnesium addition) (Jaffer et al., 2002). In addition, most of the referenced processes are suitable only coupled to wastewater treatment systems, not for application to natural water bodies. In the case of water bodies, traditional adsorption processes for reducing phosphorus availability in water bodies rely on the application and dispersion of chemical compounds on the water surface, in many cases with coagulation effects of other substances that are also found. present in the water column, becoming, after sedimentation, to definitively integrate the bottom sediments. The products used have been prepared from alumina (aluminum oxide), iron and calcium salts or industrial by-products, all of which are commercially available (eg: Phoslock ™, Plocher ™, Baraclear ™, AlgalBLOCK ™, Aqua-P ™ ). The essential purpose of these techniques is to cover the sediment surface, which is intended to prevent the internal recycling of phosphorus and, as such, does not have any reusability of the captured phosphorus. Another equally important issue is not addressed by these systems except at the time of application throughout sedimentation: the need to also reduce the concentration value of phosphorus available in the body of water (not just sediment). As nutrients in the body of water are present, it is the increase in luminosity that stimulates the occurrence of algal blooms that persist until orthophosphate depletion, so that these episodes can be prevented by achieving competition between the biological system and the system. adsorption chemical present in the body of water is gained by the latter, making the phosphorus
(mais) limitante do crescimento biológico. Assim, a melhor aproximação reside em sistemas por adsorção com materiais presentes em continuo na massa de água e que, após esgotamento da sua capacidade de adsorção, possam ser facilmente retirados da água. Existem já sistemas de adsorção baseados em óxido de alumínio em polipropileno enxertado com anidrido maleico (Oliveira et al . , 2012) e imobilização de óxido de alumínio activado em poliolefinas(more) limiting biological growth. Thus, the best approximation resides in systems by adsorption with materials present continuously in the body of water and which, after exhaustion of their adsorption capacity, can be easily removed from water. Aluminum oxide based adsorption systems on maleic anhydride grafted polypropylene (Oliveira et al., 2012) and polyolefin activated aluminum oxide immobilization already exist
(Oliveira et al . , 2011). (Oliveira et al., 2011).
Até ao momento, as membranas nanoporosas de alumina têm sido aplicadas como moldes para formar materiais nanoestruturados, nomeadamente nanocondutores , sendo estas peças membranas totalmente porosas em toda a sua espessura (Shingubara, 2003) . Por outro lado, e apesar da capacidade de adsorção da alumina ser conhecida (Hano et al., 1997; Xie et al., 2005; JP62014984), a capacidade de conjugar, numa única peça, a camada nanoporosa de alumina e o suporte rígido de alumínio para a adsorção de fósforo em ecossistemas aquáticos naturais e construídos, nunca foi desenvolvido. Deste modo, a presente invenção constitui um novo avanço e é baseada na criação de nanoestruturas de óxido de alumínio suportadas em alumínio e permite remover fósforo de forma mais rápida e eficaz e ainda efectuar uma posterior recuperação do fósforo por uma solução aquosa. A tecnologia é baseada num processo de separação física por nanotecnologia que utiliza estruturas de alumina produzidas em condições técnicas específicas e singulares que, permitem induzir nanoporosidades de configuração apropriada para efectuar uma recuperação de fósforo com alta eficácia. A sua aplicação no tratamento de águas permite a captura de fósforo e a regeneração do material. A alumina nanoporosa pode ser fabricada electroquimicamente por oxidação anódica do alumínio, através da auto-organização dos átomos de alumínio, produzindo arranjos de poros dispostos de forma altamente ordenada. To date, nanoporous alumina membranes have been applied as molds to form nanostructured materials, namely nanoconductors, and these parts are totally porous membranes in all their thickness (Shingubara, 2003). On the other hand, and although alumina adsorption capacity is known (Hano et al., 1997; Xie et al., 2005; JP62014984), the ability to combine the nanoporous alumina layer and the rigid support in one piece. of aluminum for phosphorus adsorption in natural and built aquatic ecosystems has never been developed. Thus, the present invention is a new advance and is based on the creation of aluminum supported aluminum oxide nanostructures and allows for faster and more efficient removal of phosphorus and further recovery of phosphorus by an aqueous solution. THE The technology is based on a process of physical separation by nanotechnology that uses alumina structures produced under specific and unique technical conditions that allow inducing nanoporosities of appropriate configuration to effect a phosphorus recovery with high efficiency. Its application in water treatment allows phosphorus capture and material regeneration. Nanoporous alumina can be electrochemically manufactured by anodic oxidation of aluminum by self-organizing aluminum atoms, producing highly orderly arranged pore arrangements.
