JP2012061441A - Adsorbent and wastewater treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorbent which efficiently collects oil in water and is excellent in dispersibility.SOLUTION: The adsorbent includes first particles and second particles different in contact angle.

Description

  The present embodiment relates to an adsorbent.

  Conventionally, effective use of industrial wastewater has been demanded. Industrial wastewater inevitably contains oil, and the separation and recovery of oil has become a serious issue.

  As one means for recovering oil in water, a magnetic separation and recovery method for water containing oil using magnetic particles has been studied. For example, there is a method in which oil is collected by forming an oil adsorption film on fine particles of a magnetic material, spreading the magnetic material on the sea surface, and attracting the magnetic material with magnetic force (for example, Patent Document 1).

  However, a hydrophobic film of fatty acid such as stearic acid is formed on the magnetic material, has low dispersibility in water, and the magnetic material tends to settle or float on the surface. Recovery could not be performed.

JP 2000-176306 A

  An object of the present invention is to provide an adsorbent that efficiently recovers oil in water and has excellent dispersibility.

  The adsorbent of the embodiment includes first particles and second particles having different contact angles.

  Hereinafter, embodiments will be described.

(Adsorbent)
The adsorbent in the present embodiment includes first particles and second particles having different contact angles.
As will be described below, the first particles have high hydrophilicity due to their structural characteristics. For example, the contact angle is 0 degree to 90 degrees, and further, 0 degree to 40 degrees. However, in order to bring the lower limit value of the contact angle close to 0 degrees, various parameters must be optimally controlled, and generally ranges from 30 degrees to 40 degrees.

  The second particles exhibit hydrophobicity due to their structural characteristics. For example, the contact angle is 10 degrees to 100 degrees, and further 50 degrees to 100 degrees. As described in detail below, in general, the contact angle tends to increase when the magnetic particles are covered with a hydrophobic polymer layer.

  As described above, since the first particles exhibit hydrophilicity, when used as an adsorbent, the first particles have excellent dispersibility in waste water. On the other hand, since the second particles are hydrophobic, when used as an adsorbent, aggregation of the adsorbent in the waste water is suppressed. Therefore, although the range of the contact angle of the first particle and the range of the contact angle of the second particle partially overlap, in selecting the first particle and the second particle to be used, contact with each other The angle is selected to be different so that the above-described dispersibility and non-condensability are ensured, and the function as an adsorbent can be sufficiently exerted when adsorbing oil in the waste water.

  For example, in the case where the contact angle of the second particles is large and the hydrophobicity is excellent, aggregation of the adsorbent in the waste water can be suppressed even if the content ratio is relatively small, so the content ratio of the first particles is Inevitably increases. On the other hand, in the case where the contact angle of the second particles is small and the hydrophobicity is not so high, it is necessary to increase the content ratio thereof, so that the content ratio of the first particles inevitably decreases.

  In addition, a contact angle can be calculated | required by putting particle | grains in a container and making the surface flat, and measuring the contact angle of the water droplet formed on this surface. Specifically, using a contact angle measuring device (FAMAS, manufactured by Kyowa Interface Science Co., Ltd.), the static contact angle of water droplets on the surface of the adsorbent was measured by the θ / 2 method.

  Next, the first particles and the second particles constituting the adsorbent will be described.

<First particle>
The first particles are at least one selected from the group consisting of magnetic particles and silica, titania, alumina, zirconia, and zinc oxide obtained by hydrolyzing a metal alkoxide formed on the surface of the magnetic particles. And an inorganic oxide layer.

Ferromagnetic materials can be generally used for the magnetic particles. Ferromagnetic materials can be generally used, and examples thereof include iron and iron-containing alloys, magnetite, titanite, pyrrhotite, magnesia ferrite, cobalt ferrite, nickel ferrite, barium ferrite, and the like. Of these, ferrite compounds having excellent stability in water can achieve the present invention more effectively. For example, magnetite (Fe ₃ O ₄ ), which is a magnetite, is preferable because it is not only inexpensive, but also stable as a magnetic substance in water and safe as an element, so that it can be easily used for water treatment.

