Disclosure of Invention
The invention aims to: the high salt-resistant super absorbent resin and the preparation process thereof have good biodegradability, high water absorption and simple preparation process.
The technical scheme of the invention is as follows: the high salt-resistant super absorbent resin comprises the following raw materials: sodium alginate, acrylic acid, acrylamide, chitosan, diatomite, humic acid, an initiator, a cross-linking agent and an antioxidant.
Preferably, the raw materials comprise the following components in mass percentage: 5-10 parts of sodium alginate, 80-100 parts of acrylic acid, 50-60 parts of acrylamide, 20-30 parts of chitosan, 10-20 parts of diatomite, 10-20 parts of humic acid, 0.05-2.5 parts of an initiator, 0.3-5 parts of a cross-linking agent and 0.05-3 parts of an antioxidant.
Preferably, the cross-linking agent is one or a mixture of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, glycerol, pentaerythritol, trimethylolmethane triacrylate and sodium citrate.
Preferably, the initiator is benzoyl peroxide or azobisisobutyronitrile peroxide or dilauroyl peroxide or di-tert-butyl peroxide.
Preferably, the antioxidant is any one of 2, 6-di-tert-butyl-4-methylphenol, 4-hydroxydodecanoic acid anilide, antioxidant 1076 and antioxidant 264.
The invention also provides a preparation process of the high salt-resistant super absorbent resin, which comprises the following steps:
step 1, directly dissolving chitosan in acrylic acid to neutralize the acrylic acid, wherein the neutralization degree is 60-80%, and the reaction temperature is 25-30 ℃;
step 2, adding acrylamide and humic acid solution, stirring for 20min, and uniformly mixing to obtain a mixed solution A; slowly adding the sodium alginate solution and the diatomite, stirring for 15min at room temperature, and uniformly mixing to obtain a turbid solution B;
step 4, introducing nitrogen and formaldehyde into the turbid liquid B, removing oxygen, adding an initiator under a stirring state for polymerization reaction at the reaction temperature of 60-90 ℃, adding a cross-linking agent, uniformly mixing, and after the reaction is finished, granulating, drying, crushing and screening to obtain high-salt-resistance high-water-absorption resin particles;
and 5, soaking the high-salt-tolerance super absorbent resin particles in an antioxidant solution for 20-30 min, taking out and drying.
Preferably, the concentration of the sodium alginate solution is 15 g/L-40 g/L.
Preferably, the drying temperature in the step 4 and the step 5 is 60-70 ℃.
Preferably, the particle size of the high salt-resistant super absorbent resin particles sieved in the step 4 is 20-100 meshes.
Preferably, the cross-linking agent is one or a mixture of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, glycerol, pentaerythritol, trimethylolmethane triacrylate and sodium citrate; the initiator is benzoyl peroxide or azobisisobutyronitrile peroxide or dilauroyl peroxide or di-tert-butyl peroxide; the antioxidant is any one of 2, 6-di-tert-butyl-4-methylphenol, 4-hydroxydodecanoic acid anilide, antioxidant 1076 and antioxidant 264.
The invention has the beneficial effects that:
1. the chitosan is directly dissolved in the acrylic acid solution for reaction, the acrylic acid solution replaces the common solvent acetic acid solution of the common chitosan, except that the solvent acetic acid can be subtracted, the chitosan has amino groups and plays a role in neutralizing the acrylic acid, so that the acrylic acid does not need to be neutralized before the reaction, the process steps are reduced, and the production cost is reduced.
2. Acrylamide is added into acrylic acid, is a non-ionic substance and cannot be ionized in a solution, and the salt resistance of the resin is improved by utilizing the acrylamide.
3. The sodium alginate has wide source and low cost, has good degradability and biocompatibility, improves the degradability of the resin, and plays a role in protecting the environment.
4. The porous structure of the diatomite plays a bearing role for other raw materials, the water absorption rate of the resin is improved, and the flocculation performance of the diatomite is improved through the reaction of the diatomite and the sodium alginate.
