CN108642965B - Method for deacidifying paper by adopting electro-adsorption method - Google Patents

Abstract

The present application provides a method for deacidification of paper by electro-absorption, comprising the following steps: S1, contacting the paper to be treated with a water-absorbing cushion layer, and the water-absorbing cushion layer contains water to wet the paper to be treated; S2 , place the wetted paper in S1 and the water-absorbing cushion it is in contact with between the inert anode plate and the inert cathode plate, the surface of the inert anode plate is covered with porous carbon material, and the direct current is used for electro-adsorption to obtain dehydration. Acid treated paper. The electro-adsorption deacidification speed of the invention is much faster than that of the traditional aqueous solution method, and only a few minutes is needed for one operation, which greatly reduces the negative impact of the traditional soaking deacidification technology on paper, and can be carried out on a single sheet, multiple sheets and the whole volume at the same time. Processing, can achieve more precise control of pH value. The method of the invention has the advantages of simplicity, reliability, green safety, and low cost, and can also avoid problems such as paper deformation, handwriting fading, ink penetration and the like that may be caused by prolonged wet state.

Description

A kind of method for deacidification of paper by electro-adsorption method

technical field

The invention relates to the technical field of deacidification protection of paper, in particular to the deacidification protection technology of paper cultural relics, archives and books, in particular to a method for deacidification of paper by an electro-adsorption method.

Background technique

The acidity of document paper is an important factor affecting the preservation life of documents; since the phenomenon of self-destruction of paper was discovered in the nineteenth century, scientists from all over the world have been studying methods and equipment for deacidification and protection of paper. At present, the commonly used paper deacidification methods in the world mainly include gas phase deacidification method, organic solvent deacidification method and aqueous solution deacidification method. Among them, because the aqueous solution deacidification method is simple, easy to implement, and relatively environmentally friendly, there are many researches in the industry.

The aqueous solution deacidification method, which is similar to the traditional Chinese alkaline washing calligraphy, is to soak the pages in the prepared alkaline solution, and the alkaline substances (such as calcium hydroxide, etc.) will neutralize the acid in the paper, so as to achieve deacidification. acid purpose. The aqueous solution deacidification method has the advantages of environmental safety, easy operation, economy and good deacidification effect.

But on the other hand, this method of treatment also has disadvantages that must be overcome. The deacidification treatment of the aqueous solution takes a long time. It takes a long time for the aqueous solution to penetrate the paper and produce a neutralization reaction and subsequent drying of the wet paper. In the wet state for a long time, the paper is easily damaged and swells during drying. , wrinkles, etc. If the soaking time is shortened, the alkaline deacidification agent can only be deposited on the surface of the paper and cannot penetrate into the inside of the paper. Moreover, this processing method can usually only be processed on a single sheet, and the processing volume is small and the efficiency is low.

SUMMARY OF THE INVENTION

In view of this, the present application provides a method for deacidification of paper by an electro-adsorption method. The deacidification method for paper provided by the present application has a short processing time, and can deacidify a single page, multiple pages and the entire book at the same time, with high efficiency, high efficiency and high efficiency. Low cost, environmental protection and safety.

The application provides a method for deacidification of paper by electrosorption, comprising the following steps:

S1, the paper to be treated is brought into contact with a water-absorbing cushion layer, and the water-absorbing cushion layer contains water, so that the paper to be treated is wetted;

S2, placing the wetted paper in S1 and the water-absorbing cushion layer in contact between the inert anode plate and the inert cathode plate, the surface of the inert anode plate is covered with porous carbon material, and electric adsorption is carried out by passing a direct current to obtain Deacidified paper.

Preferably, the pH value of the paper to be treated is 4.5-6.5.

Preferably, the water-absorbing cushion layer is a soft material that absorbs water and has a certain strength.

Preferably, the water-absorbing cushion layer is a water-containing woven cloth, a water-containing non-woven fabric or a water-containing moisture-absorbing paper.

