WO2021052484A1 - Material for recovery of gold from waste water - Google Patents

Abstract

A graphene composite comprises a carrier and a graphene composition comprising a structural compound expressed in formula (I). The graphene composition is positioned on a surface of the carrier. Also disclosed are a method of preparing a thiourea-graphene-zeolite material, and a method employing the above graphene composition/composite to adsorb gold ions in a gold-containing solution.

Description

A material for recycling gold-containing wastewater

This application claims the priority of CN201910895143.6 filed on September 20, 2019, and the content of the above-mentioned earlier application is incorporated into this text by way of introduction.

Technical field

The invention relates to a thiourea graphene zeolite, and also relates to a preparation method of the thiourea graphene zeolite, in particular to the use of the thiourea graphene zeolite to absorb and desorb gold ions in a gold-containing solution.

Background technique

At present, the method of recovering gold from wastewater is mainly based on ion exchange resin as the adsorption material. Compared with the traditional electrolysis method, it is more in line with the trend of environmental protection and energy saving, and at the same time has good adsorption efficiency and recovery rate. . However, ion-exchange resin has no effect in the nitric acid system, and its lowest adsorption limit for gold ions is only 1 mg/L. Therefore, when the concentration of gold ions in the wastewater is lower than 1 mg/L, the absorption efficiency of the ion exchange resin for gold ions will be significantly worse.

Summary of the invention

The present invention provides a graphene composition and its use for the adsorption of gold. The high selectivity of the graphene composition for gold ions is utilized, so that the use of the graphene composition for the adsorption of gold can have Lower adsorption limit, better adsorption efficiency and higher saturated adsorption capacity.

In one aspect, the present case provides a graphene composition, which comprises at least one compound of formula (I).

In one embodiment, the nitrogen content of the aforementioned graphene composition is 2 to 4% by weight, and the sulfur content is 20 to 23% by weight.

In another aspect, the present application provides a method for using a graphene composition to adsorb a gold ion in a gold-containing solution, wherein the graphene composition includes at least one compound of the formula (I) structure.

In one embodiment, the pH of the gold-containing solution in the above method is 2-6.

In one embodiment, the graphene composition in the above method has an adsorption efficiency of 45% to 100% for the gold ions.

In an embodiment, the saturated adsorption capacity of the gold ions per gram of the graphene composition in the above method is 810 to 850 mg.

In one embodiment, in the above method, when the gold-containing solution further includes a copper ion, a lead ion, a zinc ion or a combination thereof, the adsorption efficiency of the graphene composition on the lead ion is 1% To 2%, and the adsorption efficiency of the copper ions and the zinc ions is 0%.

In another aspect, the present application provides a method for processing a gold ion in a gold-containing solution, which comprises combining a graphene composition containing a compound of formula (I) with the gold ion in the gold-containing solution Steps of contact.

In one embodiment, the above method further includes the step of desorbing the gold ions from the graphene composition containing the compound of formula (I) with a desorbent.

In one embodiment, the desorption efficiency of gold ions in the above method is 90% to 96%.

In another aspect, the present case also provides a graphene composite, the graphene composite comprising a carrier, and a graphene composition comprising the structure compound of formula (I), the graphene composition is located on the carrier s surface.

In one embodiment, the aforementioned carrier is a zeolite.

In one embodiment, the above-mentioned graphene composite has obvious diffraction peaks after X-ray diffraction at 2θ=12.46° and 23.68°.

In one embodiment, the carbon content on the surface of the aforementioned graphene composite is 49-52 weight.

In one embodiment, the nitrogen content on the surface of the aforementioned graphene composite is 2 to 5% by weight.

In one embodiment, the sulfur content on the surface of the aforementioned graphene composite is 3 to 6% by weight.

In another aspect, this case provides a method for manufacturing thiourea graphene zeolite, which includes the following steps: reacting a zeolite with a mixed solution containing 3-aminopropyltriethoxysilane and ethanol to obtain a reacted zeolite Mixing graphene oxide with water to form a suspension; dissolving thiourea in water to form a thiourea solution; and mixing and heating the thiourea solution, the suspension, and the reacted zeolite, To form a thiourea graphene zeolite.

