TWI617515B - Modified rice brans as adsorbent and method of removal dye from wastewater using the same - Google Patents

Abstract

The present invention relates to a method of removing dyes in dye wastewater comprising adsorbing dyes in the dye wastewater using rice bran. The invention also relates to a dye adsorbent comprising a group selected from the group consisting of acid treatment modification, alkali treatment modification, alkali treatment after extraction, magnetic modification after extraction, and magnetic alkali treatment after extraction. Group of rice bran. The adsorbent of the present invention is made by recycling agricultural waste, which has good adsorption capacity and low preparation cost.

Description

Modified rice bran as adsorbent and method for removing dye from wastewater

The present invention relates to a dye adsorbent and a method thereof for removing dyes from dye wastewater.

In recent years, along with the continuous progress of the dyeing and finishing and printing technology industry, the application of dyes has not been limited to the dyeing and printing of textiles, but also widely used in many fields such as paint, plastics, leather, food, etc., while textiles, printing and leather, etc. Industrial processing requires a lot of water resources, so the printing and dyeing industry wastewater has become a major industrial wastewater discharge, and the wastewater discharged from dyeing and finishing industries or textile mills contains a large amount of dyes or organic matter. Wastewater not only affects the appearance of water, but organic matter in water can also adversely affect the human body. Dye wastewater is mainly from dye factories, food processing plants and fiber dyeing and finishing plants. Currently, there are more than 100,000 commercially available dyes, and the annual output of dyes exceeds 700,000 tons. Since most of the dyes and their intermediates of degradation are often highly toxic and carcinogenic, they are the cause of water pollution. In addition, since most of the dyes are organic compounds of macromolecules, which are biodegradable and photo-insoluble, and if the dye wastewater is not further processed, these dyes can remain in the water for a long time because of their stable properties. In fact, as long as a small amount of dye is present in the water, even if it is harmless, its color will still affect the appearance of the water. Therefore, how to remove the dye and decolorization in wastewater is a big challenge for environmental managers.

At present, it is known that decolorization methods from dye wastewater mainly include adsorption, extraction, coagulation, redox, ion exchange, filtration, biochemical and electrochemical methods. Among them, the adsorption method is simple and effective, and the treatment effect of activated carbon is optimal among many adsorbents, but the production cost of activated carbon is relatively expensive and the regeneration procedure is complicated, so it is not economical.

There are many researches on the preparation of wastes into adsorbents in the literature. The wastes used include banana peel, orange peel, pine sawdust, waste tea leaves, bagasse and white bamboo shoots. All kinds of adsorbents mentioned above are all kinds of pollutants. There is a certain treatment effect. Since the raw material for the preparation of the adsorbent is agricultural waste, it is not easy to cause secondary pollution, and it is worthy of widespread implementation, thereby developing a low-cost, high-efficiency and more environmentally friendly adsorption method.

In recent years, with the rise of environmental awareness, the sustainable development strategy of energy conservation, carbon reduction, and resource reuse is a global trend. How to reuse waste to prepare a highly efficient decolorizing adsorbent is the object of the present invention. On the premise of recycling agricultural waste, the inventors have unexpectedly discovered that rice bran can be used as an adsorbent for wastewater dyes, and using a simple treatment method, rice bran is prepared into an inexpensive adsorbent, which can be recycled. Reuse of materials, and can effectively reduce the cost of wastewater treatment.

Therefore, one of the main objects of the present invention is to prepare a dye adsorbent comprising selected from the group consisting of acid treatment modification, alkali treatment modification, extraction treatment, alkali treatment after extraction, magnetic modification after extraction, and magnetic properties after extraction. The rice bran of the group consisting of the alkali treatment.

In a preferred embodiment, the alkali-treated rice bran is obtained by immersing the rice bran in an aqueous ammonia solution and drying the rice bran; the acid-treated rice bran is obtained by soaking the rice bran with an aqueous hydrochloric acid solution and drying.