5. The chitosan not only plays a role in neutralizing acrylic acid, can enhance the bridging and net capturing effects of the sodium alginate in the reaction process with the sodium alginate, improves the flocculation effect, further promotes aggregation and growth of flocs on the basis of the adsorption bridging of the chitosan by the sodium alginate, is more favorable for forming a molecular chain net structure, promotes the net capturing effect, has a certain chelating effect on metal, also has a certain adsorption effect on copper ions by the sodium alginate, and can achieve a good turbidity removal effect.
6. The cross-linking agent mainly plays a cross-linking role in a polymerization system, so that the system can form a three-dimensional network structure, when the cross-linking agent is used in an excessive amount, pores among the network structure of the system are reduced due to the excessive cross-linking degree of the resin, molecules and ions are not easy to permeate into the resin, and meanwhile, the swelling degree of the resin is limited, so that the water absorption capacity of the resin is reduced; when the dosage of the cross-linking agent is too small, the solubility of the copolymer resin is larger due to too low cross-linking degree, and the copolymer resin is not beneficial to absorbing and maintaining water, the cross-linking agent is selected in a proper amount, the mass component value is between 0.3 and 5 parts, the proportion of the cross-linking agent and other raw materials is moderate, and the water absorption rate of the resin is further improved.
7. The degree of monomer neutralization directly influences the types of hydrophilic groups on resin molecular chains and the number of charges, and further influences the water absorption capacity of the polymer. When the neutralization degree is lower, the system is acidic, which is beneficial to initiating reaction, so that the monomer conversion rate is higher, the ion concentration in the resin is reduced, the electrostatic repulsion and osmotic pressure of a network structure are reduced, the water absorption of the copolymer resin is reduced, the metal ion concentration in the copolymer resin is increased due to the excessively high neutralization degree, the water solubility of the resin is enhanced, and the stability of the resin and the improvement of the water absorption rate are also not beneficial. The neutralization degree of the chitosan and the acrylic acid is 60-80%, and the neutralization degree is proper, so that the resin stability is facilitated, and the water absorption rate is improved. When the neutralization degree of the acrylic acid is continuously increased, the water absorption performance of the resin is gradually reduced, mainly because the reaction time is too long due to the excessively high neutralization degree, the acrylic acid cannot form a high molecular polymer, meanwhile, a large amount of cations have a shielding effect on anions on molecular chains, the expansion among the molecular chains is hindered, and the water absorption performance of the product is reduced, so the optimal neutralization degree in the invention is 70%.
8. Humic acid is added in the formula, the source of the humic acid is wide, the humic acid has good biological activity and chemical activity, and the humic acid contains a large amount of-OH, -NH2And hydrophilic groups such as-O' -CO-and the like are favorable for improving the hydrophilic performance of the resin, increasing the space network structure of the resin and improving the water absorption performance of the resin.
9. After the sodium alginate and the humic acid are mixed, free hydroxyl can appear in the solution, the binding capacity to heavy metal ions is increased, the sodium alginate and the humic acid both contain carboxyl and hydroxyl, formaldehyde is added in the preparation process, the sodium alginate and the humic acid are crosslinked, and the adsorption surface area is increased, so that the water absorption effect generated by mixing the sodium alginate and the humic acid is better than the treatment effect generated by singly using the sodium alginate.
Detailed Description
The technical solution of the present invention will be described in detail with reference to specific examples.
Example 1
The high-salt-tolerance super absorbent resin comprises the following raw materials in parts by mass: 5 parts of sodium alginate, 80 parts of acrylic acid, 50 parts of acrylamide, 20 parts of chitosan, 10 parts of diatomite, 10 parts of humic acid, 0.05 part of initiator, 0.3 part of cross-linking agent and 0.05 part of antioxidant.
The cross-linking agent is one or a plurality of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, glycerol, pentaerythritol, trimethylol methane triacrylate and sodium citrate.