Preferably, the porous carbon material is one or more of activated carbon fibers, carbon aerogels and carbon nanotubes.

Preferably, the BET of the porous carbon material is above 500 m ² /g.

Preferably, the surface of the inert anode plate is covered with activated carbon fiber cloth or activated carbon fiber felt; the thickness of the activated carbon fiber cloth or activated carbon fiber felt is 1-5 mm.

Preferably, the direct current voltage is 0.6-1.6V, more preferably the voltage is 0.8V-1.5V; the time of the electro-adsorption is not more than 15 minutes.

Preferably, the time of the electrosorption is 1 minute to 8 minutes.

Preferably, the water-absorbing cushion layer further contains a deacidification agent, and the deacidification agent is selected from one of calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, magnesium carbonate, magnesium bicarbonate and magnesium hydroxide or several.

The method for deacidification of paper by electrosorption method provided by the present invention uses an aqueous solution as a carrier, and wets the paper to be treated by contacting a water-absorbing cushion layer. Under the action of electrophoresis, F ^- , Cl ^- , SO ₄ ^2- , NO ₃ ^- and organic anions in the paper move to the anode under the action of electrophoresis, and are adsorbed by the porous carbon material electrode, and finally achieve the purpose of rapid deacidification and decontamination of the paper . The electro-adsorption deacidification speed of the invention is much faster than that of the traditional aqueous solution method, and only a few minutes is needed for one operation, which greatly reduces the negative impact of the traditional soaking deacidification technology on paper, and can be used for single sheets, multiple sheets and whole volumes at the same time. Treatment allows for more precise pH control than any other acid removal method. The method of the invention not only retains the advantages of simple, reliable, green, safe and low-cost deacidification of the traditional aqueous solution, but also avoids the problems of paper deformation, handwriting fading, ink penetration and the like that may be caused by a long wet state; The organic solvent liquid phase deacidification equipment has problems such as high requirements, high cost, high risk and environmental pollution, which can be widely used.

Description of drawings

Fig. 1 is the situation comparison diagram of the paper before and after the deacidification of embodiment 1;

Figure 2 is a comparison diagram of the paper before and after deacidification in Example 2.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The invention provides a method for deacidification of paper by electro-adsorption method, comprising the following steps:

S1, the paper to be treated is brought into contact with a water-absorbing cushion layer, and the water-absorbing cushion layer contains water, so that the paper to be treated is wetted;

S2, placing the wetted paper in S1 and the water-absorbing cushion layer in contact between the inert anode plate and the inert cathode plate, the surface of the inert anode plate is covered with porous carbon material, and electric adsorption is carried out by passing a direct current to obtain Deacidified paper.

The invention utilizes the electro-adsorption method of the porous carbon electrode, which can quickly and accurately realize the purpose of deacidification and decontamination of paper cultural relics, archives and books, and greatly reduces the negative impact of the traditional aqueous solution deacidification method on paper.

The present invention is mainly used for deacidification treatment of these document papers, such as paper cultural relics, archives and books, so that they can be well protected and are convenient for preservation and research. Wherein, the paper to be treated has a certain acidity, and the pH value is generally less than 7. In the embodiment of the present invention, the pH value of the paper to be treated is 4.5-6.5, preferably 5.0-6.5. In addition, the paper to be treated is generally light brown or light yellow brown, and is brittle.

The paper to be processed in the present invention can be a single page, multiple pages, or a whole book; the thickness, area and printing method of the paper are not particularly limited, and it can be a 16K, offset paper printed paper, or a copper plate paper for printing. Among them, if the book is thick, the binding position is not conducive to deacidification.

