GB2071076A - Adsorbent materials for oils and fats - Google Patents

Abstract

The porous adsorbent material for oils and fats according to the present invention is composed mainly of a sintered product of a basic composition consisting of a mixture of silica and clay, whereby an infinite number of continuous, open pores are formed on, and the hydrophobic property is imparted to, said sintered product to thus be converted into the porous adsorbent material capable of adsorbing oils and fats.

Description

SPECIFICATION Adsorbent materials for oils and fats Spilt crude oil or a variety of waste oils contained in waste waters discharged from petrochemical plants, petroleum refineries, iron works, ship building yards and others float, or are contained in the state of emulsion, in fresh or sea water, and constitute pollutants of rivers, streams and oceans. Furthermore, such oily substances in some cases tend to cohere and precipitate or settle after being maintained in the floating condition for a certain period of time, and thus exert adverse effects on organisms living on the bottoms of rivers and the sea, while they continue to be kept in the sediments semipermanently. In view of the above, development of appropriate treatment processes for oils and fats is urgently requested.

Under these circumstances, it is deemed the most effective to eliminate such oils and fats while they are in the hydrated condition and before they get to cohere and settle. And a great number of processes for eliminating oils and fats have been conventionally developed in the past. By way of example, actually adopted for commercial use is the process for eliminating oils and fats floating over the surface of the sea water which comprises allowing mat-shaped, fibrous materials to float on the surface of the sea water and contacting for sticking them with oils and fats to permit adequate impregnation of said mats therewith.

When the mats exhibit a lowered degree of adsorption for oils and fats and are composed of chemical fibers, nevertheless the process has brought about difficult problems after having adsorbed oils and fats, such as flowing out of adsorbed oils and fats from adsorbent mats, evolution of toxic gases during incineration of such mats and damaging of an incinerator due to higher burning temperatures.

The porous adsorbent material for oils and fats according to the present invention, with a specific aim to solving the above-mentioned problems so far encountered, realizing a cost reduction and facilitating handling, has been developed.

The present invention relates to a porous adsorbent material for oils and fats, and has for its object to provide the porous adsorbent material for oils and fats which exhibit excellent adsorption capacity for oils and fats, is easy to mold and handle, and can be regenerated for recycled use. The present invention comprises the porous adsorbent material for oils and fats having the following composition and construction. That is to say; the adsorbent material, being formed to the desired shape in accordance with its final application purpose and place and other conditions, is composed mainly of a sintered product of silica and clay, whereby an infinite number of contineous, open pores are formed on said sintered product and are subjected to hydrophobic treatment.In the accompanying drawings: Figure 1 is a graph representing a remaining oil content in a sample water containing a fixed concentration of oil measured in relation to a passage rate at which the sample water is passed through a determined amount of the adsorbent material; Figure 2 is a graph showing a remaining oil content in a sample water containing a fixed concentration of oil as described in Figure 1 in relation to a passage rate at which the sample water is passed through the absorbent material according to the present invention and pearlite based one of equal quantities; Figure 3 is a graph showing a remaining oil content in a sample water containing a fixed concentration of oil in relation to a passage amount with which the sample water is passed through a determined amount of the adsorbent material at a constant rate;; Figure 4 is a graph representing a remaining oil content in a sample water in relation to an amount used of the adsorbent material according to the present invention.

The porous adsorbent material for oils and fats according to the present invention, developed with a specific view to the excellent adsorption capacity for oils and fats, ease of molding and handling and regeneration for recycled use, is composed mainly of a sintered product of a mixture of silica and clay, whereby an infinite number of contineous, open pores imparted with the hydrophobic property are formed on said sintered product to thus constitute the adsorbent material.

Referring now in more detail to the present invention, the compositions of silica and clay, which are raw materials for a sintered product, the main component for the adsorbent material, have great influence upon physical properties of adsorbent material resulting therefrom through sintering, while they in fact vary to some extent depending upon places of origin. And, in producing a sintered product from a mixture of silica and clay, recommended to be used are the silica and clay having the compositions shown respectively in the hereinafter mentioned tables, or such a clay as may have a content of aluminium oxide not more than 3 times that of silicon oxide, which are adjusted in grain size (e.g., to 250 to 300 mesh) and in formulation ratio.

TABLE 1 Compositions of silica and clay, in % by weight Silica: Clay: SiO2, 96.00 SiO2, 40.0 Al203, 1.09 Al203, 40.0 Fe203, 0.15 Fe203, 0.8 to 0.9 K20, 1.50 CaO, 0.7 Loss , 0.26 MgO, 0.55 Loss' ) 12.0 Remarks: 1); Loss stands for ignition loss.

