Quaternary ammonium group-grafted cation resin and preparation method thereof

A preparation method of a quaternary ammonium group-grafted cation resin, comprising the following steps:

• 1) introducing a quaternary ammonium group into a chloromethylated cross-linked polystyrene (PS) resin comprising:
• 1.1) adding a chloromethylated cross-linked PS resin and trimethylamine hydrochloride successively to a reaction vessel;
• 1.2) adding a 20% sodium hydroxide aqueous solution dropwise to the reaction vessel within 1 hour, keeping a first temperature at 30° C. to 40° C., and continuously stirring to allow a first reaction for 2 hours;
• 1.3) after the first reaction is completed, filtering a first reaction solution to obtain a first intermediate resin, and washing the first intermediate resin with a 5% sodium hydroxide aqueous solution, a 5% hydrochloric acid aqueous solution, and deionized water successively until a first effluent has a pH of 7 to obtain a first washed resin;
• and
• 1.4) drying the first washed resin at 60° C. to obtain a quaternary ammonium group-grafted chloromethylated cross-linked PS resin;
• and
• 2) sulfonating the quaternary ammonium group-grafted chloromethylated cross-linked PS resin comprising:
• 2.1) adding the quaternary ammonium group-grafted chloromethylated cross-linked PS resin obtained in step 1.4), 1,2-dichloroethane, silver sulfate, concentrated sulfuric acid, and fuming sulfuric acid successively to the reaction vessel;
• 2.2) keeping a second temperature at 50° C. to 60° C., and continuously stirring to allow a second reaction for 1 hour;
• 2.3) raising the second temperature to 70° C. to 80° C., and continuously stirring to allow the second reaction for 1 hour;
• 2.4) raising the second temperature to 115° C. to 125° C., and continuously stirring to allow the second reaction for 5 hours;
• 2.5) after the second reaction is completed, cooling a second reaction solution to room temperature, and diluting and filtering the second reaction solution to obtain a second intermediate resin;
• and washing the second intermediate resin with deionized water to obtain a second washed resin, converting the second washed resin with a 5% hydrochloric acid aqueous solution to obtain a converted resin, and washing the converted resin with deionized water until a second effluent has a pH of 7;
• and
• 2.6) drying the converted resin at 60° C. to obtain the quaternary ammonium group-grafted cation resin;
• wherein the method features the following relative amounts of raw materials in parts by weight:
• 10 to 20 parts of chloromethylated cross-linked PS resin,
• 40 to 80 parts of 1,2-dichloroethane,
• 5 to 20 parts of trimethylamine hydrochloride,
• 20 to 80 parts of 20% sodium hydroxide aqueous solution,
• 500 to 1,000 parts of 5% sodium hydroxide aqueous solution,
• 1,000 to 2,000 parts total of 5% hydrochloric acid aqueous solution,
• 0.5 to 1 part of silver sulfate,
• 15 to 30 parts of concentrated sulfuric acid,
• 15 to 30 parts of fuming sulfuric acid, and
• 9,000 to 18,000 parts total of deionized water.