  The magnetic particles can have various shapes such as a spherical shape, a polyhedron, and an indeterminate shape, but a spherical shape or a polyhedral structure with rounded corners is preferable. This is because particles having acute angles may damage the inorganic oxide layer and impair the function of oil adsorption when the inorganic oxide layer is formed. The surface of the magnetic particles may be subjected to a surface treatment for the purpose of preventing corrosion, or may be subjected to a treatment such as Cu plating or Ni plating as necessary.

  The average particle diameter of the magnetic particles is preferably 0.1 to 1000 μm, and more preferably 10 to 500 μm. When the average particle diameter is less than 0.1 μm, the magnetic force is small, and thus recovery by magnetism becomes difficult, which is not preferable. On the other hand, when the average particle diameter exceeds 1000 μm, the specific surface area becomes small, which may deteriorate the impurity recovery rate, which is not preferable.

  The average particle diameter of the magnetic particles is measured by a laser diffraction method. Specifically, a SALD-DS21 type measuring device (manufactured by Shimadzu Corporation) can be used. X-ray diffraction measurement and transmission electron microscope (TEM) measurement can also be employed. Or an average particle diameter can be calculated | required with a microscope. The magnetic particles need not all be composed of a magnetic material. That is, very fine magnetic particles may be bonded with a binder such as an inorganic oxide layer or a resin.

  The inorganic oxide layer preferably contains silica, titania, alumina, zirconia, and zinc oxide. This is because the material is easily available and the reaction is easily controlled.

  The inorganic oxide layer containing silica is formed using a silicon compound or an organosilicon compound as a precursor material.

  As the silicon compound, alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane can be used.

  As the organosilicon compound, an organosilicon compound represented by the general formula RaSi (OR ′) 4-a can be used. In the general formula, R is a vinyl group, an aryl group, an acrylic group, an alkyl group having 1 to 18 carbon atoms, a hydrogen atom or a halogen atom, and R 'is a vinyl group, an aryl group, an acrylic group, an alkyl group having 1 to 8 carbon atoms. A group or a hydrogen atom. It is preferable that a is an integer of 0-3. Specifically, known compounds such as methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, methyltriisopropoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, and dimethyldimethoxysilane can be used. In addition, the silica layer having the functional group specified by R or R ′ in the above general formula not only contributes to improving the hydrophilicity and dispersibility of the adsorbent in water, but also serves to adsorb oil in water. .

  The inorganic oxide layer containing titania is formed using an organic titanium compound such as titanium alkoxide.

  As the organic titanium compound, a compound represented by the general formula RaTi (OR ′) 3-a can be used. In the general formula, R is a vinyl group, an aryl group, an acryl group, an alkyl group having 1 to 18 carbon atoms, a hydrogen atom or a halogen atom, and R ′ is a vinyl group, an aryl group, an acryl group, 1 to 1 carbon atom. 8 is an alkyl group or a hydrogen atom, and a is an integer of 0-2. Specifically, for example, titanium trimethoxide, titanium triethoxide, titanium tri-n-propoxide, titanium tri-i-propoxide, titanium tri-n-butoxide, titanium tri-sec-butoxide, titanium tri-tert-butoxide, iso Use of known titanium alkoxide compounds such as propoxybis (ethyl acetoacetate) titanium, tetraisopropoxy titanium, tetra-n-butoxy titanium, tetraalkoxide titanium compounds such as tetramethoxy titanium, titanium chelate compounds, titanium acylate compounds, etc. Can do. In addition, the titania layer having the functional group specified by R or R ′ in the above general formula not only contributes to the improvement of hydrophilicity and dispersibility of the adsorbent in water, but also plays a role of adsorbing oil in water. .

  For the inorganic oxide layer containing alumina, an aluminum metal compound such as aluminum alkoxide can be used. Specific examples include trialkoxyaluminum compounds such as aluminum isopropylate, aluminum trisecondary butoxide, and mono sec-butoxyaluminum diisopropylate. Aluminum ethyl acetoacetate diisopropylate, aluminum tris (ethyl acetoacetate), aluminum tris (acetyl acetate), and aluminum bisethyl acetoacetate monoacetylacetonate may also be used.