In one embodiment, the heating range in the above method is 75°C to 85°C.

In another aspect, the present application provides a method for adsorbing gold ions in a gold-containing solution using a graphene composite, the graphene composite comprising a carrier, and a graphene composition comprising a structure compound of formula (I) The graphene composition is located on the surface of the carrier.

In one embodiment, the pH of the gold-containing solution in the above method is 0-5.

In one embodiment, the adsorption efficiency of the graphene zeolite for the gold ions in the above method is 60% to 100%.

In one embodiment, the saturated adsorption capacity of the graphene zeolite for the gold ions per gram in the above method is 90 to 100 mg.

In one embodiment, in the above method, when the gold-containing solution further includes copper ions, lead ions, zinc ions, nickel ions, or a combination thereof, the adsorption efficiency of the thiourea graphene zeolite for the copper ions is 0.5 % To 5%, the adsorption efficiency for the lead ions is 2% to 5%, the adsorption efficiency for zinc ions is 0% to 5%, and the adsorption efficiency for nickel ions is 0.5% to 5%.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail in conjunction with the accompanying drawings.

Description of the drawings

FIG. 1 shows a flowchart of a method for recovering gold from thiourea graphene according to an embodiment of the present invention.

Figure 2A shows the analysis result of X-ray diffraction.

Figure 2B shows the analysis result of the scanning electron microscope.

Figure 2C shows the analysis result of a transmission electron microscope.

Figure 3A shows the effect of different reaction times on the adsorption efficiency of thiourea graphene.

Figure 3B shows the effect of different reaction pH values on the adsorption efficiency of thiourea graphene.

Figure 3C shows the effect of different doses of thiourea graphene on its adsorption efficiency.

Figure 3D shows the effect of different concentrations of ammonium thiosulfate solution on its desorption efficiency.

Figure 4 shows the isothermal adsorption curve of thiourea graphene for gold ions.

Figure 5A shows the adsorption efficiency of graphene oxide and graphene thiourea for gold ions, copper ions, lead ions, and zinc ions, respectively.

Figure 5B shows the selectivity and lowest adsorption limit of thiourea graphene for gold ions, copper ions, lead ions and zinc ions in wastewater.

Figure 5C shows the effect of copper ion concentration in wastewater on the adsorption efficiency of thiourea graphene.

Figure 6A shows the X-ray diffraction analysis result of thiourea graphene zeolite.

Figure 6B shows the scanning electron microscope analysis results of the thiourea graphene zeolite.

Figure 7 shows the effect of different reaction pH values on the adsorption efficiency of thiourea graphene zeolite.

Figure 8 shows the isotherm adsorption curve of thiourea graphene zeolite for gold ions.

Figure 9 shows the selectivity of thiourea graphene zeolite to gold ions, copper ions, lead ions, zinc ions, and nickel ions, respectively.

Description of Reference Signs

S110, S120, S130, S140: steps

detailed description

Example 1: Preparation and characterization of thiourea graphene and method for recovering gold

FIG. 1 shows a flowchart of a method for recovering gold from thiourea graphene according to an embodiment of the present invention.

Please refer to FIG. 1 to perform step S110 to provide thiourea graphene. In this embodiment, for example, the following steps are used to prepare thiourea graphene, but it is not limited thereto. First, graphene oxide (GO) is mixed with ultrapure water to form a colloidal suspension of graphene oxide. Dissolve thiourea in ultrapure water to form a thiourea solution. Then, the thiourea solution was added to the colloidal suspension of graphene oxide, and stirred with a magnetic stir bar at 95°C for 8 hours to form thiourea graphene (TU-rGO), the chemical structure of which is as follows: (I) shown.

Subsequently, the TU-rGO solution was washed with ultrapure water and filtered to obtain thiourea graphene solids. Finally, the solid was dried at 50°C for 24 hours, and then the thiourea graphene solid was ground with an agate mortar. Then, pass through a 30-mesh sieve and a 60-mesh sieve in sequence to obtain thiourea graphene with a particle size between 0.25 mm and 0.59 mm.

