CN110860695A

CN110860695A - Preparation method of silver nanoparticles with adjustable size and distribution

Info

Publication number: CN110860695A
Application number: CN201911161855.1A
Authority: CN
Inventors: 安兴业; 杨健; 刘洪斌
Original assignee: Tianjin University of Science and Technology
Current assignee: Tianjin University of Science and Technology
Priority date: 2019-11-25
Filing date: 2019-11-25
Publication date: 2020-03-06

Abstract

The invention belongs to a preparation method of silver nanoparticles with adjustable size and distribution, which comprises the following components: 0.2-2 wt% of nano cellulose, 0.01-1.0 wt% of silver nitrate, 0.01-0.1 wt% of lignosulfonate and 0.01-1.0 wt% of sodium borohydride, and the preparation method comprises the following steps: 1) diluting the prepared nano-cellulose suspension to 0.2-2 wt%, carrying out ultrasonic treatment for 10-30 min, and adding 25-50 g of 0.2-2 wt% dispersed nano-cellulose suspension into a beaker under the condition of magnetic stirring; 2) adjusting the pH value of the nano-cellulose suspension to 3.5-4.5 by using 0.1M HAC-NaAC (Hadoop-NaAC) buffer solution; 3) adding 10-100 mL of lignosulfonate solution into the nano-cellulose suspension and stirring for 10min, and then adding 5-50 mL of silver nitrate solution and stirring for 10 min; 4) dropwise adding a newly prepared 5-50 mL of sodium borohydride aqueous solution into the mixed suspension, and stirring for 10-30 min under magnetic stirring after dropwise adding; 5) and (4) freeze-drying the mixed solution obtained in the step (4) to obtain the nano-cellulose/lignosulfonate/silver nano-composite material.

Description

Preparation method of silver nanoparticles with adjustable size and distribution

Technical Field

The invention relates to a preparation method of silver nanoparticles with adjustable size and distribution, which is mainly applied to the treatment of organic pollutants and emerging pollutants in sewage, in particular to the treatment of the emerging pollutants.

Background

With the continuous development of nano science and nano technology, the preparation and application of nano materials become the research hotspots of researchers at home and abroad. Among them, metal nanoparticles (e.g., metal silver particles) have many advantages, such as good catalytic activity, electrical conductivity, unique electro-optical properties, chemical stability, antibacterial property, and the like, and are widely used in the fields of food, pharmacy, sensor manufacturing, biomedicine, sewage treatment, and the like. However, many of the excellent properties of metal nanoparticles are closely related to the size of their dimensions. The smaller the particle size of the metal nanoparticles to be produced and the narrower the particle size distribution, the higher the performance (catalytic activity, surface reaction activity) thereof. However, when the particle size of the metal nanoparticles becomes smaller and smaller, the high specific surface area and thermal instability thereof will cause aggregation of the nanoparticles, thereby causing a great reduction in performance thereof. One common approach is to incorporate a support to overcome its inherent limitations by supporting/stabilizing the metal nanoparticles. At present, many supports with high specific surface area, such as zeolite, carbon nanotube, titanium dioxide nanotube, polyphosphazene nanotube, etc., have been used to synthesize metal nanoparticles in situ on their surface, and can effectively avoid aggregation of nanoparticles into large particles while keeping the metal nanoparticles at high specific surface area.

In recent years, nanocellulose has been attracting attention as a carrier, mainly due to its characteristics of environmental friendliness, sustainability, biodegradability, high specific surface area, high thermal stability and functionalized surface, and also to be able to effectively overcome the aggregation tendency of metal nanoparticles, as compared with the aforementioned carbon materials, metal oxides and polymers as carriers. Although the introduction of the carrier can effectively overcome the aggregation tendency of the nanoparticles, the uniformity of the particle size distribution cannot be controlled. In addition, the non-uniformity of the particle size distribution of the nanoparticles is caused by the poor solubility of the nanocellulose and the incomplete degradation of the nanocellulose obtained by the degradation of the raw material, which results in some groups that are not conducive to the dispersion of the nanoparticles. Therefore, there is a limitation in using only nanocellulose as a carrier. In order to overcome the inherent limitation of the nano-cellulose and simultaneously enable the particle size of the metal nano-particles to have uniform size distribution and narrow distribution, a surfactant can be added for regulation. The commonly used surfactant is mainly Cetyl Trimethyl Ammonium Bromide (CTAB), the main mechanism of action: 1) the hydroxyl (hydration) on the silver nano-particles and a CTAB hydrophilic group act to generate a space effect; 2) the exposed quaternary ammonium salt ions of CTAB increase the surface charge density of the nano silver. However, the biotoxicity and non-degradability of CTAB compel us to find another green, sustainable, degradable, efficient alternative.

