GO-SiO2 solid-phase extraction adsorbent as well as preparation method and application thereof

Abstract

According to the GO-SiO2 solid-phase extraction adsorbent and the preparation method and application thereof, a GO-SiO2 hybrid material is successfully synthesized through a simple and economical method, GO-SiO2 prepared through the method can be successfully used as a solid-phase extraction agent to be used for enriching and removing Ni, Cr, Zn, Cu and Co in a water sample by means of the large surface area of GO-SiO2, and the GO-SiO2 can be used as a solid-phase extraction agent. The removal rate of the solid-phase extraction agent on the heavy metals in the water can reach 95% or above in a relatively wide pH range (4-10) and under the solid-phase dosage of 0.15 g; the method has the biggest advantages that the synthesis is simple, the solid phase dosage is small, the adsorption surface area is large, the FAAS detection limit is low, and the synthesized GO-SiO2 solid phase extraction adsorbent can be widely applied to extraction and recovery of heavy metals in water.

Description

Technical Field

[0001] The invention relates to the technical field of solid phase extraction, in particular to a GO-SiO2 solid phase extraction adsorbent and a preparation method and application thereof. Background Art

[0002] One of the serious problems facing the world in the future is the lack of sufficient water resources. This problem can be caused by the scarcity, dryness and pollution of available water resources. The increase in industrialization, environmental pollution, population growth and human waste are the main causes of water pollution. Water pollution impurities can be divided into organic and inorganic chemicals. Heavy metals are the source of inorganic chemical impurities. It plays an important role in the water resources of organisms within a certain limit, but water with heavy metal content exceeding the limit may threaten life.

[0003] In order to prevent poisoning and environmental pollution caused by toxic metals, it is necessary to selectively separate such toxic metal pollution. People use various technologies to remove some metals and compounds that cause environmental pollution, especially water pollution. Therefore, the removal and pre-enrichment methods of heavy metal ions in water include chemical precipitation, electrochemical treatment, liquid phase extraction and solid phase extraction (SPE).

[0004] In recent years, there has been a development of adsorbent-based solid phase extraction techniques such as dispersed solid phase extraction (DSPE), stir bar sorptive extraction (SBSE), and packed adsorbent microextraction (MEPS). Dispersed solid phase extraction has similar properties to solid phase extraction, with the characteristics of low adsorbent dosage, strong dispersion ability, large adsorbent interaction, and high extraction efficiency. There are many types of adsorbents, such as inorganic oxides such as silica and alumina, and absorbent polymers such as polystyrene-divinylbenzene resins and carbon-based materials. Materials such as nanoparticles, films, and nanotubes have a wide range of applications in technology due to their physical properties and very small size.

[0005] In recent years, carbon-based materials have been transformed into innovative nanomaterials, resulting in solid phases with different characteristics. In particular, graphene (G) and graphene oxide (GO) have been used as solid phase extraction adsorbents due to their easy derivatization process, high surface-to-volume ratio, and unique thermal, mechanical, and electronic properties. In solid phase extraction, graphene oxide is a more favorable material than GO, which contains a considerable number of oxygen atoms on the surface, such as hydroxyl, epoxy, and carbonyl groups. Due to this property, GO is more hydrophilic than G.

[0006] At present, it is still a difficult problem to develop a universal building block that can be directly applied to most surfaces to promote the development of superhydrophilic coatings. The role of the universal building block is to construct a superhydrophilic surface through GO sheets coated with silica nanoparticles. Therefore, the present inventors designed and developed a modified dispersed solid phase material to obtain a more effective and selective adsorbent to effectively extract and recover heavy metals from water. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a GO-SiO2 solid phase extraction adsorbent and a preparation method and application thereof. The technical scheme adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing a GO-SiO2 solid phase extraction adsorbent, the steps comprising:

[0009] S1. dispersing graphene oxide in a mixture of ethanol and water so that the concentration of graphene oxide is 8 g / mL;

[0010] S2. Add NH4OH to the graphite oxide solution prepared in step S1 to adjust the pH to 8-11, add 98% tetraethyl orthosilicate, stir evenly, wash the mixture with distilled water until the pH value of the medium is 6.5-7.5, and dry to obtain GO-SiO2.