Next, the element components and contents in graphene oxide and graphene thiourea were analyzed, and the results are shown in Table 1.

Table 1

To	C(%)	O(%)	H(%)	N(%)	S(%)
GO	47.21±0.01	39.99±1.70	2.75±0.08	0.13±0.02	3.72±0.00
TU-rGO	60.38±1.22	10.00±0.08	1.05±0.10	2.01±0.22	22.87±0.34

From the results in Table 1, it can be seen that compared to graphene oxide, the nitrogen content and sulfur content of graphene thiourea are increased to 2.01% and 22.87%, respectively, and the oxygen content is reduced to 10.00%. It means that graphene thiourea increases the content of nitrogen and sulfur by substituting oxygen.

Next, from the X-ray diffraction analysis results of Figure 2A, it can be seen that compared with the diffraction peak position of graphene (2θ=26.5°) and the diffraction peak position of graphene oxide (2θ=26.5° or 10.5°), thiourea graphite The diffraction peak position of alkene is 2θ=23.05°.

From the analysis result of the scanning electron microscope in FIG. 2B, it can be seen that the surface of the graphene thiourea has a highly folded structure in a magnified view of 3000 times. From the analysis result of the transmission electron microscope in FIG. 2C, it can be seen that in the 60,000 times magnification, the thiourea graphene has a multilayer structure, and the measured specific surface area is 4.5 m2/g.

Then, step S120 is performed to add thiourea graphene to the wastewater to perform an adsorption reaction. In this embodiment, the wastewater includes at least gold ions.

In the following, different examples will be used to explore the reaction conditions for the adsorption reaction of thiourea graphene to gold ions in the wastewater.

Example 2: Effect of reaction time on adsorption efficiency

In this embodiment, the reaction conditions are: graphene thiourea is 0.5 mg, the concentration of gold ions is 10 mg/liter, the reaction temperature is 30°C, the oscillation speed is 150 rpm, the pH value is 2, and the reaction volume is 50 ml. And the reaction time is 12, 24, 48, 72, 96, 120 hours, respectively.

It can be seen from the result of FIG. 3A that when the reaction time is 96 hours, the adsorption efficiency of thiourea graphene for gold ions is about 82.7±6.1%. When the reaction time is 120 hours, the adsorption efficiency of thiourea graphene for gold ions does not increase significantly. That is to say, when the reaction time is 96 hours, the adsorption kinetics of thiourea graphene to gold ions can reach an equilibrium, and can exhibit good adsorption efficiency.

It should be noted that in this embodiment, the adsorption efficiency is calculated according to Formula 1. Formula 1: Adsorption efficiency (%) = (C0-Ct)/C0×100%, where C0 is the concentration of gold ions before the adsorption reaction (mg/L), and Ct is the concentration of gold ions after the adsorption reaction (mg/L) .

Example 3: The effect of pH value of reaction on adsorption efficiency

In this embodiment, the reaction conditions are: graphene thiourea is 0.5 mg, the concentration of gold ions is 10 mg/liter, the reaction temperature is 30°C, the oscillation speed is 150 rpm, the reaction time is 96 hours, and the reaction volume is 50 ml. , And the pH values of the reaction are 2, 3, 4, 5, 6, 7, 8, 9, 10 respectively.

It can be seen from the result of FIG. 3B that when the pH of the reaction is 2-5, the adsorption efficiency of thiourea graphene for gold ions is about 80-85%. When the pH of the reaction is 6, the adsorption efficiency of thiourea graphene for gold ions is about 40-50%. However, when the pH of the reaction exceeds 6, the adsorption efficiency of thiourea graphene for gold ions quickly drops below 20%. In other words, when the pH of the reaction is 2 to 5, graphene thiourea can exhibit good adsorption efficiency for gold ions.

Example 4: The effect of the dosage of thiourea graphene on the adsorption efficiency

In this embodiment, the reaction conditions are: the concentration of gold ions is 10 mg/liter, the reaction temperature is 30° C., the oscillation speed is 150 rpm, the reaction time is 96 hours, the reaction volume is 50 ml, the pH value is 5, and the sulfur The dosages of urea graphene are 0.5, 1.0, 1.5, and 2.0 mg, respectively.

