Activated carbon deep filter paperboard, preparation method and decolorization process using the same

Abstract

The application relates to the field of deep filtration, in particular to an activated carbon deep filtration paperboard, a preparation method and a decoloring process using the same. The activated carbon deep filtration paperboard comprises a paperboard main body, one side of the paperboard main body is a liquid inlet surface, the other side of the paperboard main body is a liquid outlet surface, the paperboard main body comprises fibers, activated carbon particles and a binder; the activated carbon content of the paperboard main body is increased along the thickness direction of the paperboard main body from the liquid inlet surface to the liquid outlet surface; the total activated carbon content X of the paperboard main body is 45-80%; the paperboard main body is equally divided into a first region, a second region and a third region along the thickness direction from the liquid inlet surface to the liquid outlet surface; the difference between the wet weight of the paperboard main body after being completely wetted by pure water and the dry weight of the paperboard main body is M 差 ; the ratio Y of the M 差 to the wet weight M 湿 of the paperboard after being completely wetted by pure water is 30-80%; and the X / Y is 0.6-2. The activated carbon deep filtration paperboard has the advantages of improving the utilization rate of activated carbon particles and improving the adsorption effect and adsorption efficiency of the activated carbon deep filtration paperboard on impurities such as pigments in raw medicinal materials and synthetic drugs.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of deep filtration medium, more particularly, it relates to an activated carbon deep filtration paperboard, a preparation method and a decolorization process using the same. BACKGROUND

[0002] In the production process of drugs, especially in the production process of raw materials of cephalosporins, the decolorization step is an essential and key step. The reasons for decolorization are as follows: first, the appearance of the drug will directly affect the trust of the patient, and the colored impurities will make the drug appear impure appearance, which may cause the user to feel unacceptable. Second, some colored impurities are usually formed due to non-desired reactions such as oxidation, and these impurities may affect the stability of the drug, especially the light stability. Third, colored impurities will affect the accuracy of drug analysis, such as various spectroscopy, chromatography and other analysis methods. Therefore, in the production process of drugs, especially in the production process of some organic synthetic drugs such as cephalosporins, decolorization is helpful to improve the appearance quality, stability and purity of the drug, so as to better meet the treatment needs.

[0003] The decolorizing agent can be divided into three categories according to the principle of decolorization: flocculation decolorizing agent, oxidation decolorizing agent and adsorption decolorizing agent. The flocculation decolorizing agent is mostly a quaternary amine type cationic polymer compound; the oxidation decolorizing agent is a compound with oxidation property such as potassium permanganate, ozone, etc. to oxidize and destroy the colored groups to remove color; the adsorption decolorizing agent is generally activated carbon, white clay, silica gel or adsorption resin, etc. which can directly remove impurities by filtration. In the preparation process of synthetic drugs, the decolorizing agent commonly used for decolorization is the powder of porous substances such as activated carbon, activated clay, silica gel or adsorption resin.

[0004] A dobutamine hydrochloride decolorization process disclosed in Chinese patent CN105906515B, dobutamine hydrochloride, chemical name: 4-[2-[[1-methyl-3-(4-hydroxyphenyl) propyl] amino] ethyl]-1, 2-benzene diol hydrochloride, English name Dobutamine Hydrochloride, molecular formula is C 18 H 23NO3·HCl, a dopamine homolog, is a selective cardiac beta1-receptor stimulant, clinically used for the treatment of heart failure caused by the decrease of myocardial contractility of organic heart disease, cardiogenic shock caused by myocardial infarction and postoperative hypotension. The decolorization process is: (1) first add a certain amount of water-soluble antioxidant in purified water, then add the dopamine hydrochloride to be decolorized, replace the system with protective gas, heat to the material solution, add medicinal activated carbon, heat to the decolorization temperature, and decolorize for several minutes; (2) filter out the activated carbon while hot, and the filtrate is put into a crystallization kettle, a certain amount of concentrated hydrochloric acid is added, and then slowly cooled to room temperature, and the solid is gradually precipitated, and after filtration and drying, dopamine hydrochloride is obtained.

[0005] A kind of decolorization device and method of vitamin B6 is disclosed in Chinese invention patent with publication number CN117323695A, its decolorization device is mainly decolorization tank, its decolorization step is "1) solution preparation: vitamin B6 crude product is dissolved in distilled water according to the proportion of 18.5g:100ml, to prepare vitamin B6 crude product aqueous solution;2) material mixing: vitamin B6 crude product aqueous solution is placed in decolorization tank, and a proper amount of activated carbon is added, the input ratio of activated carbon and vitamin B6 crude product aqueous solution is 4.5g:100ml;3) primary decolorization: decolorization tank is equipped with interlayer, can be heated by circulating steam (or hot water), heating temperature is 80-85℃, time is 30min, and powder activated carbon is mixed with material in tank by the operation of stirrer, and after stirring, adsorption decolorization is carried out;4) secondary decolorization: vitamin B6 semi-finished product obtained by decolorization in 3) is taken out again by filtration, and the obtained solution is filled into decolorization tank again, activated carbon is added, the input ratio of activated carbon and vitamin B6 crude product aqueous solution is 2.3g:100ml, and random stirring and heating, heating temperature is 80-85℃, time is 30min;5) crystalline product: the mixed solution obtained after secondary decolorization is filtered, the filtrate is concentrated to dryness, and a proper amount of ethanol is added to crystallize to obtain the decolorized product vitamin B6."

[0006] From the above decolorization device and method of dopamine hydrochloride and vitamin B6 drugs, for the activated carbon decoloring agent currently used for drug or intermediate decolorization, the traditional utilization form is to mix activated carbon powder with liquid, so that the liquid is in full contact with the activated carbon powder, thereby removing the impurities such as pigment in the liquid by the adsorption of the activated carbon powder. Generally, after decolorization is completed, the activated carbon needs to be filtered out, and then the liquid with impurities removed is obtained. The overall process is relatively complicated, and the utilization rate and utilization efficiency of activated carbon powder are difficult to grasp, and efficient utilization of activated carbon is difficult to achieve. SUMMARY

[0007] In view of the problems existing in the prior art, the purpose of the present application is to provide an activated carbon deep filter paper board and a preparation method and a decolorization process using the same.

[0008] To achieve the above object, the present application provides the following technical solutions.