Sumário da invenção Summary of the invention
É objectivo da presente invenção descrever uma membrana para remoção de aniões em meio líquidos nomeadamente fósforo que compreende uma estrutura metálica em alumínio a qual contém:  It is an object of the present invention to describe an anion removal membrane in a liquid medium namely phosphorus comprising an aluminum metal structure which contains:
uma camada interna com duas faces, de alumínio não anodizado e não poroso;  a double-sided inner layer of non-anodized, non-porous aluminum;
uma camada externa que reveste a referida camada interna, a qual contém óxido de alumínio anodizado com nanoporosidades, em que os poros das referidas nanoporosidades possuem uma estrutura essencialmente rectilínea .  an outer layer covering said inner layer which contains nanoporosity anodized aluminum oxide, wherein the pores of said nanoporosities have an essentially straight structure.
Numa realização preferencial da invenção, a membrana apresenta poros com uma estrutura rectilínea. In a preferred embodiment of the invention, the membrane has pores with a straight structure.
Numa outra realização preferencial da invenção, a membrana apresenta uma distância entre poros compreendida entre 50 - 100 nm. Numa realização preferencial da invenção, a membrana apresenta um comprimento dos poros igual a 120 vezes o valor da sua largura. In another preferred embodiment of the invention, the membrane has a pore distance of 50 - 100 nm. In a preferred embodiment of the invention, the membrane has a pore length of 120 times its width value.
Numa outra realização preferencial da invenção, a membrana apresenta poros circulares e o diâmetro dos poros está compreendido entre 35-50 nm. In another preferred embodiment of the invention, the membrane has circular pores and the pore diameter is between 35-50 nm.
Numa realização preferencial da invenção, a membrana apresenta uma relação área/ espessura de membrana de 42 mg/ (m2. ym) . In a preferred embodiment of the invention, the membrane has a membrane area / thickness ratio of 42 mg / (m 2. Ym).
Numa outra realização preferencial da invenção, a membrana é utilizada no sentido de remover o anião fosfato. In another preferred embodiment of the invention, the membrane is used to remove the phosphate anion.
Numa realização preferencial da invenção, a membrana apresenta uma velocidade de adsorção de fosfatos, em condições de referência de água destilada à temperatura de 20°C, descrita pela equação In a preferred embodiment of the invention, the membrane has a phosphate adsorption rate under reference conditions of distilled water at a temperature of 20 ° C, described by equation
CP(t) = CPmáximo / [2b* (t + c) ] em que CP representa a concentração de fósforo em solução em função do tempo (t) , e b e c são constantes cinéticas com b igual a 2,5 e c igual a 0,2 para uma concentração de fósforo inicial inferior a 70 mg/L. CP (t) = maximum CP / [2b * (t + c)] where CP represents the concentration of phosphorus in solution as a function of time (t), ebec are kinetic constants with b equal to 2,5 and c equal to 0 , 2 for an initial phosphorus concentration below 70 mg / L.
Numa outra realização preferencial da invenção, a membrana compreende uma camada interna de alumínio que apresenta uma espessura não superior a 20 mm. In another preferred embodiment of the invention, the membrane comprises an inner aluminum layer having a thickness of not more than 20 mm.
Numa realização preferencial da invenção, a membrana compreende uma camada externa apresenta uma espessura não superior a 60 nm. É ainda objectivo da presente invenção descrever um método de produção da membrana que compreende os seguintes passos: dissolver lâminas de alumínio num eletrólito que compreende ácido sulfúrico de preferência numa concentração de 190 g/L; In a preferred embodiment of the invention, the membrane comprises an outer layer having a thickness not exceeding 60 nm. It is a further object of the present invention to describe a membrane production method comprising the following steps: dissolving aluminum foils in an electrolyte comprising sulfuric acid preferably at a concentration of 190 g / l;
após a dissolução do alumínio, anodizar a amostra numa concentração entre 10-15 mg/L de alumínio dissolvido em condições fixas de temperatura entre 17° e 20°C;  after dissolution of aluminum, anodize the sample at a concentration of 10-15 mg / l of dissolved aluminum under fixed temperature conditions of 17 ° to 20 ° C;
aplicar uma tensão eléctrica entre 18-20V entre a lâmina de alumínio -ânodo- e o cátodo resultando numa densidade elétrica entre 1,2- 1,5 A/m2, para a razão da área do cátodo em relação ao ânodo ser 2,5. apply an electrical voltage between 18-20V between the anode-aluminum foil and the cathode resulting in an electrical density between 1.2-1.5 A / m 2 , for the ratio of cathode area to anode being 2, 5
Numa realização preferencial da invenção, o método de produção da membrana apresenta lâminas de alumínio utilizadas que são previamente extrudidas a partir de ligas 6060 ou 6063. In a preferred embodiment of the invention, the membrane production method features used aluminum sheets which are previously extruded from 6060 or 6063 alloys.