It can be seen from the result of FIG. 3C that when the dose of thiourea graphene is 0.5 mg, the adsorption efficiency of thiourea graphene for gold ions is about 82.7±6.1%. However, when the dose of thiourea graphene is 1.0, 1.5, or 2.0 mg, the adsorption efficiency of thiourea graphene for gold ions only slightly increases. In other words, when the dosage of thiourea graphene is 0.5-2.0 mg, it can exhibit good adsorption efficiency for gold ions.

Then, step S130 is performed to separate the thiourea graphene adsorbing gold ions from the wastewater. In this embodiment, after the thiourea graphene adsorbs the gold ions in the wastewater, for example, it is filtered with a Syringe filter with a pore size of 0.45 microns, so that the reacted thiourea graphene cannot pass through. The pores further separate the thiourea graphene that adsorbs gold ions from the wastewater after the reaction. Next, the gold ion concentration in the separated wastewater is measured with an inductively coupled plasma emission spectrometer (ICP-OES), and used as the gold ion concentration after the reaction in Formula 1.

Finally, step S140 is performed to perform a desorption reaction on the thiourea graphene adsorbing gold ions to obtain gold ions. In this embodiment, for example, a desorbent is added to the thiourea graphene separated from the wastewater after the reaction and adsorbed with gold ions, so that the gold ions can be desorbed from the thiourea graphene. In this embodiment, the desorption agent is, for example, ammonium thiosulfate, but it is not limited to this.

In the following, different examples will be used to discuss the reaction conditions of the desorption reaction of ammonium thiosulfate on thiourea graphene adsorbed with gold ions.

Example 5: Influence of concentration of ammonium thiosulfate solution on desorption efficiency

In this embodiment, the ammonium thiosulfate solution is divided into three groups A, B, and C according to the concentration of the ammonium thiosulfate solution used, and each group undergoes two desorption reactions. First, each group adds 0.2M ammonium thiosulfate solution to 2.0 mg of thiourea graphene with gold ions adsorbed (the content of gold ions adsorbed per gram of thiourea graphene is 2500 mg) to perform the first Second desorption reaction. Then, after the first desorption reaction is completed, the three groups A, B, and C are respectively used for the second desorption reaction with 0.05, 0.1 or 0.2M ammonium thiosulfate solution. In addition, the first desorption reaction and the second desorption reaction are carried out according to the following reaction conditions: the reaction temperature is 30°C, the shaking speed is 150 rpm, the reaction time is 24 hours, the reaction volume is 50 ml, and the pH value of the reaction Respectively 7.4.

From the results in Figure 3D, it can be seen that the first desorption reaction can desorb most of the gold ions from the thiourea graphene, and the desorption efficiency is about 93% or more. In the second desorption reaction, 0.2M ammonium thiosulfate solution (group C) can increase the desorption efficiency by about 1.4%. That is to say, the desorption reaction with ammonium thiosulfate solution can make the desorption efficiency of gold ions on the thiourea graphene be 93% to 96%.

It should be noted that in this embodiment, the desorption efficiency is calculated according to Formula 2. Formula 2: Desorption efficiency (%)=Mt/M0×100%, where M0 is the weight (mg) of gold ions on the thiourea graphene before the desorption reaction, and Mt is the gold ions in the solution after the desorption reaction The weight in milligrams.

It is worth noting that in order to further understand the adsorption effect of thiourea graphene on gold ions, the experimental data of the above examples can be applied to the Langmuir adsorption equation to simulate the adsorption isotherm curve. The results are shown in Figure 4. . From the simulation results in Figure 4, it can be seen that the correlation coefficient R2 of the adsorption isotherm curve is 0.91, and the saturated adsorption capacity of gold ions per gram of thiourea graphene is 833.33 mg.

Since the above adsorption experiments all take the gold ion concentration of 10 mg/L as an example, the concentration of gold ions in the wastewater in the real environment may be lower than 10 mg/L, and may also contain other metal ions, such as copper. Ions, lead ions, zinc ions, or combinations thereof. Therefore, in the following, different examples will be used to discuss the minimum adsorbable concentration of thiourea graphene for gold ions, and to discuss the selectivity of thiourea graphene for gold ions and other metal ions.