[0009] An active carbon deep filter paperboard, comprising a paperboard body, one side of the paperboard body being a liquid inlet surface, the other side of the paperboard body being a liquid outlet surface,

[0010] The paperboard body comprises fibers, active carbon particles and a binder;

[0011] The active carbon content of the paperboard body increases gradually along the thickness direction of the paperboard body from the liquid inlet surface to the liquid outlet surface;

[0012] The total active carbon content X of the paperboard body is 45-80%;

[0013] The paperboard body is equally divided into a first region, a second region and a third region along the thickness direction of the paperboard body from the liquid inlet surface to the liquid outlet surface; the active carbon contents of the first region, the second region and the third region are X1, X2 and X3 respectively; X1 is 40-65%, X2 is 45-70% and X3 is 50-80%;

[0014] The difference between the wet weight of the paperboard body after being completely wetted with pure water and the dry weight of the paperboard body is M 差 ; the ratio Y of M 差 to the wet weight M 湿 of the paperboard after being completely wetted with pure water is 30-80%;

[0015] X / Y is 0.6-2.

[0016] The active carbon particles in the active carbon paperboard have a certain binding effect with the fibers, so that the position of the active carbon particles is basically fixed, and when filtering raw medicinal materials or other feed liquid, the active carbon will not flow with the feed liquid, thereby solving the influence of active carbon particle dust on equipment and process environment and improving the working safety of workers.

[0017] The utilization rate of the activated carbon particles for adsorbing pigment impurities in the raw drug is also improved after the activated carbon particles are combined with the fibers to form the activated carbon paperboard. Overall, the distribution of the activated carbon particles in the paperboard is more orderly than the direct use of activated carbon particles, and the more orderly distribution of the activated carbon particles makes the activated carbon particles not lose part of the filtration area due to mutual collision and other factors during the filtration of the material. Secondly, the distribution of the fibers also makes the material flow quickly contact the activated carbon surface at the position where the material flows through the paperboard, and the material flow is in adsorption with different activated carbon particles during the whole process of flowing through the paperboard, so that the utilization rate and adsorption efficiency of the activated carbon particles are greatly improved. It should be noted that the fibers and activated carbon particles in the paperboard synergistically form a more complex and more beneficial flow channel for the material flow to fully and quickly contact the activated carbon particles, which is mainly determined by more specific paperboard detail parameter control.

[0018] Firstly, the content of activated carbon in the paperboard as a whole in the present application is controlled within the range, on the one hand, in order to avoid the adsorption effect of the activated carbon on the pigment impurities from being not ideal due to the low content of activated carbon, and to need multiple filtration to reach the standard of impurity removal. On the other hand, it is also to avoid the content of activated carbon being too high, which causes the activated carbon particles in the activated carbon paperboard to aggregate more and reduce the utilization rate of the activated carbon particles. Too much activated carbon particles may also cause some fine activated carbon particles near the downstream to fall off into the filtrate.

[0019] Secondly, the paperboard body is divided into a first region, a second region and a third region from the liquid inlet surface to the liquid outlet surface along the thickness direction of the paperboard, and then the specific content of activated carbon in each region is controlled and the content of activated carbon in the thickness direction of the paperboard is made to show an increasing trend, so that the degree or ability of the pigment being adsorbed in the filtration of the material liquid shows a gradually increasing trend in the thickness direction of the paperboard, so that the pigment and other impurities in the material liquid can be adsorbed more completely.

[0020] In the present application, the improvement of the removal effect of the activated carbon deep filter paperboard on the pigment in the feed liquid mainly lies in two aspects: one aspect is that the distribution of the activated carbon particles in the paperboard is more uniform in the vertical liquid flow direction, and the other aspect is that the flow channel distribution of the liquid flow in the paperboard is optimized, so that the flow channel distribution can help to increase the contact area of the feed liquid with the surface of the activated carbon particles and improve the contact efficiency. Specifically, the present application mainly controls the value of X / Y within the range, wherein X represents the content of the activated carbon particles contained in the activated carbon paperboard, which can be obtained by burning the activated carbon deep filter paperboard at a certain temperature to remove other substances outside the activated carbon, then testing the weight of the ash to obtain the content of the activated carbon particles, and then obtaining the content ratio X of the activated carbon in the activated carbon deep filter paperboard by dividing the total mass of the paperboard. Y represents the proportion of the increased weight of the paperboard after being completely wetted with pure water to the wet weight after being completely wetted. The specific test can be carried out by soaking the activated carbon deep filter paperboard in pure water for a suitable time, removing the paperboard and weighing to obtain the wet weight of the paperboard after being completely wetted, and then testing the dry weight to obtain the difference between the two. In the present application, the value of X / Y is limited to control the relationship between the content of the activated carbon particles in the activated carbon deep filter paperboard and the parameters such as the fiber gap and the fineness of the fiber in the deep filter paperboard, so that the distribution structure between the activated carbon particles and the fiber can meet the reasonable distribution structure, so as to increase the effective filter area of the activated carbon on the one hand, and improve the contact efficiency of the feed liquid with the activated carbon in the filter flow channel of the deep filter paperboard on the other hand, thereby improving the adsorption effect and adsorption efficiency.

[0021] Further, the SEM average particle size D in of the activated carbon particles on the liquid inlet surface of the paperboard body is 5-20 μm, and the SEM average particle size D out of the activated carbon particles on the liquid outlet surface is 3-15 μm; D in :D out is 1.05-1.5.

[0022] The measurement method of the SEM average particle size of the activated carbon particles on the liquid inlet surface and the SEM average particle size on the liquid outlet surface can be carried out by using a scanning electron microscope to characterize the morphology of the deep filter medium, and then using computer software (such as Matlab, NIS-Elements, etc.) or manual measurement and corresponding calculation. In actual measurement, the surface (or cross section) of the deep filter medium can be characterized by an electron microscope first, the corresponding SEM image is obtained, and a certain area is selected, for example, 100 μm 2 (10 μm x 10 μm) or 625 μm 2(25 μm by 25 μm), and the specific area size is determined according to the actual situation, and then the particle size of all activated carbon particles in the area is measured by using corresponding computer software or manually, and then calculation is performed to obtain the average particle size of the area; the SEM average particle size of the granular cellulose is preferably measured in the present application by measuring the length and width of the granular cellulose and taking the average value as the particle size of the granular cellulose. Of course, the above-mentioned parameters can also be obtained by other measuring means by those skilled in the art, and the above-mentioned measuring means are only for reference.