The initiator is benzoyl peroxide or azobisisobutyronitrile peroxide or dilauroyl peroxide or di-tert-butyl peroxide.
The antioxidant is any one of 2, 6-di-tert-butyl-4-methylphenol, 4-hydroxydodecanoic acid anilide, antioxidant 1076 and antioxidant 264.
The high-salt-resistance super absorbent resin is prepared by the following preparation process, and comprises the following steps:
step 1, directly dissolving chitosan in acrylic acid to neutralize the acrylic acid, wherein the neutralization degree is 60 percent, and the reaction temperature is 25 ℃;
step 2, adding acrylamide and humic acid solution, stirring for 20min, and uniformly mixing to obtain a mixed solution A; slowly adding the sodium alginate solution and the diatomite, stirring for 15min at room temperature, and uniformly mixing to obtain a turbid solution B; the concentration of the sodium alginate solution is 15 g/L.
Step 4, introducing nitrogen and formaldehyde into the turbid liquid B, removing oxygen, adding an initiator under a stirring state for polymerization reaction at the reaction temperature of 60 ℃, adding a cross-linking agent, uniformly mixing, and after the reaction is finished, granulating, drying, crushing and screening to obtain high-salt-resistant super-absorbent resin particles, wherein the drying temperature is 60 ℃; the particle size of the screened high salt-resistant high water-absorbent resin particles is 100 meshes.
And 5, soaking the high-salt-tolerance super absorbent resin particles in an antioxidant solution for 20min, taking out and drying at the drying temperature of 60 ℃.
Example 2
The high-salt-tolerance super absorbent resin comprises the following raw materials in parts by mass: 10 parts of sodium alginate, 100 parts of acrylic acid, 60 parts of acrylamide, 30 parts of chitosan, 20 parts of diatomite, 15 parts of humic acid, 2.5 parts of an initiator, 5 parts of a cross-linking agent and 3 parts of an antioxidant.
The cross-linking agent is one or a plurality of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, glycerol, pentaerythritol, trimethylol methane triacrylate and sodium citrate.
The initiator is benzoyl peroxide or azobisisobutyronitrile peroxide or dilauroyl peroxide or di-tert-butyl peroxide.
The antioxidant is any one of 2, 6-di-tert-butyl-4-methylphenol, 4-hydroxydodecanoic acid anilide, antioxidant 1076 and antioxidant 264.
The high-salt-resistance super absorbent resin is prepared by the following preparation process, and comprises the following steps:
step 1, directly dissolving chitosan in acrylic acid to neutralize the acrylic acid, wherein the neutralization degree is 80%, and the reaction temperature is 30 ℃;
step 2, adding acrylamide and humic acid solution, stirring for 20min, and uniformly mixing to obtain a mixed solution A; slowly adding the sodium alginate solution and the diatomite, stirring for 15min at room temperature, and uniformly mixing to obtain a turbid solution B;
step 4, introducing nitrogen and formaldehyde into the turbid liquid B, removing oxygen, adding an initiator under a stirring state for polymerization reaction at the reaction temperature of 90 ℃, adding a cross-linking agent, uniformly mixing, and after the reaction is finished, granulating, drying, crushing and screening to obtain high-salt-resistance super-absorbent resin particles;
and 5, soaking the high-salt-tolerance super absorbent resin particles in an antioxidant solution for 30min, taking out and drying.
The concentration of the sodium alginate solution is 15 g/L-40 g/L.
The drying temperature in the step 4 and the step 5 is 60-70 ℃.
The granularity of the high-salt-tolerance super absorbent resin particles screened in the step 4 is 90 meshes.
Example 3
The high-salt-tolerance super absorbent resin comprises the following raw materials in parts by mass: 8 parts of sodium alginate, 90 parts of acrylic acid, 55 parts of acrylamide, 25 parts of chitosan, 15 parts of diatomite, 20 parts of humic acid, 0.1 part of initiator, 0.6 part of cross-linking agent and 0.5 part of antioxidant.
