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CN-117624388-B - Method for synthesizing acid-base indicator by cellulose

CN117624388BCN 117624388 BCN117624388 BCN 117624388BCN-117624388-B

Abstract

The invention relates to a method for synthesizing an acid-base indicator by cellulose, which comprises the steps of mixing a cellulose raw material with a hard volatile acid, heating and carbonizing the mixture in high-temperature air, adding water to wash carbide, adding alkali to neutralize suspension, filtering the suspension, removing inorganic salt, evaporating water to dryness to obtain the acid-base indicator, wherein the cellulose raw material is cellulose and/or a material containing cellulose, and the hard volatile acid comprises one or more of sulfuric acid, phosphoric acid, perchloric acid, benzenesulfonic acid, p-toluenesulfonic acid and benzoic acid. The invention can utilize nontoxic harmless cellulose with low cost as raw material, and prepare the acid-base indicator through simple and environment-friendly production flow, and the synthesis technology has the advantages of low raw material price, easy acquisition, simple preparation process, no environmental pollution, simple and convenient product separation, and the like.

Inventors

  • AI SHUO
  • GAO KAILI
  • FENG ZHENHUA
  • YU WANGUO
  • HUANG CHENGDU

Assignees

  • 广西科技大学

Dates

Publication Date
20260505
Application Date
20231113

Claims (8)

  1. 1. A method for synthesizing an acid-base indicator by cellulose is characterized by comprising the following steps: Mixing a cellulose raw material and a hard volatile acid according to a mass ratio of 1:0.1-0.8, heating and carbonizing in high-temperature air at 80-250 ℃ for 0.2-6 hours, adding water to wash carbide, adding alkali to neutralize suspension, filtering, collecting filtrate, removing inorganic salt, and evaporating water to dryness to obtain an acid-base indicator; The cellulose raw material is cellulose and/or a material containing cellulose, and the nonvolatile acid comprises one or more of sulfuric acid, phosphoric acid, perchloric acid, benzenesulfonic acid, p-toluenesulfonic acid and benzoic acid.
  2. 2. The method of claim 1, wherein the cellulosic synthetic acid-base indicator comprises one or more of woody plants, herbaceous plants, agricultural waste, paper, and bacterial cellulose.
  3. 3. A method for synthesizing an acid-base indicator from cellulose according to claim 1 or 2, wherein the acid-base indicator is colorless in acidic and neutral environments and green in alkaline environments.
  4. 4. The method for synthesizing an acid-base indicator by using cellulose according to claim 3, wherein the cellulose raw material and the hard volatile acid are mixed according to a mass ratio of 1:0.2-0.4.
  5. 5. The method for synthesizing an acid-base indicator by using cellulose according to claim 3, wherein the carbonization temperature is 170-230 ℃.
  6. 6. The method for synthesizing an acid-base indicator by using cellulose according to claim 3, wherein the carbonization time is 3-5 hours.
  7. 7. A method for preparing an acid-base indicator for cellulose synthesis according to claim 3, wherein the step of washing the carbonized material with water comprises the steps of immersing the carbonized material in water, and stirring thoroughly, wherein the amount of water is 0.8-1.5 ml based on 1g of cellulose material.
  8. 8. The method for removing inorganic salt of cellulose synthesis acid-base indicator according to claim 3, wherein the method comprises evaporating water from filtrate to obtain concentrated solution, cooling the concentrated solution to 0-5 ℃ to crystallize and separate out inorganic salt, and filtering to remove inorganic salt.

Description

Method for synthesizing acid-base indicator by cellulose Technical Field The invention relates to a method for synthesizing an acid-base indicator by cellulose, belonging to the technical field of chemical synthesis. Background The acid-base indicator is a kind of organic weak acid or organic weak base with a complex structure, when the acid-base indicator reacts with acid and base, molecules are mutually converted with ions, and the solution color changes along with the pH value due to the fact that the molecules and the ions have different colors. Common acid-base indicators comprise phenolphthalein, thymol blue, bromophenol blue, methyl orange, methyl yellow, methyl red, neutral red and congo red, which are synthesized by adopting toxic raw materials through organic reaction, have high cost and form certain pollution to the environment. Therefore, a method for simply synthesizing an acid-base indicator by using a nontoxic raw material has been sought. Disclosure of Invention The invention aims to solve the technical problem of providing a synthesis method of an acid-base indicator, which can utilize nontoxic and harmless cellulose and cellulose-containing materials with low cost as raw materials to prepare the acid-base indicator through a simple and environment-friendly production flow. The technical scheme for solving the technical problems is that the method for synthesizing the acid-base indicator by using the cellulose comprises the following steps of mixing a cellulose raw material with a hard volatile acid according to a mass ratio of 1:0.1-0.8, heating and carbonizing in high-temperature air at a carbonization temperature of 80-250 ℃ for 0.2-6 hours, adding water to wash the carbonized substance, adding alkali to neutralize suspension, filtering, collecting filtrate, removing inorganic salt, and evaporating water to dryness to obtain the acid-base indicator. The cellulose raw material is cellulose and/or a material containing cellulose, and the nonvolatile acid comprises one or more of sulfuric acid, phosphoric acid, perchloric acid, benzenesulfonic acid, p-toluenesulfonic acid and benzoic acid. Further, the cellulose-containing material comprises one or more of woody plants, herbaceous plants, agricultural wastes, paper, and bacterial cellulose. Furthermore, the prepared acid-base indicator is colorless in acidic and neutral environments and green in alkaline environments. Further, the cellulose raw material and the hard volatile acid are mixed according to the mass ratio of 1:0.2-0.4. Further, the carbonization temperature is 170-230 ℃. Further, the carbonization time is 3-5 hours. Further, the operation of washing the carbide by adding water is to add water into the carbide to soak the carbide, and fully stir, wherein the water is added according to the amount of 0.8-1.5 ml of water added into 1g of cellulose raw material. And further, removing inorganic salt, namely evaporating water from the filtrate to obtain concentrated solution, cooling the concentrated solution to 0-5 ℃ to crystallize and separate out the inorganic salt, and filtering to remove the inorganic salt. The principle of the synthetic acid-base indicator of the invention is as follows: In a high-temperature aerobic environment, cellulose is dehydrated, oxidized and condensed under the catalysis of acid to generate substances containing phenolic hydroxyl groups and carboxyl groups, and the substances are weak acids and lose protons after contacting alkali to become basic molecular structures after being washed by water to indicate the acidity and alkalinity of the solution because the acid and basic molecular structures are in different colors. Compared with the prior art, the invention has the advantages that: the cellulose raw material has low price, wide sources, easy acquisition, quick regeneration, simple carbonization processing process, no toxic gas and toxic liquid, and simple and convenient product separation. Drawings FIG. 1 is an ultraviolet-visible absorption spectrum of an acid-base indicator prepared according to an embodiment of the present invention. FIG. 2 is an infrared-visible absorption spectrum of an acid-base indicator prepared according to an embodiment of the present invention. FIG. 3 shows the Raman spectrum of the acid-base indicator prepared in the first embodiment of the invention. Description of the embodiments The required equipment comprises a heating furnace, a filtering device, an evaporating device and the like. Example 1 1 G of microcrystalline cellulose and 0.3 g of sulfuric acid were thoroughly mixed, and the mixture was placed in a muffle furnace, the heating temperature was set at 180℃and the high-temperature treatment was performed for 4 hours. Taking out the carbide, adding 1ml of water to soak the carbide, fully stirring, dripping 10% NaOH solution to adjust the pH of the suspension to 7, filtering, collecting filtrate, evaporating water in a rotary evaporator, cooling the concentrated