[0023] By controlling the SEM average particle size of the activated carbon particles on the liquid inlet surface of the depth filter paper board to be greater than the SEM average particle size of the activated carbon particles on the liquid outlet surface, the depth filter paper board can have more distinct levels in the thickness direction. First, the activated carbon particles have a good adsorption effect on impurities such as pigments in addition to the porous structure on the surface of the activated carbon particles. Therefore, optimizing the particle size of the activated carbon particles on the side of the depth filter paper board close to the liquid inlet surface can make the bulkiness of the side of the depth filter paper board close to the liquid inlet surface higher, that is, the porosity in the area is higher. In other words, the area of the activated carbon particles exposed to the flow channel is larger, and the physical interception scale of the side of the depth filter paper board close to the liquid inlet surface is larger, so that the pre-filtering effect in the area of the side of the depth filter paper board close to the liquid inlet surface is optimized. The pre-filtering effect not only refers to the filtration of large-particle impurities in the filter feed liquid, but also includes the preliminary adsorption of impurities such as pigment molecules with high initial content, which greatly reduces the concentration of pigments in the feed liquid.

[0024] On the contrary, the particle size of the activated carbon particles in the area on the side of the depth filter paper board close to the liquid outlet surface is smaller, which on the one hand improves the adsorption capacity of the activated carbon particles, and on the other hand, the smaller particle size of the activated carbon particles makes the physical interception scale in the area on the side of the depth filter paper board close to the liquid outlet surface smaller, so that the small-particle impurities and pigment molecules with low concentration in the feed liquid after pre-filtering can be more thoroughly adsorbed after passing through the area on the side of the depth filter paper board close to the liquid outlet surface, thereby ensuring the filtering performance of the depth filter paper board, optimizing the filtering capacity of the depth filter paper board, and improving the filtering precision and stability.

[0025] Further, the SEM average fiber diameter d of the cellulose fibers is 1-20 μm, and the D in ∶d is 0.3-18.

[0026] Through the technical scheme, the SEM average fiber diameter of the cellulose fiber and the particle diameter of the activated carbon particles need to have a certain correlation. If the two are too different, that is, the gap between the cellulose fibers is too large, the activated carbon particles with smaller particle diameter are easy to be aggregated and accumulated, causing the loss of the adsorption area of the surface of the activated carbon particles. If the SEM average diameter of the cellulose fiber and the particle diameter of the activated carbon particles are too small, the gap between the fibers for accommodating the activated carbon particles is too small, and the activated carbon particles are easy to be covered by the fibers in the paperboard, which also causes the loss of the adsorption area of the surface of the activated carbon particles. Therefore, the present application can control the SEM average diameter of the cellulose fiber and the SEM average particle diameter of the activated carbon particles on the liquid inlet surface and the liquid outlet surface, so that the cellulose fiber can effectively disperse the activated carbon particles in the paperboard, and the cellulose fiber does not cause the surface of the activated carbon particles to be covered by too much adsorption area which does not form an anchor point for the activated carbon particles, thereby effectively maintaining the adsorption effect and adsorption utilization rate of the activated carbon particles.

[0027] Further, the activated carbon particles include SEM average particle diameter D max The coarse activated carbon particles with a particle diameter of 20-60 μm and the SEM average particle diameter D min The fine activated carbon particles with a particle diameter of 0.1-5 μm, D max ∶D min is 2-40.

[0028] The coarse particles and the fine particles of the activated carbon particles need to have a gap in the particle diameter. The coarse particles mainly have the effect of fluffing the paperboard, improving the contact area between the activated carbon in the paperboard and the filter material liquid, and improving the adsorption capacity. The fine activated carbon particles have a high specific surface area, and can have a stronger adsorption effect on impurities, thereby improving the filtration effect and filtration precision of the paperboard.

[0029] Secondly, the gap between the coarse particles and the fine particles of the activated carbon particles cannot be too large, because the too large activated carbon particles can cause the fine particles to be more easily detached to the rear-end material liquid in the filtration process due to the too fluffy paperboard structure, causing unnecessary pollution.

[0030] The activated carbon particles preferably include coarse activated carbon particles having a relatively large particle size and fine activated carbon particles having a relatively small particle size, and the SEM average particle size range and the SEM average particle size ratio of the two are controlled so that the activated carbon particles of different particle sizes have a more favorable directional distribution in the thickness direction of the depth filter paper sheet that is more conducive to improving the adsorption effect and adsorption efficiency. Specifically, it is desirable that the coarse activated carbon particles having a relatively large particle size be more distributed in the region near the liquid inlet side of the depth filter paper sheet, and the fine activated carbon particles having a relatively small particle size be more distributed in the region near the liquid outlet side of the depth filter paper sheet. Because the coarse activated carbon particles have a larger particle size, and the region near the liquid inlet side of the depth filter paper sheet has a more loose fiber structure, this makes the activated carbon particles in this region more exposed to the flow channel of the depth filter paper sheet as a whole and have a larger contact area with the feed liquid, thereby improving the pre-filtering effect of the region near the liquid inlet side of the depth filter paper sheet, and improving the impurity adsorption capacity of the region near the liquid inlet side of the depth filter paper sheet, thereby improving the adsorption effect, adsorption capacity and adsorption life of the depth filter paper sheet. On the other hand, the fine activated carbon particles have a larger specific surface area and a stronger adsorption capacity per unit particle, so that the fine activated carbon particles are more concentrated in the region near the liquid outlet side of the depth filter paper sheet, which can effectively improve the filtering capacity and filtering precision of the region near the liquid outlet side of the depth filter paper sheet, and can effectively adsorb the impurities such as pigments in the feed liquid that have been reduced in concentration more thoroughly.

[0031] Further, the fiber is a cellulose fiber, and the SEM fiber diameter of the cellulose fiber is d min ~ d max , and d min satisfies 0.5D min ≤ d min ≤ D min , and d max satisfies D max ≤ d max ≤ 1.5D max .

[0032] The diameter range of the cellulose fiber should be associated with the maximum particle size and the minimum particle size of the activated carbon particles. In the depth filter paper sheet of the present application, the minimum value of the SEM diameter of the cellulose fiber is smaller than the minimum value of the particle size of the activated carbon particles, because the activated carbon particles with a small particle size in the paper sheet need to be anchored by the cellulose fibers with a finer diameter after being interwoven and entangled, in order to achieve a more stable and firm fixing effect. However, the fiber diameter of the cellulose fiber cannot be too small, and the fine fibers and the small activated carbon particles are easy to form a relatively tight region, which reduces the flowability of the flow channel in the paper sheet and reduces the filtering efficiency.