In a preferred embodiment, after the extraction, the alkali-treated rice bran extracts the rice bran with a methanol solution, and the extracted rice bran is then immersed in an aqueous ammonia solution and then dried. The rice bran which is magnetically modified after the extraction is obtained by extracting rice bran with a methanol solution, and then extracting the rice bran into an aqueous solution containing ferric chloride and ferrous chloride, and reacting in an alkaline environment. The rice bran which is modified by the magnetic alkali treatment after the extraction is obtained by magnetically modifying the rice bran after the extraction, and further drying it with an aqueous ammonia solution and drying it.

Another primary object of the present invention is a method of removing dyes from dye wastewater comprising the use of rice bran to adsorb dyes in the dye wastewater.

In a preferred embodiment, the rice bran is modified by acid treatment, modified by alkali treatment, modified by alkali treatment after extraction, magnetically modified after extraction or modified by magnetic alkali treatment after extraction. Wherein the dye is a reactive dye such as an anthraquinone dye, an indigo dye, a phthalocyanine dye, a carbon ion dye or a p-quinone imine dye; wherein the dye adsorbed in the dye wastewater is 40 ^o C to 70 ^o C.

In a preferred embodiment, the rice bran which is adsorbed by the dye is further immersed in ammonia water to desorb the dye, and then the rice bran is regenerated.

Compared with the prior art, the present invention provides the following advantages: by performing some simple treatments of rice bran, and then using hydrochloric acid and ammonia water, the treated rice bran is respectively modified by acid and alkali treatment, thereby improving the rice bran adsorbent. Adsorption capacity. Moreover, if the magnetic particles are further combined with the magnetic particles to prepare the magnetically treated alkali-treated rice bran adsorbent, the adsorbent is magnetically facilitated for subsequent recycling and reuse, thereby obtaining a low-cost, high-efficiency and environmentally-friendly wastewater treatment method.

The present invention provides a method of removing dyes in dye wastewater comprising adsorbing dyes in the dye wastewater using rice bran.

The term "dye" as used herein refers to a substance which can color fibers and other materials, and is preferably an anionic dye which can be adsorbed by the rice bran of the present invention, preferably but not limited to, for example, a reactive dye (蒽醌Dyes, indigo dyes, phthalocyanine dyes, carbon ion dyes or p-quinone imine dyes, etc.

As used herein, "rice bran" refers to the plant nutrient layer between brown rice and white rice, which is the skin layer of rice. The rice bran used in this paper as a dye adsorbent can be the original rice bran, acid-treated, and alkali. Treatment of modification, extraction treatment, alkali treatment after extraction, magnetic modification after extraction or magnetic alkali treatment after extraction and modification of rice bran.

As used herein, "original rice bran" refers to rice bran which is directly treated from the brown rice to the plant nutrient layer between white rice without treatment, or washed with water and then washed and dried with deionized water.

The term "acid-treated rice bran" as used herein refers to a method in which the raw rice bran is soaked in an acidic aqueous solution and then washed with deionized water; wherein the acidic aqueous solution is not limited and can be used by a user such as an aqueous hydrochloric acid solution. The aqueous solution of sulfuric acid, the aqueous solution of nitric acid, the aqueous solution of acetic acid, etc., may have a concentration of 30 to 50% v/v, such as 30, 40, 50% v/v, and the soaking time may be 16 to 48 hours, such as 16, 20, 24, 28 36, 48 hours.

The term "alkali-treated rice bran" as used herein refers to the process of immersing the raw rice bran in an alkaline aqueous solution and then washing it with deionized water; wherein the alkaline aqueous solution is not limited, and the user can be ammonia-like. The aqueous solution, the aqueous sodium hydroxide solution, the aqueous potassium hydroxide solution, the aqueous solution of baking soda, etc., may have a concentration of 30 to 50% v/v, such as 30, 40, 50% v/v, and the soaking time may be 16 to 48 hours, such as 16, 20, 24, 28, 36, 48 hours.

The term "extracted rice bran" as used herein refers to that the raw rice bran is extracted with rice bran oil by extraction solvent and then washed with deionized water; wherein the extraction solvent is not limited, and a polar solvent such as Methanol, ethanol, acetone, toluene, and the like. The extracted rice bran may be further subjected to the above acid treatment, alkali treatment or magnetic modification.

