CN106000319A - Adsorption material for removal of trace arsenic from water and method for removal of trace arsenic from water therewith - Google Patents

Abstract

The invention discloses an adsorption material for removal of trace arsenic from water and a method for removal of trace arsenic from water with the adsorption material. The adsorption material is prepared by the method of: mixing a graphene oxide dispersion liquid with a polyvinyl alcohol solution, then performing vacuum pumping filtration to obtain a graphene oxide membrane, and finally carrying out hydrazine hydrate reduction to obtain a graphene membrane, i.e. the adsorption material. The method for removal of trace arsenic from water consists of: adjusting the concentration of arsenic in to-be-treated water to 0.1-5mg/L, and adjusting the pH value of the water to 2-9, and then adding the adsorption material to perform adsorption for more than 12h, thus realizing removal of trace arsenic (III) from water. And the adding amount of the adsorption material is 0.1g/L-0.4g/L. The adsorption material graphene membrane obtained by the invention has high removal efficiency on trace arsenic (III) in water, and can reach 99% or more than 99%.

Description

Adsorbent material for removing trace arsenic in water and its removal of trace arsenic in water method

technical field

The invention relates to the removal of arsenic in water, in particular to an adsorption material for removing trace arsenic in water and a method for removing trace arsenic in water, belonging to the technical field of water treatment.

Background technique

As one of the most toxic elements, arsenic (Ⅲ) widely exists in natural water bodies and human drinking water, and poses a serious threat to human health and ecological environment, so it has attracted widespread attention. The U.S. Environmental Protection Agency recently stipulated that the concentration of arsenic in drinking water should not exceed 10ppb. How to effectively eradicate arsenic in water is very important. The traditional arsenic removal methods mainly include oxidation method, precipitation method, flocculation method, ion exchange method, reverse osmosis method, adsorption method, etc. Among them, the adsorption method has been valued by people because of its simplicity, high efficiency and low cost. Conventional adsorption materials such as activated carbon, fly ash, minerals, etc. can remove arsenic (Ⅲ) in water, but it is difficult to eradicate trace arsenic (Ⅲ) in water, and the regeneration performance is poor. Therefore, finding an adsorbent material that can effectively remove trace arsenic in water is a goal pursued by people.

Graphene is a new type of two-dimensional carbon nanomaterial with a large specific surface area (2630m ² /g) and abundant π electrons, so it can adsorb heavy metal ions through Lewis acid-base interaction, and shows strong adsorption performance. Similarly, graphene also showed strong removal efficiency for trace arsenic in water. However, due to the π-π stacking effect, graphene in aqueous solution is easy to agglomerate, and it is difficult to recycle and reuse. Therefore, it is particularly urgent to develop separable graphene-based composites for the removal of trace arsenic in water.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide an adsorption material for removing trace arsenic in water and a method for removing trace arsenic in water. The present invention can efficiently remove trace arsenic in water.

Technical scheme of the present invention is realized like this:

An adsorption material for removing traces of arsenic in water, prepared as follows, mixing graphene oxide dispersion liquid and polyvinyl alcohol solution, then vacuum filtration to obtain graphene oxide film, and finally preparing graphite through hydrazine hydrate reduction Graphene film, the graphene film is the adsorption material.

The specific preparation steps are as follows,

1) Prepare a graphene oxide dispersion with a concentration of 5 mg/ml and a polyvinyl alcohol solution with a concentration of 0.2 wt%, respectively;

2) Mix the graphene oxide dispersion and polyvinyl alcohol solution with ultrasound to obtain a mixed solution. The volume ratio of graphene oxide dispersion and polyvinyl alcohol solution is 1: (0-4);

3) Add the mixed solution to a vacuum filtration device and filter to obtain a graphene oxide membrane;

4) adding an appropriate amount of deionized water to the graphene oxide film, and then adding an appropriate amount of hydrazine hydrate to the deionized water to reduce the graphene oxide film to obtain a graphene film;

5) Wash the graphene membrane with deionized water until neutral, and dry it in a drying oven.

The graphene oxide dispersion is prepared as follows, graphene oxide is added to deionized water, and ultrasonically dispersed for 1 to 4 hours; the polyvinyl alcohol solution is prepared as follows, polyvinyl alcohol is added to 90 ~ Dissolve in deionized water at 98°C for 3-5 hours.

