Method for preparing attapulgite-activated carbon composite material from natural attapulgite

Abstract

The invention relates to a method for preparing an attapulgite-activated carbon composite material from natural attapulgite, which specifically comprises the following steps: by taking the natural attapulgite as a raw material, adding a certain amount of acid, a suspending agent and water according to mass fraction, stirring at normal temperature, washing, drying and crushing to obtain purified attapulgite, and drying to obtain the attapulgite-activated carbon composite material. Then adsorbing coked stronger ammonia water by using purified attapulgite, filtering and drying the adsorbed attapulgite, and performing oxygen-isolated calcination in a tubular furnace to obtain the attapulgite-activated carbon composite material. Oil substances adsorbed on the surface of the attapulgite adsorbed with strong ammonia water are used as a carbon source of activated carbon and are converted into a mesoporous activated carbon material with adsorption capacity through a one-step calcination method, and meanwhile, the pore structure of the attapulgite is also dredged under the action of acid. According to the invention, the adsorption and oil removal of the coked stronger ammonia water by the attapulgite are realized, the adsorbed oil substances are further utilized to generate the activated carbon, the adsorption performance of the attapulgite and the activated carbon is fully utilized, and the obtained product has high adsorption capacity, good thermal stability and better application prospect.

Description

Technical Field

[0001] The invention relates to a method for preparing a attapulgite-activated carbon composite material, and in particular to a method for preparing a high-efficiency adsorption composite material by taking natural attapulgite decolorized waste soil as a raw material. Background Art

[0002] Coking concentrated ammonia water is obtained by distilling the residual ammonia water during the coking process. It usually contains impurities such as tar and sulfide, and must be purified by degreasing, removing sulfide and other purification methods before it can be used later. Degreasing is an important link in the refining process of concentrated ammonia water. The effect of degreasing is directly related to the quality of subsequent use of ammonia water, which in turn affects the interests of manufacturers. The purpose of degreasing is to remove phenol, tar, sulfide and other harmful impurities contained in concentrated ammonia water. The adsorption method is often selected for degreasing concentrated ammonia water because of its low cost, simple method and mild conditions. Among them, activated white clay is a more commonly used adsorbent. Then, after absorbing grease, activated white clay is difficult to regenerate, thus forming a large amount of waste soil. In addition to about 20% of grease, these waste soils also contain a large amount of sulfide, phenolic compounds, heavy metal ions, etc. If they are not well treated, they will cause certain harm to the environment. Therefore, how to reuse the decolorized waste soil is one of the problems that need to be solved urgently.

[0003] To this end, the present invention uses natural attapulgite as raw material, first performs adsorption and oil removal treatment on coking concentrated ammonia water, and while the concentrated ammonia water is refined, the residual grease therein contains a natural carbon source, and a attapulgite-activated carbon nanocomposite adsorbent is obtained through a one-step calcination and carbonization method, which can provide a new way for the resource recycling of attapulgite. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing attapulgite-activated carbon composite materials using attapulgite after deoiling based on the structural characteristics of attapulgite and the adsorption of oil substances in coking concentrated ammonia water, so as to realize the refining of coking concentrated ammonia water. The method can increase the utilization rate of attapulgite and further realize the resource utilization and harmless treatment of attapulgite deoiling waste soil.

[0005] 1. Preparation of attapulgite-activated carbon composite adsorbent

[0006] The natural attapulgite is dispersed in water to form a suspension with a mass concentration of 10%-20%, and a 5M sulfuric acid solution is added and stirred for 60 minutes, then washed to neutrality, and then added to a 3wt% sodium hexametaphosphate solution under magnetic stirring, ultrasonicated for 60 minutes, allowed to stand for 120 minutes, centrifuged and dried; the dried attapulgite is then dispersed in coking concentrated ammonia water to form a suspension with a mass concentration of 10%-20%, and filtered after stirring for 1-3 hours. After drying at 110°C, the suspension is transferred to a tubular furnace, and under nitrogen protection, the temperature is raised to 500°C at a rate of 10°C / min, and the temperature is kept for 3 hours to obtain a attapulgite-activated carbon composite adsorbent.

[0007] Among them, the attapulgite is natural attapulgite taken from Xuyi, Jiangsu Province, and the coking concentrated ammonia water is taken from the concentrated ammonia water after the ammonia distillation section of Hubei Xinye Steel Co., Ltd. The oil content is 600 mg / L, and the mass fraction of the residual oil rate in the attapulgite deoiling waste soil after adsorption is 60%-70%.