Therefore, it is very important to develop a low-toxicity, easily-degradable, low-cost, low-carbon and green surfactant to completely replace Cetyl Trimethyl Ammonium Bromide (CTAB), and to effectively regulate and control the metal nanoparticles to have smaller particle size and narrow distribution.

Disclosure of Invention

The invention aims to develop a preparation method of silver nanoparticles with adjustable size and distribution, overcomes the inherent thermal instability and aggregation tendency of the silver nanoparticles, realizes the adjustability of the size and the distribution of the silver nanoparticles, reduces the production cost, and has the characteristics of low carbon and environmental protection.

The invention is realized by the following steps of the technical scheme:

step 1: diluting the prepared nano-cellulose suspension to 0.2-2 wt%, carrying out ultrasonic treatment for 10-30 min, and adding 25-50 g of 0.2-2 wt% dispersed nano-cellulose suspension into a beaker under the condition of magnetic stirring;

step 2: adjusting the pH value of the nano-cellulose suspension to 3.5-4.5 by using 0.1M HAC-NaAC (Hadoop-NaAC) buffer solution;

and step 3: adding 10-100 mL of lignosulfonate solution into the nano-cellulose suspension and stirring for 10min, and then adding 5-50 mL of silver nitrate solution and stirring for 10 min;

and 4, step 4: dropwise adding a newly prepared 5-50 mL sodium borohydride aqueous solution into the mixed suspension, and after dropwise adding, magnetically treating

Stirring for 10-30 min under force stirring;

and 5: and (4) freeze-drying the mixed solution obtained in the step (4) to obtain the nano-cellulose/lignosulfonate/silver nano-composite material.

The nano-cellulose in the step 1 is obtained by acid hydrolysis of raw materials, wherein the raw materials are selected from any one of softwood, hardwood, chitin and bacterial fibers.

The lignosulfonate described in the step 3 is any one of sodium lignosulfonate, calcium lignosulfonate, potassium lignosulfonate, magnesium lignosulfonate and ammonium lignosulfonate.

The concentration of the lignosulfonate solution is 0.01-0.1 wt%.

The concentration of the silver nitrate solution is 0.01-1.0 wt%.

The concentration of the sodium borohydride solution is 0.01-1.0 wt%.

And 4, adding the sodium borohydride in a way of 4-8 seconds one drop.

The invention has the beneficial effects that:

the preparation process of the silver nanoparticles with adjustable size and distribution is simple and feasible, and the particle size (5-20 nm) and the distribution uniformity of the silver nanoparticles are effectively adjusted and controlled under the synergistic effect of the nano-cellulose and the lignosulfonate.

The nano-cellulose and the lignosulfonate have the advantages of wide raw material source, low price, biodegradability, environmental-friendly and pollution-free preparation process, and capability of reducing excessive dependence on non-degradable and biotoxic carriers such as carbon materials, metal oxides and polymers or surfactant Cetyl Trimethyl Ammonium Bromide (CTAB). Meanwhile, the discovery has the characteristics of simple and feasible preparation process and no need of purification.

Drawings

FIG. 1 is a (a) TEM image, (b) AFM image and (c) 3D structure diagram of AFM of nano-silver particles; FIG. 2 is (a) TEM image and (b) EDS image of nanocellulose/silver nanocomposite; FIG. 3 is (a) TEM image and (b) EDS image of nanocellulose/lignosulfonate/silver nanocomposite; fig. 4 is a statistical graph of (a) ultraviolet-visible (UV-vis) absorption spectra of nanocellulose/lignosulfonate, nanosilver, nanocellulose/lignosulfonate/nanosilver, and particle size distributions of nanocellulose/nanosilver composite (b) and nanocellulose/lignosulfonate/nanosilver composite.

Detailed Description

The invention will be further illustrated by the following examples

Example 1

Adding 20mL of silver nitrate solution into a beaker, adjusting the pH of the solution to about 4 by using 0.1M HAC-NaAC buffer solution, then dropwise adding 30mL of newly prepared sodium borohydride aqueous solution into the solution, stirring for 30min under magnetic stirring after dropwise adding, and finally carrying out Transmission Electron Microscope (TEM) and Atomic Force Microscope (AFM) tests on the obtained colloidal solution (the test result is shown in attached figure 1).