The present invention uses an aqueous solution as a carrier for deacidification technology, and the paper to be treated can be laid flat on a water-absorbing cushion layer, wherein the water-absorbing cushion layer contains water and can wet the paper to be treated. These inorganic acids in the paper are in the state of ions (such as SO ₄ ^2- , NO ₃ ^- , Cl ^- , CO ₃ ^2- , etc.) in the water-containing state, and are adsorbed by the paper fibers. Wherein, the matrix of the water-absorbing cushion layer is a layered material with water absorption, generally a soft material that can absorb water and has a certain strength, such as a transverse tensile strength of not less than 8.0 N/m; the cushion material can be conventional Textile cloth, non-woven fabric or absorbent paper, etc. The cushion can be used repeatedly, and the area of the cushion is usually larger than that of the paper; if the number of pages to be processed at one time is large, a thinner cushion should be selected.

In addition, the water-absorbing cushion preferably further contains a deacidification agent, which can accelerate the deacidification effect and make the treated paper have a certain alkali residue. In the embodiment of the present invention, the water-absorbing cushion layer can be soaked in an electrolyte solution containing a deacidifying agent, usually for several minutes, such as 3 to 5 minutes, to make it contain a certain amount of the deacidifying agent electrolyte solution. The deacidification agent can be selected from one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, magnesium carbonate, magnesium bicarbonate and magnesium hydroxide, preferably calcium hydroxide. In the embodiment of the present invention, the mass concentration of the deacidification agent in the solution is preferably 0.1% to 0.15%. Wherein, the deacidifying agent electrolyte solution is an aqueous solution containing these alkaline deacidifying agents.

After the paper to be treated is quickly wetted, in the embodiment of the present invention, it is sandwiched between two flat electrodes together with the cushion layer, and the DC power supply is turned on to form a closed loop. Among them, the anode plate is an inert electrode plate, and the surface is covered with a porous carbon material. Porous carbon materials not only have good electrical conductivity, but also have a large specific surface area (BET) and high chemical stability. 1nm ~ 10nm), can adsorb a large number of ions. Driven by an external DC electric field, the above-mentioned acidic ions of the present invention will be separated from the paper and move in the direction of the anode (electrophoresis), so as to be adsorbed and stored in the electric double layer on the surface of the porous carbon material electrode. With the gradual increase of the adsorbed ions of the electrode, the various acid ions in the paper gradually decrease, and the purpose of deacidification can be quickly achieved.

In the embodiment of the present invention, the water-absorbing cushion layer can be laid flat on the plate-shaped inert anode plate covered with porous carbon material, and then the single-sheet paper to be treated can be laid flat on the cushion layer; if multi-layer paper is processed Or the whole book, you need to stack one layer of cushion and one layer of paper. Then, the inert cathode plate is pressed on and the two plates are clamped. In the present invention, the inert cathode plate and the inert cathode plate are preferably graphite electrode plates (inert graphite). In an embodiment of the present invention, the porous carbon material may be one or more of activated carbon fibers, carbon aerogels and carbon nanotubes, preferably activated carbon fibers. Preferably, the BET of the porous carbon material is above 500 m ² /g, such as 600-1000 m ² /g, or even higher, and corresponding commercial products can be used. Specifically, the surface of the inert anode plate is covered with activated carbon fiber cloth or activated carbon fiber felt with a thickness of 1 mm to 5 mm, preferably 1.5 to 4 mm.

In the embodiment of the present invention, direct current is applied to the two pole plates, the voltage is 0.6V-1.6V, and a closed loop is formed, which means that the acid removal process starts, which can be appropriately adjusted according to the thickness and number of sheets of paper. The time for acid removal by the electrosorption (also known as capacitive deionization method or capacitive method) is generally not more than 15 minutes, preferably 1 minute to 8 minutes, more preferably 2 minutes to 5 minutes; The number of layers in one treatment and the final pH requirement are adjusted.

In the embodiment of the present invention, the voltage required for deacidification of the paper by the capacitive or electro-adsorption method is lower, and the operation is easier and safer. Especially in terms of safety: due to the low voltage, only the electro-adsorption process, there is no electrolytic reaction at the electrode plate, etc., and the temperature of the electrode plate is relatively low, which ensures the safety of the processed paper documents. In addition, the deacidification time can also be shortened. At the same time, the porous carbon electrode of the present invention can be easily desorbed and can be used repeatedly. A more important point is that the capacitance or electro-adsorption energy of the present invention reserves space for the subsequent integration of paper deacidification-cleaning-reinforcement (even sterilization), and has broader application prospects.