[0033] The maximum value of the SEM diameter of the cellulose fiber is larger than that of the activated carbon particle, because the gap between the cellulose fibers with large SEM diameter is large, and the strength is high, so that the paperboard skeleton structure formed by the fibers is more stable, and the overall flowability of the paperboard is better.

[0034] Further, the bulk density p of the activated carbon is 0.3-0.5 g / cm 3 , and the tightness T of the paperboard body is 0.15-0.5 g / cm 3 .

[0035] The bulk density of the ash is the mass per unit volume of the ash particles when the particles are freely filled in a container and measured immediately after the filling is completed. The tightness of the paperboard body can be obtained by measuring the volume and mass of the paperboard body.

[0036] In the present application, the temperature of the paperboard burning is controlled to burn the cellulose fibers other than the activated carbon, so that the ash mainly contains the activated carbon particles. The ash after the paperboard body is completely burned at 600-800℃ mainly contains the activated carbon particles, so that the bulk density of the ash can reflect the properties of the activated carbon particles in the original paperboard body to some extent. The bulk density of the ash is mainly affected by the size and shape of the activated carbon particles in the ash, and the porosity of the activated carbon also has some effect on the bulk density of the ash. Therefore, the bulk density of the ash needs to be controlled within a suitable range to ensure that the effective area of the activated carbon particles exposed in the paperboard body and the adsorption capacity of the activated carbon particles themselves are within a relatively optimal range.

[0037] The effective area of the activated carbon particles exposed in the paperboard refers to the area of the activated carbon particles exposed in the flow channel of the filter liquid in the paperboard body. In theory, the larger the particle size of the activated carbon particles, the more effective area of the activated carbon particles exposed in the paperboard body. However, the larger the particle size of the activated carbon particles, the lower the specific surface area of the activated carbon particles, which easily causes the adsorption capacity of the deep layer filter paperboard to be poor. Therefore, the present application needs to balance the contact efficiency of the activated carbon particles in the paperboard body with the filter liquid and the adsorption capacity of the activated carbon particles. The bulk density of the ash can reflect the distribution of the activated carbon particles in the original paperboard body and the adsorption capacity of the activated carbon particles to some extent. In order to more accurately control the utilization rate and the adsorption capacity of the activated carbon particles in the paperboard body by controlling the bulk density of the ash after the paperboard is burned, the tightness range that the paperboard body should meet is also limited. The main factor affecting the tightness of the paperboard body is the arrangement relationship between the fibers in the paperboard body. Too large tightness indicates that the arrangement between the fibers is too close, which on the one hand will lead to the reduction of the porosity of the paperboard body, the reduction of the flow channel, and the reduction of the filtration flow rate; on the other hand, it will also lead to the coverage of the effective filtration area of the activated carbon particles by the fibers arranged too closely, which will greatly reduce the adsorption utilization rate of the activated carbon particles. Too small tightness indicates that the arrangement between the fibers is loose, which is beneficial to improving the utilization rate of the activated carbon particles, but the too loose fibers will make the gap between the fibers too large, which will lead to the impurities penetrating into the downstream through the paperboard body, and the flow channel being too smooth, which will make it difficult for the pigment impurities to be completely adsorbed by the activated carbon.

[0038] Further, the X1:X2 is 0.8-0.99, and the X1:X3 is 0.65-0.9.

[0039] The ratio between the content of activated carbon particles in the first region, the content of activated carbon particles in the second region and the content of activated carbon particles in the third region is defined in the present application in order to control the increasing range of the content of activated carbon particles in the thickness direction of the paperboard body. If the content of activated carbon particles increases too fast without changing the total content of activated carbon, it means that there is a high possibility that the content of activated carbon particles is too high in the region of the paperboard body close to the liquid outlet side, which leads to an adverse region that significantly affects the flow rate. Moreover, the content of activated carbon particles increases too fast, which means that the content of activated carbon is very high in the region of the paperboard body close to the liquid outlet side, and the activated carbon particles are mainly anchored by fibers in the paperboard body, and the high content of activated carbon leads to too few anchor points in this region, and part of the activated carbon particles is prone to fall off during filtration and enter the rear-end feed liquid. If the content of activated carbon particles increases too slowly without changing the total content of activated carbon, it is difficult to achieve the effect of the pre-filtration and fine-filtration partition caused by the difference between the region of the paperboard body close to the liquid inlet side and the region close to the liquid outlet side. Even it is possible to cause the service life of the paperboard body to decrease significantly, mainly because the region of the paperboard body close to the liquid inlet side is more likely to reach adsorption saturation.

[0040] Further, the tightness of the first region, the second region and the third region is T1, T2, T3 respectively; T1:T2 is 0.75-0.99, and T1:T3 is 0.6-0.95.

[0041] In the case of defining the ratio between the content of activated carbon particles in the first region, the content of activated carbon particles in the second region and the content of activated carbon particles in the third region, the tightness of the first region, the second region and the third region and the ratio between the tightness are further controlled in order to expect a correlation and synergistic effect between the tightness of the fiber arrangement in the thickness direction of the paperboard body and the content of activated carbon particles. The tightness mainly reflects the tightness of the fiber arrangement in the paperboard, and the content of activated carbon particles increases in a certain increasing range in the thickness direction of the paperboard body, so for each thickness region in the thickness direction, there is theoretically a tightness value that has the optimal activated carbon utilization rate for the region. However, the preparation of the paperboard body cannot precisely adjust each region in the thickness direction of the paperboard body, so under the limited conditions, the present application has found that controlling the tightness of the first region, the second region and the third region and the specific ratio between the tightness can further optimize the filtration effect and efficiency of the paperboard body.

[0042] Further, the fiber is selected from one or more of cellulose fiber, synthetic fiber or activated carbon fiber.

[0043] In the active carbon deep filter paperboard in the present application, the cellulose fiber has higher hydrophilicity, the synthetic fiber has a certain degree of hydrophobicity, and the two are used together to maintain the deep filter paperboard with better hydrophilicity and to improve the affinity of the deep filter paperboard to organic solvents, which can help the impurities dissolved in the organic solvents to be adsorbed by the paperboard to a certain extent. The surface of the active carbon fiber also has more pores, which can be used as the framework of the paperboard to improve the strength of the paperboard and improve the adsorption effect of the paperboard when added as fiber.