  A material such as zirconium alkoxide can be used for the inorganic oxide layer containing zirconia. Specific examples include tetraalkoxyzirconium compounds such as diacetylacetone tributoxyzirconium and tetra-n-butoxyzirconium.

  For the inorganic oxide layer containing zinc oxide, a zinc metal compound such as zinc alkoxide can be used. Specific examples include dialkoxy zinc compounds such as zinc isopropylate, zinc disecondary butoxide, and mono sec-butoxy zinc diisopropylate. Alternatively, zinc ethyl acetoacetate isopropylate, zinc di (ethyl acetoacetate), zinc di (acetyl acetate), or zinc bisethyl acetoacetate monoacetylacetonate may be used.

In addition to the above, as a precursor material of the inorganic oxide layer, cobalt trioxide (CoO ₃ ), cobalt oxide (CoO), tungsten oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), indium tin oxide (ITO) , Indium oxide (In ₂ O ₃ ), lead oxide (PbO ₂ ), PZT, niobium oxide (Nb ₂ O ₅ ), thorium oxide (ThO ₂ ), tantalum oxide (Ta ₂ O ₅ ), calcium titanate (CaTiO ₃₎ ), Lanthanum cobaltate (LaCoO ₃ ), rhenium trioxide (ReO ₃ ), chromium oxide (Cr ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ), lanthanum chromate (LaCrO ₃ ), barium titanate (BaTiO ₃₎ ) And the like can also be used.

  Further, as precursor materials, metals such as Si, Ti, Zr, Al, Zn, Sn, W, Mo, Co, In, Sb, As, Ti, Co, Al, Zr, Yb, Sr, Th, Ta, etc. Known organic compounds or metal compounds such as metal complexes such as alkoxides, acetates and metal organic acid salts, metal salts, metal soaps and halides can be used alone or as a mixture.

  In addition, it is preferable that the average particle diameter of a 1st particle is the range of 5 micrometers-100 micrometers. When it exceeds 100 μm, when these particles are aggregated, the particle diameter becomes too large, the dispersion in the waste water is deteriorated, and the degree of oil adsorption may be reduced. Moreover, when it is less than 5 μm, the surface area becomes too small, and the degree of adsorption of oil in the wastewater may be reduced.

Further, the specific gravity of the first particles is generally 2 g / cm ³ or more, preferably 3 g / cm ³ or more and is preferably 10 g / cm ³ or less. If the specific gravity is too low, the first particles float on the water, and there are cases where energy is required to stir and disperse in the water. On the other hand, if the specific gravity is too high, the first particles may settle, and energy may be required for stirring and dispersing in water.

  Since the first particles have hydroxyl groups on their surfaces, the oil is adsorbed mainly via the hydroxyl groups.

<Second particle>
The second particles are at least one selected from the group consisting of magnetic particles and silica, titania, alumina, zirconia, and zinc oxide obtained by hydrolyzing a metal alkoxide formed on the surface of the magnetic particles. The inorganic oxide layer can be obtained by treating the surface of the inorganic oxide layer with a silane coupling agent. That is, it can be obtained by treating the first particles obtained as described above with a silane coupling agent.

  In general, it is known that an alkyl group is formed on the surface of a particle treated with a silane coupling agent, thereby hydrophobizing the particle surface. Accordingly, the second particles are obtained by performing the silane coupling agent treatment on the first particles based on such properties of the silane coupling agent.

  Examples of such silane coupling agents include methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane, dodecatrimethoxysilane, octadecyltrimethoxysilane, ethyltriethoxysilane, and other alkylsilanes, phenyltrimethoxysilane, and naphthalene. Aromatic silane such as trimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, epoxy-silane such as β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyl Vinyl silanes such as triethoxysilane, vinyltrimethoxysilane, γ-methacryloxymethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-γ-amino B pills aminosilane such as trimethoxysilane, .gamma.-mercaptopropyltrimethoxysilane, mercaptosilane or titanates etc., aluminum chelate, and a coupling agent such as zircoaluminate.