Numa outra realização preferencial da invenção, o método de produção da membrana apresenta uma geometria das lâminas de alumínio com dimensões até 6,00x0,12 m e espessura até 0,02 m. In another preferred embodiment of the invention, the membrane production method has a geometry of aluminum blades with dimensions up to 6.00 x 0.12 m and thickness up to 0.02 m.
É ainda objectivo da presente invenção descrever a utilização da membrana no tratamento de águas residuais, nomeadamente na remoção de fósforo das referidas águas residuais . It is a further object of the present invention to describe the use of the membrane in wastewater treatment, namely in the removal of phosphorus from said wastewater.
Descrição Geral General description
A invenção destina-se à recuperação de um recurso não- renovável, o fósforo que, simultaneamente, constitui o elemento limitante dos processos de eutrofização de massas de água e factor-chave para o seu restauro, com a minimização do risco para a saúde pública derivado de episódios recorrentes de libertação de cianotoxinas . Com esta nova abordagem conceptual, mesmo as águas residuais podem atingir um impacte positivo na comunidade, com restauro de funções e criação de valor. A visão regenerativa é generalizada e alargada para a protecção dos recursos hídricos, ou seja, para a mineração de recursos aparentemente dissipados, ao qual se adiciona o contexto de protecção da saúde pública presente em muitos desses problemas ambientais. The invention is intended for the recovery of a non-renewable resource, phosphorus which at the same time constitutes the limiting element of mass eutrophication processes. and key to its restoration, while minimizing the risk to public health from recurrent episodes of cyanotoxin release. With this new conceptual approach, even wastewater can have a positive impact on the community, restoring functions and creating value. The regenerative vision is widespread and broadened for the protection of water resources, ie for the mining of apparently dissipated resources, to which is added the context of protection of public health present in many of these environmental problems.
A tecnologia baseia-se num processo nanotecnológico de separação molecular baseado em estruturas de óxido de alumínio (alumina) produzidas em condições específicas para induzir nanoporosidades apropriadas de tortuosidade nula para efectuar uma recuperação de fósforo com alta eficácia. Esse efeito é obtido colocando as lâminas de alumínio num electrólito preparado com ácido sulfúrico com concentração de 190 g/L, sendo aplicada uma diferença de potencial (tensão elétrica) entre a lâmina de alumínio (pólo positivo) e o cátodo (pólo negativo) de 18 a 20 V, obtendo- se uma densidade eléctrica entre 1,2 a 1,5 A/m2, com razão da área do cátodo em relação ao ânodo deve ser de 2,5. A alumina produzida encontra-se no estado amorfo, mas mantém uma elevada estabilidade química, o que permite que ocorra o processo de adsorção e desorção do fósforo sem alterar a estrutura física e química da membrana constituída por óxido de alumínio anodizado com nanoporosidades, operando o sistema dentro de uma gama de pH entre 4 a 8 e sendo que as nanoporosidades são desenvolvidas na face dupla de uma estrutura de alumínio não anodizado e não poroso de espessura máxima de 20mm, para lhe conferir a necessária rigidez. A membrana possui uma distância interporo entre 50 e 100 nm e de diâmetro de poro entre 35 e 50 nm, com comprimento do poro igual a 120 vezes a largura e com tortuosidade nula. Este conjunto de dimensões e propriedades foram selecionados de forma a procurar melhorar a adequação entre os tempos de produção fabril na anodização e a garantir adequada capacidade de adsorção para o seu desempenho nos meios aquáticos. The technology is based on a nanotechnological process of molecular separation based on aluminum oxide (alumina) structures produced under specific conditions to induce appropriate zero tortuosity nanoporosities to effect high phosphorus recovery. This effect is achieved by placing the aluminum foils in an electrolyte prepared with 190 g / L sulfuric acid, and applying a potential difference (electrical voltage) between the aluminum foil (positive pole) and the cathode (negative pole). 18 to 20 V, obtaining an electrical density between 1.2 to 1.5 A / m2, with a ratio of cathode area to anode ratio of 2.5. The alumina produced is in the amorphous state, but maintains a high chemical stability, which allows the phosphorus adsorption and desorption process to occur without altering the physical and chemical structure of the nanoporosity anodized aluminum oxide membrane. within a pH range of 4 to 8 and the nanoporosities are developed on the double face of a non-porous, non-porous aluminum structure with a maximum thickness of 20mm to give it the necessary rigidity. The membrane has an interporum distance between 50 and 100 nm and pore diameter between 35 and 50 nm, with pore length 120 times the width and zero tortuosity. This set of dimensions and properties has been selected in order to improve the suitability between anodizing plant production times and to ensure adequate adsorption capacity for its performance in aquatic environments.