As used herein, "magnetically modified rice bran" refers to the modification of rice bran by magnetic particles. The method can be modified by magnetic precipitation using a coprecipitation method, a pyrolysis method, a microemulsification method or a hydrothermal method. Preferably, the coprecipitation method is carried out by adding rice hydrate to Fe ²⁺ and Fe ³⁺ to an alkaline solution (such as ammonia or sodium hydroxide), and heating to raise the temperature for nucleation reaction, the heating temperature may be 60 to 90 ^o C . The magnetically treated rice bran can be further modified by the above acid treatment or alkali treatment.

As used herein, "rice regeneration" refers to immersing the dyed rice bran in an alkaline aqueous solution, shaking it to desorb the dye, and drying it after washing with deionized water, which can be reused; the alkaline aqueous solution It is preferred to use the alkali treated modified waste liquid as referred to herein for environmental protection.

The method for removing dyes in the dye wastewater of the present invention, wherein in the treatment step of adsorbing the wastewater by the rice bran, the wastewater is preferably heated water, and the rice bran can increase the adsorption force under the condition of increasing temperature, and the temperature can be 40. Up to 80 ^o C, preferably 50 to 70 ^o C, such as 50, 60, 70 ^o C.

The present invention is further described in the following examples, however, it should be understood that the embodiments are not intended to limit the scope of the invention.

[Examples]

Preparation example

Preparation Example 1 - rice bran adsorbent (or raw rice bran adsorbent)

Rice bran (purchased in Taichungpu District, variety: Tainan No. 11 rice) is washed several times with water, then washed with deionized water, and the washed rice bran is dried in an oven (100 °C, 24 hours) to complete the pretreatment preparation. , obtain rice bran adsorbent.

Preparation Example 2 - Acid Treatment Modified Rice Blast Adsorbent

The rice bran adsorbent of Preparation Example 1 was subjected to acid treatment modification, that is, rice bran adsorbent (40 g / L) was added to an aqueous hydrochloric acid solution (50% v/v), continuously soaked for 24 hours, and then deionized water was combined with suction filtration. Wash several times and dry in an oven (100 °C).

Preparation Example 3 - alkali treated modified rice bran adsorbent

The rice bran adsorbent of Preparation Example 1 was subjected to alkali treatment modification, that is, rice bran adsorbent (40 g / L) was added to an aqueous ammonia solution (50% v/v), continuously soaked for 24 hours, and then degassed with deionized water. Filter and wash several times and dry in an oven (100 °C).

Preparation Example 4 - Extraction of rice bran adsorbent

The rice bran was rinsed several times with water, washed with deionized water, and baked in an oven for 10 minutes at a temperature of 120 °C. The baked rice bran was soaked in a methanol solution (1 g / 25 ml), and placed in a constant temperature shaking tank, set at a temperature of 50 ° C, and rotated at 100 rpm for 2 hours. The extracted rice bran is washed several times with water, then washed with deionized water, and the washed rice bran is dried in an oven (100 ° C, 24 hours) to complete the pretreatment preparation.

Preparation Example 5 - Alkali Treatment Modified Rice Bran Adsorbent

The extracted rice bran adsorbent of Preparation Example 4 was subjected to alkali treatment modification, that is, the extracted rice bran (40 g/L) was added to the aqueous ammonia solution (50% v/v), continuously soaked for 24 hours, and then mixed with deionized water. The air filter is cleaned several times and dried in an oven (100 °C).

Preparation Example 6 - Magnetically Modified Extracted Rice Bran Adsorbent

The extracted rice bran adsorbent of Preparation Example 4 was magnetically modified, and the magnetic fine particles were synthesized by the coprecipitation method, and the extracted rice bran 2 g, ferric chloride 4 g, and ferrous chloride 2 g were first added to contain 100 ml of deionized water. In the water beaker, add ammonia water to make it react, put it into a constant temperature shaking water tank, set the temperature to 85 °C, rotate at 100 rpm, and let it stand for 1 hour to obtain magnetically extracted rice bran, then mix with deionized water. Filter and wash several times and dry in an oven (100 °C). Its chemical equation is as follows: Fe ²⁺ + 2Fe ³⁺ +8OH ^- → Fe ₃ O ₄ + 4H ₂ O.

