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Cellulose foam capable of visually identifying and removing chromium as well as preparation method thereof and chromium removal method

A technology of cellulose foam and cellulose solution, which is applied in chemical instruments and methods, separation methods, and combustible gas purification, etc., can solve problems such as difficulty in reaching, high reactor processing cost, and long time-consuming adsorbent regeneration process.

Active Publication Date: 2020-06-09
SOUTHWEST JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A large amount of water filled in the hydrogel is unfavorable to the mass transfer of pollutants, and during the adsorption process, the adsorption-bound Cr(VI) undergoes a redox reaction with the hydrogel, so the structure of the hydrogel will be affected by oxidation. effect and be destroyed, ultimately affecting the adsorption effect
(2) Using cellulose as a raw material, one-dimensional modified cellulose fibers and two-dimensional modified cellulose membranes were prepared by oxidation-grafting method. Neither of them has a rich porous structure, which is not conducive to the activity of Site exposure and mass transfer of pollutants, and during the adsorption process, Cr(VI) is reduced to Cr(III) by the hydroxyl groups on the cellulose, the reaction cannot be controlled and stays in the electrostatic adsorption stage, and the structure of the adsorbent itself will inevitably be destroyed
It can be seen that the current adsorbents for removing Cr(VI) mainly have the following problems: (1) The adsorbent has no fluorescence and cannot recognize Cr(VI) at the same time.
(2) The removal of Cr(VI) is slow, resulting in higher reactor processing costs
(3) It is difficult to treat the effluent to reach the Cr(VI) limit of 0.05mg / L in the Hygienic Standard for Drinking Water
(4) The PEI-modified adsorbent cannot regulate the two processes of electrostatic adsorption and oxidation-reduction reaction when removing Cr(VI), and the adsorbent will partially or completely reduce Cr(VI) to Cr(III), which is to a certain extent It will inevitably destroy the structure of the adsorbent and affect the regeneration and use of the adsorbent.
(5) The regeneration process of the adsorbent after use takes a long time, and the adsorption performance decreases rapidly during repeated use

Method used

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  • Cellulose foam capable of visually identifying and removing chromium as well as preparation method thereof and chromium removal method
  • Cellulose foam capable of visually identifying and removing chromium as well as preparation method thereof and chromium removal method
  • Cellulose foam capable of visually identifying and removing chromium as well as preparation method thereof and chromium removal method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] A method for preparing cellulose foam capable of visually identifying and removing chromium, comprising the following steps:

[0026] Take 8.333g of dried cotton, add 145.45ml DMSO solution, then add 42.6mL 40wt% TBAH aqueous solution, mechanically stir to dissolve, put it in a refrigerator at 4°C for 2 hours after standing for defoaming, and obtain a fiber with a mass fraction of 4%. prime solution. Take 10mL of the above solution in a 50ml beaker, add 1mL of epichlorohydrin, stir until the color of the solution becomes lighter, add 0.1mL of 5wt% PEI, stir well, pour it into a mold, put it in a 50°C oven for 60min, take it out to get After replacing the solvent with deionized water, put the hydrogel into the freezer (-18°C) to freeze for 12 hours, and then put it into a freeze dryer at -81°C for 24 hours to obtain cellulose foam (also known as PEI-modified foam). permanent cellulose foam).

[0027] Take 0.02 g of the prepared cellulose foam, put it into 20 ml of Cr(V...

Embodiment 2

[0029] A method for preparing cellulose foam capable of visually identifying and removing chromium, comprising the following steps:

[0030] Take 10mL of the cellulose solution prepared in Example 1 in a 50mL beaker, add 1mL of epichlorohydrin, stir until the color of the solution becomes lighter, then add 10wt% PEI 1mL, stir well, pour it into a mold, and put it in 50 React in an oven at ℃ for 60 minutes, take out the hydrogel, replace the solvent with deionized water, put it in the freezer of the refrigerator (-18 ℃) to freeze for 12 hours, and then put it in a freeze dryer at -81 ℃ for 24 hours to obtain Cellulose foam.

[0031] Take 0.02 g of the prepared cellulose foam, put it into 20 mL of Cr(VI)-containing simulated wastewater with a concentration of 100 mg / L and a pH value of 2, and take a sample for analysis after magnetic stirring and adsorption at 25 ° C for 30 min. The removal rate is measured to be 65.57 %.

Embodiment 3

[0033] A method for preparing cellulose foam capable of visually identifying and removing chromium, comprising the following steps:

[0034] Take 10mL of the cellulose solution prepared in Example 1 in a 50ml beaker, add 0.5mL of epichlorohydrin, stir until the color of the solution becomes lighter, then add 1mL of 6wt% PEI, stir well, pour into a mold, put in 50 Regenerate in an oven at ℃ for 30 minutes, take out the hydrogel, replace the solvent with deionized water, freeze in the freezer (-18℃) for 12h, and then put it in a freeze dryer at -81℃ for 24h to obtain Cellulose foam.

[0035] Take 0.05 g of the prepared cellulose foam, put it into 25 mL of Cr(VI)-containing simulated wastewater with a concentration of 100 mg / L and a pH value of 2, take a sample for analysis after magnetic stirring and adsorption at 25 °C for 30 min, and the removal rate is measured to be 95.53 %.

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Abstract

The invention provides cellulose foam capable of visually identifying and removing chromium as well as a preparation method thereof and a chromium removal method. The preparation method comprises thefollowing steps: adding epichlorohydrin into a cellulose solution, stirring until the color of the solution becomes light, adding a PEI solution, uniformly stirring, crosslinking at 25-60 DEG C for 5-60 minutes to form hydrogel, washing with deionized water, and carrying out freezing and freeze-drying, thereby obtaining the product. The cellulose foam prepared by the invention can be used for quickly identifying and removing Cr(VI) in a relatively wide pH range. According to the method, the electrostatic adsorption and subsequent oxidation-reduction process of Cr(VI) can be regulated and controlled, it is guaranteed that the structure of the adsorbent cannot be damaged due to the oxidation reaction while Cr(VI) is removed, the regeneration speed of the material adsorbing Cr(VI) is high, and the structure of the adsorbent cannot be damaged in the regeneration process.

Description

technical field [0001] The invention belongs to the technical field of chromium adsorption materials, and in particular relates to a cellulose foam capable of visually identifying and removing chromium, a preparation method thereof, and a chromium removal method. Background technique [0002] my country is the world's largest producer of chromium salts and a major consumer of chromium and its compounds. Due to historical reasons, although more than 6.7 million tons of chromium slag have been disposed of in 15 provinces, the restoration and treatment of soil and groundwater contaminated by chromium slag still has a long way to go. In addition, the discharge of industrial "three wastes" such as metallurgy, electroplating, tanning, paint, printing and dyeing, pigments, ceramics, catalysis, and anticorrosion has further aggravated environmental chromium pollution and seriously threatened human health. Chromium is a highly toxic heavy metal, listed as one of the most toxic pollu...

Claims

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Application Information

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IPC IPC(8): B01J20/26B01J20/28B01J20/30B01J20/34C02F1/28C02F101/22
CPCB01J20/267B01J20/22B01J20/24B01J20/28045B01J20/3475C02F1/285C02F2101/22
Inventor 张胜利张思略裴彥博杨红薇刘伯芳周祚万
Owner SOUTHWEST JIAOTONG UNIV
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