[0044] Further, the synthetic fiber is polyacrylonitrile fiber and / or polyacrylonitrile fibrillated fiber.

[0045] Further, the binder comprises a water-soluble synthetic polymer based on a urea or melamine-formaldehyde polymer, a polyamino polyamide-epichlorohydrin polymer, or an oxalated polyacrylamide resin.

[0046] Further, the D50 of the active carbon particles in the paperboard body is 5-100 μm. 50 The particle size is 5-100 μm.

[0047] A preparation method of an active carbon deep filter paperboard, comprising the following steps:

[0048] S1: beating, selecting fiber beating to obtain fiber slurry; wherein the fiber slurry comprises a beating degree of 10-90°SR;

[0049] S2: mixing, adding a binder and active carbon to the fiber slurry, stirring and mixing to obtain a mixed slurry; wherein the D50 of the active carbon particles is 5-100 μm; the mixed slurry comprises a first mixed slurry, a second mixed slurry, and a third mixed slurry, the first mixed slurry comprises active carbon particles and fiber with a mass ratio of 1:6-10, the second mixed slurry comprises active carbon particles and fiber with a mass ratio of 1:3-8, and the third mixed slurry comprises active carbon particles and fiber with a mass ratio of 1:1.5-5; 50

[0050] S3: forming, equally dividing the first mixed slurry, the second mixed slurry, and the third mixed slurry, then sequentially laying them on a screen in the order of the first mixed slurry, the second mixed slurry, the first mixed slurry, the third mixed slurry, the second mixed slurry, and the third mixed slurry, vacuum pre-suction is performed after each laying of the slurry, pre-pressing is performed after all the slurry is laid, and finally vacuum suction is performed on the side of the screen where no mixed slurry is laid, to obtain a preliminary product after pre-shaping;

[0051] S4: drying, performing shaping and drying of the preliminary product until the moisture content is not higher than 5%;

[0052] ​S5: punching, cutting the initial product to form a finished product.

[0053] The active carbon deep filter paperboard in the application is formed by sequentially laying the first mixed pulp, the second mixed pulp and the third mixed pulp on the screen in a certain order. The ratio of the active carbon particles to the fibers in the three mixed pulps and the beating degree of the fibers are different, so that the active carbon particles are distributed in a certain way in the thickness direction in the preformed deep filter paperboard structure, and after vacuum suction preforming, the active carbon particles and the fibers in the deep filter paperboard will partially migrate under the action of the vacuum suction force, so that the distribution of the active carbon particle content and other parameters in the deep filter paperboard meets the desired distribution to achieve better adsorption effect of the impurities such as pigments in the feed liquid.

[0054] Further, the D 50 of the active carbon particles in the first mixed pulp is 30-100 μm; the D 50 of the active carbon particles in the second mixed pulp is 20-50 μm; and the D 50 of the active carbon particles in the third mixed pulp is 5-30 μm.

[0055] Further, the beating degree of the fiber pulp in the first mixed pulp is 80-90 °SR; the beating degree of the fiber pulp in the second mixed pulp is 50-70 °SR; and the beating degree of the fiber pulp in the third mixed pulp is 10-20 °SR.

[0056] By controlling the D 50 particle size of the active carbon particles in the first mixed pulp, the second mixed pulp and the third mixed pulp and the beating degree of the three pulps, the distribution of the active carbon particles in the deep filter paperboard prepared by stacking the three mixed pulps in a certain order can better meet the improvement of the prefiltration and fine filtration effect of the pigments in the feed liquid by the deep filter paperboard.

[0057] Further, the vacuum suction includes weak suction and strong suction in sequence, the vacuum degree of the weak suction is-50 to-20 kpa, the vacuum degree of the strong suction is-120 to-70 kpa, and the time of the weak suction is between 1 / 5 and 1 / 2 of the time of the strong suction.

[0058] By controlling the vacuum suction as weak suction and strong suction, the tightness of the mixed connection between the different pulp layers of the deep filter paperboard is improved in the weak suction stage, and the whole deep filter paperboard is further preformed in the strong suction stage, so as to form the desired deep filter paperboard.

[0059] A synthetic drug decolorization process using the active carbon deep filtration paperboard, comprising the following steps: passing a raw drug solution containing color through the active carbon deep filtration paperboard at a filtration speed of 100-500 LMH.

[0060] In summary, the present application has the following advantages:

[0061] First, the deep filtration paperboard of the present application comprises fibers, active carbon particles and a binder, the content of active carbon is gradually increased along the thickness direction by controlling the content of active carbon, and is divided into first, second and third regions, the overall content of active carbon and the content of active carbon in each region are controlled, and the range of X / Y is further controlled, to obtain an active carbon deep filtration paperboard with ordered distribution of active carbon particles combined with fibers, thereby improving the utilization rate of active carbon, making the paperboard show obvious hierarchy, and optimizing the pre-filtration effect and filtration stability.

[0062] Second, the deep filtration paperboard of the present application adjusts the SEM average particle size of active carbon particles at the liquid inlet surface and the liquid outlet surface and the SEM average diameter of cellulose fibers, to ensure that they are uniformly dispersed in the paperboard, thereby maintaining the adsorption effect and utilization rate of active carbon particles. BRIEF DESCRIPTION OF DRAWINGS

[0063] Figure 1 is a 500-fold SEM electron microscope image of the liquid outlet surface of the active carbon deep filtration paperboard in Example 1 of the present application;

[0064] Figure 2 is a 500-fold SEM electron microscope image of the liquid inlet surface of the active carbon deep filtration paperboard in Example 1 of the present application. DETAILED DESCRIPTION

[0065] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application will be further described in detail below with reference to the drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0066] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other ways different from those described herein, therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0067] EMBODIMENT

[0068] EMBODIMENT 1

[0069] An active carbon deep filtration paperboard, comprising a paperboard main body, referring to Figure 1 and Figure 2The paperboard body has a liquid inlet surface on one side and a liquid outlet surface on the other side. The paperboard body comprises 39% fibers, 60% activated carbon particles and 1% binder. The fibers are cellulose fibers, and the binder is polyamino polyamide-epichlorohydrin polymer.