A referida membrana é introduzida na massa de água mediante metodologias cientificas suportadas em modelação matemática da massa de água e/ou do ecossistema aquático. Em meios aquáticos, a adsorção do fosfato ao óxido de alumínio poderá igualmente ocorrer por uma ligação dupla, independentemente da cinética de adsorção e o dimensionamento e implementação do sistema é suportado por balanços matemáticos para cenarização da concentração de fósforo dissolvido na coluna de água, os quais incluem a avaliação do potencial de espécies de fósforo presente nos sedimentos para se mobilizarem para a coluna de água, assim optimizando-se os benefícios da colocação do produto. Said membrane is introduced into the water body by scientific methodologies supported by mathematical modeling of the water body and / or aquatic ecosystem. In aquatic media, the adsorption of phosphate to aluminum oxide may also occur by double bonding regardless of the adsorption kinetics and the sizing and implementation of the system is supported by mathematical balances for the concentration of dissolved phosphorus concentration in the water column. These include assessing the potential of phosphorus species present in the sediment to mobilize to the water column, thereby optimizing the benefits of product placement.
Breve descrição das figuras Brief Description of the Figures
A fim de que a presente invenção seja plenamente compreendida e levada à prática por qualquer perito na técnica deste sector tecnológico, estão representadas realizações preferências do invento que, contudo, não pretendem, limitar o objecto da presente invenção. Figura 1 - Membrana nanoporosa com vista de topo por SEM, onde está descrito a estrutura porosa da alumina, visto de topo, por microscopia electrónica de varrimento (SEM) . In order that the present invention may be fully understood and practiced by any person skilled in the art, preferred embodiments of the invention are represented, but are not intended to limit the scope of the present invention. Figure 1 - SEM top-view nanoporous membrane depicting the porous structure of alumina viewed from the top by scanning electron microscopy (SEM).
Figura 2 - Membrana nanoporosa - vista dos poros e estrutura não tortuosa por (SEM) em que : 1. Plano horizontal (vista de topo) : Poros na superfície da membrana; 2. Plano vertical: vista dos poros em corte: 0 corte seccionado permite observar a linearidade dos poros e a sua não macrotortuosidade . Figure 2 - Nanoporous membrane - View of pores and non-tortuous structure by (SEM) where: 1. Horizontal plane (top view): Pores on membrane surface; 2. Vertical plane: view of the pores in section: The sectioned section allows to observe the linearity of the pores and their non macrotortuosity.
Figura 3 - Membrana nanoporosa: camada nano e liga de alumínio visto em corte por SEM. Figure 3 - Nanoporous membrane: nano layer and aluminum alloy seen in section by SEM.
A fotografia demonstra a interface entre a camada de alumina e a liga de alumínio.  The photograph demonstrates the interface between the alumina layer and the aluminum alloy.
Figura 4- Concentração de fósforo em solução em função do tempo . Figure 4- Concentration of phosphorus in solution as a function of time.
0 gráfico demonstra a adsorção rápida de fosfatos em condições de referência (adsorção de 90%) .  The graph shows rapid phosphate adsorption under reference conditions (90% adsorption).
Figura 5 - Percentagem de remoção de fósforo na solução a tratar, em função do tempo. Figure 5 - Percentage of phosphorus removal in the solution to be treated as a function of time.
Descrição detalhada da invenção Detailed Description of the Invention
A presente invenção divulga uma membrana que compreende uma estrutura metálica resistente compreendida por uma camada interna de alumínio e uma camada externa a qual compreende estruturas de óxido de alumínio (alumina) com nanoporosidade com distância interporo entre 50 e 100 nm e de diâmetro de poro entre 35 e 50 nm e tortuosidade de poros nula para efectuar uma retenção de alta eficácia de fósforo dissolvido em meios aquáticos. The present invention discloses a membrane comprising a sturdy metal structure comprised of an inner aluminum layer and an outer layer which comprises nanoporosity aluminum oxide (alumina) structures having an interporum distance between 50 and 100 nm and a pore diameter between 35 and 50 nm and tortuosity of void pores to effect high efficiency retention of dissolved phosphorus in aquatic media.