Example 6: Comparison of graphene oxide and graphene thiourea, respectively, the adsorption efficiency of gold ions, copper ions, lead ions and zinc ions

In this embodiment, 2.0 mg of graphene oxide (or 2.0 mg of thiourea graphene) is used with gold ions (labeled as Au) at a concentration of 10 mg/L and copper ions at a concentration of 20 mg/L ( The adsorption reaction is carried out with lead ions with a concentration of 20 mg/L (labeled as Pb), and zinc ions with a concentration of 20 mg/L (labeled as Zn), and the reaction conditions are: reaction temperature of 30°C, The shaking speed is 150 rpm, the pH value is 2, the reaction volume is 50 ml, and the reaction time is 96 hours.

From the result of Figure 5A, it can be seen that the adsorption efficiency of graphene oxide on gold ions is about 12%, the adsorption efficiency of thiourea graphene on gold ions is about 98%, and the adsorption efficiency of thiourea graphene on copper ions, lead ions, and zinc ions None of them have adsorption efficiency. Therefore, compared with graphene oxide, graphene thiourea has a higher adsorption efficiency for gold ions. In addition, graphene thiourea has high selectivity to gold ions compared to copper ions, lead ions, and zinc ions.

Example 7: Selectivity of thiourea graphene to gold ions, copper ions, lead ions and zinc ions in wastewater

In this embodiment, the wastewater is divided into experimental example 1, experimental example 2, and experimental example 3 according to the composition and content of the wastewater. Among them, the wastewater of Experimental Example 1 includes gold ions with a concentration of 10 mg/L, copper ions with a concentration of 20 mg/L, lead ions with a concentration of 20 mg/L, and zinc ions with a concentration of 20 mg/L. The wastewater of Experimental Example 2 includes gold ions with a concentration of 1 mg/L, copper ions with a concentration of 20 mg/L, lead ions with a concentration of 20 mg/L, and zinc ions with a concentration of 20 mg/L. The wastewater of Experimental Example 3 includes gold ions with a concentration of 0.1 mg/L, copper ions with a concentration of 20 mg/L, lead ions with a concentration of 20 mg/L, and zinc ions with a concentration of 20 mg/L. The wastewater of Experimental Example 4 includes gold ions with a concentration of 0.01 mg/L, copper ions with a concentration of 20 mg/L, lead ions with a concentration of 20 mg/L, and zinc ions with a concentration of 20 mg/L. The reaction conditions of Experimental Example 1, Experimental Example 2, Experimental Example 3, and Experimental Example 4 are: thiourea graphene is 2.0 mg, the reaction temperature is 30°C, the oscillation speed is 150 rpm, the pH value is 2, and the reaction volume is 50. The reaction time is 96 hours.

It can be seen from the result of FIG. 5B that in Experimental Example 1, the adsorption efficiency of thiourea graphene for gold ions is 98.3±0.8%, but it has no adsorption efficiency for copper ions, lead ions, and zinc ions. In Experimental Example 3, the adsorption efficiency of thiourea graphene for gold ions is 98.9±0.3%, and the adsorption efficiency for lead ions is about 1% to 2%, but it has no adsorption efficiency for copper ions and zinc ions. In Experimental Example 4, the adsorption efficiency of thiourea graphene for gold ions is 100%, but it has no adsorption efficiency for copper ions, lead ions, and zinc ions. Therefore, the lowest adsorbable concentration (lowest adsorption limit) of thiourea graphene for gold ions is 0.01 mg/L. In addition, when the gold ion is 0.01 mg/L to 10 mg/L, the thiourea graphene has high selectivity for gold ions and an adsorption efficiency of more than 98%.