Preparation Example 7 - Extraction of rice bran adsorbent by alkali treatment after magnetization

The magnetically extracted rice bran of Preparation Example 6 was placed in an aqueous ammonia solution (50% v/v), continuously soaked for 24 hours, and then washed with deionized water and suction filtration several times, and dried in an oven (100 ° C).

Example

Example 1 - Adsorption experiment and characteristics analysis of rice bran adsorbent

Dye solutions (Reactive Blue, Reactive Blue-4, C ₂₃ H ₁₄ C _l2 N ₆ O ₈ S ₂ , purchased from Sigma-Aldrich) at 100 ppm, 200 ppm, 300 ppm, 400 ppm and 500 ppm dye solutions were prepared separately. The rice bran adsorption dose is 5 g, the dye pH is adjusted to 2, and it is placed in a constant temperature shaking water tank, the temperature is adjusted to 30 ° C, the rotation speed is 100 rpm, the adsorption time is 36 hours, and then the ultraviolet/visible spectrometer (UV) -VIS) The absorbance after adsorption was measured separately. As a result, as shown in Fig. 1, it can be found that the higher the dye concentration, the more the amount of RB dye adsorbed per gram of the adsorbent, because the adsorbent generates competitive adsorption with each other before the adsorption saturation is reached. Therefore, the amount of the dye adsorbed per gram of the adsorbent increases as the amount of the dye is equal before the amount of adsorption of the adsorbent is equal.

The surface structure of the rice bran adsorbent was photographed by field emission scanning electron microscopy (SEM). The surface structure changes before and after adsorption of the adsorbent prepared by different modification methods were observed, and the unextracted rice bran adsorbent was found. Preparation Example 1) The difference in surface structure was as shown in Fig. 2. It was found that there were many pores on the surface of the rice bran adsorbent, and it was indirectly confirmed that the specific surface area was large. From the SEM image, it can be found that before the adsorption and adsorption of the rice bran adsorbent, it can be clearly seen that the pore structure of the rice bran adsorbent before adsorption is relatively complete.

As shown in Fig. 3, it was found that the pores on the surface of the extracted rice bran adsorbent (Preparation Example 4) were denser than the unextracted rice bran adsorbent (Preparation Example 1), and that the surface area thereof was larger than that of the unextracted rice bran, and the adsorption effect was better. From the SEM image, it can be found that after adsorption, the pores on the surface of the extracted rice bran adsorbent are slightly enlarged compared with the rice bran adsorbent before adsorption. This is because the extracted rice bran adsorbent is extracted and its structure is destroyed, so that the rice bran becomes It is fragile. Therefore, when the dye is adsorbed, the pores are affected by an external force, causing the pores on the surface of the adsorbent to become large.

After analysis of the original rice bran and the extracted rice bran adsorbent modified by different methods using energy dispersive spectroscopy (EDX), it can be found that the main component of the raw rice bran adsorbent or the extracted rice bran adsorbent is C. And O, the elemental structure of rice bran did not cause significant changes due to extraction. In the magnetically treated rice bran, it can be seen that it contains Fe element, and the Fe content is not reduced by the adsorption of the dye, which represents the magnetic rice bran adsorbent, which has the ability to be adsorbed by the magnetic substance, and is not adsorbed by the dye. By reducing the magnetic properties, the magnetic rice bran adsorbent can be reused after being regenerated, and can still be recycled and reused by magnetic force.

The prepared adsorbent was measured by a BET specific surface area analyzer to compare the effect of the specific surface area of the rice bran adsorbent on the adsorption efficiency. The results are shown in Table 1. The results showed that the original rice bran adsorbent (Preparation Example 1) having a surface area of 0.36 m ² /g had a slight change in the BET specific surface area after being treated with the acid (Preparation Example 2) or the base (Preparation Example 3). is 0.38 m ² / g (prepared in Example 2, acid treatment) and 0.41m ² / g (3, preparation alkali treatment), and the micropore volume is increased from 0.0061 cm ² / g, was changed to 0.0149 cm ² / g (Preparation Example 2, acid treatment) and 0.0061 cm ² /g (Preparation Example 3, alkali treatment). The alkali-treated rice bran adsorbent has a dense and narrow pore, so that the pore volume is small and the BET surface area is large.