  The second particles can be obtained by including magnetic particles and a hydrophobic polymer layer formed on the surfaces of the magnetic particles.

As the magnetic particles, the same magnetic particles as those constituting the first particles can be used.
The hydrophobic polymer layer can be composed of a layer that does not dissolve in a predetermined organic solvent in a cleaning step described later. Specific examples include polystyrene resin, water-added polystyrene resin, butadiene resin, isoprene resin, acrylonitrile resin, or cycloolefin resin, polyvinyl pyridine resin, and polyvinyl butyral resin. More specifically, polystyrene, polyvinyl pyridine, polycycloolefin (for example, ZEONEX 480 (trade name, manufactured by ZEON CORPORATION)), polyvinyl butyral, polystyrene / polybutadiene block copolymer, polybutadiene, acrylonitrile / butadiene copolymer Examples thereof include a polymer, a polystyrene / polyisoprene copolymer, and a water-added polystyrene / butadiene copolymer.

  The second particles can also be formed as an aggregate containing the plurality of magnetic particles described above, with the polymer layer functioning as a binder. In this case, a large number of irregularities can be formed on the surface depending on the amount of the polymer layer and the forming method. Therefore, the second particles exhibit high oil adsorbability due to such a porous structure.

  The average particle diameter of the second particles is preferably in the range of 5 μm to 50 μm. If it exceeds 50 μm, dispersion in the waste water is deteriorated, and the degree of oil adsorption may be reduced. Moreover, when it is less than 5 μm, the surface area becomes too small, and the degree of adsorption of oil in the wastewater may be reduced.

Further, the specific gravity of the second particles is generally 2 g / cm ³ or more, preferably 3 g / cm ³ or more and is preferably 10 g / cm ³ or less. If the specific gravity is too low, the second particles float on the water, and there is a case where energy is required to stir and disperse in the water. On the other hand, if the specific gravity is too high, the second particles may settle, and energy may be required for stirring and dispersing in water.

  Since the second particle has a hydrophobic, that is, lipophilic polymer layer on the surface thereof, the adsorption of oil is mainly performed through the polymer layer.

<Method for producing first particle>
First, the magnetic particles are subjected to cleaning with an organic solvent such as ethanol, UV cleaning, plasma treatment, and the like to form hydroxyl groups on the surfaces of the magnetic particles.

Next, the metal alkoxide is mixed with water and hydrolyzed. The metal alkoxide is a precursor material of the inorganic oxide layer formed on the surface of the magnetic particles as described in the configuration of the first particles. The concentration of the metal alkoxide is 1 × 10 ^{−5 to} 1 mol / L, and the hydrolysis temperature (conditions) is from room temperature to 100 ° C.

  Next, magnetic particles are put into the solution after hydrolysis of the metal alkoxide described above to form a slurry solution, and this slurry solution is spray-dried by a spray drying method to obtain an aggregate. Since the aggregate is formed by coating magnetic particles with an inorganic oxide layer, the first particles are obtained as a result.

  According to the spray drying method, the average particle diameter can be adjusted by adjusting the environmental temperature of the spray drying, the ejection speed, etc., and pores are formed when the organic solvent is removed from between the agglomerated particles. As such, a suitable porous structure can be easily formed.

  In addition, it is preferable that the environmental temperature at the time of spray drying of spray drying is higher than the boiling point of water. The reason is that water can be quickly evaporated from the adsorbent, the outer shell can be formed before the inner water volatilizes, and the existence density difference can be formed between the inner shell and the outer shell.

  The viscosity of the slurry is 10 poise or less, preferably 5.0 poise or less. When the viscosity of the slurry is greater than 10 poise, problems such as precipitation of magnetic particles and metal alkoxide occur on the disk of the spray dryer.