The method of removing trace arsenic in water is to adjust the concentration of arsenic in the water to be treated to 0.1~5mg/L, adjust the pH value of the water to 2-9, and then add the above-mentioned adsorption material to absorb for more than 12 hours, that is, to realize trace arsenic in water. The amount of arsenic (Ⅲ) removal; the amount of adsorption material added is 0.1g/L~0.4g/L.

Preferably, the concentration of arsenic in the water to be treated is adjusted to 5ppm, and the pH value of the water is adjusted to 6, and then the adsorption material described in any one of claims 1-3 is added for adsorption for more than 12 hours, that is, trace arsenic (Ⅲ) in water can be achieved removal.

Compared with the prior art, the present invention has the following beneficial effects:

1) The adsorption material graphene membrane obtained in the present invention has a high removal efficiency for trace arsenic (Ⅲ) in water, up to more than 99%.

2) The graphene membrane of the adsorption material of the present invention is prepared by vacuum filtration technology and chemical reduction method, the preparation process is simple and fast, the operation is convenient, and it can be produced on a large scale.

3) Appropriate polyvinyl alcohol in the graphene film can prevent the mutual accumulation of graphene, and has a supporting effect on the graphene nanosheets. Through the support, the layer spacing is increased, and more adsorption sites are exposed, which is beneficial to the arsenic in graphene. Diffusion and Adsorption in Membrane Interlayers.

Description of drawings

Fig. 1 is the digital photo figure of the graphene film that embodiment 4 makes.

Fig. 2 is the cross-sectional SEM figure of the graphene film that embodiment 4 makes.

detailed description

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings.

The adsorption material for removing trace arsenic in the water body of the present invention is prepared as follows: the graphene oxide dispersion liquid and the polyvinyl alcohol solution are mixed, then the graphene oxide film is obtained by vacuum filtration, and finally the graphite is obtained by reducing with hydrazine hydrate Graphene film, the graphene film is the adsorption material.

Concrete preparation steps of the present invention are as follows,

1) Prepare graphene oxide dispersion and polyvinyl alcohol solution respectively; wherein the concentration of graphene oxide dispersion is 5 mg/ml and it is prepared according to the following method, adding graphene oxide into deionized water and ultrasonically dispersing for 1-4 hours; The polyvinyl alcohol solution has a concentration of 0.2 wt% and is prepared as follows: add polyvinyl alcohol into deionized water at 90-98°C and dissolve for 3-5 hours.

2) Mix the graphene oxide dispersion and polyvinyl alcohol solution with ultrasound to obtain a mixed solution; the volume ratio of graphene oxide dispersion and polyvinyl alcohol solution is 1: (0-4); preferably 1: (1-3); The optimum is 1:2;

3) Add the mixed solution to a vacuum filtration device and filter to obtain a graphene oxide membrane;

4) Add the graphene oxide film to an appropriate amount of deionized water, and then add an appropriate amount of hydrazine hydrate to reduce the graphene oxide film to obtain a graphene film; the purpose of adding hydrazine hydrate is to reduce the oxygen-containing groups on the surface of graphene oxide. The amount may be controlled according to the purpose.

5) Wash the graphene membrane with deionized water until neutral, and dry it in a drying oven.

The method for removing trace arsenic in the water body of the present invention first prepares the concentration of arsenic in the water body to be treated to 0.1-5 mg/L, and adjusts the pH value of the water body to 2-9, and then adds the adsorption material prepared by the present invention to absorb for more than 12 hours , that is to achieve the removal of trace arsenic (Ⅲ) in water; the amount of adsorption material added is 0.1g/L~0.4g/L.

Preferably, first prepare the concentration of arsenic in the water to be treated to 5ppm, and adjust the pH value of the water to 6, then add 0.2g per liter of water to the adsorption material prepared by the present invention for adsorption for more than 12 hours, that is, trace arsenic in water ( Ⅴ) Removal.

Below in conjunction with specific embodiment, further illustrate the present invention.