The extracted rice bran adsorbent (Preparation Example 4) had a surface area of 0.34 m ² /g, which was not much different from the surface area of the original rice bran (Preparation Example 1), but was subjected to alkali treatment (Preparation Example 5) and alkali treatment after magnetization ( Preparation Example 7) showed a slight increase in the BET specific surface area of 0.53 m ² /g (Preparation Example 5, alkali treatment) and 0.58 m ² /g (Preparation Example 7, alkali treatment after magnetization), and micropores. the volume of the original 0.0037cm ² / g, was changed to 0.0038cm ² / g (prepared in Example 5, the alkali treatment) and 0.0046cm ² / g (7, alkali treatment after the magnetic preparation Example). This is because the structure of the rice bran after being extracted by methanol is destroyed, and the rice bran becomes weaker than before the extraction, so the alkali treatment can more easily increase the pore depth and the number of pores, and obtain a larger surface area. In addition, it can be found that the surface area of the adsorbent which has been subjected to alkali treatment after being magnetized is not reduced by magnetization, but is increased because when the rice bran adsorbent is combined with Fe ₃ O _{4 by the} coprecipitation method, Ammonia is added to carry out the reaction, which is equivalent to a single treatment.

Table 1. Surface area and micropore volume results of different modified rice bran adsorbents         <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> sorbent</td><td> BET surface area (m² /g) </td><td> t-Plot micropore volume (cm²/g) </td></tr><tr><td> raw rice bran (preparation example 1) </td><td> 0.36 </td><td> 0.0061 </td></tr><tr><td> Acid-treated rice bran (Preparation Example 2) </td><td> 0.38 </td> <td> 0.0149 </td></tr><tr><td> Alkali-treated rice bran (Preparation Example 3) </td><td> 0.41 </td><td> 0.0061 </td></tr> <tr><td> Rice bran after extraction (Preparation Example 4) </td><td> 0.34 </td><td> 0.0037 </td></tr><tr><td> Alkali-treated rice bran after extraction Preparation Example 5) </td><td> 0.53 </td><td> 0.0038 </td></tr><tr><td> Magnetic alkali treatment of rice bran after extraction (Preparation Example 7) </td>< Td> 0.58 </td><td> 0.0046 </td></tr></TBODY></TABLE>

In order to observe the change of surface functional groups of rice bran adsorbent, the infrared spectroscopy (FTIR) was used for analysis and identification. The original rice bran and the extracted rice bran adsorbent modified by different methods were first loaded into the mold by tableting method to form tablets.狀Analysis, the analysis results (as shown in Fig. 4(a)~(d)), can find the C=O-based stretching vibration at 1750 cm ^-1 at 2930 cm ^-1 and 2860 cm ^-1 , find the CH-based telescopic vibration. Further, at 3600 cm ^-1 to 3200 cm ^-1 , the presence of an NH group was observed, and the stretching vibration of the OH group also appeared in this range, and at 1040 cm ^-1 , the stretching vibration of the Si-O group was found. The NH group and the OH group were found to prove that the functional group of the adsorbent is favorable for the adsorption of the RB-4 dye because the RB-4 dye contains an anion SO ₃ ^- (sulfo group), and the NH group has a positive charge, SO ₃ ^- is negatively charged, so polar adsorption is possible, and OH groups are exchangeable with SO ₃ ^- . As shown in Fig. 4-(a)~(d), before and after the adsorption of the adsorbent, it can be found that the stretching vibration of the NH group and the OH group is changed at 3600 cm ^-1 to 3200 cm ^-1 . A group absorption peak which is helpful for adsorbing RB-4 dye by adsorbent and a significant change of strength before and after adsorption can prove that OH group and NH group are helpful in the process of adsorbing RB-4 dye by adsorbent.

The rice bran is extracted (as in Preparation Example 4), and after obtaining the rice bran essential oil, the extracted residue is used for secondary use to prepare a post-extracted rice bran adsorbent, the purpose of which is to achieve real waste utilization. As a result, as shown in Fig. 5, the adsorbent prepared by the extracted rice bran has higher adsorption effect than the adsorbent prepared by unextracted rice bran, which means that if the rice bran is extracted, not only rice bran oil but also rice bran oil can be obtained. It can improve the adsorption effect of the adsorbent and is more efficient for rice bran.

