KR101239125B1 - Copolymer modified lignin derived from byproduct of paper processing process and Concrete additives comprising the same - Google Patents

Abstract

The present invention relates to a method for preparing copolymer-modified lignin from by-products generated in the papermaking process, copolymer-modified lignin prepared therefrom, and admixtures for concrete comprising the same. The copolymer-modified lignin of the present invention is environmentally friendly because it is not necessary to mix a large amount of acidic solution separately, and may be used in various applications including admixtures for concrete, having various properties depending on molecular weight and molecular structure.

Description

Copolymer modified lignin derived from by product of paper processing process and Concrete additives comprising the same}

The present invention relates to copolymer modified lignin derived from by-products of the papermaking process and admixtures for concrete comprising the same. More specifically, the present invention relates to a copolymer-modified lignin and a concrete admixture containing the same by removing organic salts from by-products of the papermaking process, copolymerizing with a comonomer, and filtering the same.

Concrete is the foundation of modern construction and civil engineering, and the strength of concrete depends on how homogeneously the added materials and components are mixed. In this respect, it is essential to develop new admixtures that are superior in the use and performance of admixtures to maximize the homogeneous state of the materials and components used in the manufacture of concrete. As safety accidents increase due to the recent increase in large-scale safety accidents, high strength and high quality of concrete are required as the size of buildings increases, and the amount of admixtures in the manufacture of concrete increases steadily every year. In-house technology development is actively underway.

Admixtures provide many functionalities to concrete, and are used for the purpose of improving the properties of hardened concrete and hardened concrete by physical and chemical effects, and increasing economic efficiency. These admixtures are generally classified according to their effects and uses when using admixtures. Depending on the effects of air volume, unit quantity, condensation, and initial cure rate of concrete, AE (air entraining agent), water reducing agent, AE It is divided into air entraining and water reducing agent, high performance water reducing agent, fluidizing agent, super delaying agent, admixture for underwater concrete, rust preventing agent, shrinkage reducing agent, hydration heat inhibitor, swelling agent and antifreeze cold protection agent.

In particular, sensitizers are classified into lignin sulfonates, oxycarboxates, alkylaryl sulfonates, melamine sulfonates, polycarbonates, polyol derivatives and the like. Among them, lignin sulfonate, which is a natural polymer electrolyte, is the most commonly used admixture and has the characteristic of dissociating into lignin sulfonic anion and calcium cation in water. The anion part is adsorbed on the surface of the cement particles to form a charging layer, and by the electrostatic mutual repulsion of the charging layer, the cement particles are dispersed to prevent reagglomeration, and the flow of concrete is released by releasing water and air bubbles. Is increased.

On the other hand, the paper is produced by going through a number of processes, such as dissociating the pulp, which is a vegetable fiber, blending fillers, sizers and the like. At this time, the pulp used as a papermaking material is manufactured using various raw materials, such as flax, rice straw, waste paper, as well as wood such as coniferous and hardwood, depending on the purpose and material of the paper. Papermaking by-products produced during the production of such paper contain a large amount of inorganic materials such as lignin and various organic substances (about 60%) and inorganic acids added during the manufacturing process. Among them, lignin is used for various purposes such as concrete additives, animal feed, dye dispersant, etc. In order to recover lignin from the by-products of papermaking process, by using a considerable amount of acidic solution, the pH of the by-product is lowered to precipitate only lignin, followed by washing and filtration. By the post-treatment step. However, this process is environmentally problematic due to the use of a large amount of acidic solution, and has an economic advantage only when the yield of lignin is higher than a certain level, so it is mainly used only in kraft pulp manufacturing process, and is rarely used in other papermaking processes. .

Accordingly, the present invention is to solve the problems caused in the process of processing the by-products of the paper making process as described above, to modify and recover the lignin from the by-products generated in various paper making processes other than kraft pulp paper making process to use them in concrete admixtures, etc. The purpose.

Therefore, the present invention removes organic salts from the lignin-containing papermaking process by-products, adds a co-monomer and copolymerizes it by adding a polymerization initiator, and then filters the copolymer to separate the copolymer-modified lignin. It is an object of the present invention to provide a method for producing a copolymer-modified lignin from a papermaking by-product comprising.

It is also an object of the present invention to provide a admixture for concrete comprising the copolymer-modified lignin prepared above.