An infinite number of continuous, open pores to be formed on a sintered product are formed during sintering of the aforementioned basic composition consisting of silica and clay. Examples of the pore forming materials which are useful for this purpose may include the materials (e.g., sawdust, rice hulls, etc.) that can be easily mixed for dispersion with the aforementioned basic composition and burnt off completely at a sintering temperature of the basic composition to form continuous, open pores and may have the particle size to be determined by taking into consideration the desired diameter, shape and extent of continuity of pores to be formed.

More specifically, a mud-formed basic composition produced by adding an appropriate portion of water (e.g., 3 to 4.5 times by weight that of the basic composition) is admixed for dispersion with the aforementioned pore-forming material (e.g., 100 to 140 parts by weight), and moulded to the desired shape, followed by sintering at increased temperatures after forced or air dyring to thus form the sintered product as well as burn off the pore-forming material to produce an infinite number of continuous, open pores.In this case, the used amount of the pore-forming material is determined by taking into consideration desired properties of resulting continuous open pores (e.g., water-penetrating property) and specific gravity of adsorbent material to be produced, etc. and, is suitably in the range of 1 to 1.4 times that of the basic composition. Furthermore, the pores formed in this way are subjected to a hydrophobic treatment with a hydrophobic agent such as silicone based water repellent agent to impart the lipophilic property or enhance the adsorption effect for oils and fats.

Following is a description by way of example only of a method of carrying the invention into effect.

To be made available are 500 kg of silica, 500 kg of clay (the one which contains 40 % by weight of SiO2 and 40 /O by weight of AI2O3), 1000 kg of sawdust and 3500 kg of water; in the first place, silica and clay are charged into a Pot mill and mixed, followed by adding sawdust as a pore-forming material to mix to a uniform dispersion. Mixing is continued while water is added, until the mud state is produced. The basic composition having thus been made mud-formed is poured in a mold, followed by carrying out air drying for 5 days and forced drying for 1 day at about 130 C to effect demolding. Molded products being thus dried are placed in a burning furnace and, after the temperature is gradually increased, sintered at the temperature of 1350 to 1370 0C maximum for 1 hour. After the temperature is allowed to decrease, the sintered products are taken out from the furnace and, after being cooled, immersed into a 0.2 % aqueous solution of a hydrophobic agent (silicone-based water repellent agent), followed by pulling up to be dried and heating at 130 to 3000C for not less than 2 hours to carry out heat treatment. By the above procedure, there is obtained the adsorbent material according to the present invention.

The adsorbent material according to the present invention produced under the aforementioned conditions exhibits the specific gravity and composition as described below, and can be used as an adsorbent material for oils and fats present in the liquids, whereby results of the experiment with said adsorbent material are illustrated in Figures 1 through 4 accompanied hereto.

Specific gravity: 0.25 to 0.35 Composition: SiO2, 68.00 (% by weight) Al2O3, 21.00 Fe203, 0.56 K20, 1.50 CaO, 0.70 MgO, 0.55 In the Experiment (1), the remaining oil contents in a sample water containing a fixed concentration of an oil are measured with varying passage rates at which the sample water is passed through a determined amount of adsorbent material, with the obtained results being shown in the graphs of Figures 1 and 2.In Figure 1, the sample water employed is composed of water containing 100 ppm of an oil produced by adding 1 cc of an oil to 1 owe of water; the signs, and, as shown in the graphs, designate type of oils mixed into sample waters, or represents data obtained with heavy oil A, those with olive oil and those with gasoline, whereby the sign, designates the data obtained with the experiment in which heavy oil A is employed as the oil in the sample water, along with the adsorbent material according to the present invention and an adsorbent (based on pearlite subjected to hydrophobic treatment).

As may be obvious from Figure 1, the adsorbent material according to the present invention permits the remaining oil content to decrease down to not more than about 13 ppm with any cases of heavy oil A, olive oil and gasoline, and shows the great difference of about 10 to 15 ppm in the case of heavy oil A, as compared with the case of a pearlite adsorbent material. These findings indicate that the adsorbent material according to the present invention possesses the very high adsorption capacity for oils and fats.

The graphs in Figure 2 are graphs showing comparative data with regard to the remaining oil contents obtained in the experiments in which the sample water consisting of water containing 3000 ppm of heavy oil A prepared by adding 30 cc of heavy oil Ato 10e of water is passed through equal quantities of the adsorbent material according to the present invention and the pearlite based adsorbent material at varying rates; in the graphs, the signs, o and 0, designate the adsorbent material according to the present invention and the pearlite based one, respectively.

Figure 2 shows that the adsorbent material according to the present invention, indicating 150 to 230 ppm of the difference in the remaining oil contents from the pearlite adsorbent material, possesses the very high adsorption capacity for oily substances.

