Frustules extracted from benthic pennate diatoms harvested from an industrial biofilm process

Abstract

A method of extracting frustules from benthic pennate diatoms is disclosed. The method includes culturing benthic pennate diatoms in an industrial biofilm process, wherein in the industrial biofilm process the benthic pennate diatoms are growing on at least one surface in a water-containing compartment and wherein the benthic pennate diatoms forms a biofilm on the at least one surface; harvesting the benthic pennate diatoms from the at least one surface; and extracting the frustules by separating the frustules from organic biomass contained in the benthic pennate diatoms.

Claims

1. A method for obtaining frustules from benthic pennate diatoms comprising the steps of: culturing benthic pennate diatoms in an biofilm process, wherein in said biofilm process said benthic pennate diatoms are growing on at least one surface in a water-comprising compartment and wherein said benthic pennate diatoms form a biofilm on said at least one surface; harvesting said benthic pennate diatoms from said at least one surface, said benthic pennate diatoms being in an exponential growth phase; extracting frustules from the harvested benthic pennate diatoms by separating said frustules from organic biomass comprised in said benthic pennate diatoms.

2. The method according to claim 1, wherein said water-comprising compartment is a pool.

3. The method according to claim 1, wherein said water-comprising compartment comprises at least one of: a nutritious water with a concentration of from 0.01 to 500 g/m.sup.3 nitrogen and/or from 0.01 to 100 g/m.sup.3 phosphorous; and a silicon compound added to the water in said water-comprising compartment such that the concentration of silicon in the water in said water-comprising compartment is in the range of 0.01-100 g/m.sup.3.

4. The method according to claim 3, wherein said culturing is performed in waste water.

5. The method according to claim 4, wherein the water is received from a fish farm, the food or biomass industry and/or household waste water.

6. The method according to claim 2, wherein the water comprising compartment is a shallow pool comprising water at a depth of no more than 0.5 m.

7. The method according to claim 1, wherein several water comprising compartments are arranged stacked on top of each other.

8. The method according to claim 1, wherein the at least one surface is a horizontal surface.

9. The method of claim 3, wherein the silicon compound is Na.sub.2SiO.sub.3.5H.sub.2O or Na.sub.2SiO.sub.3.9H.sub.2O.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above objects, as well as additional objects, features and advantages of the present invention, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, when taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1a is a micrograph of benthic pennate diatoms in accordance with at least one embodiment of the invention;

(3) FIG. 1b is a SEM image of frustules extracted from benthic pennate diatoms in accordance with at least one embodiment of the invention;

(4) FIG. 2 shows a cross-sectional view of a surface coated with frustules extracted from benthic pennate diatoms according to at least one embodiment of the invention;

(5) FIG. 3 shows a cross-sectional view of a composite containing frustules extracted from benthic pennate diatoms in accordance to at least one embodiment of the invention.

(6) FIG. 4 shows a schematic and cross-sectional view of a frustule extracted from a benthic pennate diatom in accordance with at least one example embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) In the present detailed description, embodiments of frustules extracted from benthic pennate diatoms and use of the same are discussed. It should be noted that this by no means limits the scope of the invention, which is also applicable in other circumstances for instance with other types or variants of frustules extracted from benthic pennate diatoms than the embodiments shown in the appended drawings. Further, that specific components are mentioned in connection to an embodiment of the invention does not mean that those components cannot be used to an advantage together with other embodiments of the invention.

(8) The frustules extracted from benthic pennate diatoms according to the invention can advantageously be used for in several applications. The industrial biofilm process provides a controlled way to grow and harvest the desired species of benthic pennate diatom, from which the frustules are being extracted.

(9) FIG. 1a shows benthic pennate diatoms which have been cultured through an industrial biofilm process. The benthic pennate diatoms are grown on a surface in a water compartment and the benthic pennate diatoms are harvested from said surface. The said benthic pennate diatoms are provided in a liquid medium and/or as a dry product.

(10) FIG. 1b shows frustules extracted from said benthic pennate diatoms.

(11) According to at least one example embodiment of the invention the frustules extracted from benthic pennate diatoms are used for uptake of energy, chemical substances and/or mechanical waves.

(12) FIG. 2 shows a cross-sectional view of frustules extracted from benthic pennate diatoms 210 provided in a liquid medium and deposited on a surface 220 by the use a coating method.

(13) According to at least one example embodiment of the invention the frustules extracted from benthic pennate diatoms 210 provided in a liquid medium. The frustules extracted from benthic pennate diatoms are being deposited on a surface 220 with a coating method which is chosen from a list comprising but not limited to: doctor blading, spin-coating, roller coating, screen printing, spray coating and dip coating

(14) According to at least one example embodiment of the invention such frustules extracted from benthic pennate diatoms 210 being deposited on a surface 220 may be used for uptake of energy which corresponds to wavelengths within the infrared range, within the visible range and/or within the ultraviolet range. This may for example be used for enhancing the efficiency in solar cells.

(15) According to at least one example embodiment of the invention such frustules extracted from benthic pennate diatoms 210 being deposited on a surface 220 are used for absorption of mechanical waves are sound waves and the absorption of sound waves is used for sound insulation.