[0011] Preferably, in step S1, in the mixture of ethanol and water, the volume ratio of ethanol to water is 7:1.

[0012] In a second aspect, a GO-SiO2 solid phase extraction adsorbent prepared by the above-mentioned preparation method of the GO-SiO2 solid phase extraction adsorbent is provided.

[0013] In a third aspect, the above-mentioned GO-SiO2 solid phase extraction adsorbent is provided for use in removing heavy metals from water.

[0014] The beneficial effects of the present invention are as follows: the present invention successfully synthesizes GO-SiO2 hybrid material by a simple and economical method. The GO-SiO2 prepared by the method is successfully used as a solid phase extractant to remove Ni, Cr, Pb, Zn, Cd, Cu and Co, and enrich Ni, Cr, Zn, Cu and Co in water samples by virtue of its large surface area. The removal rate of the optimized solid phase extractant can reach more than 95% in a wide pH range (4-10) and a solid phase dosage of 0.15g; the greatest advantage of this method is that it is simple to synthesize, has a small solid phase dosage, has a large adsorption surface area, and has a low FAAS detection limit, and can be widely used in extracting and recovering heavy metals in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0016] Figure 1 This is the transmission electron microscopy image of GO-SiO2;

[0017] Figure 2 (a) The effect of GO-SiO2 dosage on metal ion removal rate (0.1-0.2 g), (b) The effect of pH on metal ion removal rate. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with embodiments and drawings.

[0019] First, 98% ethanol and water (18.3 μS) solution were added to a beaker at a volume ratio of 7:1, and then 14.4 g of graphene oxide was added and dispersed therein to make the concentration 8 g / mL.

[0020] Then, NH4OH was added to the prepared graphene dispersion to adjust the pH to about 10, and 5.6 mL of 98% TEOS was added and stirred for 12 h. At the end of the synthesis, the mixture was washed with distilled water until the pH of the medium was 7 and dried in a vacuum desiccator to obtain GO-SiO2.

[0021] Furthermore, in the present embodiment, the volume ratio of ethanol to water in the aqueous solution is 7:1. The method is simple to operate, low in cost, does not require high temperature and high pressure, does not require strong acid or alkali, and has little pollution to the environment.

[0022] The silica particles are spherical, and the silica nanoparticles are densely bound to the graphene oxide layer. After the graphene oxide flakes are self-assembled with SiO2, the GO-SiO2 hybrid structure evenly covers the silica nanoparticles on the surface of the layered graphene oxide flakes.

[0023] In summary, the present invention successfully synthesized GO-SiO2 hybrid material by a simple and economical method. After testing, GO-SiO2 can be successfully used for the enrichment of Ni, Cr, Zn, Cu and Co in water samples by virtue of its large surface area, and can be used as a solid phase extractant for the removal of Ni, Cr, Pb, Zn, Cd, Cu and Co. The solid phase extractant prepared by the present invention can achieve a removal rate of more than 95% for heavy metals in water in a wide pH range (4-10) and a solid phase dosage of 0.15g.

[0024] In addition, this method has simple synthesis, small amount of solid phase, large adsorption surface area and low FAAS detection limit.

[0025] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a GO-SiO2 solid phase extraction adsorbent, characterized in that the steps include: S1. dispersing graphene oxide in a mixture of ethanol and water so that the concentration of graphene oxide is 8 g / mL; S2. Add NH4OH to the graphite oxide solution prepared in step S1 to adjust the pH to 8-11, add 98% tetraethyl orthosilicate, stir evenly, wash the mixture with distilled water until the pH value of the medium is 6.5-7.5, and dry to obtain GO-SiO2.

2. The method for preparing a GO-SiO2 solid phase extraction adsorbent according to claim 1, characterized in that: In step S1, in the mixed solution of ethanol and water, the volume ratio of ethanol to water is 7:

1.

3. A GO-SiO2 solid phase extraction adsorbent, characterized in that: The GO-SiO2 solid phase extraction adsorbent is prepared by the preparation method of the GO-SiO2 solid phase extraction adsorbent in claim 1 or 2.

4. The GO-SiO2 solid phase extraction adsorbent as described in claim 3 is used to remove heavy metals in water.

Images