Example 1

(1) Add graphene oxide into deionized water, sonicate for 1 hour to obtain a 5 mg/ml graphene oxide dispersion;

(2) Add polyvinyl alcohol to 95°C deionized water and dissolve for 3 hours to obtain a 0.2 wt% polyvinyl alcohol solution;

(3) Mix 1ml of graphene oxide dispersion with 0ml of polyvinyl alcohol solution for ultrasound, that is, the volume ratio of the two is 1:0, that is, no polyvinyl alcohol solution is added;

(4) Add the mixed solution into a vacuum filtration device and filter to obtain a graphene oxide membrane;

(5) Put the graphene oxide membrane prepared above into 5ml of deionized water, and then add 1ml of hydrazine hydrate for reduction to obtain a graphene membrane;

(6) Wash the graphene membrane with deionized water until it is neutral, and dry it in a drying oven.

Example 2

(1) Add graphene oxide into deionized water, sonicate for 2 hours to obtain a 5 mg/ml graphene oxide dispersion;

(2) Add polyvinyl alcohol to 92°C deionized water and dissolve for 3 hours to obtain a 0.2 wt% polyvinyl alcohol solution;

(3) Mix 1ml of graphene oxide dispersion with 1ml of polyvinyl alcohol solution for ultrasound, that is, the volume ratio of the two is 1:1;

(4) Add the mixed solution into a vacuum filtration device and filter to obtain a graphene oxide membrane;

(5) Put the graphene oxide membrane prepared above into 5ml of deionized water, and then add 1ml of hydrazine hydrate for reduction to obtain a graphene membrane;

(6) Wash the graphene membrane with deionized water until it is neutral, and dry it in a drying oven.

Example 3

(1) Add graphene oxide into deionized water, sonicate for 2 hours to obtain a 5 mg/ml graphene oxide dispersion;

(2) Add polyvinyl alcohol to 96°C deionized water and dissolve for 4 hours to obtain a 0.2 wt% polyvinyl alcohol solution;

(3) Mix 1ml of graphene oxide dispersion with 2ml of polyvinyl alcohol solution for ultrasound, that is, the volume ratio of the two is 1:2;

(4) Add the mixed solution into a vacuum filtration device and filter to obtain a graphene oxide membrane;

(5) Put the graphene oxide membrane prepared above into 5ml of deionized water, and then add 3ml of hydrazine hydrate for reduction to obtain a graphene membrane;

(6) Wash the graphene membrane with deionized water until it is neutral, and dry it in a drying oven.

Example 4

(1) Add graphene oxide into deionized water, sonicate for 4 hours to obtain a 5 mg/ml graphene oxide dispersion;

(2) Add polyvinyl alcohol to 98°C deionized water and dissolve for 4 hours to obtain a 0.2 wt% polyvinyl alcohol solution;

(3) Mix 1ml of graphene oxide dispersion with 3ml of polyvinyl alcohol solution for ultrasound, that is, the volume ratio of the two is 1:3;

(4) Add the mixed solution into a vacuum filtration device and filter to obtain a graphene oxide membrane;

(5) Put the graphene oxide membrane prepared above into 5ml of deionized water, and then add 5ml of hydrazine hydrate for reduction to obtain a graphene membrane;

(6) Wash the graphene membrane with deionized water until it is neutral, and dry it in a drying oven.

Fig. 1 is the digital photo figure of the graphene film that embodiment 4 makes. Fig. 2 is the cross-sectional SEM figure of the graphene film that embodiment 4 makes.

Example 5

(1) Add graphene oxide into deionized water, sonicate for 4 hours to obtain a 5 mg/ml graphene oxide dispersion;

(2) Add polyvinyl alcohol to 98°C deionized water and dissolve for 4 hours to obtain a 0.2 wt% polyvinyl alcohol solution;

(3) Mix 1ml of graphene oxide dispersion with 4ml of polyvinyl alcohol solution for ultrasound, that is, the volume ratio of the two is 1:4;

(4) Add the mixed solution into a vacuum filtration device and filter to obtain a graphene oxide membrane;

(5) Put the graphene oxide membrane prepared above into 5ml of deionized water, and then add 4ml of hydrazine hydrate for reduction to obtain a graphene membrane;

(6) Wash the graphene membrane with deionized water until it is neutral, and dry it in a drying oven.

In order to verify the effect of the graphene membrane adsorption material prepared by the present invention on removing traces of arsenic (Ⅲ) in water: first prepare 5 parts of the same 5 ppm arsenic solution, then adjust their pH to 6 respectively, and then add 5 parts of arsenic (Ⅲ) solution The graphene membrane adsorption materials prepared in Examples 1-5 were sequentially added to the mixture and treated for more than 12 hours to complete the adsorption of trace arsenic (III) in water. The experimental results are shown in Table 1.