Example 2

The prepared nanocellulose suspension is diluted to 0.2 wt%, treated with ultrasound for 10min, 25g of the 0.2 wt% dispersed nanocellulose suspension is added to a 150mL beaker under magnetic stirring, and the pH of the solution is adjusted to about 4 with a buffer solution of 0.1 MHAC-NaAC. Then adding 20mL of silver nitrate solution into the suspension, dropwise adding a newly prepared 30mL of sodium borohydride aqueous solution into the mixed suspension, stirring for 30min under magnetic stirring after dropwise adding, and finally carrying out Transmission Electron Microscope (TEM) and energy spectrum (EDS) tests on the obtained colloidal solution (the test result is shown in figure 2).

Example 3

Diluting the prepared nano-fiber rope suspension to 0.2 wt%, carrying out ultrasonic treatment for 10min, adding 25g of the 0.2 wt% dispersed nano-cellulose suspension into a 150mL beaker under the condition of magnetic stirring, and adjusting the pH of the solution to about 4 by using a buffer solution of 0.1 MHAC-NaAC. Then adding 10mL of lignosulfonate solution into the nano-cellulose suspension and stirring for 10min, and then adding 200mL of silver nitrate solution and stirring for 10 min; and (3) dropwise adding the newly prepared 30mL of sodium borohydride aqueous solution into the mixed suspension, stirring for 30min under magnetic stirring after dropwise adding is finished, and finally carrying out Transmission Electron Microscope (TEM) and energy spectrum (EDS) tests on the obtained colloidal solution (the test result is shown in attached figure 3).

Example 4

The nano-silver sol, the nano-cellulose/silver nano-sol, the nano-cellulose/lignosulfonate/silver nano-sol and the nano-cellulose/lignosulfonate mixed suspension respectively obtained in the embodiments 1, 2 and 3 are prepared to the same concentration, and an ultraviolet-visible (UV-vis) spectrophotometer is respectively carried out for testing and particle size distribution statistics is carried out on nano-silver particles of the nano-cellulose/silver nano-composite material and the nano-cellulose/lignosulfonate/silver nano-composite material from a TEM picture (the test and the statistical result are shown in figure 4).

Test results show that the silver nanoparticles are easy to aggregate into clusters, have large size and poor uniformity, and can effectively avoid the aggregation of the silver nanoparticles after the nanocellulose is introduced as a carrier, but the uniformity of size distribution is still poor. After the surfactant lignosulfonate is introduced, the size and the distribution of the silver nanoparticles can be regulated and controlled again, and the silver nanoparticles with smaller size and more uniform particle size distribution are obtained. It can be seen from the ultraviolet-visible (UV-vis) spectrophotometer that the characteristic peak of nano silver at about 405nm wavelength is more obvious under the synergistic regulation and control of nano cellulose and lignosulfonate. Therefore, under the co-regulation and control action of the nano-cellulose and the lignosulfonate, the preparation of the nano-silver particles with controllable size and distribution can be realized.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A preparation method of silver nanoparticles with adjustable size and distribution is characterized by comprising the following steps:

and 4, step 4: dropwise adding a newly prepared 5-50 mL of sodium borohydride aqueous solution into the mixed suspension, and stirring for 10-30 min under magnetic stirring after dropwise adding;

2. The method of claim 1, further comprising: the nano-cellulose is obtained by acid hydrolysis of raw materials, wherein the raw materials are derived from any one of softwood, hardwood, chitin and bacterial fibers.

3. The method of claim 1, further comprising: the lignosulfonate is any one of sodium lignosulfonate, calcium lignosulfonate, potassium lignosulfonate, magnesium lignosulfonate and ammonium lignosulfonate.

4. The method of claim 1, further comprising: the concentration of the lignosulfonate solution is 0.01-0.1 wt%.

5. The method of claim 1, further comprising: the concentration of the silver nitrate solution is 0.01-1.0 wt%.

6. The method of claim 1, further comprising: the concentration of the sodium borohydride solution is 0.01-1.0 wt%.

7. The method of claim 1, further comprising: and 4, adding the sodium borohydride in a way of 4-8 seconds one drop.

8. The method of claim 1, further comprising: the sodium borohydride solution is prepared for use.

9. The method of claim 1, further comprising: the preparation method comprises the step of firstly adjusting the pH value of the nano-cellulose suspension to 3.5-4.5.

10. The method of claim 1, further comprising: the preparation method comprises the step of obtaining the nano-cellulose/lignosulfonate/silver nano-composite material by freezing and drying the mixed solution after the reaction.

11. The method of claim 1, further comprising: the preparation method comprises the step of carrying out ultrasonic treatment on the nano-cellulose for 10-30 min to obtain a uniformly dispersed suspension.