The cross-linking agent is one or a plurality of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, glycerol, pentaerythritol, trimethylol methane triacrylate and sodium citrate.
The initiator is benzoyl peroxide or azobisisobutyronitrile peroxide or dilauroyl peroxide or di-tert-butyl peroxide.
The antioxidant is any one of 2, 6-di-tert-butyl-4-methylphenol, 4-hydroxydodecanoic acid anilide, antioxidant 1076 and antioxidant 264.
The high-salt-resistance super absorbent resin is prepared by the following preparation process, and comprises the following steps:
step 1, directly dissolving chitosan in acrylic acid to neutralize the acrylic acid, wherein the neutralization degree is 70%, and the reaction temperature is 28 ℃;
step 2, adding acrylamide and humic acid solution, stirring for 20min, and uniformly mixing to obtain a mixed solution A; slowly adding the sodium alginate solution and the diatomite, stirring for 15min at room temperature, and uniformly mixing to obtain a turbid solution B;
step 4, introducing nitrogen and formaldehyde into the turbid liquid B, removing oxygen, adding an initiator under a stirring state for polymerization reaction at the reaction temperature of 70 ℃, adding a cross-linking agent, uniformly mixing, and after the reaction is finished, granulating, drying, crushing and screening to obtain high-salt-resistance super-absorbent resin particles;
and 5, soaking the high-salt-tolerance super absorbent resin particles in an antioxidant solution for 25min, taking out and drying.
The concentration of the sodium alginate solution is 20 g/L.
The drying temperature in the step 4 and the step 5 is 65 ℃.
The particle size of the high-salt-tolerance super absorbent resin sieved in the step 4 is 80 meshes.
Example 4
The high-salt-tolerance super absorbent resin comprises the following raw materials in parts by mass: 9 parts of sodium alginate, 95 parts of acrylic acid, 55 parts of acrylamide, 23 parts of chitosan, 16 parts of diatomite, 20 parts of humic acid, 2 parts of an initiator, 0.6 part of a cross-linking agent and 1 part of an antioxidant.
The cross-linking agent is one or a plurality of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, glycerol, pentaerythritol, trimethylol methane triacrylate and sodium citrate.
The initiator is benzoyl peroxide or azobisisobutyronitrile peroxide or dilauroyl peroxide or di-tert-butyl peroxide.
The antioxidant is any one of 2, 6-di-tert-butyl-4-methylphenol, 4-hydroxydodecanoic acid anilide, antioxidant 1076 and antioxidant 264.
The high-salt-resistance super absorbent resin is prepared by the following preparation process, and comprises the following steps:
step 1, directly dissolving chitosan in acrylic acid to neutralize the acrylic acid, wherein the neutralization degree is 70%, and the reaction temperature is 30 ℃;
step 2, adding acrylamide and humic acid solution, stirring for 20min, and uniformly mixing to obtain a mixed solution A; slowly adding the sodium alginate solution and the diatomite, stirring for 15min at room temperature, and uniformly mixing to obtain a turbid solution B;
step 4, introducing nitrogen and formaldehyde into the turbid liquid B, removing oxygen, adding an initiator under a stirring state for polymerization reaction at the reaction temperature of 90 ℃, adding a cross-linking agent, uniformly mixing, and after the reaction is finished, granulating, drying, crushing and screening to obtain high-salt-resistance super-absorbent resin particles;
and 5, soaking the high-salt-tolerance super absorbent resin particles in an antioxidant solution for 30min, taking out and drying.
The concentration of the sodium alginate solution is 40 g/L.
The drying temperature in the step 4 and the step 5 is 65 ℃.
The particle size of the high-salt-tolerance super absorbent resin sieved in the step 4 is 80 meshes.