In one embodiment, the present invention removes organic salts from lignin-containing papermaking by-products, adds a co-monomer and copolymerizes it by adding a polymerization initiator, and then filters the copolymer-modified lignin. It provides a method for preparing copolymer-modified lignin from papermaking by-products comprising the step of separating.

More specifically, (a) removing the organic salts contained in the papermaking by-product containing lignin; (b) injecting a co-monomer into the papermaking by-product; (c) copolymerizing by adding a polymerization initiator to the byproduct into which the co-monomer is added; (d) filtering the byproduct to separate the copolymer modified lignin.

In the present invention, the papermaking by-product refers to wastewater generated in the papermaking and pulp manufacturing process of separating cellulose pulp from lignin by processing lignocellulosic materials such as wood, straw, corn stalks, bagasses and the like.

Therefore, in the present invention, the papermaking process by-product contains lignin, and preferably contains 50 to 650 g of lignin per 1 kg of dry weight of the papermaking process by-product. Here, the lignin is a compound in which two or more phenylpropene monomers are bonded.

The by-products of the present invention may be in the form of sludge or residues, but are not limited thereto.

Removal of organic salts in step (a) of the production method is performed by an electrolysis method, a chemical decomposition method or a sequential application of these methods. The sequential application here is a method of chemically decomposing the residues remaining after electrolysis. The chemical decomposition method is mainly a method of adding an alkali solution, the alkali solution is selected from the group consisting of NaOH solution, KOH solution, Ca (OH) ₂ solution, CaO solution, Mg (OH) ₂ solution and MgO solution It is preferable to be. By the step (a), the organic salts contained in the by-products, in particular, Ca (OH) _2, are prevented from reacting with the cement to generate ammonia gas. This is to prevent.

The by-product from which the organic salts are removed is preferably left to stand for 1 to 5 hours at a temperature of 60 to 90 ° C., but is not limited thereto.

Step (b) of the manufacturing method is a step of adding a co-monomer (co-monomer) to the papermaking process by-products from which the organic salts are removed.

Examples of co-monomers used in the graft copolymerization include monocarboxylic acid monomers such as acrylic acid, methacrylic acid, C ₁ -C ₆ alkylmethacrylic acid and crotonic acid, anhydrides and salts thereof; Dicarboxylic acid monomers such as maleic acid, itaconic acid and fumaric acid, anhydrides and salts thereof; Sulfonic acid monomers such as metharyl sulfonic acid and p-methacryloxybenzene sulfonic acid, anhydrides and salts thereof; Methoxy polyethylene glycol (meth) acrylate, methoxy polyethylene glycol polypropylene glycol (meth) acrylate, methoxy polypropylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol polypropylene Glycol (meth) acrylate, ethoxy polypropylene glycol (meth) acrylate, n-propoxy polyethylene glycol (meth) acrylate, n-propoxy polyethylene glycol polypropylene glycol (meth) acrylate, isopropoxy polyethylene glycol C ₁ -C ₆ alkoxypolyC ₂ -C ₆ alkylene glycol (meth) acrylates such as mono (meth) acrylate and isopropoxy polyethylene glycol polypropylene glycol (meth) acrylate; PolyC ₂ -C ₆ alkylene glycol mono (meth) acrylates such as polyethylene glycol mono (meth) acrylate, polyethylene glycol polypropylene glycol mono (meth) acrylate and polypropylene glycol (meth) acrylate; And methoxypolyethoxyethyl (meth) acrylate, ethoxypolyethoxyethyl (meth) acrylate, n-propoxypolyethoxyethyl (meth) acrylate, isopropoxypolyethoxyethyl (meth) acrylic a C ₁ -C ₆ alkoxy, such as poly acrylate include methoxyethyl (meth) acrylates. Preferably it is a monocarboxylic acid type monomer, a dicarboxylic acid type monomer, or a sulfonic acid type monomer.

In this case, the salt may be an alkali metal salt, an alkaline earth metal salt, a trivalent metal salt, an ammonium salt, or an organic amine salt.

In addition, the said comonomer (co-monomer) may be used independently or may use 2 or more types together.

