A gaseous arsenic adsorbing material of pyrolusite and a preparation method and application thereof

Abstract

The application discloses a pyrolusite gaseous arsenic adsorption material and a preparation method and application thereof, and belongs to the technical field of industrial flue gas pollution prevention and control. The adsorption material is prepared by pretreating pyrolusite and then ball-milling and activating the pyrolusite. The pyrolusite is mechanically activated and applied to the adsorption of gaseous arsenic in high-temperature industrial flue gas as an adsorbent. The application widens a new way for comprehensive utilization of pyrolusite resources and expands the raw material source of high-value-added adsorbents. The prepared pyrolusite gaseous arsenic adsorption material has more significant adsorption effect on gaseous arsenic than common pyrolusite, and the adsorption capacity of the prepared adsorption material on gaseous arsenic is 13.9 mg / g at 300 DEG C under the optimal condition, which is 1.62 times that of unactivated pyrolusite.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial flue gas pollution prevention and control, and particularly relates to a manganite gaseous arsenic adsorption material and a preparation method and application thereof. BACKGROUND

[0002] Arsenic pollution in the atmosphere is an environmental challenge that needs to be urgently addressed. Arsenic in the air can accumulate in the human body through direct inhalation or the cumulative effect of the food chain. Given the obvious toxicity of arsenic and its compounds, even relatively low levels of exposure can cause a series of adverse health effects on the human nervous system, digestive system and skin. As of 2015, about 4.09 billion people worldwide lived in environments where the risk of cancer due to atmospheric arsenic pollution exceeded the acceptable threshold, of which about 66 million were children. And the environmental risk of arsenic in the atmosphere is also higher than that in water bodies and solid waste. Therefore, reducing the emission of arsenic into the atmosphere is currently the focus of arsenic pollution control.

[0003] The flue gas of non-ferrous smelting and coal-fired power plants is the main source of arsenic in the atmosphere. Currently, there are two main methods for removing gaseous arsenic from flue gas: wet arsenic removal and dry adsorption arsenic removal. Compared with wet arsenic removal, dry adsorption arsenic removal has the advantages of flexible adsorption position, unaffected quality of subsequent by-products, and good prospects for arsenic resource recovery. Currently, the adsorbents used in dry adsorption arsenic removal mainly include natural minerals, activated carbon, fly ash, metal oxides, etc. Among them, natural mineral adsorbents have the advantages of low cost and wide source, and have the potential for large-scale industrial application. As a natural mineral, manganite has not been reported to be applied to the adsorption of gaseous arsenic in flue gas. Patent VN20001719000Y discloses a production process for surface-modified manganite material, which processes natural manganite with a MnO2 content of about 62-65% to a particle size of about 0.2-0.5 mm, acidifies it in an HCl acid solution, alkalinizes it with a NaOH and H2O2 mixture, and surface-modifies it by adding aluminum and iron salts. The process is complicated, requires a large number of chemical reagents, needs to be surface-modified with iron and aluminum, and can only be used for the adsorption of arsenic in solution.

[0004] Due to the low specific surface area and active surface, the adsorption capacity of natural manganite for gaseous arsenic is limited, and therefore, it is necessary to develop a simple preparation method to activate natural manganite and improve its adsorption capacity for gaseous arsenic. SUMMARY

[0005] In view of the problems in the prior art, the present application aims to provide a manganite gaseous arsenic adsorption material and a preparation method and application thereof, to enhance the adsorption capacity of manganite for gaseous arsenic in flue gas by mechanical activation, and to provide the application of the activated manganite in adsorbing gaseous arsenic from flue gas containing arsenic.

[0006] To achieve the above objectives, the present invention provides a pyrolusite gaseous arsenic adsorbent material, which is prepared by ball milling and activation of pyrolusite after pretreatment.

[0007] Preferably, the pretreatment involves crushing and sieving to remove impurities. The purpose of the pretreatment is to crush the pyrolusite and remove impurities.

