CN104475063A - Method for preparing heavy metal adsorbent - Google Patents

Abstract

The invention discloses a preparation method of a heavy metal adsorbent. The steps of the method are: firstly treating the bagasse with alkali to prepare the bagasse cellulose; then ultrasonically activating the bagasse cellulose, and then sequentially adding an initiator, acrylic acid and N,N'-methylenebisacrylamide neutralized by NaOH solution , carry out grafting reaction to prepare the graft copolymerization product; wash with distilled water and absolute ethanol, dry and pulverize in sequence to obtain the crude product of the heavy metal adsorbent; then extract with acetone to obtain the purified heavy metal adsorbent. The beneficial effect of the present invention is: compared with the prior art, the bagasse fiber is subjected to ultrasonic activation treatment, the outer layer of the bagasse fiber cell wall is broken and removed, the chemical reactivity of the bagasse fiber is enhanced, and the reaction grafting rate and product quality are improved. adsorption properties.

Description

A kind of preparation method of heavy metal adsorbent

technical field

The invention relates to the field of preparation of a heavy metal adsorbent, in particular to a preparation method of a heavy metal adsorbent.

Background technique

The discharge of industrial wastewater containing heavy metal ions has caused serious pollution to the environment and a threat to people's health. Therefore, it is very important to remove heavy metal ions in wastewater. Cellulose is cheap, easy to obtain, and environmentally friendly. Therefore, cellulose-based heavy metal ion adsorption materials have attracted the attention of researchers.

In natural cellulose, about 70% of the crystalline structure makes the accessibility of cellulose lower, making it difficult to increase the grafting rate on cellulose molecules. Ultrasound can produce mechanical action, thermal action and cavitation action. When propagating in liquid, it can generate huge pressure, break and remove the outer layer of fiber cell wall, enhance the chemical reactivity of fiber, and increase the reaction grafting rate and product stability. Adsorption properties.

Contents of the invention

The object of the present invention is to provide a method for preparing a heavy metal adsorbent with low cost, environmental friendliness and excellent adsorption effect.

The technical scheme that the present invention solves the problems of the technologies described above is as follows:

A preparation method of a heavy metal adsorbent, the operation steps are as follows:

1. Preparation of bagasse cellulose:

After pulverizing the bagasse, screen it with a 100-mesh sieve, keep the small parts, add 80-120ml of NaOH with a mass concentration of 15-20% to the bagasse, treat it at 120°C for 0.5-1.0h, wash with distilled water until neutral , dried to obtain bagasse cellulose.

2. Activation of bagasse cellulose:

Take 1.0 g of the absolute-dried bagasse cellulose obtained in step 1 and place it in a three-necked flask, add 15-18 ml of distilled water, and react for 15-30 minutes under ultrasonic conditions with a power of 150-400 W to obtain an activated cellulose suspension.

3. Graft copolymerization of bagasse cellulose and acrylic acid:

Take step 2 to obtain the activated bagasse cellulose suspension, add neutralized acrylic acid; add initiator and crosslinking agent successively; control the quality of bagasse cellulose: initiator: N,N'-methylenebisacrylamide The ratio is 2:0.1~0.5:0.0~0.05; stir and react in a water bath at 60~70°C for 1.5~3.0h to obtain a graft copolymer. The neutralized acrylic acid is obtained by adding sodium hydroxide solution into acrylic acid, and controlling the mass ratio of sodium hydroxide:acrylic acid to be 2:3-7. The initiator is potassium persulfate or ammonium persulfate.

4. Purification of graft copolymer:

Wash the graft copolymer obtained in step 3 with distilled water and absolute ethanol in turn, dry, and pulverize, then extract the pulverized graft copolymer at 60-75°C for 24-48 hours, and dry to obtain purified heavy metal adsorbent.

Beneficial effects of the present invention:

The cellulose is activated by ultrasonic technology, the chemical reactivity of the bagasse fiber is enhanced, the reaction grafting rate and the adsorption performance of the product are improved, and a cheap heavy metal adsorbent preparation method is provided. The economic added value of bagasse is improved, and water bodies polluted by heavy metals are purified.

Detailed ways

The present invention will be further described below in conjunction with embodiment.

Example 1

A kind of preparation method of heavy metal adsorbent, carries out according to the following steps:

1. Preparation of bagasse cellulose:

After crushing the bagasse, sieve it with a 100-mesh sieve to keep the small parts, add 80ml of 15% NaOH to the bagasse, treat at 120°C for 0.5h, wash with distilled water until neutral, and dry to obtain bagasse cellulose.

2. Activation of bagasse cellulose:

Take 1.0 g of the absolute-dried bagasse cellulose obtained in step 1 and place it in a three-necked flask, add 15 ml of distilled water, and react for 30 minutes under ultrasonic conditions with a power of 150 W to obtain an activated cellulose suspension.

3. Graft copolymerization of bagasse cellulose and acrylic acid:

Take the bagasse cellulose suspension obtained in step 2, add neutralized acrylic acid (sodium hydroxide:acrylic acid mass ratio is 2:3); add initiator ammonium persulfate and N,N'-methylenebisacrylamide in sequence ; Control bagasse cellulose: initiator ammonium persulfate: N, N'-methylenebisacrylamide mass ratio is 2:0.1:0.01; Stir and react in a water bath at 60°C for 1.5h to obtain a graft copolymer .

4. Purification of graft copolymer;

The graft copolymer obtained in step 3 was washed successively with distilled water and absolute ethanol, dried, and pulverized, and then the pulverized graft copolymer was extracted at 75°C for 24 hours, and dried to obtain the purified heavy metal adsorption agent.