0 processo para adsorção de fósforo compreende no fabrico de lâminas de alumínio a partir da liga comercial 6060 ou 6063, numa geometria que maximiza a área superficial com dimensões máximas de 6,00x0,12m e espessura 0,02m, produzida por extrusão. A produção das nanoporosidades de óxido de alumínio (AI2O3) produzidas nas duas faces da placa plana é efectuado por um processo de anodização por reação electroquímica do alumínio (Al) com oxigénio (02) , sendo optimizado para adsorção de fósforo. Este processo é, para esse efeito, efectuado colocando as lâminas de alumínio num electrólito preparado com ácido sulfúrico com concentração de 190 g/L, sendo aplicada uma densidade eléctrica entre 1,2 a 1,5 A/m2, com razão da área do cátodo em relação ao ânodo de 2,5. Desta forma, é produzida para adsorção de fósforo uma camada de óxido de alumínio sobre a estrutura de alumínio, camada essa com uma espessura máxima de 60 nm, com poros com diâmetro médio de 40 nm e distância interporo de 50 nm, sendo que a camada de alumina produzida na superfície recobre totalmente o alumínio, optimizando a relação entre os tempos de produção fabril, minimizando custos de energia, mas com a garantia de capacidade de adsorção de fósforo, isolando-o do meio líquido exterior, ou seja, impedindo a contaminação da água com alumínio dissolvido. A estrutura nanoporosa é colocada com ajuda de meio mecânico na margem da massa de água ou transportada por barco e colocada em diferentes locais e profundidades, dependendo de prévia modelação matemática do ecossistema natural ou construído a tratar para optimizar a eficácia na adsorção de fósforo, junto aos sedimentos em momentos de mobilidade de fósforo na interface água-sedimentos , ou junto às entradas superficiais de água para capturar cargas externas, podendo ser aplicado em reactor de módulos fechados, chicanas/ serpentina, ou em suspensão na massa de água . The process for phosphorus adsorption comprises the manufacture of aluminum sheets from the commercial alloy 6060 or 6063, in a geometry that maximizes the surface area with maximum dimensions of 6.00x0.12m and thickness 0.02m, produced by extrusion. The aluminum oxide (AI 2 O3) nanoporosities produced on both sides of the flat plate are produced by an anodizing process by electrochemical reaction of aluminum (Al) with oxygen (0 2 ) and optimized for phosphorus adsorption. This is done by placing the aluminum foils in an electrolyte prepared with sulfuric acid with a concentration of 190 g / l, and an electrical density of 1.2 to 1.5 A / m2 being applied, based on the area of the cathode to anode 2.5. Thus, a layer of aluminum oxide on the aluminum structure is produced for phosphorus adsorption, which layer has a maximum thickness of 60 nm, with pores with an average diameter of 40 nm and an interporum distance of 50 nm. surface-produced alumina completely covers aluminum, optimizing the relationship between factory production times, minimizing energy costs, but with the guarantee of phosphorus adsorption capacity, isolating it from the outside liquid environment, ie preventing contamination of water with dissolved aluminum. The nanoporous structure is mechanically placed at the margin of the water body or transported by boat and placed at different locations and depths, depending on prior mathematical modeling of the natural ecosystem or constructed to be treated to optimize phosphorus adsorption efficiency along to sediments at times of phosphorus mobility at the water-sediment interface, or near surface water inlets to capture external loads, and can be applied in closed module reactors, baffles / coils, or suspended in the water body.
Desenvolveu-se uma membrana nanoporosa de óxido de alumínio com capacidade de adsorção para recuperação de fósforo desenvolvida para possuir uma relação por área e espessura de membrana, de 42mg/ (m2.ym) e uma velocidade de adsorção de fosfatos, em condições de referência de água destilada à temperatura de 20°C, descrita por CP(t)= CPmáK±mo I [2b* (t + c) ] em que CP representa a concentração de fósforo em solução em função do tempo (t) , e b e c são constantes cinéticas (b=2,5 e c=0,2) para uma concentração de fósforo inicial inferior a 70 mg/L. A nanoporous aluminum oxide membrane capable of phosphorus recovery was developed, developed to have a membrane area and thickness ratio of 42mg / (m 2 .ym) and a phosphate adsorption velocity under conditions of reference of distilled water at a temperature of 20 ° C described by CP (t) = CP maK ± m I [2b * (t + c)] where CP represents the concentration of phosphorus in solution as a function of time (t), ebec are kinetic constants (b = 2.5 and c = 0.2) for an initial phosphorus concentration below 70 mg / L.