Table 1 Removal efficiency of arsenic(Ⅲ) in water by graphene membrane

Example 1 Example 2 Example 3 Example 4 Example 5 Removal efficiency 88.2% 95.4% 99.6% 93.1% 84.9%

If no polyvinyl alcohol is added, the graphene will be packed and its adsorption sites will be shielded, so it is very low. The purpose of adding polyvinyl alcohol in the present invention is to increase the interlayer spacing of the graphene film, thereby increasing the adsorption capacity. However, if a large amount of polyvinyl alcohol is added, the excess polyvinyl alcohol will cover the adsorption sites inside the graphene film, so its adsorption capacity will decrease instead. The adsorption material proposed by the present invention is actually the supporting effect (playing the role of increasing the layer spacing, exposing more adsorption sites, thereby increasing the adsorption capacity) and the covering effect (excessive polyvinyl alcohol can also play the role of increasing the layer spacing) , but covers a large number of adsorption sites) is a trade-off relationship. Based on this, the present invention adds graphene oxide dispersion (concentration: 5 mg/ml) to polyvinyl alcohol solution (concentration: 0.2 wt%) at a volume ratio of 1:0-4 after comprehensive weighing.

The outstanding advantages of the present invention are that the preparation process of the graphene film is simple and fast, and the operation is convenient; the prepared graphene film has high removal efficiency for trace arsenic in water.

The above-mentioned embodiments of the present invention are only examples for illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, on the basis of the above description, other changes and changes in different forms can also be made, and all implementation modes cannot be exhaustively listed here. All obvious changes or changes derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (5)

1. remove the adsorbing material of trace arsenic in water body for one kind, it is characterised in that: it is prepared as follows obtaining, by graphite oxide Alkene dispersion liquid and poly-vinyl alcohol solution mixing, then obtain graphene oxide membrane through vacuum filtration, after through hydrazine hydrate reduction system Obtaining graphene film, this graphene film is adsorbing material.

2. according to the adsorbing material of trace arsenic in the removal water body described in claim 1, it is characterised in that: concrete preparation process It is as follows,

1) graphene oxide dispersion that concentration is 5mg/ml and the poly-vinyl alcohol solution that concentration is 0.2 wt% are prepared respectively；

2) mixing with poly-vinyl alcohol solution ultrasonic by graphene oxide dispersion, obtain mixed liquor, graphene oxide dispersion is with poly- Glycohol solution volume ratio is 1:(0-4)；

3) mixed liquor is added sucking filtration in Vacuum filtration device, obtain graphene oxide membrane；

4) graphene oxide membrane is added in appropriate amount of deionized water, add appropriate hydrazine hydrate the most in deionized water to oxidation stone Ink alkene film reduces, and obtains graphene film；

5) being washed with deionized water by graphene film to neutrality, drying baker is dried.

3. according to the adsorbing material of trace arsenic in the removal water body described in claim 2, it is characterised in that: described graphite oxide Alkene dispersion liquid is prepared as follows obtaining, and adds graphene oxide in deionized water, ultrasonic disperse 1 ~ 4h；

Described poly-vinyl alcohol solution is prepared as follows obtaining, and is joined by polyvinyl alcohol in 90 ~ 98 DEG C of deionized waters, dissolves 3 ~ 5 hours.

4. remove the method for trace arsenic in water body, it is characterised in that: the concentration of arsenic in staying water is allocated as 0.1 ~ 5mg/ L, and to regulate water pH value be 2-9, is subsequently adding the arbitrary described adsorbing material of claim 1-3 and adsorbs more than 12 hours, i.e. Realize the removal of Trace Arsenic in Water (III)；The addition of adsorbing material is 0.1g/L ~ 0.4g/L.

The method of trace arsenic in removal water body the most according to claim 4, it is characterised in that: in staying water, arsenic is dense Degree is allocated as 5ppm, and to regulate water pH value be 6, and being subsequently adding the arbitrary described adsorbing material of claim 1-3, to adsorb 12 little More than time, i.e. realize the removal of Trace Arsenic in Water (III).