Example 2

A kind of preparation method of heavy metal adsorbent, carries out according to the following steps:

1. Preparation of bagasse cellulose:

After crushing the bagasse, sieve it with a 100-mesh sieve to keep the fine parts, add 100ml of 20% NaOH to the bagasse, treat at 120°C for 1.0h, wash with distilled water until neutral, and dry to obtain bagasse cellulose.

2. Activation of bagasse cellulose:

Take 1.0 g of the absolute-dried bagasse cellulose obtained in step 1 and place it in a three-necked flask, add 18 ml of distilled water, and react for 30 minutes under ultrasonic conditions with a power of 300 W to obtain an activated cellulose suspension.

3. Graft copolymerization of bagasse cellulose and acrylic acid:

Take the bagasse cellulose suspension obtained in step 2, add neutralized acrylic acid (sodium hydroxide:acrylic acid mass ratio is 2:5); add initiator potassium persulfate and N,N'-methylenebisacrylamide in sequence , control the mass ratio of bagasse cellulose:initiator:N,N'-methylenebisacrylamide to 2:0.3:0.03; stir and react in a water bath at 70°C for 2.0h to obtain a graft copolymer.

(4) purification of graft copolymer;

The graft copolymer obtained in step (3) was washed successively with distilled water and absolute ethanol, dried, and pulverized, and then the pulverized graft copolymer was extracted at 70° C. for 48 hours, and dried to obtain purified heavy metal adsorbent.

Example 3

A kind of preparation method of heavy metal adsorbent, carries out according to the following steps:

1. Preparation of bagasse cellulose:

After crushing the bagasse, sieve it with a 100-mesh sieve to keep the fine parts, add 120ml of 20% NaOH to the bagasse, treat at 120°C for 1.0h, wash with distilled water until neutral, and dry to obtain bagasse cellulose.

2. Activation of bagasse cellulose:

Take 1.0 g of the absolute-dried bagasse cellulose obtained in step 1 and place it in a three-necked flask, add 18 ml of distilled water, and react for 30 minutes under ultrasonic conditions with a power of 400 W to obtain an activated cellulose suspension.

3. Graft copolymerization of bagasse cellulose and acrylic acid:

Take the bagasse cellulose suspension obtained in step 2, add neutralized acrylic acid (sodium hydroxide: acrylic acid mass ratio is 2:7); add initiator ammonium persulfate and N,N'-methylenebisacrylamide successively ; Control bagasse cellulose: the mass ratio of initiator ammonium persulfate: N,N'-methylenebisacrylamide is 2:0.5:0.05; stir and react in a water bath at 70°C for 3.0h to obtain a graft copolymer .

4. Purification of graft copolymer;

The graft copolymer obtained in step 3 was washed with distilled water and absolute ethanol in sequence, dried, and pulverized, and then the pulverized graft copolymer was extracted at 70°C for 24 hours, and dried to obtain the purified heavy metal adsorption agent.

Example 4

Application of heavy metal adsorbent:

The heavy metal copper was used for adsorption test.

Get 0.1000g of the heavy metal adsorbent prepared in Example 2 in a 250ml Erlenmeyer flask, add a concentration of 150mg/L copper ion solution, shake for 0.5h in a water bath oscillator with a rotating speed of 150r/min at normal temperature, filter, and take 30ml of clear solution, measure the remaining copper ion content in the solution by inductively coupled plasma spectrometry, and calculate the adsorption capacity and adsorption rate according to the following formula:

$\begin{array}{cc}\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}& \mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>\end{array}$

In the formula:

q——the adsorption capacity of superabsorbent resin on Cu ²⁺ per unit mass, mg/g;

η——Cu ²⁺ removal rate, %;

C ₀ ——the initial concentration of Cu ²⁺ , mg/L;

C - the concentration of Cu ²⁺ in the filtrate after filtration, mg/L;

V - the volume of the solution, L;

Experimental results: The adsorption capacity is 82.98mg/g, and the adsorption rate is 98.34%.

Claims (1)

1. a preparation method for heavy metal absorbent, is characterized in that, operating procedure is as follows:

(1) bagasse cellulose is prepared:

After being pulverized by bagasse, with 100 eye mesh screen screenings, retain thin, the mass concentration adding 80 ~ 120ml in bagasse is the NaOH of 15 ~ 20%, processes 0.5 ~ 1.0h, be washed with distilled water to neutrality at 120 DEG C, dries, obtains bagasse cellulose;

(2) activation of bagasse cellulose:

Get the bagasse cellulose 1.0g that step (1) obtains and be placed in there-necked flask, add 15-18ml distilled water, be react 15 ~ 30min under the ultrasound condition of 150 ~ 400W at power, obtain the cellulose suspension after activating;

(3) bagasse cellulose and acrylic acid graft copolymerization:

Get step (2) and obtain the bagasse cellulose suspension after activating, add the acrylic acid after neutralization; Add initator and crosslinking agent successively; Controlling bagasse cellulose: initator: N, N ' mass ratio of-methylene-bisacrylamide is 2:0.1 ~ 0.5:0.0 ~ 0.05; In the water-bath of 60 ~ 70 DEG C, stirring reaction 1.5 ~ 3.0h, obtains graft copolymer, and the acrylic acid after described neutralization joins in acrylic acid by sodium hydroxide solution, controls NaOH: acrylic acid mass ratio is 2:3 ~ 7; Described initator is potassium peroxydisulfate or ammonium persulfate;

(4) purification of graft copolymer:

By the graft copolymer that step (3) obtains, use distilled water, absolute ethanol washing respectively successively, dry, pulverize, then by the graft copolymer extracting 24 ~ 48h at 60 ~ 75 DEG C after pulverizing, dry, obtain the heavy metal absorbent after purifying.