Example 8: The effect of copper ion concentration in wastewater on the adsorption efficiency of thiourea graphene

In this embodiment, the wastewater is divided into experimental example 5, experimental example 6, experimental example 7, and experimental example 8 according to the composition and content of the wastewater. The wastewater of Experimental Example 5 includes gold ions with a concentration of 10 mg/L, copper ions with a concentration of 100 mg/L, lead ions with a concentration of 20 mg/L, and zinc ions with a concentration of 20 mg/L. The wastewater of Experimental Example 6 includes gold ions with a concentration of 1 mg/L, copper ions with a concentration of 100 mg/L, lead ions with a concentration of 20 mg/L, and zinc ions with a concentration of 20 mg/L. The wastewater of Experimental Example 7 includes gold ions with a concentration of 0.1 mg/L, copper ions with a concentration of 100 mg/L, lead ions with a concentration of 20 mg/L, and zinc ions with a concentration of 20 mg/L. The wastewater of Experimental Example 8 includes gold ions with a concentration of 0.01 mg/L, copper ions with a concentration of 100 mg/L, lead ions with a concentration of 20 mg/L, and zinc ions with a concentration of 20 mg/L. The reaction conditions of experimental example 5, experimental example 6, experimental example 7 and experimental example 8 are: thiourea graphene is 2.0 mg, the reaction temperature is 30°C, the oscillation speed is 150 rpm, the pH value is 2, and the reaction volume is 50. The reaction time is 96 hours.

It can be seen from the results of Figure 5C that compared with Experimental Example 1 in Figure 5B, the adsorption efficiency of thiourea graphene for gold ions in Experimental Example 5 is slightly reduced to 95.4±0.5%, but for copper ions, lead ions, and zinc ions. It still does not have adsorption efficiency. In addition, compared to Experimental Example 3 in Figure 5B, the thiourea graphene in Experimental Example 7 has an adsorption efficiency of 98±1.5% for gold ions, and the adsorption efficiency for lead ions is still about 1% to 2%, but the Copper ions and zinc ions still have no adsorption efficiency. Compared with Experimental Example 4 in Figure 5B, the thiourea graphene in Experimental Example 8 has an adsorption efficiency of 100% for gold ions and an adsorption efficiency of about 5% for lead ions, but it still has no effect on copper ions and zinc ions. Adsorption efficiency. Therefore, even if the concentration of copper ions in the wastewater is increased, graphene thiourea still has high selectivity for gold ions and an adsorption efficiency of 95% to 100%.

Example 9: Preparation and characterization of thiourea graphene zeolite

In this embodiment, for example, the following steps are used to prepare the thiourea graphene zeolite, but it is not limited thereto. First, after immersing the zeolite in a mixed solution containing 3-aminopropyltriethoxysilane and ethanol for 4 hours, the zeolite is dried at 50° C. for 24 hours to obtain a surface organically modified zeolite. Subsequently, graphene oxide is mixed with ultrapure water to form a colloidal suspension of graphene oxide, and thiourea is dissolved in ultrapure water to form a thiourea solution. Finally, the thiourea solution was added to the colloidal suspension of graphene oxide to form a thiourea-graphene mixed solution, and then put into the organically modified zeolite, reacted at 80°C for 4 hours, and finally the solid was dried at 50°C for 24 hours After hours, thiourea graphene zeolite was obtained.

The appearance of thiourea graphene zeolite is black, and it is composed of multiple unit elements including zeolite, graphene and thiourea. Among them, graphene is a kind of hexagonal honeycomb lattice composed of carbon atoms and sp2 hybrid orbitals. A flat film, a two-dimensional material with the thickness of only one carbon atom. After being modified by thiourea, the appearance presents a highly folded three-dimensional ridgeline structure. It is composed of graphene sheets with a radial size of 2-6μm, and the graphene sheets cross each other. The connection forms a macroporous structure with a size of 50 nm or more. The structure of thiourea graphene zeolite is based on zeolite, and the outer surface of the zeolite is covered by thiourea graphene composed of graphene and thiourea. The chemical structure of thiourea graphene is shown in formula (I).

Next, the element composition and content on the surface of the thiourea graphene zeolite were analyzed, and the results are shown in Table 2.