<Method for Producing Second Particle>
In the case where the second particles are obtained by treating the first particles with a silane coupling agent, the first particles obtained as described above are treated with a silane coupling agent. The treatment with the silane coupling agent may be either a wet method or a dry method.

  When the second particles are constituted to include magnetic particles and a hydrophobic polymer layer formed on the surface of the magnetic particles, the polymer such as the polystyrene resin constituting the polymer layer is placed in an organic solvent. It can be obtained by preparing a dispersion medium (slurry) in which the magnetic particles are dissolved and dispersing the magnetic particles in the solution, and spray-drying the dispersion medium (slurry) by a spray drying method. According to this method, it is possible to obtain the second particles as a secondary aggregate formed by aggregating magnetic particles by causing the polymer to function as a binder by adjusting the environmental temperature of spray drying, the ejection speed, and the like. it can.

  In this case, pores are formed when the organic solvent is removed from between the aggregated primary particles, and a suitable porous structure can be easily formed.

  On the other hand, industrially, a polymer solution in which a polymer is dissolved in an organic solvent capable of dissolving the polymer is prepared, the polymer solution is poured onto the surface of magnetic particles put in a mold, and the organic solvent is further removed. The second particles can also be obtained by crushing the solidified material or by crushing the solidified material by removing the organic solvent from the dispersion medium (slurry) in which the magnetic particles are dispersed in the polymer solution. be able to. Also in this case, when the organic solvent is removed from the dispersion medium (slurry), pores are formed in the solidified product, and the pores remain in the second particles, thereby realizing a porous structure.

  In addition, the second particles can be produced by dropping a dispersion medium (slurry) in which a polymer is dissolved in a solvent into a Henschel mixer, a ball mill, or a granulator and drying it.

(Recovery of oil by adsorbent)
Next, a method for recovering oil using the adsorbent according to the present embodiment will be described. Oil recovery is to separate the oil from water containing the oil. As used herein, “oil” refers to organic substances mixed / dispersed in water that are generally liquid at room temperature, are hardly soluble in water, have a relatively high viscosity, and have a lower specific gravity than water. More specifically, animal and vegetable oils, hydrocarbons, aromatic oils and the like. These are represented by fatty acid glycerides, petroleum, higher alcohols and the like. Since these oils are characterized by the functional groups and the like, the resin and functional groups constituting the adsorbent can be selected accordingly.

  First, the adsorbent is immersed and dispersed in water containing the oil defined as described above. The adsorbent has a functional group (first particle) such as a hydroxyl group and a new oily group (second particle) such as a hydrocarbon derived from the material composition constituting the coating layer, and is porous if necessary. Since it has a high quality structure, it has a high affinity for oil. Accordingly, a relatively large amount is adsorbed on the adsorbent.

  After the adsorbent adsorbs the oil, the adsorbent is separated from the water, and as a result, the oil present in the water is separated and removed. Note that when separating the adsorbent, the first particles and the second particles constituting the adsorbent contain magnetic particles, and therefore can be easily separated using magnetism.

  In addition, the water used as the object of an oil recovery process is not specifically limited. Specifically, it can be used for industrial wastewater, sewage, domestic wastewater and the like. The concentration of oil contained in the water to be treated is not particularly limited.

(Regeneration of adsorbent)
After the oil is adsorbed by the adsorbent and removed from the water as described above, the adsorbed oil is removed by washing the adsorbent with a predetermined solvent. This solvent must not dissolve the coating layer of the adsorbent. Specifically, a solvent having a solubility in a solvent of 10 mg / L or less is used.

  Examples of the solvent include methanol, ethanol, n-propanol, isopropanol, butanol, isobutanol, hexyl alcohol, cyclohexanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, diethyl ether, Examples include isopropyl ether, dibutyl ether, tetrahydrofuran, dioxane, cyclohexane, chloroform, dimethylaniline, chlorofluorocarbon, n-hexane, cyclohexanone, toluene, and xylene.

