High-viscosity lithium carboxymethyl cellulose and preparation method therefor and application thereof

A method for preparing a lithium carboxymethyl cellulose, comprising the following steps:

• a) mixing 3 to 10 parts by weight of cellulose, 2 to 15 parts by weight of an aqueous solution of a polar solvent, and 1 to 8 parts by weight of a sodium hydroxide solution in 5 to 25 parts by weight of an ethanol solution, wherein
• the aqueous solution of the polar solvent contains 20% to 85% by weight of methanol or isopropanol;
• the ethanol solution contains 70% to 95% by volume of ethanol;
• and
• the sodium hydroxide solution contains 25% to 50% by weight of sodium hydroxide;
• b) performing an alkalization reaction with the mixture obtained from step a) under an inert atmosphere, wherein the alkalization reaction is carried out by the following steps:
• putting the mixture obtained from step a) into a reactor, vacuumizing to −10 to −25 KPa for a first time, then filling with nitrogen to 3 to 10 KPa, vacuumizing to −25 to −80 KPa for a second time, filling with nitrogen to 3 to 10 KPa again, and performing the alkalization reaction under a pressure of nitrogen gas at 3 to 10 KPa for 30 min;
• c) subjecting a reaction product from step b) to an etherification reaction for 30 to 80 min under a normal pressure to obtain crude sodium carboxymethyl cellulose (CMC-Na), wherein the etherification reaction is carried out by the following steps:
• adding the reaction product from step b) into 2 to 10 parts by weight of a monochloroacetic acid-ethanol solution to perform the etherification reaction under normal pressure, wherein
• the monochloroacetic acid-ethanol solution contains 45% to 65% by weight of monochloroacetic acid and ≥93% by volume of ethanol;
• d) acidifying the crude CMC-Na to obtain carboxymethyl cellulose (CMC-H) by the following steps:
• adding the crude CMC-Na into a sulfuric acid solution to perform an acidizing reaction for 60 to 180 min in a normal-pressure system, wherein the sulfuric acid solution contains 10% to 40% by weight of sulfuric acid;
• and
• e) adding the CMC-H into a lithium salt-ethanol solution to perform a substitution reaction for 30 to 120 min under a pH of 6.5 to 10.0, thereby obtaining the lithium carboxymethyl cellulose;
• wherein the total of cellulose, the aqueous solution of a polar solvent, the sodium hydroxide solution, the ethanol solution, and the monochloroacetic acid-ethanol solution is 100 parts by weights.