Table 2

To	C(%)	O(%)	H(%)	N(%)	S(%)
Thiourea Graphene Zeolite	50.78	27.30	3.65	3.07	4.96

From the results of elemental analysis in Table 2, it can be seen that the carbon, nitrogen, and sulfur content on the surface of the material are 50.78%, 3.07%, and 4.96%, respectively, indicating that graphene thiourea has been supported on the zeolite substrate.

Next, from the X-ray diffraction analysis result of FIG. 6A, it can be seen that the thiourea graphene zeolite has obvious diffraction peaks at 2θ=12.46° and 23.68°.

From the analysis result of the scanning electron microscope in FIG. 6B, it can be seen that in the 2000 times magnification, the surface of the thiourea graphene zeolite has a highly folded three-dimensional ridgeline structure.

Example 10: The influence of the pH value of the reaction on the adsorption efficiency of thiourea graphene zeolite

In this embodiment, the test conditions are: 0.01 g of thiourea graphene zeolite, a gold ion concentration of 10 ml/liter, a reaction temperature of 30°C, an oscillation speed of 150 rpm, a reaction time of 24 hours, and a reaction volume of 50 ml , And the pH of the reaction is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, respectively.

It can be seen from the results in Figure 7 that when the pH of the reaction is 0 to 3, the adsorption efficiency of thiourea graphene zeolite for gold ions can reach more than 90%. When the pH of the reaction is 4 to 5, the thiourea graphene zeolite The adsorption efficiency of gold ions is about 60% to 70%. When the pH value of the reaction is 6-10, the adsorption efficiency of the thiourea graphene zeolite for gold ions is rapidly reduced to below 10%.

Example 11: Determination of the saturated adsorption capacity of thiourea graphene zeolite for gold ions

In this example, in order to further understand the adsorption effect of thiourea graphene zeolite on gold ions, thiourea graphene zeolite was used to perform adsorption experiments in solutions of different gold ion concentrations, and the obtained experimental data was applied to Langmuir adsorption In the equation, a simulation of the adsorption isotherm curve is performed, and the result is shown in Figure 8. It can be seen from the simulation results in Fig. 8 that the correlation coefficient R2 of the adsorption isotherm curve is 0.97, and the saturated adsorption capacity of gold ions per gram of thiourea graphene zeolite is 97.1 mg.

Example 12: Selectivity of thiourea graphene zeolite to gold ions, copper ions, lead ions and zinc ions in wastewater

In this embodiment, according to the composition and content of the wastewater, the wastewater of Experimental Example 1 includes gold ions with a concentration of 1 ml/liter, copper ions with a concentration of 100 ml/liter, and lead with a concentration of 20 ml/liter. Ions, zinc ions with a concentration of 20 ml/liter, nickel ions with a concentration of 20 ml/liter. The wastewater of Example 2 includes gold ions with a concentration of 10 ml/liter, copper ions with a concentration of 100 ml/liter, lead ions with a concentration of 20 ml/liter, zinc ions with a concentration of 20 ml/liter, and a concentration of 20 ml. /L of nickel ion.

The reaction conditions of Experimental Example 1 and Experimental Example 2 are: 0.01 g of thiourea graphene zeolite, reaction temperature of 30° C., oscillation speed of 150 rpm, reaction time of 24 hours, and reaction volume of 50 ml.

It can be seen from the results of FIG. 9 that in Experimental Example 1, the adsorption efficiency of thiourea graphene zeolite for gold ions is about 93.13%, and the adsorption efficiency for copper ions, lead ions, zinc ions, and nickel ions are all less than 5%. In Experimental Example 2, the adsorption efficiency of thiourea graphene zeolite for gold ions was 94.05%, and the adsorption efficiency for copper ions, lead ions, zinc ions, and nickel ions were 0.86%, 2.73%, 4.36%, and 0.81%, respectively. Therefore, thiourea graphene zeolite has high selectivity for gold ions and an adsorption efficiency of 93% to 94%.

In summary, in the use of thiourea graphene zeolite and its use for gold adsorption provided by the present invention, the high selectivity of thiourea graphene zeolite for gold ions makes the use of thiourea graphene zeolite to When the gold ion in the gold-containing solution undergoes an adsorption reaction, it can have a lower adsorption limit, a better adsorption efficiency, and a higher saturated adsorption capacity.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone skilled in the art, without departing from the spirit and scope of the present invention, can make some changes and modifications, so the present invention The scope of protection shall be subject to what is defined in the claims.