[0008] The natural attapulgite adsorbent is yellow-white in color. The attapulgite-activated carbon composite adsorbent prepared by the present invention has a significant change in color compared with the natural attapulgite. The color of the obtained adsorbent is black-gray, indicating that the carbonaceous material is successfully loaded on the surface of the attapulgite, and the attapulgite-activated carbon composite adsorbent is successfully formed.

[0009] Figure 1 This is a SEM photo of the attapulgite-activated carbon composite adsorbent prepared by the present invention. It can be seen from the electron microscope photo that the attapulgite-activated carbon composite adsorbent presents a typical rod-like structure of attapulgite, and carbonaceous particles are attached to the surface of the attapulgite. The presence of carbon provides more adsorption sites for the material, allowing sufficient contact between the adsorbent and the adsorbate, thereby achieving effective adsorption of pollutants.

[0010] 2. Adsorption and reusability performance of attapulgite-activated carbon composite adsorbent

[0011] 1. Adsorption performance of polystyrene (PS) microplastics

[0012] 100 ml of simulated wastewater containing 100 mg / L polystyrene (PS) microplastics was selected. The attapulgite-activated carbon composite adsorbent of the present invention was added thereto, and the mixture was oscillated at a constant temperature for different adsorption times, and the mixture was centrifuged. The supernatant was used to determine the concentration of polystyrene (PS) microplastics by ultraviolet spectrophotometry. Figure 2 The adsorption capacity and adsorption rate curve of the attapulgite-activated carbon composite adsorbent prepared by the present invention for polystyrene (PS). Figure 2It can be seen that the material can reach adsorption equilibrium for polystyrene (PS) microplastics in 8 hours, and the maximum adsorption capacity for polystyrene (PS) microplastics can reach 181.3 mg / g. This result shows that the prepared attapulgite-activated carbon composite adsorbent can achieve efficient removal of microplastic pollutants.

[0013] 2. Reusability of polystyrene (PS) microplastics.

[0014] 100 ml of simulated wastewater containing 100 mg / L polystyrene (PS) microplastics was selected. The attapulgite-activated carbon composite adsorbent of the present invention was added thereto, and the adsorption time was changed at a constant temperature, and the adsorption was centrifuged. The supernatant was used to determine the concentration of polystyrene (PS) microplastics by ultraviolet spectrophotometry. The adsorbent was separated, and after calcination and desorption at 150°C, it was repeatedly used to adsorb simulated wastewater containing polystyrene (PS) microplastics. Figure 3 The figure is the performance curve of the attapulgite-activated carbon composite adsorbent prepared by the present invention for repeated use of polystyrene (PS). Figure 3 It can be seen that for polystyrene (PS) microplastics, the composite adsorbent still maintains a relatively high and stable adsorption-desorption capacity after 5 adsorption-desorption processes. This result shows that the prepared composite adsorbent has good reusability.

[0015] In summary, the present invention has the following beneficial effects compared with the prior art:

[0016] 1. The present invention utilizes purified natural attapulgite to adsorb and remove oil from coking concentrated ammonia water, and uses the adsorbed oil substances as carbon sources to prepare new adsorption materials, which not only plays a role in refining coking concentrated ammonia water, but also prepares a carbon composite adsorption material with high added value, realizes the multiple utilization of attapulgite adsorbent, and is both economical and efficient;

[0017] 2. Carbonization is carried out by a relatively simple one-step calcination method, so that the oil substances are formed into carbon particles under high temperature conditions and loaded on the surface of attapulgite, which can make full use of the adsorption properties of activated carbon and attapulgite and significantly improve the adsorption performance;

[0018] 3. The attapulgite-activated carbon composite adsorbent prepared by this method has the advantages of large adsorption capacity, fast adsorption rate, good reusability, wide pH range, etc., and has broad application prospects in water purification and other aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a SEM photograph of the attapulgite-activated carbon composite adsorbent prepared in the present invention.

[0020] Figure 2The adsorption capacity and rate curve of the prepared attapulgite-activated carbon composite adsorbent for polystyrene (PS) microplastics.

[0021] Figure 3 This is the repeated adsorption performance curve of the attapulgite-activated carbon composite adsorbent prepared in the present invention for polystyrene (PS) microplastics.

[0022] Specific implementation cases

[0023] The preparation of the attapulgite-activated carbon composite adsorbent of the present invention is further described below through specific examples.