[0070] The preparation method of the activated carbon deep filtration paperboard comprises the following steps:

[0071] S1: beating, select cellulose fibers for beating to obtain three fiber slurries with different beating degrees; the beating degrees of the three fiber slurries are 82°SR, 51°SR and 12°SR, respectively;

[0072] S2: mixing, adding the binder, activated carbon particles and binder into the three fiber slurries, stirring and mixing to obtain three mixed slurries, namely a first mixed slurry, a second mixed slurry and a third mixed slurry;

[0073] The first mixed slurry comprises activated carbon particles with a mass ratio of 0.72, the second mixed slurry comprises activated carbon particles with a mass ratio of 0.57, and the third mixed slurry comprises activated carbon particles with a mass ratio of 0.48.

[0074] The D 50 of the activated carbon particles in the first mixed slurry is 13 μm; the D 50 of the activated carbon particles in the second mixed slurry is 30 μm; and the D 50 of the activated carbon particles in the third mixed slurry is 67 μm.

[0075] The beating degree of the fiber slurry in the first mixed slurry is 82°SR; the beating degree of the fiber slurry in the second mixed slurry is 51°SR; and the beating degree of the fiber slurry in the third mixed slurry is 12°SR.

[0076] S3: forming, equally dividing the first mixed slurry, the second mixed slurry and the third mixed slurry, then sequentially laying them on a screen in the order of the first mixed slurry, the second mixed slurry, the first mixed slurry, the third mixed slurry, the second mixed slurry and the third mixed slurry, and performing vacuum pre-suction after each laying of the slurry, with a vacuum degree of -80 kpa and a suction time of 1 min, then performing pre-pressing after all the slurry is laid, and finally performing vacuum suction on the side of the screen where no mixed slurry is laid, to obtain a preliminary product after pre-forming; the vacuum suction after pre-pressing comprises weak suction and strong suction in sequence, the vacuum degree of the weak suction is -27 kpa, the vacuum degree of the strong suction is -90 kpa, and the time of the weak suction is 0.4 times the time of the strong suction.

[0077] S4: drying, performing drying and setting of the preliminary product until the moisture content is not higher than 5%;

[0078] S5: cutting, cutting the initial product to form a finished product.

[0079] A synthetic drug decolorization process using the above-mentioned activated carbon deep filtration paperboard, comprising the following steps:

[0080] S1: the activated carbon deep filtration paperboard installed in the shell is washed with 100L / m 2 of pure water;

[0081] S2: the colored raw drug solution is passed through the activated carbon deep filtration paperboard at a filtration speed of 200LMH.

[0082] Examples 2-11 also prepared activated carbon deep filtration paperboard according to the above preparation steps, and the process parameters in the preparation process were adjusted.

[0083] Table 1 Parameters of the first mixed pulp of examples 2-11

[0084]

[0085] Table 2 Parameters of the second mixed pulp of examples 2-11

[0086]

[0087] Table 3 Parameters of the third mixed pulp of examples 2-11

[0088]

[0089]

[0090] Table 4 Vacuum suction parameters of the stacked mixed pulp of examples 2-11

[0091]

[0092] The activated carbon paperboard prepared above is tested for various parameters of the paperboard finished product.

[0093] 1. Test the total content of activated carbon in the paperboard body: put the paperboard into an oven for burning, control the temperature to be the temperature at which only the activated carbon particles are burned clean, the specific temperature can be determined according to the actual activated carbon type, the present application selects a burning temperature of 600℃ for burning to remove cellulose fibers. After the ash content is constant, the mass of the ash is m, and the self-weight of the paperboard itself is M, then the content X of activated carbon is

[0094] 2. Test of activated carbon content of paperboard layer: the tested paperboard body is divided into three parts along the thickness direction, sequentially from the liquid inlet surface to the liquid outlet surface as the first region, the second region and the third region. Then each layer of paperboard is sent into an oven at 800℃ for complete burning, and the mass of ash is weighed as m1, and the mass M1 corresponding to each layer of paperboard, and then the activated carbon content of each layer is wherein n is 1, 2, 3, representing the activated carbon content of different regions.

[0095] 3. Test of Y value of paperboard body: the paperboard body is immersed in pure water, and then after 24 hours of immersion, the paperboard body is taken out and weighed as M 湿 , and the self-weight of dry paperboard is M

[0096] 4. Bulk density of ash or activated carbon: activated carbon particles or ash particles are loaded in a 100ml measuring cylinder without applying pressure, and after being filled, the mass m 堆 (g) is taken out and weighed.

[0097] 5. Test of SEM average particle size of activated carbon particles on the liquid inlet surface and the liquid outlet surface of paperboard body, test of SEM diameter and average diameter of fibers, and test of SEM average particle size of coarse and fine activated carbon particles: after the liquid inlet surface and / or the liquid outlet surface of the paperboard body are characterized by using a scanning electron microscope, computer software (such as Matlab, NIS-Elements, etc.) or manual measurement is used for measurement, and corresponding calculation is performed; in actual measurement, the surface (or cross section) of the paperboard body can be characterized by using an electron microscope, and a SEM image with a suitable magnification is obtained, and a certain area is selected, for example, 10 4 μm 2 (100μm by 100μm) or 4×10 4 μm 2 (200μm by 200μm), and the specific area size is determined according to the actual situation, and then the particle size or fiber diameter of all activated carbon particles in the area is measured by using corresponding computer software or manually, and then calculation is performed to obtain the average particle size of activated carbon particles or the average diameter of fibers in the region; the particle size of activated carbon particles is preferably the length and width of the activated carbon particles, and the average value is taken as the particle size of the measured granular cellulose. Of course, the above-mentioned parameters can also be obtained by other measurement means, and the above-mentioned measurement means are only for reference.