Claims (24)

1. A graphene composition, characterized in that the graphene composition at least comprises a compound of formula (I):

   
2. The graphene composition of claim 1, wherein the nitrogen content of the graphene composition is 2 to 4% by weight, and the sulfur content is 20 to 23% by weight.
3. A method for using a graphene composition to adsorb a gold ion in a gold-containing solution, wherein the graphene composition at least comprises a compound of formula (I):

   
4. The method according to claim 3, wherein the pH of the gold-containing solution is 2-10.
5. The method according to claim 3, wherein the adsorption efficiency of the graphene composition to the gold ions is 45% to 100%.
6. The method according to claim 3, wherein the saturated adsorption capacity of the gold ions per gram of the graphene composition is 810 to 850 mg.
7. The method of claim 3, wherein when the gold-containing solution further includes a copper ion, a lead ion, a zinc ion, or a combination thereof, the graphene composition adsorbs the lead ion The efficiency is 1% to 2%, and the adsorption efficiency of the copper ion and the zinc ion is 0%.
8. A method for processing a gold ion in a gold-containing solution, which is characterized in that it comprises a step:

   Contacting a graphene composition containing a structure compound of formula (I) with the gold ions in the gold-containing solution:

   
9. 8. The method according to claim 8, wherein the method further comprises a step of desorbing the gold ions from the graphene composition containing the compound of formula (I) with a desorbent.
10. The method according to claim 9, wherein the desorption efficiency of the gold ions is 90% to 96%.
11. A graphene composite, characterized in that the graphene composite comprises:

    A carrier, and

    A graphene composition comprising a structure compound of formula (I), the graphene composition being located on the surface of the carrier:

    
12. The graphene composite of claim 11, wherein the carrier is a zeolite.
13. The graphene composite of claim 12, wherein the graphene composite has obvious diffraction peaks at 2θ=12.46° and 23.68° by X-ray diffraction.
14. The graphene composite according to claim 12, wherein the carbon content on the surface of the graphene composite is 49-52% by weight.
15. The graphene composite according to claim 12, wherein the nitrogen content on the surface of the graphene composite is 2 to 5% by weight.
16. The graphene composite according to claim 12, wherein the sulfur content on the surface of the graphene composite is 3 to 6% by weight.
17. A method for manufacturing thiourea graphene zeolite is characterized in that it comprises the following steps:

    a) Reacting a zeolite with a mixed solution containing 3-aminopropyltriethoxysilane and ethanol to obtain a reacted zeolite;

    b) Mixing graphene oxide with water to form a suspension;

    c) dissolving thiourea in water to form a thiourea solution; and

    d) The thiourea solution, the suspension and the reacted zeolite are mixed and heated to form a thiourea graphene zeolite.
18. The method according to claim 17, wherein the heating range is 75°C to 85°C.
19. A method for using a graphene composite to adsorb gold ions in a gold-containing solution, wherein the graphene composite comprises:

    A carrier, and

    A graphene composition comprising a structure compound of formula (I), the graphene composition being located on the surface of the carrier:

    
20. The method of claim 19, wherein the carrier of the graphene composite is a zeolite.
21. The method of claim 19, wherein the pH of the gold-containing solution is 0-10.
22. 22. The method of claim 20, wherein the adsorption efficiency of the graphene composite for the gold ions is 60% to 100%.
23. 22. The method of claim 20, wherein the saturated adsorption capacity of the gold ions per gram of the graphene composite is 90 to 100 mg.
24. The method according to claim 20, wherein when the gold-containing solution further includes copper ions, lead ions, zinc ions, nickel ions, or a combination thereof, the graphene composite adsorbs the copper ions The efficiency is 0.5% to 5%, the adsorption efficiency for the lead ions is 2% to 5%, the adsorption efficiency for zinc ions is 0% to 5%, and the adsorption efficiency for nickel ions is 0.5% to 5%.

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