Meanwhile, the method may further include adjusting the pH of the papermaking by-product from which the organic salts are removed before the step (b) and after the step (a) to 6.0 to 8.0. This control means adjusting the pH within the pH range by adding and stirring a basic solution or an acidic solution according to the initial pH of the papermaking process by-products from which the organic salts are removed, and whether or not the organic salts are removed in step (a). It is determined when the pH of the produced papermaking by-product is measured and is outside the above range. Here, the basic solution is, but is not limited to, sodium hydroxide, potassium hydroxide, calcium hydroxide, or a combination thereof, and the like, but the acidic solution is sulfuric acid, nitric acid or acetic acid and the like. In addition, when adding a basic or acidic solution to the by-products and stirring, the temperature is preferably 20 to 100 ℃, preferably 20 to 60 ℃ temperature, and stirred for 5 to 60 minutes so that sufficient reaction can occur It is preferable. The lignin in the byproduct from which the organic salts are removed by the pH adjustment makes it easier to form a copolymer with a comonomer.

Step (c) of the manufacturing method is a step of copolymerizing a polymerization initiator by adding a co-monomer-injected by-product.

In the present invention, a general initiator may be used as the polymerization initiator, and is not limited. Examples of such a polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate and potassium persulfate; Hydrogen peroxide; Azo compounds, such as azobis-2 methyl propionamidine hydrochloric acid and azoisobutylonitrile; Peroxides, such as a benzoyl peroxide, lauroyl peroxide, and cuman hydroperoxide, etc. are mentioned, One or two or more of these can be used.

Further, in the present invention, as an accelerator together with a polymerization initiator, reducing agents such as sodium hydrogen sulfite, sodium sulfite, mohr's salt, sodium pyro sulfite, sodium formaldehyde sulfoxylate and ascorbic acid; One kind or two or more kinds of amine compounds such as ethylenediamine, sodium ethylenediamine tetraacetate, and glycine may be used in combination.

In the present invention, a chain transfer agent during copolymerization may be used as necessary. As a chain transfer agent, a general thing can be used and it does not specifically limit, For example, a mercap propionic acid, a mercap propionic acid 2-ethylhexyl ester, a oxic acid 2-mel cap ethyl ester, a 1,8- dimalcap-3,6- Dioxaoctane, decanthriolol, dodecyl multicaptan, nucleodecanethiol, decanthiol, carbon tetrachloride, 4-brocarbon, α-methylstyrene dimer, talpinene, and the like, may be used. Can be.

In the present invention, the temperature of the copolymerization reaction can be adjusted differently depending on the active temperature of the comonomer used, specifically, about 50 to 120 ℃ is not limited thereto.

In this invention, there is no big restriction | limiting in the time of dripping (adding) a polymerization initiator, and it is not a big problem if dripping time is between 30 minutes and 5 hours.

Step (d) of the preparation method is a step of separating the copolymer-modified lignin produced by filtering the by-product of step (c).

That is, by-products containing the copolymer-modified lignin formed by the copolymerization reaction of the lignin and the comonomer are filtered to separate and recover only the copolymer-modified lignin. Here, the filtration may be used differently depending on the characteristics of the comonomer used in the present invention, preferably cartridge type or hollow fiber membrane ultrafiltration or glass filter filtration. In addition, the molecular weight cut off of the membrane in the ultrafiltration or filter filtration may be used differently depending on the comonomer used in the copolymerization reaction, preferably 3,000 to 50,000, more preferably 3,000 to 30,000. Fractional molecular weight is used.

The copolymer-modified lignin prepared by the method of the present invention can be prepared from a papermaking process by-product without using a large amount of acidic solution, and can be used for various purposes because it can have various properties depending on molecular weight and molecular structure. . As one example thereof, admixtures for concrete comprising the copolymer modified lignin of the present invention.

Specifically, the copolymer-modified lignin of the present invention is used alone as a admixture for concrete, or a special admixture used for a specific use, such as an air entrainer, a slump maintaining agent, an antifoaming agent, a fastener, a retardant, a bleeding inhibitor, a water reducing agent, It can be mixed with fragrances, fire retardants or mixtures thereof and used as admixtures for concrete. For example, an air entrainer is added to the concrete admixture prepared by the present invention to impart an air entraining effect, a slump retainer to impart slump retention performance, and an antifoaming agent to impart defoaming action, Copolymer modifications of the present invention include a fastener to induce quenching, a retardant to induce condensation retardation of concrete, a bleeding inhibitor to suppress bleeding of large concrete, and a water reducing agent to increase susceptibility. It can be used in combination with lignin.