[0098] Table 5 Test parameters of deep filtration paperboard in Example 1 to Example 11

[0099] Examples X(％) Y(％) X / Y X1(%) X2 (%) X3 (%) [X1:X2] [X1:X3] Example 1 60 50 1.2 53 56 65 0.95 0.82 Example 2 76 40 1.9 65 70 85 0.93 0.76 Example 3 67 42 1.6 50 61 68 0.82 0.74 Example 4 60 30 2.0 51 57 67 0.89 0.76 Example 5 46 76 0.6 40 45 50 0.89 0.80 Example 6 54 68 0.8 46 54 69 0.85 0.67 Example 7 58 46 1.8 54 57 64 0.95 0.84 Example 8 57 48 2.8 52 58 65 0.90 0.80 Example 9 62 49 3.8 53 58 61 0.91 0.87 Example 10 63 47 4.8 46 62 73 0.74 0.63 Example 11 61 52 5.8 51 56 63 0.91 0.81

[0100] Table 6 Test parameters for deep bed filter paperboard of Examples 1-11

[0101] Examples ρ (g / cm 3 )]]> [T(g / cm 3 )]]> [T1(g / cm 3 )]]> [T2(g / cm 3 )]]> [T3(g / cm 3 )]]> [T1:T2] [T1:T3] Example 1 0.38 0.30 0.27 0.28 0.32 0.96 0.84 Example 2 0.37 0.38 0.32 0.40 0.42 0.80 0.76 Example 3 0.42 0.42 0.34 0.44 0.48 0.77 0.71 Example 4 0.35 0.24 0.21 0.25 0.26 0.84 0.81 Example 5 0.36 0.15 0.12 0.15 0.18 0.80 0.67 Example 6 0.45 0.48 0.43 0.48 0.53 0.90 0.81 Example 7 0.55 0.52 0.41 0.62 0.53 0.66 0.77 Example 8 0.52 0.39 0.35 0.36 0.46 0.97 0.76 Example 9 0.38 0.51 0.49 0.51 0.53 0.96 0.92 Example 10 0.38 0.31 0.26 0.33 0.34 0.79 0.76 Example 11 0.37 0.26 0.18 0.29 0.32 0.62 0.56

[0102] Table 7 Characteristics of deep bed filter paperboard of Examples 1 and 12-18

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[0104]

[0105] Table 8 Characteristics of deep bed filter paperboard of Examples 1 and 19-24

[0106] Examples D max (μm) D min (μm) D max ∶D min ]]> d min (μm) d max (μm) Example 1 26 1 26 5 20 Example 19 37 5 7.4 6 35 Example 20 48 2 24 3 50 Example 21 60 4 15 10 60 Example 22 21 0.6 35 1 20 Example 23 19 3 6.3 3 21 Example 24 23 0.5 46 4 30

[0107] In the preparation of the deep bed filter paperboard of Examples 12-24, the D 50 particle size of the activated carbon particles and the diameter of the fibers added were controlled to obtain deep bed filter paperboard having the above parameters.

[0108] Example 25 differs from Example 1 in that the fibers comprise cellulose fibers and polyacrylonitrile fibers in a mass ratio of 3:1.

[0109] Example 26 differs from Example 1 in that the fibers comprise cellulose fibers, polyacrylonitrile fibers and activated carbon fibers in a mass ratio of 5:3:1.

[0110] Comparative Example

[0111] Comparative Example 1 differs from Example 1 in that the paperboard body comprises 60% fibers, 39% activated carbon particles and 1% binder.

[0112] Comparative Example 2 differs from Example 1 in that the activated carbon content of the activated carbon paperboard prepared is substantially uniformly dispersed in the activated carbon paperboard, and the activated carbon deep bed filter paperboard is preformed by means of pressure rather than vacuum.

[0113] Comparative Example 3 differs from Example 1 in that the value of X / Y of the activated carbon deep bed filter paperboard prepared is 2.3.

[0114] Comparative Example 4 differs from Example 1 in that the activated carbon deep bed filter paperboard prepared has X1 of 30%, X2 of 40% and X3 of 70%.

[0115] Performance Test:

[0116] (1) Flow rate test: The deep bed filter paperboard was assembled into a filter to obtain a flow rate of 4.5 x 10 -4 m 2Deep filter with effective filtration area; the filtration rate of each example and comparative example was measured at a constant pressure of 100 kPa and 20℃ using an ultra-pure water source to filter the double-layer filter.

[0117] (2) 400 ppm methylene blue adsorption amount test: the deep filter paper board was assembled into a filter housing to obtain a 1.3 x 10 -3 cm 2 Effective filtration area, deep filter with a thickness of 5 mm; using methylene blue dye as a standard reagent, water was added to prepare a solution with a concentration of 400 ppm. The 400 ppm safflower dye solution was constantly supplied at a speed of 5 ml / min, and when the transmittance of the permeate at 430 nm decreased to 95%, the total volume of the permeated methylene blue dye at this time was measured.

[0118] The test results are as follows:

[0119] Table 9 Test results related to Examples 1-11 and Comparative Examples 1-5

[0120] Examples Flow rate (L / min m 2 ) 1 bar 400 ppm methylene blue adsorption (L / m 2 )]]> Example 1 300 350 Example 2 294 375 Example 3 291 362 Example 4 286 356 Example 5 330 318 Example 6 310 326 Example 7 296 332 Example 8 278 311 Example 9 279 315 Example 10 276 305 Example 11 274 308 Comparative Example 1 312 264 Comparative Example 2 298 281 Comparative Example 3 306 268 Comparative Example 4 308 294

[0121] Conclusion: By comparing the test data between the examples and the comparative examples, it can be seen that by controlling the overall content of activated carbon, the content of activated carbon in each region, and the ratio of X / Y in the activated carbon deep filter paper board prepared in the present application, the filtration efficiency and adsorption capacity of the activated carbon deep filter paper board are significantly improved. Secondly, by comparing Examples 1-7 with Examples 7-9, it can be seen that controlling the tightness of the deep filter paper board and the bulk density of the activated carbon in the present application can effectively improve the filtration efficiency and filtration capacity of the activated carbon deep filter paper board. By comparing Examples 1-7 with Examples 10 and 11, it can be seen that controlling the content of activated carbon particles in different depth regions of the deep filter paper board and the tightness of different depth regions can significantly improve the filtration efficiency and filtration capacity of the deep filter paper board.

[0122] Table 10 Test results related to Examples 12-26

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[0124]

[0125] Conclusion: By comparing Examples 12-13 with Examples 14-18, it can be seen that by controlling the particle size of the activated carbon particles on the liquid inlet and outlet surface of the deep filter paper board and the fiber diameter in the deep filter paper board in the present application, an activated carbon deep filter paper board with good filtration effect and adsorption capacity can be effectively obtained. Secondly, by comparing Examples 19-20 with Examples 21-24, it can be seen that by controlling the D max and Dmin and their relationship with the fiber diameter d max and d min and their relationship with the fiber diameter d

[0126] The embodiment is only an explanation of the present application, and is not a limitation of the present application. Those skilled in the art can make modifications to the embodiment without creative contribution, as long as the modifications are within the scope of the present application.