After the deacidification treatment is completed, in the embodiment of the present invention, the power supply is cut off, the cushion is removed, and the paper is naturally dried or dried by other methods.

At present, the paper deacidification methods used in the world all have major defects, and the traditional aqueous solution method is no exception. Paper that has been soaked for a long time is often deformed and wrinkled after drying, and it needs to be disassembled for single-page processing, because it will take longer for the whole book to soak through, and sticking between the papers is inevitable. , difficult to handle. The technology of the invention is suitable for the processing of single, multiple and whole volumes of paper cultural relics, archives and books, and can control the pH value more accurately than other acid removal methods. Since the paper is only in a wet state and is tightly pressed between the electrode plates, the electrode plates flatten the paper like an electric iron, no separate secondary flattening process is required, and the efficiency is greatly improved, which can minimize the traditional Problems such as paper shrinkage, deformation, sticking of the whole book and low efficiency caused by the aqueous solution deacidification method. To sum up, the deacidification technology of the present invention has significant advantages such as good effect, high efficiency, low cost, good controllability, safety, green environmental protection and the like.

In order to further understand the present application, the following specifically describes the method for deacidification of paper by electrosorption method provided by the present application with reference to the examples.

In the following examples, the non-woven cushions involved are all commercially available ordinary chemical fiber non-woven fabrics, and the area may be slightly larger than that of the book pages to be processed.

Example 1

Soak the non-woven cushion with deionized water, and then spread the soaked cushion on the anode plate, which is a flat graphite covered with activated carbon fiber cloth (thickness 1.5mm, BET: 1000m ² / g);

The single-page paper to be processed (one page of the book page of "Nine Hundred Sentences of English Translation Notes" printed by Beijing Commercial Press in 1978; 16K, offset paper printing) is flatly laid on the above-mentioned cushion, and the flat graphite cathode plate is placed. Press on and clamp the two plates;

Connect the two polar plates to regulated direct current, the voltage is 1.5V, and the electro-adsorption time is 5 minutes; then the power is cut off, the cushion is removed, and the paper is naturally air-dried. See Table 1 and Figure 1 for the comparison of the situation before and after the deacidification of the paper. Figure 1 is a comparison diagram of the situation of the paper before and after the deacidification in Example 1. In Figure 1, the right side is the paper before deacidification, and the left side is the paper after deacidification.

Table 1 embodiment 1 paper before and after deacidification analysis index comparison table

Remarks: The pH value is obtained according to the method of Chinese national standard GB/T 1545-2008 "Determination of acidity or alkalinity of aqueous extracts of paper, cardboard and pulp", and the pH value of Shanghai Sanaisi Reagent Co., Ltd. is 5.5 -9.0 precision test paper test; the following examples are the same.

Example 2

Soak the non-woven cushion with deionized water, and then spread the soaked cushion on the anode plate, which is a flat graphite covered with activated carbon fiber cloth (thickness 1.5mm, BET: 1000m ² / g);

The single-page paper to be processed (one page of the page of "Summary of Rhetoric" printed by Shanghai New Knowledge Publishing House in 1957; 16K, printed on offset paper) was flattened on the above-mentioned cushion layer, and the flat graphite cathode plate was pressed on, and Clamp the two pole plates;

Connect the two polar plates to regulated direct current, the voltage is 1.5V, and the electro-adsorption time is 5 minutes; then the power is cut off, the cushion is removed, and the paper is naturally air-dried. See Table 2 and Figure 2 for the comparison of the situation before and after the deacidification of the paper, and Figure 2 is a comparison diagram of the situation of the paper before and after the deacidification of Example 2. In Figure 2, the right side is the paper before deacidification, and the left side is the paper after deacidification.