In the above, examples of the air entrainer which can be mixed in the admixture with the copolymer-modified lignin of the present invention include polyoxymethylene alkylether sulfates, polyoxymethylene alkylaryl ethers, sulfate derivatives of polyoxymethylene alkylaryl ethers, It may be, but is not limited to, phosphate ester derivatives, alkylarylsulfonates or alkylbenzolsulfonates of polyoxymethylene alkylaryl ethers. In addition, examples of the sensitizers that can be mixed in the admixture with the copolymer-modified lignin of the present invention include oxycarboxates, polyol derivatives, polyoxyethylene alkylarylether derivatives, alkylarylsulfonates, formalin condensates of melamine sulfonates, naphthalene It may be a formalin condensate, a polyamine condensate, or a polycarboxylic acid-based high molecular compound of sulfonate, but is not limited thereto. Other slump retainers, antifoams, fasteners, retardants, bleeding inhibitors, fragrances and fire retardants that can be mixed into the admixture with the copolymer modified lignin of the present invention can use products commercially available on the market.

Concrete admixtures comprising copolymer-modified lignin according to the present invention are easy to modify the structure of the molecule, have a variety of properties depending on the molecular weight and molecular structure, and the electrical interaction between the particles having a similar potential of the charging layer between the cement Generates repulsive force and has excellent dispersibility and stability. Therefore, even a small amount can impart the flow characteristics of the cement and concrete system.

The amount of copolymer-modified lignin added to the admixture according to the present invention may be added in an appropriate amount in consideration of economic aspects. That is, although it may be added in a small amount to the existing expensive air entrainer, water reducing agent, etc., in order to reduce the production cost, 0.5 to 95% by weight, preferably 5 to 95% by weight of the admixture for concrete, more preferably Will comprise 30 to 80% by weight, most preferably 50 to 70% by weight.

The copolymer-modified lignin according to the present invention can be obtained from the papermaking process by-products by a simple process without using a large amount of acidic solution, and can be used for various purposes because it can have various properties depending on molecular weight and molecular structure. In addition, it is possible to solve the problem of environmental pollution due to incineration and landfill by-products of the papermaking process.

In addition, the admixture for concrete comprising the copolymer modified lignin according to the present invention has excellent dispersibility and stability, so that it can impart the flow characteristics of cement and concrete system in a small amount, as well as general water reducing agent, high performance, high flow, It can be used as various functional admixtures such as high strength.

Hereinafter, the present invention will be described in detail through production examples and examples. The following Preparation Examples and Examples are only intended to illustrate the present invention in more detail, and are not intended to limit the present invention thereto.

Manufacturing example  One

A device equipped with a thermometer, a stirrer, a nitrogen injector, and a reflux cooler was prepared in a four-necked flask, and 500 g of the by-product of the papermaking process was placed in a reactor, and then stirred at 180 rpm at a temperature of 80 ° C. While stirring, 200 g of a KOH (1000 g of water + 1000 g of KOH) solution was added dropwise over 5 minutes, and then cooled to room temperature while standing for 2 hours. Then, the pH was adjusted to 7.0 ± 0.2 while adding sulfuric acid at 180 rpm, and then 0.6 g of acrylic acid (AA, 99%) was slowly added dropwise with a comonomer and stirred for 10 minutes, followed by stirring with Potassium persulfate (K ₂ S _{2) as a} polymerization initiator. O ₈ , 99%) 0.2g and 2.0 g of hydrogen peroxide (H ₂ O ₂ , 35%) were slowly added dropwise for 1 hour, and then reacted for 1 hour at 75 ° C., followed by filtration through a cartridge type ultrafiltration membrane having a molecular weight of 5,000. Copolymer-modified lignin was prepared.

Manufacturing example  2

Preparation Example 2 was carried out in the same sample and the same conditions as Preparation Example 1, copolymer modified lignin using the same molar ratio of Ethyl acrylate (CH ₂ = CHCOOC ₂ H ₅ , 99%) instead of Acrylic acid as comonomer Was prepared.