Claims

1. An activated carbon depth filter paperboard, comprising a paperboard body, wherein one side of the paperboard body is a liquid inlet surface and the other side of the paperboard body is a liquid outlet surface, characterized in that: The paperboard body comprises fibers, activated carbon particles, and a binder; The activated carbon content of the paperboard body increases gradually from the liquid inlet surface to the liquid outlet surface along the thickness direction of the paperboard body. The total activated carbon content X in the cardboard body is 45-80%; The cardboard body is divided into a first region, a second region, and a third region along its thickness direction from the liquid inlet to the liquid outlet; the activated carbon contents of the first region, the second region, and the third region are X1, X2, and X3, respectively; X1 is 40-65%, X2 is 45-70%, and X3 is 50-80%; The difference between the wet weight of the cardboard body after it has been completely wetted with pure water and the weight of the dried cardboard body is M. 差 The M 差 The wet weight M of the cardboard after it has been fully wetted with pure water 湿 The proportion Y is 30-80%; The X / Y ratio is 0.6 to 2.

2. The activated carbon deep filter paperboard according to claim 1, characterized in that, The average particle size D of the activated carbon particles on the liquid inlet surface of the cardboard body is measured by SEM. in The average particle size D of SEM at the liquid outlet surface is 5–20 μm. out 3–15 μm; D in ∶D out It ranges from 1.05 to 1.

5.

3. The activated carbon deep filter paperboard according to claim 2, characterized in that, If the fiber is cellulose fiber, and the average SEM fiber diameter d of the cellulose fiber is 1–20 μm, then D in :d is 0.3 to 18.

4. The activated carbon deep filter paperboard according to claim 1, characterized in that, The activated carbon particles include an SEM average particle size D max The coarse activated carbon particles are 20–60 μm in size and have an average particle size D as measured by SEM. min It consists of fine activated carbon particles of 0.1–5 μm, D max ∶D min The range is 2 to 40.

5. The activated carbon deep filter paperboard according to claim 4, characterized in that, The fiber is a cellulose fiber, and the SEM fiber diameter of the cellulose fiber is d. min ~d max The d min Satisfying 0.5D min ≤d min ≤D min The d max Satisfy D max ≤d max ≤1.5D max .

6. The activated carbon deep filter paperboard according to claim 1, characterized in that, The bulk density ρ of the activated carbon is 0.3–0.5 g / cm³. 3 The density T of the cardboard body is 0.15–0.5 g / cm³. 3 .

7. The activated carbon deep filter paperboard according to claim 1, characterized in that, The ratio of X1:X2 is 0.8 to 0.99, and the ratio of X1:X3 is 0.65 to 0.

9.

8. The activated carbon deep filter paperboard according to claim 7, characterized in that, The tightness of the first region, the second region, and the third region are T1, T2, and T3, respectively; T1:T2 is 0.75 to 0.99, and T1:T3 is 0.6 to 0.

95.

9. The activated carbon deep filter paperboard according to claim 1, characterized in that, The fiber is selected from one or more of cellulose fiber, synthetic fiber or activated carbon fiber.

10. The activated carbon deep filter paperboard according to claim 9, characterized in that, The synthetic fiber is polyacrylonitrile fiber and / or polyacrylonitrile fibrillated fiber.

11. The activated carbon deep filter paperboard according to claim 1, characterized in that, The adhesive comprises a water-soluble synthetic polymer based on urea or melamine-formaldehyde polymers, a polyamino-polyamide-epioclosan polymer, or a acetaldehyde-oxidized polyacrylamide resin.

12. The activated carbon deep filter paperboard according to claim 1, characterized in that, The activated carbon particles in the cardboard body have D 50 The particle size is 5–100 μm.

13. A method for preparing activated carbon deep filter paperboard according to any one of claims 1 to 12, characterized in that, Includes the following steps: S1: Pulping, selecting fibers for pulping to obtain fiber pulp; The beating degree of the fiber pulp is 10–90°SR; S2: Mixing. The binder and activated carbon are added to the fiber slurry and stirred to obtain a mixed slurry; wherein, the activated carbon particles have a D... 50 The size is 5-100 μm; the mixed slurry includes a first mixed slurry, a second mixed slurry and a third mixed slurry, the first mixed slurry includes activated carbon particles and fibers in a mass ratio of 1:6-10, the second mixed slurry includes activated carbon particles and fibers in a mass ratio of 1:3-8, and the third mixed slurry includes activated carbon particles and fibers in a mass ratio of 1:1.5-5. S3: Shaping. The first mixed slurry, the second mixed slurry, and the third mixed slurry are divided into equal portions. Then, they are laid on the screen in the order of the first mixed slurry, the second mixed slurry, the first mixed slurry, the third mixed slurry, the second mixed slurry, and the third mixed slurry. After each slurry is laid, vacuum pre-extraction is performed. After all the slurry is laid, pre-pressurization is performed. Finally, vacuum suction is performed on the side of the screen where no mixed slurry is laid to obtain the pre-shaped initial product. S4: Drying, shaping and drying the initial finished product until the moisture content is no higher than 5%; S5: Punching, cutting the initial product into the finished product.

14. The preparation method according to claim 13, characterized in that, D of activated carbon particles in the first mixed slurry 50 The diameter of the activated carbon particles in the second mixed slurry is 5–30 μm. 50 The size is 20–50 μm; the D of the activated carbon particles in the third mixed slurry is... 50 The size ranges from 30 to 100 μm.

15. The preparation method according to claim 13, characterized in that, The freeness of the fiber pulp in the first mixed pulp is 10-20°SR; the freeness of the fiber pulp in the second mixed pulp is 50-70°SR; and the freeness of the fiber pulp in the third mixed pulp is 80-90°SR.

16. The preparation method according to claim 13, characterized in that, The vacuum suction includes weak suction and strong suction in sequence. The vacuum degree of the weak suction is -50 to -20 kPa, and the vacuum degree of the strong suction is -120 to -70 kPa. The time of the weak suction is between 1 / 5 and 1 / 2 of the time of the strong suction.

17. A decolorization process for synthetic drugs using an activated carbon deep filter paperboard according to any one of claims 1 to 12, characterized in that, Includes the following steps: The colored raw material solution is filtered through activated carbon deep filter paper at a filtration rate of 100-500 LMH.

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