Example 5
The high-salt-tolerance super absorbent resin comprises the following raw materials in parts by mass: 6 parts of sodium alginate, 95 parts of acrylic acid, 58 parts of acrylamide, 26 parts of chitosan, 10 parts of diatomite, 15 parts of humic acid, 2 parts of an initiator, 3 parts of a cross-linking agent and 0.08 part of an antioxidant.
The cross-linking agent is one or a plurality of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, glycerol, pentaerythritol, trimethylol methane triacrylate and sodium citrate.
The initiator is benzoyl peroxide or azobisisobutyronitrile peroxide or dilauroyl peroxide or di-tert-butyl peroxide.
The antioxidant is any one of 2, 6-di-tert-butyl-4-methylphenol, 4-hydroxydodecanoic acid anilide, antioxidant 1076 and antioxidant 264.
The high-salt-resistance super absorbent resin is prepared by the following preparation process, and comprises the following steps:
step 1, directly dissolving chitosan in acrylic acid to neutralize the acrylic acid, wherein the neutralization degree is 75%, and the reaction temperature is 26 ℃;
step 2, adding acrylamide and humic acid solution, stirring for 20min, and uniformly mixing to obtain a mixed solution A; slowly adding the sodium alginate solution and the diatomite, stirring for 15min at room temperature, and uniformly mixing to obtain a turbid solution B;
step 4, introducing nitrogen and formaldehyde into the turbid liquid B, removing oxygen, adding an initiator under a stirring state for polymerization reaction at the reaction temperature of 75 ℃, adding a cross-linking agent, uniformly mixing, and after the reaction is finished, granulating, drying, crushing and screening to obtain high-salt-resistance super-absorbent resin particles;
and 5, soaking the high-salt-tolerance super absorbent resin particles in an antioxidant solution for 28min, taking out and drying.
The concentration of the sodium alginate solution is 30 g/L.
The drying temperature in the step 4 and the step 5 is 66 ℃.
The particle size of the high-salt-tolerance super absorbent resin screened in the step 4 is 50 meshes.
The preparation processes in embodiments 1 to 5 all add chitosan directly into the acrylic acid solution, chitosan not only plays a role in neutralizing acrylic acid, in the reaction process with sodium alginate, the bridging and net capturing effects of sodium alginate can be enhanced, the flocculation effect is improved, sodium alginate further promotes aggregation and growth of flocs on the basis of the adsorption bridging of chitosan, formation of a molecular chain network structure is facilitated, the net capturing effect is promoted, chitosan has a certain chelating effect on metal, and sodium alginate also has a certain adsorption effect on copper ions, so that a good turbidity removal effect can be achieved.
And (3) carrying out water absorption performance test on the resin in the embodiment 1-5, wherein the water absorption performance test method comprises the following steps: accurately weighing a certain amount of sample (the mass is recorded as m)1) Adding sufficient distilled water into a 1L beaker, standing for 24h, filtering with a standard sieve (100 meshes), weighing again when no water drops to obtain the resin mass (recorded as m) after water absorption2). The water absorption capacity Q is calculated as follows:
as shown in Table 1, Table 1 is a table of the water absorption performance data of the highly salt-resistant super absorbent resin in examples 1 to 5.
TABLE 1
Number of times of water absorption
|
1
|
2
|
3
|
4
|
5
|
Example 1
|
89%
|
80%
|
75%
|
70%
|
60%
|
Example 2
|
95%
|
85%
|
80%
|
75%
|
65%
|
Example 3
|
85%
|
75%
|
70%
|
65%
|
58%
|
Example 4
|
90%
|
85%
|
80%
|
75%
|
68%
|
Example 5
|
92%
|
85%
|
80%
|
75%
|
65% |
According to the data in table 1, it can be preliminarily speculated that the crosslinking agent mainly plays a crosslinking role in the polymerization system, so that the system can form a three-dimensional network structure, when the dosage of the crosslinking agent is too large, the pores among the network structure of the system are reduced due to too large crosslinking degree of the resin, molecules and ions are not easy to permeate into the resin, and meanwhile, the swelling degree of the resin is limited, so that the water absorption capacity of the resin is reduced; when the dosage of the cross-linking agent is too small, the solubility of the copolymer resin is larger due to too low cross-linking degree, which is not beneficial to the absorption and the retention of the copolymer resin on moisture.
