CN103908951B - The preparation method of thiocarbohydrazide cross-linked chitosan heavy metal absorbent - Google Patents

Abstract

The present invention discloses the preparation method of a kind of thiocarbohydrazide cross-linked chitosan heavy metal absorbent, and processing step is: at room temperature, is dissolved completely by chitosan (deacetylation degree reaches 90%) in certain density acetum; Add thiocarbohydrazide to above-mentioned solution, it is stirred to solute and all dissolves. Add formalin (40%, v/v) to above-mentioned solution, stir. Above-mentioned acquisition product is added sodium hydroxide lye neutralize, through repeatedly washing, methanol wash, washing, filtration. At 40 DEG C, vacuum-drying is to constant weight, can obtain product color sorrel thiocarbohydrazide cross-linked chitosan heavy metal absorbent. The method has synthesis step short (one kettle way), and aftertreatment is simple, low production cost and the feature such as environmental friendliness, advantages of good adsorption effect. If dropping into concrete Application and Development, with the obvious advantage.

Description

The preparation method of thiocarbohydrazide cross-linked chitosan heavy metal absorbent

Technical field

The invention belongs to sorbent material manufacture technology field, it is specifically related to the preparation method of a kind of thiocarbohydrazide cross-linked chitosan heavy metal absorbent.

Background technology

The development of modern industry so that heavy metal water pollution is all the more serious. This kind of harm not only relates to the surface water resources such as rivers and lakes, and spreads gradually to underground water. " water crisis " becomes the problem hindering China's economic construction and living standards of the people to improve. And on the other hand, metals resources is also exhausted gradually. Therefore strictly carrying out purifying water process, strengthen emission standard and reclaim heavy metals in industrial wastewater ion, carrying out Sustainable development has very meaning. The process of current waste water has 4 kinds: chemical precipitation method, charcoal absorption, solvent extration and ion-exchange absorption. Chemical precipitation method adopts basic material, makes heavy metal precipitate out with its hydroxide form, and method steps is complicated, and place area occupied reaches, poor efficiency and do not have advantage economically; Charcoal absorption efficiency height, but equipment requirements height, thus cause Financial cost height; Extraction is difficult to extensive expansion substantially. Therefore, research in recent years concentrates on the research and development of lower cost high-level efficiency heavy metal absorbent. Chitosan is the abundant natural polymer of a class content, has cheap and easy to get, the feature of good biocompatibility, and therefore sorbent material based on natural material receives much concern.

Chitosan (chitosan), also known as chitosan, is that the chitin (chitin) extensively existed by nature obtains through deacetylation, and chemical name is Chitosan (1-4)-2-amino-B-D glucose. A remarkable characteristic of chitosan is adsorptive power. The material of many lower molecular weights, such as metal ion, cholesterol, triglyceride level, cholic acid and organic mercury etc., can be adsorbed by chitosan. Particularly chitosan is possible not only to absorption magnesium, potassium, and can adsorb zinc, calcium, mercury and uranium. The adsorption activity of chitosan can play a role selectively. These metal ions concentration in human body is too high is harmful. Such as, in blood, cupric ion (Cu2+) excessive concentration can cause copper poisoning, even produces carcinogenic consequence. Now prove that chitosan is efficient inner complex medium. The size of the adsorptive power of chitosan depends on its deacetylation. Deacetylation is more big, and adsorptive power is more strong.

Chitosan is insoluble to water, can form throwing out in acid condition. Its absorption property and a large amount of activity hydroxy and the amino that contain are inseparable. These chemical active radicals can be easy to participate in some chemical reactions, therefore makes chitosan have and is modified the possibility being called more excellent performance material.

Summary of the invention

The bright object of this is, a kind of thiocarbohydrazide is provided (to have another name called 1,3-diamino thiocarbamide) preparation method of cross-linked chitosan heavy metal absorbent, the method is by chemical modification method, and transformation chitosan structure, makes it to become cross-linked structure, the thiocarbohydrazide cross-linked chitosan heavy metal absorbent obtained, it is applicable to sewage treatment process, increases absorption reaction site and Swelling Capacity, it is achieved the dissolution of contaminated water of the wider acidity scope of maximum.

In order to realize above-mentioned task, the present invention takes following technical solution:

The preparation method of a kind of thiocarbohydrazide cross-linked chitosan heavy metal absorbent, it is characterised in that, operate as follows:

Step one, at room temperature (30 degrees centigrade), be dissolved in the acetum that concentration is 20% by chitosan;

Step 2, adds the thiocarbohydrazide that mol ratio is 1.3 times amount in above-mentioned solution, stirs and all dissolves to thiocarbohydrazide for 45 minutes;

Step 3, in the solution of step 2, adds the formalin that concentration is 40%, and when low whipping speed is 1000-2000 rev/min, stirring reaction 6 hours, obtains reaction product;

Step 4, adds the reaction product of acquisition the sodium hydroxide lye that the mass concentration with acetic acid equivalent is 5%wt and carries out being neutralized to alkalescence, filters after 3 washings, then with methanol wash, filtration under diminished pressure;

Step 5, the product after methanol wash, filtration under diminished pressure is inserted in vacuum drying oven, is dried to constant weight when 40 DEG C, can obtain the thiocarbohydrazide cross-linked chitosan heavy metal absorbent of color sorrel.