Conforme se pode verificar na Figura 4, que demonstra a evolução da concentração de fósforo em função do tempo de aplicação da membrana, a concentração diminui ao longo do tempo, o que permite concluir que ao fim de 20 horas, a concentração de fósforo presente na massa de água é próxima de zero. Ao analisar a Figura 5, que representa uma comparação entre os dados reais e os dados modelados do sistema com uma cinética aproximada a Langmuir, verifica-se uma boa convergência entre os dados reais e os estimados pelo modelo matemático. Conclui-se portanto que a remoção ao fim de 24horas tende para 100%. As can be seen in Figure 4, which shows the evolution of phosphorus concentration as a function of membrane application time, the concentration decreases over time, which allows us to conclude that after 20 hours, the phosphorus concentration present in the body of water is close to zero. Analyzing Figure 5, which represents a comparison between the actual data and the modeled data of the system with approximate Langmuir kinetics, there is a good convergence between the real data and those estimated by the mathematical model. It is therefore concluded that removal after 24 hours tends to 100%.
Referências References
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Cordell, D . , Neset, T.S., Prior, . , (2012) The phosphorus mass balance: identifying ,hotspots' in the food system as a roadmap to phosphorus security, Curr Opin Biotechnol 23: 1-7. Cordell, D. , Neset, TS, Prior,. , (2012) The phosphorus mass balance: identifying , hotspots' in the food system as a roadmap to phosphorus security, Curr Opin Biotechnol 23: 1-7.
Cordell, D., Rosemarin, A., Schrõder, J.J., Smit, A.L., (2011) Towards global phosphorus security: a systems framework for phosphorus recovery and reuse options. Chemosphere, 84: 747-758. Cordell, D., Rosemarin, A., Schroder, J.J., Smit, A.L., (2011) Towards global phosphorus security: a systems framework for phosphorus recovery and reuse options. Chemosphere, 84: 747-758.
Elser, J.J. (2012) Phosphorus: a limiting nutrient for humanity?, Current Opinion in Biotechnology, 23, 1-6. Elser, J.J. (2012) Phosphorus: A Limiting Nutrient for Humanity, Current Opinion in Biotechnology, 23, 1-6.
FAOStat (2009). Online database providing time-series and cross sectional data relating to food and agriculture for some 200 countries. Food and Agriculture Organization of the United Nations, Rome . http://faostat.fao.org. FAOStat (2009). Online database providing time-series and cross-sectional data relating to food and agriculture for some 200 countries. Food and Agriculture Organization of the United Nations, Rome. http://faostat.fao.org.
Gibbs, M., Õzkundakci, D., (2011) Effects of a modified zeolite on P and N processes and fluxes across the lake sediment-water interface using core incubations. Hydrobiologia 661, 21-35. Gibbs, M., Õzkundakci, D., (2011) Effects of a modified zeolite on P and N processes and fluxes across the lake sediment-water interface using core incubations. Hydrobiology 661, 21-35.
Jaffer, Y . , Clark, . , Pearce, P., Parsons, S., (2002) Potential phosphorus recovery by struvite formation. Water Research, 36(7), 1834-1842. van Kauwenbergh, S., (2010) World Phosphate Reserves and Resources. Washington, DC: International Fertilizer Development Centre (IFDC) . van Lier, R.J.M., Buisman, C.J.N., Giesen, A., (1999) Crystalactor® technology and its applications in the mining and metallurgical industry, In Solid/liquid separation including hydrometallurgy and the environment, ed. G.B. Harris and S.J. Omelon, Canadian Institute of Mining, Metallurgy and Petroleum, Montreal, 1999, pp . 221-231. Jaffer, Y. Clark,. , Pearce, P., Parsons, S., (2002) Potential phosphorus recovery by struvite formation. Water Research, 36 (7), 1834-1842. van Kauwenbergh, S., (2010) World Phosphate Reserves and Resources. Washington, DC: International Fertilizer Development Center (IFDC). van Lier, RJM, Buisman, CJN, Giesen, A., (1999) Crystalactor® technology and its applications in mining and metallurgical industry, In Solid / liquid separation including hydrometallurgy and the environment, ed. GB Harris and SJ Omelon, Canadian Institute of Mining, Metallurgy and Petroleum, Montreal, 1999, p. 221-231.
Oliveira M., Machado A.V., Nogueira, R. (2012) Phosphorus Removal from Eutrophic Waters with an Aluminium Hybrid Nanocomposite . Water Air Soil Pollut. DOI 10.1007/sll270- 012-1239-9. Oliveira M., Machado A.V., Nogueira, R. (2012) Phosphorus Removal from Eutrophic Waters with Aluminum Hybrid Nanocomposite. Water Air Soil Pollut. DOI 10,1007 / s1170-012-1239-9.