The water absorption rate of the resin tends to increase first and then decrease with the increase of the reaction temperature. This is probably because when the reaction temperature is low, the decomposition rate of the initiator is slow, resulting in a decrease in the reaction rate, a decrease in the degree of polymerization, and further a low water absorption of the resin; however, when the reaction temperature is too high, the copolymerization rate is reduced due to the excessively fast reaction rate and the increase of chain termination and chain transfer, and a macromolecular network structure is not easily formed, so that the relative molecular mass of the polymerization product is reduced, the water solubility is increased, and the water absorption is reduced. The reaction temperatures of examples 1 to 5 were all suitable, and no significant negative effect of reducing the water absorption of the resin occurred. The water absorption rates of examples 1 to 5 were all maintained at high levels.
The degree of monomer neutralization directly influences the types of hydrophilic groups on resin molecular chains and the number of charges, and further influences the water absorption capacity of the polymer. When the neutralization degree is lower, the system is acidic, which is beneficial to initiating reaction, so that the monomer conversion rate is higher, the ion concentration in the resin is reduced, the electrostatic repulsion and osmotic pressure of a network structure are reduced, the water absorption of the copolymer resin is reduced, the metal ion concentration in the copolymer resin is increased due to the excessively high neutralization degree, the water solubility of the resin is enhanced, and the stability of the resin and the improvement of the water absorption rate are also not beneficial.
The water absorption rate of the resins in examples 1 to 5 was gradually reduced during the repeated use, but the water absorption rates of the resins in examples 1 to 5 were all 60% or more at the time of 5 th use, which indicates that the water absorption performance of the resin of the present invention was stable and the resin could be repeatedly used for many times.
A set of comparative experiments are carried out, and by taking example 5 as a reference, the high-salt-resistance high-water-absorption resin is prepared, which is different from example 5 in that the raw materials of the high-salt-resistance high-water-absorption resin do not contain humic acid, formaldehyde is not introduced into the turbid solution B in the preparation process, only nitrogen is introduced, oxygen is removed, and the other steps are the same. Table 2 is a table of water absorption performance data of the comparative experiment and the highly salt-resistant super absorbent resin in example 5.
Example 5
|
92%
|
85%
|
80%
|
75%
|
65%
|
Comparative experiment
|
80%
|
62%
|
55%
|
48%
|
35% |
The alginic acid molecular chain contains carboxyl and hydroxyl, is a polyanionic electrolyte, can form a chelating ligand with various metal ions, is different from a hydrophobic organic gel formed by organic molecule crosslinking of the traditional ion exchange resin, is a hydrophilic ion crosslinking gel formed by ionic bond crosslinking, can adsorb Cu2+, Co2+, Cd2+ and Zn2+ ions, and the metal ions replace Na + to form a new ion crosslinking structure.
The humic acid is an organic high-molecular polymer with more carboxyl groups, phenolic hydroxyl groups and N-and S-binding sites, so that the humic acid has acidic cation exchange performance and complexing and chelating properties as same as alginic acid, and the adsorption of the humic acid on heavy metal ions is not only cation exchange but also forms a chelating relation, so that a plurality of metal ions can be adsorbed.
After the sodium alginate and the humic acid are mixed, free hydroxyl groups can appear in the solution, the binding capacity to heavy metal ions is increased, the sodium alginate and the humic acid both contain carboxyl groups and hydroxyl groups, formaldehyde is added in the preparation process, the sodium alginate and the humic acid are crosslinked, the adsorption surface area is increased, and as can be seen from table 2, the water absorption effect generated by mixing the sodium alginate and the humic acid is better than the treatment effect generated by independently using the sodium alginate.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.