Manufacturing example  3

Preparation Example 3 was carried out in the same sample and the same conditions as in Preparation Example 1, a copolymer using the same molar ratio of Methyl methacylate (CH ₂ = C (CH ₃ ) COOCH ₃ , 99%) instead of Acrylic acid as a comonomer Modified lignin was prepared.

Manufacturing example  4

Preparation Example 4 was carried out under the same conditions as in Preparation Example 1, but a copolymer-modified lignin was prepared using a comonomer of acrylic acid (CH ₂ = CHCOOH, 99%) instead of 0.6 g of 2.4 g.

Manufacturing example  5

Preparation Example 5 was carried out under the same conditions as in Preparation Example 1, but one of the polymerization initiators, Potassium persulfate (K ₂ S ₂ O ₈ , 99%) was used instead of 0.2g to prepare copolymer modified lignin.

Manufacturing example  6

Preparation Example 6 was carried out under the same conditions as in Preparation Example 1, but copolymer-modified lignin was prepared using 10.0 g of hydrogen peroxide (H ₂ O ₂ , 35%), which is one of the polymerization initiators, instead of 2.0 g. .

Manufacturing example  7

Preparation Example 7 was carried out under the same conditions as in Preparation Example 1, but one of the polymerization initiators, Potassium persulfate (K ₂ S ₂ O ₈ , Copolymer modified lignin was prepared using the same molar ratio of Ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ , 98%) instead.

Manufacturing example  8-14

The copolymer-modified lignin prepared in Preparation Examples 1 to 7 was prepared in each of the concrete admixtures according to the composition ratios shown in Table 1 below (Preparation Example 8-14).

Concrete admixture composition ratio (Manufacturing Example 8-14), unit: g Ca-Lig Na-Lig SG AE Copolymer Modified Lignin-derived Admixtures water G Production Example 8 200 400 50 20 Preparation Example 1: 250 80 1,000 Production Example 9 200 400 50 20 Preparation Example 2: 250 80 1,000 Production Example 10 200 400 50 20 Preparation Example 3: 250 80 1,000 Production Example 11 200 400 50 20 Preparation Example 4 250 80 1,000 Production Example 12 200 400 50 20 Preparation Example 5 250 80 1,000 Production Example 13 200 400 50 20 Preparation Example 6: 250 80 1,000 Production Example 14 200 400 50 20 Preparation Example 7 250 80 1,000 Ca-Lig: Calcium Lignisulfonate-based Admixture
Na-Lig: Sodium Lignisulfonate-based Admixture
SG: Sodium Glyconate Admixture
AE agent: Air entrainer

Comparative example  One

After mixing 98.5% by weight of lignin sulfonate (gold compound paper), 1% by weight of alkylbenzol sulfonate-based AE agent (Aekyung Chemical), and 0.5% by weight of higher fatty alcohol dispersant (Samsung Chemical), the reaction was carried out at 60 ° C for 2 hours. AE reducing agent composition for concrete was prepared.

Comparative example  2

99% by weight of naphthalene sulfonate formalin (curative chemical) and 1% by weight of alkylbenzolsulfonate-based AE agent (Aekyung Chemical) were mixed and reacted at 60 ° C. for 2 hours to prepare an AE water reducing agent composition for concrete.

Example  : Comparison of Properties of Admixtures According to the Invention in Concrete

After mixing 320 kg of cement, 176 kg of water, 1,003 kg of coarse aggregate, and 746 kg of fine aggregate, 0.5 wt% of cement was added to each concrete admixture prepared in Preparation Examples 8 to 14 and Comparative Examples 1 or 2 (1.6 kg). Concrete was prepared by mixing, and the physical properties of the concrete thus prepared are described in Table 2 below in accordance with KS F 2560.