Example 2 - Effect of pH on rice bran adsorbent

A dye solution with a pH of 2 to 7 and a dye concentration of 500 ppm was placed and placed in a constant temperature shaking water tank at a temperature of 30 ° C, a rotation speed of 100 rpm, an adsorption time of 36 hours, and an ultraviolet/visible spectrometer ( UV-VIS) measured the absorbance after adsorption. The results are shown in Fig. 6. It can be found that the adsorption effect is optimal at a pH of 2, because in a low pH environment, the adsorbent can protonate the amino group with a high concentration of protons, so that the amino group - NH _{2 is} converted to -NH ₃ ⁺ to increase the positive charge on the surface of the adsorbent, while RB-4 dye contains an anionic SO ₃ ^- (sulfo group), which has a negative charge, and its adsorption mechanism is shown in Figure 7, so the adsorption effect Preferably. In addition, the alkali-treated rice bran has better adsorption effect than other treatment-modified adsorbents.

Example 3 - Effect of adsorbent on different adsorption temperatures

In a beaker, prepare a dye solution with a dye concentration of 500 ppm and adjust the pH to 2. 800 mL of the dye was evenly distributed in 4 flasks, and 1 g of rice bran adsorbent was added to each beaker. The flasks were placed in different constant temperature shaking tanks and the temperature was adjusted to 30 ° C, 40 ° C, 50 ° C and 60 ° C, respectively, at a speed of 100 rpm and an adsorption time of 36 hours. Finally, the individual absorbance was measured by UV-Vis spectrometer (Uv-Vis), and the dye adsorption amount was calculated by using the calibration curve. The results are shown in Fig. 8 and Fig. 9. The alkali-treated rice bran adsorbent has the best effect of adsorbing RB-4 dye at 50 °C, the adsorbent adsorption capacity is 75.76 mg/g, and the dye removal rate is 74.47%. The post-alkali treated rice bran adsorbent has the best adsorption effect at 60 °C, the adsorption capacity of the adsorbent reaches 94.58 mg/g, and the dye removal rate is as high as 96.24%. Both rice bran adsorbents have good adsorption effect in high temperature environment.

Example 4 - Comparison of adsorption effects of adsorbents

Comparing the adsorption capacity of the alkali-treated rice bran adsorbent of the present invention with the alkali-treated rice bran adsorbent, the maximum adsorption capacity of the alkali-treated rice bran adsorbent is 75.56 mg/g, and the highest removal rate is 74.77%, and the alkali-treated rice bran adsorption after extraction The maximum adsorption capacity was 94.58 mg/g, and the highest removal rate was 96.24%. The adsorption effect of the alkali-treated rice bran adsorbent on the RB-4 dye is better than that of the alkali-treated rice bran adsorbent. The operating conditions for dye adsorption are as follows:

Alkali-treated rice bran adsorbent: adsorption dose 5 g / L, dye concentration 500 ppm, pH 2, temperature 50 ° C, adsorption time 36 hours.

After the extraction, the alkali-treated rice bran adsorbent: adsorption dose 5 g / L, dye concentration 500 ppm, pH 2, temperature 60 ° C, adsorption time 36 hours.

Example 5 - Adsorbent regeneration

Soak the post-extracted magnetic alkali-treated rice bran adsorbent adsorbed with RB-4 dye in ammonia waste liquid, shake it for about 15 seconds to desorb it, rinse it with deionized water several times, and then bake it in an oven to absorb it. After the agent is dried, the adsorbent can be reused after completion, and the adsorbent regeneration process is as shown in FIG. As shown in Fig. 11, after the simple desorption of the adsorbent, the adsorption performance of the RB-4 dye is not significant, so the adsorption effect of the regenerated rice bran adsorbent is different from that of the adsorbent before regeneration. Big. In addition, the post-extracted magnetic alkali-treated rice bran adsorbent is adsorbed by a magnet after one, three and five desorptions, respectively, and the result is shown in Fig. 12, whether it is after one, three or five desorptions. , still possessing magnetic force is conducive to subsequent processing.

Figure 1 shows the adsorption capacity (mg/g) of the alkali treated rice bran adsorbent on dye RB-4 at different dye concentrations.