  Among these, a nonpolar solvent is particularly preferable. The nonpolar solvent exhibits hydrophobicity and particularly has a high affinity with the oil, so that the oil adsorbed on the adsorbent can be easily and efficiently washed. The term “hydrophobic” as used herein is defined as a substance having a water solubility of 10% or less and separated from water. In particular, hexane is preferable because it has a high oil dissolving power, a boiling point of about 70 ° C., and is always a stable liquid at room temperature.

  Moreover, alcohol can also be preferably used as the solvent. In this case, it is easy to replace the water adhering to or adsorbing on the surface of the adsorbent, and it is easy to remove impurities other than oil. Among alcohols, methanol and ethanol having a low boiling point are particularly preferable.

  In this step, for example, the adsorbent is packed in a column and a solvent is allowed to pass through the column. In particular, when the adsorbent contains a magnetic substance, the adsorbent is put in a washing tank and a large amount of solvent is added. And a method of separating by a method such as a cyclone or a magnetic force.

  Next, after removing the oil from the adsorbent, the solvent used for washing is dried as necessary. At this time, if the adsorbent is not deteriorated and is within the specification, the adsorbent can be reused by removing the solvent completely.

  Although a drying process is not specifically limited, For example, a solvent is removed by drying in a well-ventilated place, drying under reduced pressure, or ventilating with a column.

Example 1
Magnetic particles having an average particle diameter of 1 μm were added to ethanol and centrifuged at 5,000 rpm for 3 minutes. After removing the supernatant, washing was performed three times with ultrapure water, and the surface was washed to form hydroxyl groups on the surfaces of the magnetic particles.

  The obtained magnetic particles were put into water, and acetic acid and vinyltrimethoxysilane were further added to prepare a slurry. This was sprayed with a spray dryer to obtain first particles having an average particle size of 10 μm.

  Further, the first particles were put into toluene, and methyltrimethoxysilane was added thereto and stirred. The dispersion medium was filtered and further washed with ethanol to obtain second particles.

  The dispersibility test of the adsorbent was performed as follows. 40 ml of water was put into a 100 ml test tube, and 0.8 g of the first particles and 0.2 g of the second particles were added thereto, and the test tube was vigorously shaken to disperse the adsorbent and then left to stand. . Thereafter, it was confirmed that the adsorbent settled to the bottom of the test tube. Further, the state of the adsorbent dispersed on the bottom was confirmed by turning the test tube upside down. This operation was repeated to observe how many times the adsorbent was completely dispersed. As a result, the mixture of the first particles and the second particles was completely dispersed in the second time.

  Next, the adsorbent was weighed into a 50 ml colorimetric tube, 20 ml of water containing 100 μL of linear aliphatic oil was added, and the mixture was stirred well to adsorb the oil to the adsorbent. Then, after taking out the adsorbent out of the colorimetric tube using a magnet, 10 ml of hexane was added and stirred well to extract oil in water. The amount of oil contained in hexane was analyzed using a gas chromatograph mass spectrometer, and the amount of oil adsorbed on the adsorbent was determined. As a result, 98.7 μL of oil was adsorbed (removal rate 98.7%).

  Further, the taken out resin mixture was put into 10 ml of hexane and stirred well. When the resin composite was taken out of the hexane using a magnet and analyzed for hexane, the entire amount of oil was removed.

(Example 2)
Polymethyl methacrylate (SUMIPEX, manufactured by Sumitomo Chemical Co., Ltd.) is dissolved in acetone, and the magnetic particles are added to the slurry to form a slurry, which is then sprayed with a spray dryer to form poly on the surface of the magnetic particles having an average particle size of 10 μm. An adsorbent dispersibility test and an oil adsorbability test were performed in the same manner as in Example 1 except that the second particles formed with a polymer layer of methyl methacrylate were used. The first particles were 0.8 g, and the second particles were 0.2 g.

  As a result, the mixture of the first particles and the second particles was completely dispersed in the second time. Further, the adsorbent obtained in this example adsorbed 98.7 μL of oil and desorbed the entire amount of oil.

Example 3
The same procedure as in Example 1 was performed except that butyltrimethoxysilane was used instead of methyltrimethoxysilane.