Admixture
Kinds Quality item Reduction rate
(%) ^* % Of bleeding amount Condensation
Tea (min) Ratio of compressive strength (%) Length change ratio (%) Resistance to freeze-thawing (relative dynamic modulus,%) First closing Jaeryong ^** 3 days 7 days a year Age
28 days standard over 10 70 or less -60 ~ + 90 -60 ~ + 90 115 and above 110 and above 110 and above 120 or less 80 or more Preparation Example 8 15 64 -30 +60 131 131 133 104 96 Production Example 9 16 64 -30 +70 131 135 134 104 96 Preparation Example 10 17 65 -20 +60 132 134 134 104 95 Production Example 11 16 65 -30 +70 130 132 131 103 95 Production Example 12 17 66 -40 +50 132 137 137 103 94 Production Example 13 16 65 -40 +60 133 133 133 104 95 Production Example 14 16 66 -30 +60 132 135 134 104 96 Comparative Example 1 12 65 +10 +30 120 118 119 105 94 Comparative Example 2 17 65 -20 +20 132 133 135 102 96

* Susceptibility rate: It means the reduction value calculated by water / cement × 100.

** Element: The standing period after the concrete mixture is filled in the formwork.

As shown in Table 2, in the case of the susceptibility, it can be seen that the concrete to which the admixture of the present invention prepared in Preparation Examples 8 to 14 is higher than the concrete to which the conventional lignin-based admixture prepared in Comparative Example 1 is added, It shows almost the same performance as the concrete to which the existing naphthalene-based admixture prepared in Comparative Example 2 is added.

In addition, the amount of bleeding was about 65% of the concrete participating in the admixture according to the present invention was confirmed that the numerical value is lower than the concrete without the admixture. In other words, when using the admixture according to the present invention it was confirmed that it is possible to reduce the adverse effect due to bleeding that is often generated during concrete production because the material separation does not occur well.

On the other hand, as a result of comparing the difference in the setting time of the concrete, it can be seen that the concrete with the admixture according to the present invention is hydrated later than the concrete with the admixture prepared in Comparative Examples 1 and 2. That is, it was confirmed that the crystallinity of the concrete is delayed when adding the admixture according to the present invention.

Looking at the ratio of the compressive strength of the concrete, it can be seen that the compressive strength of the concrete with the admixture according to the present invention was increased by about 10 to 16% compared to the compressive strength of the concrete with the admixture prepared in Comparative Example 1.

In addition, the results of testing the resistance to changes in length or freeze-thawing showed that the concrete exhibited the same or better performance than the concrete added with conventional admixtures.

Claims (10)

After removing organic salts from the papermaking process by-product containing lignin and adjusting the pH to 6.0 to 8.0, a co-monomer was added and copolymerized by adding a polymerization initiator, followed by filtration to copolymer-modified lignin. Method of producing a copolymer-modified lignin from the papermaking process by-product comprising the step of separating the. delete The method of claim 1, wherein the papermaking by-products contain copolymers of lignin in an amount of 50 to 650 g per 1 kg of dry weight. The method of claim 1, wherein the removal of the organic salts is electrolysis, chemical decomposition, or sequential application of these methods. The method of claim 4, wherein the chemical decomposition method comprises adding an alkali solution selected from the group consisting of NaOH solution, KOH solution, Ca (OH) ₂ solution, CaO solution, Mg (OH) ₂ solution and MgO solution. A process for preparing copolymer modified lignin from papermaking by-products. The method of claim 1, wherein after the organic salts are removed, the by-products are allowed to stand at a temperature of 60 to 90 ° C. for 1 to 5 hours. The method of claim 1, wherein the comonomer is acrylic acid, methacrylic acid, C ₁ -C ₆ alkylmethacrylic acid, crotonic acid, anhydrides and salts thereof; Maleic acid, itaconic acid, fumaric acid, anhydrides and salts thereof; Metharylsulfonic acid, p-metharyloxybenzenesulfonic acid, anhydrides and salts thereof; C ₁ -C ₆ alkoxypolyC ₂ -C ₆ alkylene glycol (meth) acrylates; PolyC ₂ -C ₆ alkylene glycol mono (meth) acrylates; And C ₁ -C ₆ alkoxypolyethoxyethyl (meth) acrylates. A process for producing copolymer-modified lignin from a paper-making by-product, characterized in that at least one selected from the group consisting of: The method of claim 1, wherein the polymerization initiator is ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, azobis-2methylpropionamidine hydrochloride, azoisobutylonitrile, benzoyl peroxide, lauroyl peroxide And, and a method for producing a copolymer-modified lignin from paper-making by-products, characterized in that at least one selected from the group consisting of cuman hydroperoxide. delete A concrete admixture comprising copolymer-modified lignin derived from the papermaking process by-product prepared by the method of any one of claims 1 or 3-8.