[0024] Example 1

[0025] 5g 100 mesh attapulgite and 25ml 5M sulfuric acid solution were mixed evenly, stirred at room temperature for 1h, and washed with ultrapure water until neutral; added to 3wt% sodium hexametaphosphate solution under magnetic stirring, ultrasonicated for 1h, and the solution was separated from the solid and liquid after standing for 2h. The solid product was dried and crushed and then mixed evenly with 500ml coking concentrated ammonia water, and stirred at room temperature for 3h; after stirring, the solution was separated from the solid and liquid, and the solid product was dried and crushed to obtain a crude product powder; the crude product powder was placed in a tubular furnace, and under nitrogen protection, the temperature was raised to 400℃ at a heating rate of 10℃ / min, and the temperature was kept constant for 2h to obtain an attapulgite-activated carbon composite material. The adsorption capacity of the composite adsorbent for polystyrene (PS) microplastics is 175.1mg / g.

[0026] Example 2

[0027] 5g 200 mesh attapulgite and 25ml 5M sulfuric acid solution were mixed evenly, stirred at room temperature for 1h, and washed with ultrapure water until neutral; added to 3wt% sodium hexametaphosphate solution under magnetic stirring, ultrasonicated for 1h, and the solution was separated from the solid and liquid after standing for 2h. The solid product was dried and crushed and mixed evenly with 500ml coking concentrated ammonia water, and stirred at room temperature for 3h; after stirring, the solution was separated from the solid and liquid, and the solid product was dried and crushed to obtain a crude product powder; the crude product powder was placed in a tubular furnace, and heated to 500℃ at a heating rate of 15℃ / min under nitrogen protection, and kept at a constant temperature for 3h to obtain an attapulgite-activated carbon composite material. The adsorption capacity of the composite adsorbent for polystyrene (PS) microplastics is 181.3mg / g.

[0028] Example 3

[0029] 5g 400 mesh attapulgite and 25ml 5M sulfuric acid solution were mixed evenly, stirred at room temperature for 1h, and washed with ultrapure water until neutral; added to 3wt% sodium hexametaphosphate solution under magnetic stirring, ultrasonicated for 1h, and the solution was separated from the solid and liquid after standing for 2h. The solid product was dried and crushed and mixed evenly with 500ml coking concentrated ammonia water, and stirred at room temperature for 3h; after stirring, the solution was separated from the solid and liquid, and the solid product was dried and crushed to obtain a crude product powder; the crude product powder was placed in a tubular furnace, and heated to 600℃ at a heating rate of 20℃ / min under nitrogen protection, and kept at a constant temperature for 4h to obtain an attapulgite-activated carbon composite material. The adsorption capacity of the composite adsorbent for polystyrene (PS) microplastics is 168.7mg / g.

Claims

1. A method for preparing a attapulgite-activated carbon composite material using natural attapulgite, characterized in that: The method comprises the following steps: using natural attapulgite as raw material, adding a certain amount of acid according to mass fraction, stirring at room temperature for 1 hour, then adding a certain amount of suspending coagulant according to mass fraction, ultrasonicating at room temperature for 1 hour, and obtaining purified attapulgite after standing, washing, and drying, and then using the purified attapulgite to adsorb and remove oil from coking concentrated ammonia water, and carbonizing the adsorbed attapulgite through a one-step calcination method to obtain an attapulgite-activated carbon composite material. The acid is sulfuric acid; the suspending coagulant is sodium hexametaphosphate; the mass fraction of the suspending coagulant is 3%; the coking concentrated ammonia water is taken from Hubei Xinye Steel Co., Ltd., and the oil content is 600 mg / L; The carbonization process includes: firstly, the purified attapulgite is mixed with coked concentrated ammonia water (1g:100ml), stirred at room temperature for 3h to reach adsorption saturation, and then the suspension is filtered to obtain adsorbed attapulgite; secondly, the adsorbed attapulgite is ground and put into a crucible, and then put into a tube furnace for oxygen-free calcination. The one-step calcination synthesis conditions are: under nitrogen atmosphere, the calcination temperature is 400-600℃, the calcination time is 2-4h, and the heating rate is 10-20℃ / min.

2. The method for preparing attapulgite / carbon composite material adsorbent by one-step carbonization activation according to claim 1, characterized in that: The calcination process is carried out under a N2 atmosphere, that is, N2 is introduced into the tubular furnace before heating to drive out the air therein, and maintained for 5 minutes to ensure that there is no influence of air during the activation process.

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