(16) According to at least one example embodiment of the invention such frustules extracted from benthic pennate diatoms 210 is used for uptake of a chemical substance 220 and wherein said absorption of chemical substances can be used in biosensors.

(17) According to at least one example embodiment of the invention the uptaken chemical is released in a controlled manner by said frustules extracted from benthic pennate diatoms.

(18) According to at least one example embodiment of the invention such frustules extracted from benthic pennate diatoms 210 being deposited on a surface 220 are used for heat insulation.

(19) FIG. 3 shows a composite material 300 where the frustules extracted from benthic pennate diatoms 310 provided as a dry powder has been mixed with a second material forming a composite material 320.

(20) The skilled person realizes that a number of modifications of the embodiments described herein are possible without departing from the scope of the invention, which is defined in the appended claims.

(21) FIG. 4 shows a cross-sectional view of a frustule extracted from a benthic pennate diatom 400. The frustule comprises several layers, which in FIG. 4 is three. The different layers comprises pores 410, 420, 430 of different sizes. Here, the lowest layer comprises the smaller pores 430, whereas the top layer comprises the largest pores 410. The middle layer comprises pores 420 of a size which is between the pores 410, 430 of the lowest and the top layer. The pores 410, 420, 430 forms a funnel-like structure which may be used for uptake energy (e.g. light), mechanical waves and/or chemicals. The thickness of the frustule 400, or of the different layers defines the sizes of the pores.

Example 1 Solar Cell Application

(22) Method:

(23) TEC15 glass was used for all working electrodes. All electrodes were screen printed and sintered under identical conditions and settings. A ratio of 1:50 (frustules:titanium dioxide) was used in all the mixed cells boths those containing frustules from benthic pennate diatoms and those containing frustules from fossil diatoms. D35 were used as dye and standard iodide electrolyte containing ionic liquid where used as electrolyte for all cells (MPN as solvent). The incident photon-to-current efficiency (IPCE) measurements were conducted between 350-800 nm, and three cells were measured for each series.
Results:

(24) According to the incident photon-to-current efficiency (IPCE) measurements the dye sensitized solar cells with frustules extracted from benthic pennate diatoms mixed with titanium dioxide perform better than a reference dye sensitized solar cell with only titanium dioxide. Solar cells with frustules from fossil diatoms mixed with titanium dioxide perform similar to the reference dye sensitized solar cell.

(25) On average, relative to the reference dye sensitized solar cell, the solar cells with frustules extracted from benthic pennate diatoms perform approximately 60% better and the solar cells with frustules from fossil diatoms perform 9% better than the reference dye sensitized solar cell.

Example 2 Solar Cell Application

(26) Method

(27) Commercial solar cells (BP Solar 0.446W Polycrystalline Photovoltaic Solar Panel) were used for all tests. The solar cell performances were measured ‘as received’ as references. In order to achieve a stable and monolayer coating, the cell surfaces were plasma cleaned (oxygen plasma) and treated with an amino-silane monolayer via vapour phase deposition ((3-Aminopropyl)triethoxysilane, APTES) at 70 □ C. All deposition tests on solar panels were performed with the same batch of NSFD powder (Batch 3C). NSFD dispersion of 0.2 wt. % was prepared by weighing 0.06 g of the calcined powder and dispersing it in 30 mL of 1 wt. % solution of TritonX100 in milliQ water. This was placed under magnetic stirring overnight. Thereafter, the dispersion was centrifuged at 2.5 krpm; (1467 g) for 2 minutes and the supernatant was replaced with fresh milliQ water. This process was repeated and the final milliQ dispersion was labelled Disp. A. An aliquot of Disp. A was diluted to 0.01 wt. % (Disp. B). Another dispersion of the NSFD powder was prepared in ethanol with a concentration of 0.1 wt. % (Disp. C). The solar cell surfaces were coated by a adding 5 mL of the dispersions to cover the entire surface and allowed to settle for 2 hours. Thereafter the dispersions were drained out and the surfaces were rinsed with the solvent. The solar cells were dried in at 50° C. Any residual patches of dry powder were removed with a jet of compressed N2 flow. This resulted in a monolayer of the dispersion, with a particle density depending on the dispersion used for coating. As a control sample, a solar cell was plasma cleaned, treated with APTES monolayer and then pure solvent was used instead of the NSFD dispersion, followed by oven drying. From image analysis of the microscopy images of Cell 4, Cell 6 and Cell 8, we found that the disperse coating had a coverage of 7.8%, the intermediate coating had a coverage of 31.1%, and dense coating had a coverage of 79.4%.

(28) Summary

(29) In summary, I-V data of cell coated with the least disperse coating showed an improvement in output power of 3.7% after coating, when compared to the output power before coating, when measured under the same input optical power. The NSFD particles covered about 7.8% of the surface area. Denser coatings showed negligible improvement in output power (0.3% for intermediate and −0.7% for dense) when comparing the before and after coating performances. Since the input power, which is the lamp irradiance, was adjusted to be equal, this difference in output power corresponds to difference in performance efficiency of the cells.