Table 2 embodiment 2 paper before and after deacidification analysis index comparison table

Example 3

Soak the non-woven cushion with deionized water, and then spread the soaked cushion on the anode plate, which is a flat graphite covered with activated carbon fiber cloth (thickness 1.5mm, BET: 1000m ² / g);

The to-be-processed multi-page paper (three pages of the pages of "Nine Hundred Sentences of English Translation Notes" printed by the Beijing Commercial Press in 1978; 16K, offset paper printing) was flattened on the above-mentioned cushion layer, and the flat graphite cathode plate was placed. Press on and clamp the two plates;

Connect the two polar plates to a regulated direct current with a voltage of 1.5V and an electro-adsorption time of 8 minutes; then cut off the power supply, remove the cushion, and let the paper dry naturally. See Table 3 for a comparison of the situation before and after deacidification of paper.

Table 3 embodiment 3 paper before and after deacidification analysis index comparison table

Example 4

Soak the non-woven cushion with deionized water, and then spread the soaked cushion on the anode plate, which is a flat graphite covered with activated carbon fiber cloth (thickness 1.5mm, BET: 1000m ² / g);

The to-be-processed multi-page paper (three pages of the pages of "Summary of Rhetoric" printed by Shanghai New Knowledge Publishing House in 1957; 16K, printed on offset paper) was laid flat on the above-mentioned cushion layer, the flat graphite cathode plate was pressed on, and the Clamp the two pole plates;

Connect the two polar plates to a regulated direct current with a voltage of 1.5V and an electro-adsorption time of 8 minutes; then cut off the power supply, remove the cushion, and let the paper dry naturally. See Table 4 for a comparison of the situation before and after deacidification of the paper.

Table 4 embodiment 4 paper before and after deacidification analysis index comparison table

Example 5

Soak the non-woven cushion with deionized water, and then spread the soaked cushion on the anode plate, which is a flat graphite covered with activated carbon fiber cloth (thickness 1.2mm, BET: 1200m ² / g);

The single-page paper to be processed (one page of the book page of "Nine Hundred Sentences of English Translation Notes" printed by Beijing Commercial Press in 1978; 16K, offset paper printing) is flatly laid on the above-mentioned cushion, and the flat graphite cathode plate is placed. Press on and clamp the two plates;

Connect the two polar plates to regulated direct current, the voltage is 1.5V, and the electro-adsorption time is 5 minutes; then the power is cut off, the cushion is removed, and the paper is naturally air-dried. See Table 5 for a comparison of the situation before and after deacidification of the paper.

Table 5 embodiment 5 paper before and after deacidification analysis index comparison table

Example 6

Soak the non-woven cushion with saturated calcium hydroxide solution, and then spread the soaked cushion on the anode plate, the anode plate is a flat graphite covered with activated carbon fiber cloth (thickness 1.5mm, BET: 1000m ² /g);

The single-page paper to be processed (one page of the book page of "Nine Hundred Sentences of English Translation Notes" printed by Beijing Commercial Press in 1978; 16K, offset paper printing) is flatly laid on the above-mentioned cushion, and the flat graphite cathode plate is placed. Press on, and clamp the two pole plates; connect the two pole plates to regulated direct current, the voltage is 1.5V, and the electro-adsorption time is 5 minutes; then cut off the power supply, remove the cushion, and let the paper dry naturally. See Table 6 for a comparison of the situation before and after deacidification of the paper.

Table 6 embodiment 6 paper before and after deacidification analysis index comparison table

Comparative example

In order to compare with other methods of deacidification of paper, the following comparative experiments were done using the adjacent pages of the pages of "Nine Hundred Sentences of English Translation Notes" printed by the Beijing Commercial Press in 1978. The test methods, conditions and results are shown in Table 7 and Table 8.

Among them, the specific test conditions of the comparative group 1 are as follows: the book pages are soaked in a container with a concentration of 0.15% calcium hydroxide solution for 30 minutes, and they are taken out and air-dried naturally.