Figure 2 is a SEM image of the change of the rice bran modified adsorbent before and after adsorption: (a) raw rice bran (250X); (b) raw rice bran (after adsorption) (250X); (c) acid treated rice bran (250X); (d) acid treated rice bran (after adsorption) (250X); (e) alkali treated rice bran (250X); (f) alkali treated rice bran (after adsorption) (250X).

Figure 3 is a SEM image of the change before and after adsorption of the extracted rice bran modified adsorbent: (a) extraction of rice bran (250X); (b) extraction of rice bran (after adsorption) (250X); (c) extraction of alkali treated rice bran (250X) (d) extraction of alkali treated rice bran (after adsorption) (250X); (e) extraction of magnetic alkali treated rice bran (250X); (f) extraction of magnetic alkali treated rice bran (after adsorption) (250X).

Figure 4 is a FTIR image of rice bran changes: (a) raw rice bran, (b) after adsorption of raw rice bran, (c) rice bran after extraction, and (d) adsorption of rice bran after extraction.

Figure 5 is a comparison of the adsorption effects of the original rice bran and the extracted rice bran: (a) the amount of dye adsorbed by the adsorbent, and (b) C/C0.

Figure 6 is the effect of pH on the adsorption of (a) rice bran and (b) post-extracted rice bran adsorbent.

Figure 7 is a diagram showing the adsorption mechanism of the rice bran adsorbent on the RB-4 dye.

Figure 8 shows the effect of adsorption of alkali-treated rice bran adsorbent at different temperatures: (a) C/C0, (b) the amount of dye adsorbed by the adsorbent.

Figure 9 shows the effect of adsorption of alkali-treated rice bran adsorbent at different temperatures: (a) C/C0, (b) the amount of dye adsorbed by the adsorbent.

Figure 10 is a flow chart of the regeneration of the adsorbent.

Figure 11 is a regenerated magnetic adsorbent (a) dye adsorption capacity (b) dye removal rate (%).

Fig. 12 is a magnet adsorbing and regenerating a magnetic adsorbent.

Claims (14)

A method for removing dyes in dye wastewater, comprising: treating a modified rice bran with a magnetic modified or magnetic alkali; and placing the rice bran into the dye wastewater to adsorb the dye in the dye wastewater. The method of claim 1, wherein the rice bran is further treated prior to the modification by magnetic modification or magnetic alkali treatment. The method of claim 1, wherein after the modification by the magnetic modification or the magnetic alkali treatment, the rice bran is further modified by an acid treatment modification or an alkali treatment. The method of claim 1, wherein the dye is a reactive dye. The method of claim 4, wherein the reactive dye is an anthraquinone dye, an indigo dye, a phthalocyanine dye, a carbon ion dye or a p-quinone imine dye. The method of any one of claims 1 to 5, wherein the dye adsorbed in the dye wastewater is adsorbed at 40 ° C to 70 ° C. The method of claim 6, further comprising immersing the rice bran after the dye is adsorbed in ammonia water to desorb the dye, and then regenerating the rice bran. A dye adsorbent comprising rice bran modified with at least a magnetically modified or magnetically treated alkali. The dye adsorbent of claim 8, wherein the rice bran is subjected to an extraction treatment before being modified by a magnetic modification or a magnetic alkali treatment. The dye adsorbent of claim 8, wherein the rice bran is modified with a magnetic modification or a magnetic alkali treatment, and is modified with an acid treatment or an alkali treatment. The dye adsorbent of claim 10, wherein the alkali treated modified rice bran is obtained by immersing rice bran in an aqueous ammonia solution and then drying it. The dye adsorbent according to claim 10, wherein the acid-treated modified rice bran is obtained by immersing rice bran in an aqueous solution of hydrochloric acid and drying. The dye adsorbent according to claim 9, wherein after the extraction, the magnetically modified rice bran extracts the rice bran in a methanol solution, and the extracted rice bran is further added to an aqueous solution containing ferric chloride and ferrous chloride to form a base. Reacted in a sexual environment. The dye adsorbent according to claim 9, wherein the extracted rice magnetically treated alkali-modified rice bran is obtained by magnetically modifying the extracted rice after the extraction, and further drying with an aqueous ammonia solution and drying.