Example 4
The same procedure as in Example 1 was performed except that phenyltrimethoxysilane was used instead of methyltrimethoxysilane.

(Example 5)
The same procedure as in Example 1 was performed except that the first and second particles used in Example 1 were changed to 0.6 g and 0.4 g, respectively.

(Example 6)
The same procedure as in Example 1 was performed except that the first and second particles used in Example 2 were changed to 0.6 g and 0.4 g, respectively.

(Example 7)
The same procedure as in Example 1 was performed except that methyltrimethoxysilane was used instead of vinyltrimethoxysilane and butyltrimethoxysilane was used instead of trimethoxysilane.

(Example 8)
The same procedure as in Example 1 was performed except that methyltrimethoxytitanium was used instead of vinyltrimethoxysilane.

Example 9
The same procedure as in Example 1 was performed except that ethyltrimethoxyzirconium was used instead of vinyltrimethoxysilane.

(Example 10)
The same procedure as in Example 1 was performed except that ethyltrimethoxyzinc was used instead of vinyltrimethoxysilane.

(Example 11)
The same procedure as in Example 1 was performed except that ethyltrimethoxymanganese was used instead of vinyltrimethoxysilane.

(Example 12)
The same procedure as in Example 2 was performed except that polystyrene was used instead of polymethyl methacrylate (SUMIPEX, manufactured by Sumitomo Chemical Co., Ltd.).

(Comparative Example 1)
The same operation as in Example 1 was performed except that 1.0 g of the first particles in Example 1 was used and no second particles were used.

(Comparative Example 2)
The same procedure as in Example 2 was performed except that 1.0 g of the second particles in Example 2 was used and the first particles were not used.

(Comparative Example 3)
The same procedure as in Example 1 was performed except that 1.0 g of the first particles obtained using icosanetrimethoxysilane instead of methyltrimethoxysilane was used and the second particles were not used.

  It was found that any of the compositions shown in the Examples has a high oil content adsorption rate of 97% or more and is excellent in dispersibility because the number of dispersions is two. In particular, the adsorbent was superior when the first particles granulated with a silane coupling agent were used.

  As mentioned above, although several embodiment of this invention was described, these embodiment was posted as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims (10)

  An adsorbent comprising first particles and second particles having different contact angles.   The first particles are at least selected from the group consisting of magnetic particles and silica, titania, alumina, zirconia, and zinc oxide obtained by hydrolyzing a metal alkoxide formed on the surface of the magnetic particles. The adsorbent according to claim 1, comprising a kind of inorganic oxide layer.   The second particles are at least selected from the group consisting of magnetic particles and silica, titania, alumina, zirconia, and zinc oxide obtained by hydrolyzing a metal alkoxide formed on the surface of the magnetic particles. The adsorbent according to claim 1 or 2, comprising a kind of inorganic oxide layer, wherein the surface of the inorganic oxide layer is treated with a silane coupling agent.   The adsorbent according to claim 1 or 2, wherein the second particles include magnetic particles and a hydrophobic polymer layer formed on the surface of the magnetic particles.   The second particle includes a plurality of magnetic particles and a hydrophobic polymer layer. The polymer layer covers the surfaces of the plurality of magnetic particles and bonds the plurality of magnetic particles to each other. The adsorbent according to claim 1 or 2, which functions as a binder.   The adsorbent according to any one of claims 1 to 5, wherein an average particle diameter of the first particles is in a range of 5 µm to 100 µm.   The adsorbent according to any one of claims 1 to 6, wherein an average particle diameter of the second particles is in a range of 5 µm to 50 µm. A first step of dispersing the adsorbent according to any one of claims 1 to 7 in waste water containing oil and adsorbing the oil to the adsorbent;
A second step of separating the adsorbent from the waste water using magnetic force;
A method of treating waste water, comprising:   The wastewater treatment method according to claim 8, wherein the wastewater is industrial wastewater.   The drainage according to claim 9, further comprising a third step of washing the oil adhering to the adsorbent with an organic solvent and regenerating the adsorbent after the second step. Processing method.