The method of the present invention has synthesis step short (one kettle way), and aftertreatment is simple, low production cost and the feature such as environmental friendliness, advantages of good adsorption effect. If dropping into concrete Application and Development, with the obvious advantage. And can be used in the process of the pentavalent arsenic in trade effluent, lead ion, cadmium ion etc.

Accompanying drawing explanation

Fig. 1 is the composition principle schematic diagram of the method for the present invention;

Fig. 2 is the thiocarbohydrazide cross-linked chitosan heavy metal absorbent infrared spectrogram that the present invention obtains.

Fig. 3 is TGA and the DSC figure of the thiocarbohydrazide cross-linked chitosan heavy metal absorbent that the present invention obtains.

The scanning electron microscope (SEM) photograph of the thiocarbohydrazide cross-linked chitosan heavy metal absorbent surface topography that Fig. 4 the present invention obtains.

Below in conjunction with drawings and Examples, the present invention is described in further detail.

Embodiment

The design philosophy of the present invention is, introduces the functional group with adsorptive power to increase adsorption site in chitosan structure, and obtaining product is sorrel solid particulate, in an acidic solution, it is easy to occur swelling, thus improves metal biosorption ability.

Below in an example, chitosan is timbering material, and thiocarbohydrazide is that function strengthens group, and formaldehyde is linking agent.

Chitosan is that deacetylation degree reaches more than 90%; Thiocarbohydrazide can be technical grade (99%), and formaldehyde is technical grade formaldehyde (40%).

Embodiment 1: the preparation of thiocarbohydrazide cross-linked chitosan heavy metal absorbent

The present embodiment provides the preparation method of a kind of thiocarbohydrazide cross-linked chitosan heavy metal absorbent, and composition principle is see Fig. 1, and concrete making step is:

(1) at room temperature (30 degrees centigrade), in the deionized water of 40mL, 10mL Glacial acetic acid and 0.8g chitosan is added, until chitosan dissolves completely;

(2) add in 0.45g thiocarbohydrazide (1.3 times amount, mol ratio) to above-mentioned solution system, stir 45 minutes solutes to thiocarbohydrazide and all dissolve.

(3) formalin (40%, v/v is added; 1.3 times amount, calculate by formaldehyde) 1mL is to above-mentioned solution, and when low whipping speed is 1000-2000 rev/min, stirring reaction 6 hours, obtains reaction product;

(4) reaction product of acquisition is added 40mL sodium hydroxide solution (5%wt) neutralization, filtration under diminished pressure after 3 washings, then use methanol wash filtration under diminished pressure.

(5) product after methanol wash, filtration under diminished pressure is inserted in vacuum drying oven, is dried to constant weight when 40 DEG C, can obtain the thiocarbohydrazide cross-linked chitosan heavy metal adsorbent product of color sorrel. The scanning electron microscope (SEM) photograph of surface topography is as shown in Figure 4.

Embodiment 2: the adsorption experiment of thiocarbohydrazide cross-linked chitosan heavy metal absorbent

Concrete experimental procedure is:

Take the thiocarbohydrazide cross-linked chitosan heavy metal absorbent that 50mg is prepared according to the method described above, drop in the Erlenmeyer flask of 250mL, adding concentration is that 500mg/L contains mercury ion solution, 30 DEG C, rotating speed be that the vibrator of 100 revs/min shakes 8 hours, until adsorption equilibrium.

Above-mentioned solution is filtered, takes out 15mL solution, remain ion concentration of mercury with in ion concentration of mercury tester test soln. According to following formulae discovery adsorptive capacity:

$q=\left(\frac{C_0-C_e}{m}\right)V$

In formula, q represents adsorptive capacity, C₀Represent mercury ion starting point concentration, C_eRepresenting the ion concentration of mercury after adsorption equilibrium, V is liquor capacity, and m represents adsorbent amount.

As shown in Figure 2, TGA and DSC schemes as shown in Figure 3 infrared spectra. Experimental result shows, adopts this thiocarbohydrazide cross-linked chitosan heavy metal absorbent, is 99% to the adsorption rate of mercury ion, and adsorptive capacity is 2.2mmol/g.

Claims (1)

1. the preparation method of a thiocarbohydrazide cross-linked chitosan heavy metal absorbent, it is characterised in that, operate as follows:

At room temperature, (1) chitosan is dissolved in acetum that volumetric concentration is 20%;

(2) in above-mentioned solution, add the thiocarbohydrazide that mol ratio is 1.3 times amount, stir and all dissolve to thiocarbohydrazide for 45 minutes;

(3) in the solution of step (2), adding the formalin that volumetric concentration is 40%, when low whipping speed is 1000-2000 rev/min, stirring reaction 6 hours, obtain reaction product;

(4) reaction product of acquisition adds the sodium hydroxide lye that the mass concentration with acetic acid equivalent is 5%wt to carry out being neutralized to alkalescence, filter after 3 washings, then with methanol wash, filtration under diminished pressure;

(5) product after methanol wash, filtration under diminished pressure is inserted in vacuum drying oven, is dried to constant weight when 40 DEG C, can obtain the thiocarbohydrazide cross-linked chitosan heavy metal absorbent of color sorrel;

Described thiocarbohydrazide is the technical grade thiocarbohydrazide that deacetylation degree reaches more than 90%;

Described formaldehyde is technical grade formaldehyde.