Oliveira M., Ribeiro D., Nóbrega J.M., Machado A.V, Brito A.G., Nogueira' R. (2011) . Removal of phosphorus from water using active barriers : AI2O3 immobilized onto polyolefins. Environmental Technology, 32 (9), 989-995. Oliveira M., Ribeiro D., Nobrega JM, Machado AV, Brito AG, Nogueira 'R. (2011). Removal of phosphorus from water using active barriers: AI 2 O 3 immobilized onto polyolefins. Environmental Technology, 32 (9), 989-995.
Salviati V. (2010) Análise dos ciclos do fósforo nos contextos social, económico e ecológico: como o homem vem degradando as paisagens naturais pela Agricultura". Universidade Estadual Paulista. Salviati V. (2010) Analysis of phosphorus cycles in the social, economic and ecological contexts: how man has been degrading natural landscapes through agriculture. "Paulista State University.
Sengupta, S., Pandit A.. (2011) Selective removal of phosphorus from wastewater combined with its recovery as a solid-phase fertilizer. Water Research, 45(11), 3318-3330. Shingubara, S., 2003. Fabrication of Nanomaterials Using Porous Alumina Templates. Journal of Nanoparticle Research 5 (1) : 17-30. United Nations Environment Programme (UNEP) , (2012) in http : //www . unep . or . jp/ietc/publications/short_series/lakere servoirs-3/2. asp Sengupta, S., Pandit A .. (2011) Selective removal of phosphorus from wastewater combined with its recovery as a solid-phase fertilizer. Water Research, 45 (11), 3318-3330. Shingubara, S., 2003. Fabrication of Nanomaterials Using Porous Alumina Templates. Journal of Nanoparticle Research 5 (1): 17-30. United Nations Environment Program (UNEP), (2012) in http: // www. unep or. jp / ietc / publications / short_series / lakere servoirs-3/2. asp
Xie, W., Wang, Q . , Ma, H . , Ogawa H . , (2005) Phosphate removal from wastewater using aluminium oxide as adsorbent. Int. J. of Environment and Pollution, 23(4), 486-491. Xie, W., Wang, Q. , Ma, H. , Ogawa H. , (2005) Phosphate removal from wastewater using aluminum oxidizes adsorbent. Int. J. of Environment and Pollution, 23 (4), 486-491.
Martins, G., Ribeiro, D. C, Pacheco, D., Cruz, J. V., J, Cunha, R., Gonçalves, V., Nogueira, R., Brito, A.G.. (2008) Prospective scenarios for water quality and ecological status in Lake Sete Cidades (Portugal) : the integration of mathematical modelling in decision processes. Applied Geochemistry, 23, (2008) 2171-2181. Martins, G., Ribeiro, D.C., Pacheco, D., Cruz, JV, J, Cunha, R., Gonçalves, V., Nogueira, R., Brito, AG. (2008) Prospective scenarios for water quality and ecological status in Lake Sete Cities (Portugal): the integration of mathematical modeling in decision processes. Applied Geochemistry, 23, (2008) 2171-2181.
Ribeiro, D.C., Martins, G., Nogueira, R., Cruz, J.V., Ribeiro, D.C., Martins, G., Nogueira, R., Cruz, J.V.
Brito, A.G. (2008). Phosphorus fractionation in volcanic lake sediments (Azores-Portugal) . Chemosphere 70: 1256- 1263 Brito, A.G. (2008). Phosphorus fractionation in volcanic lake sediments (Azores-Portugal). Chemosphere 70: 1256-1263
As reivindicações que se seguem destacam adicionalmente formas de realização particulares da invenção. The following claims further highlight particular embodiments of the invention.

Claims

REIVINDICAÇÕES
Membrana para remoção de aniões em meio líquidos nomeadamente fósforo que compreende uma estrutura metálica em alumínio a qual contém: Anion removal membrane in a liquid medium namely phosphorus comprising an aluminum metal frame which contains:
• uma camada interna com duas faces, de alumínio não anodizado e não poroso;  • a two-sided inner layer of non-anodized non-porous aluminum;
• uma camada externa que reveste a referida camada interna, a qual contém óxido de alumínio anodizado com nanoporosidades , em que os poros das referidas nanoporosidades possuem uma estrutura essencialmente rectilínea.  An outer layer covering said inner layer which contains nanoporosity anodized aluminum oxide, wherein the pores of said nanoporosities have an essentially straight structure.
2. Membrana de acordo com a reivindicação anterior, em que os poros têm uma estrutura rectilínea. A membrane according to the preceding claim, wherein the pores have a rectilinear structure.
Membrana de acordo com qualquer uma das reivindicações anteriores, em que a distância entre poros está compreendida entre 50 - 100 nm. A membrane according to any one of the preceding claims, wherein the distance between pores is between 50 - 100 nm.