The specific test conditions of the comparative group 2 are as follows: remove the activated carbon fiber cloth covered on the pole plate in Example 1, connect the two pole plates to the DC power supply, the DC current is 0.8 ampere, and the time is 10 minutes. Power off, take it out and let it dry naturally.

Table 7 embodiment 7 different paper deacidification methods comparative experiment

Table 8 Concentrations of anions (unit: μg/mL) in the cold pumping solution of paper samples treated with different deacidification methods

Deacidification treatment method Cl^- SO₄^2- NO₃^- Untreated virgin paper samples 5.931 10.824 not detected Electrosorption method of the present invention 1.430 3.720 not detected Alkaline solution soaking method 3.569 1.707 unchecked Electrolysis 0.848 3.306 unchecked

It can be seen from the above embodiments that in the embodiment of the present invention, the voltage of paper deacidification by the capacitive or electro-adsorption method is lower, and the operation is easier and safer. Especially in terms of safety: due to the low voltage, only the electro-adsorption process, there is no electrolytic reaction at the electrode plate, etc., and the temperature of the electrode plate is also relatively low, which ensures the safety of the processed paper documents. In addition, the deacidification time can also be shortened. At the same time, the porous carbon electrode of the present invention can be easily desorbed and can be used repeatedly. A more important point is: the capacitance or electro-adsorption energy of the present invention reserves space for the subsequent integration of paper deacidification-cleaning-reinforcing (even sterilization), and has broader application prospects.

The technology of the invention is suitable for the treatment of single, multiple and whole volumes of paper cultural relics, archives and books, and can control the pH value more accurately than other acid removal methods. The invention greatly improves the efficiency, can minimize the problems of paper shrinkage, deformation, whole book sticking and low efficiency caused by the traditional aqueous solution deacidification method, and can also reinforce the paper. To sum up, the deacidification technology of the present invention has significant advantages such as good effect, high efficiency, low cost, good controllability, safety, and environmental protection.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the technical principles of the present invention, various modifications to these embodiments can be realized, while These modifications should also be regarded as the scope of protection of the present invention.

Claims (9)

1. A method for deacidification of paper by electrosorption, comprising the following steps: S1, the paper to be treated is brought into contact with a water-absorbing cushion layer, and the water-absorbing cushion layer contains water, so that the paper to be treated is wetted; S2, sandwich the paper wetted in S1 and the water-absorbing cushion in contact with it between an inert anode plate and an inert cathode plate, the surface of the inert anode plate is covered with a porous carbon material, and a direct current is applied to form a closed loop , the voltage is 0.6-1.6V, and electro-adsorption is carried out to obtain the paper after deacidification; The inert anode plate and the inert cathode plate are graphite electrode plates; the porous carbon material is one or more of activated carbon fibers, carbon aerogels and carbon nanotubes. 2 . The method according to claim 1 , wherein the pH value of the paper to be treated is 4.5-6.5. 3 . 3 . The method according to claim 1 , wherein the water-absorbing cushion layer is a water-containing textile cloth, a water-containing non-woven fabric or a water-containing water-absorbing paper. 4 . 4 . The method according to claim 1 , wherein the BET of the porous carbon material is above 500 m ² /g. 5 . 5 . The method according to claim 4 , wherein the surface of the inert anode plate is covered with activated carbon fiber cloth or activated carbon fiber felt. 6 . 6 . The method according to claim 5 , wherein the thickness of the activated carbon fiber cloth or activated carbon fiber felt is 1-5 mm. 7 . 7. The method according to any one of claims 1 to 6, wherein the time of the electro-adsorption is not more than 15 minutes. 8 . The method according to claim 7 , wherein the time for the electrosorption is 1 minute to 8 minutes. 9 . 9. The method according to any one of claims 1 to 6, wherein the water-absorbing cushion further contains a deacidifying agent selected from the group consisting of calcium oxide, calcium hydroxide, calcium carbonate, carbonic acid One or more of calcium hydrogen carbonate, magnesium carbonate, magnesium hydrogen carbonate and magnesium hydroxide.

Images