In the Experiment (2), remaining oil contents are measured with varying passage amounts of the sample water, when the sample water with a fixed concentration of oil is passed through a determined amount of the adsorbent material according to the present invention, along with the obtained results being shown in graphs in Figure 3. In this case, the sample water consists of water containing 100 ppm of heavy oil A prepared by adding 5 cc of heavy oil to 50 of water, and its average passage rate is set at about 600 cc/min.

In the Experiment (3), the remaining oil contents are measured in relation to used amounts of the adsorbent material according to the present invention, and the results obtained are illustrated in the graphs of Figure 4. In this case, the sample water consists of water containing 100 ppm of heavy oil A prepared by adding 1 cc of heavy oil to 1 owe of water. while its averate passage rate is set at about 500 cc/min.

The porous adsorbent material for oils and fats according to the present invention, which may be produced by the above procedure, has the highly excellent adsorption capacity for oils and fats as compared with pearlite-based adsorbent materials for oils and fats, as shown in Figures 1 and 2. In furthermore, said adsorbent material with its lowered specific gravity can be allowed to float on the surface of water for its uses and insure adsorption of oils and fats in advance of cohesion and settlement.

In contrast with the foregoing example where the clay with 40 % each of Awl203 and SiO2 contents is utilized, the sintered product prepared under the same conditions as the foregoing example with the use of clay containing SiO2 three times more than Al2O3, is provided with inadequate pore formation as compared with the one obtained in the foregoing example, and turns out to be of no commercial value as the adsorbent material.

Referring to the basic composition composed of silica and clay, silica and clay are preferably used in the proportion of 50: 50 in parts by weight, since the desirable sintered product can be produced. Still, the satisfactory adsorbent material according to the present invention can be produced with such a mixing ratio of silica and clay and may be selected from about 65 to 35 parts by weight and about 35 to 65 parts by weight to make the total to 100 parts by weight.By way of example, when the basic composition is formed of 70 parts by weight of silica and 30 parts by weight of clay, the resultant sintered product can not be kept in desired shape, and is not suitable as the porous adsorbent material for oils and fats; when the basic composition is composed of 30 parts by weight of silica and 70 parts by weight of clay, the resultant sintered product, though provided with the desired shape, for example, brick-like shape, shows poor pore formation and large specific gravity and exhibits the deteriorated adsorption capacity for oils and fats.More specifically, 30 kg of silica, 70 kg of clay and 100 kg of sawdust are mixed with 400 kg of water, sintered in the same manner as in the foregoing example, and subjected to a hydrophobic treatment, leading to the finding that the resultant product exhibits less pore formation and reduced adsorption capacity for oils and fats, lacking the commercial value. In contrast, the mixtures comprising 65 kg of silica, 35 kg of clay and 100 kg of sawdust with 400 kg of water and consisting of 35 kg of silica, 65 kg of clay and 100 kg of sawdust with 400 kg of water, when subjected to the same treatment as described in the foregoing example, produce the sintered products which can retain the desired shape. It is further found that the adsorbent material derived from the former posseses the adsorption capacity almost equal to the one obtained in the foregoing example, while the one derived from the latter showing the adsorption capacity corresponding to 80 % of that of the one obtained in the example, thus being usable as the commercial product.

Employed as the pore forming material in the foregoing example is sawdust, which is desirably used in such a proportion as it, with a reduced water content, may be nearly equal in weight to the basic composition, or it, with an increased water content, may be about 1.4 times as more as the basic composition.

Claims (8)

1. A porous adsorbent material for oils and fats which comprises a sintered product produced by admixing with water a mixture composed of silica, clay and pore-forming material capable of being burnt off at a temperature of not more than the sintering temperature for silica and clay to make the mixture mud4ormed, then molding to a desired shape to be dried, and sintering at the determined temperature, whereby the said sintered product is imparted with the hydrophobic property.

2. A porous adsorbent material as claimed in claim 1 wherein clay having a content of SiO2 three times or less that of Awl203 is utilized.

3. A porous adsorbent material as claimed in claim 1 or 2 wherein clay having 40 % each of the SiO2 and Awl203 contents is utilized.

4. A porous adsorbent material as claimed in any preceding claim wherein sawdust is utilized as a pore-forming material.

5. A porous adsorbent material as claimed in any preceding claim wherein employed for sintering is a mixture comprising blending about 65 and 35 parts by weight of silica and about 35 to 65 parts by weight of clay at such a proportion as the total may be 100 parts by weight, and mixing in the presence of 100 to 140 parts by weight of sawdust with 300 to 450 parts by weight of water.

6. A porous adsorbent material as claimed in claim 5, wherein employed for sintering is a mixture comprising mixing 50 parts by weight each of silica and clay prepared in advance and 100 parts by weight of dried sawdust with water.

7. A porous adsorbent material as claimed in any preceding claim wherein the burning temperature is in the range of 1300 to 1400 C.

8. A porous adsorbent material as claimed in claim 1 and substantially as described in the specific example hereinbefore set forth.