Membrana de acordo com qualquer uma das reivindicações anteriores, em que o comprimento dos poros é igual a 120 vezes o valor da sua largura. A membrane according to any one of the preceding claims, wherein the pore length is 120 times its width value.
Membrana de acordo com qualquer uma das reivindicações 1-3, em que os poros são circulares e o diâmetro dos poros está compreendido entre 35-50 nm. A membrane according to any one of claims 1-3, wherein the pores are circular and the pore diameter is between 35-50 nm.
Membrana de acordo com qualquer uma das reivindicações anteriores, em que a capacidade de adsorção de fósforo em função da relação área superficial/ espessura de membrana é de 30 mg de fósforo/ (m2.ym) . A membrane according to any preceding claim, wherein the phosphorus adsorption capacity as a function of surface area / membrane thickness ratio is 30 mg phosphorus / (m 2 .ym).
7. Membrana de acordo com qualquer uma das reivindicações anteriores, em que o anião removido é o fosfato. A membrane according to any preceding claim, wherein the anion removed is phosphate.
8. Membrana de acordo com a reivindicação anterior, em que a velocidade de adsorção de fosfatos, em condições de referência de água destilada à temperatura de 20°C, é descrita pela equação A membrane according to the preceding claim, wherein the rate of phosphate adsorption under distilled water reference conditions at a temperature of 20 ° C is described by the equation
CP(t) = CPmáximo / [2b* (t + c) ] em que CP representa a concentração de fósforo em solução em função do tempo (t) , e b e c são constantes cinéticas com b igual a 2,5 e c igual a 0,2 para uma concentração de fósforo inicial inferior a 70 mg/L. CP (t) = maximum CP / [2b * (t + c)] where CP represents the concentration of phosphorus in solution as a function of time (t), ebec are kinetic constants with b equal to 2,5 and c equal to 0 , 2 for an initial phosphorus concentration below 70 mg / L.
9. Membrana de acordo com qualquer uma das reivindicações anteriores, em que a camada interna de alumínio apresenta uma espessura não superior a 1,88 mm. Membrane according to any one of the preceding claims, wherein the inner aluminum layer has a thickness of not more than 1.88 mm.
10. Membrana de acordo com qualquer uma das reivindicações anteriores, em que a camada externa apresenta uma espessura não superior a 60 nm. Membrane according to any one of the preceding claims, wherein the outer layer has a thickness of not more than 60 nm.
11. Método de produção da membrana referida em qualquer uma das reivindicações 1 a 10, compreendendo os seguintes passos : The membrane production method of any one of claims 1 to 10, comprising the following steps:
• dissolver lâminas de alumínio num eletrólito que compreende ácido sulfúrico de preferência numa concentração de 190 g/L;  Dissolving aluminum foils in an electrolyte comprising sulfuric acid preferably at a concentration of 190 g / l;
• após a dissolução do alumínio, anodizar a amostra numa concentração entre 10-15 mg/L de alumínio dissolvido em condições fixas de temperatura entre 17°C e 20°C ;  • after dissolution of aluminum, anodize the sample to a concentration of 10-15 mg / l dissolved aluminum under fixed temperature conditions between 17 ° C and 20 ° C;
• aplicar uma tensão eléctrica entre 18-20V entre a lâmina de alumínio -ânodo- e o cátodo; resultando numa densidade elétrica entre 1,2- 1,5 A/m , para a razão da área do cátodo em relação ao ânodo ser 2,5. • apply an electrical voltage between 18-20V between the aluminum anode blade and the cathode; resulting at an electrical density between 1.2-1.5 A / m, for the ratio of cathode area to anode being 2.5.
12. Método de produção da membrana de acordo com a reivindicação anterior, em que as lâminas de alumínio utilizadas são previamente extrudidas a partir de ligas 6060 ou 6063. Membrane production method according to the preceding claim, wherein the aluminum sheets used are previously extruded from 6060 or 6063 alloys.
13. Método de produção da membrana de acordo com qualquer uma das reivindicações 8 e 9, em que a geometria das lâminas de alumínio apresentam dimensões até 6,00x0,12 m e espessura inferior ou igual a 0,02 m. Membrane production method according to any one of claims 8 and 9, wherein the geometry of the aluminum sheets has dimensions up to 6.00x0.12 m and thickness less than or equal to 0.02 m.
14. Utilização da membrana descrita nas reivindicações 1 a 10 e obtida pelo método descrito nas reivindicações 11 a 14, utilizado no tratamento de águas residuais, nomeadamente na remoção de fósforo das referidas águas residuais . Use of the membrane described in claims 1 to 10 and obtained by the method described in claims 11 to 14, used in the treatment of wastewater, namely the removal of phosphorus from said wastewater.
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