[0008] Preferably, the ball-to-material mass ratio for ball milling activation is 10-30:1; the ball milling activation time is 90-120 min; and the ball milling activation rotation speed is 150-450 r / min.

[0009] As a general technical concept, the present invention also provides a method for preparing the above-mentioned pyrolusite gaseous arsenic adsorbent material, comprising the following steps:

[0010] The pretreated pyrolusite was placed in a ball mill jar with a ball-to-material mass ratio of 10-30:1. The ball mill jar was then sealed, and the ball milling time was 90-120 min at a speed of 150-450 r / min. After the ball milling activation was completed, the pyrolusite gaseous arsenic adsorbent material was obtained.

[0011] Preferably, the pretreatment specifically involves crushing the pyrolusite through a 100-mesh sieve, followed by washing and filtering with a 1M HCl solution to obtain the pretreated pyrolusite.

[0012] This invention utilizes natural pyrolusite as the target mineral and employs a mechanochemical method to activate it, thereby enhancing its ability to capture gaseous arsenic. Mechanical ball milling increases the specific surface area and active sites of the pyrolusite, and further enhances its ability to capture gaseous arsenic by activating the surface lattice oxygen. The pyrolusite activation method described in this invention is simple, low-cost, and produces pyrolusite with a high adsorption capacity for gaseous arsenic, demonstrating promising application prospects.

[0013] As a general technical concept, the present invention also provides the application of the above-mentioned activated pyrolusite adsorbent as an adsorbent in the treatment of gaseous arsenic flue gas, wherein the gaseous arsenic flue gas is non-ferrous metal smelting flue gas or coal combustion flue gas.

[0014] Preferably, the gaseous arsenic is at least one of As2O3(g) and AsH3(g).

[0015] Preferably, the temperature of the adsorption process is 150~600℃, more preferably 200~400℃. That is to say, the temperature of the arsenic-containing flue gas to be treated can be 150~600℃, more preferably 200~400℃.

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] (1) In view of the shortcomings of existing manganese mineral adsorbents with low adsorption capacity for gaseous arsenic, the present invention provides a simple method to activate pyrolusite and enhance its adsorption capacity for gaseous arsenic. After mechanical ball milling, the crystallinity of pyrolusite decreases, the specific surface area increases, the covalent relationship between Mn and O is enhanced, and the lattice oxygen is activated, which effectively improves the oxidation-adsorption capacity of pyrolusite for gaseous arsenic.

[0018] (2) The mechanical ball milling method for activating pyrolusite provided by this invention effectively improves the adsorption capacity of pyrolusite for gaseous arsenic. This method is simple, time-saving, and energy-efficient, and pyrolusite is inexpensive and readily available, which greatly reduces costs. At the same time, this preparation method is environmentally friendly, does not produce toxic or harmful byproducts, and has low requirements for production equipment, making it suitable for large-scale preparation and meeting the needs of actual production. Attached Figure Description

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0020] Figure 1 XRD patterns of ball-milled activated pyrolusite prepared at different ball-milling times in this invention;

[0021] Figure 2 SEM images of ball-milled activated pyrolusite prepared at different ball-milling times in this invention;

[0022] Among them, (a) 30 min; (b) 60 min; (c) 90 min; (d) 120 min.

[0023] Figure 3 The adsorption capacity of ball-milled activated pyrolusite for gaseous arsenic is given by ball milling time for different purposes in this invention.

[0024] Figure 4 The adsorption capacity of ball-milled activated pyrolusite for gaseous arsenic in this invention is given by different ball-to-material ratios.

[0025] Figure 5 The adsorption capacity of ball-milled activated pyrolusite for gaseous arsenic at different rotation speeds in this invention;

[0026] Figure 6 The adsorption capacity of ball-milled activated pyrolusite for gaseous arsenic at different temperatures is shown in the figure.

[0027] Figure 7 The adsorption capacity of pretreated pyrolusite for gaseous arsenic at different temperatures in Comparative Example 1 of this invention; Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. Example 1

[0029] A method for preparing a mechanochemically activated pyrolusite adsorbent material comprises the following steps: pyrolusite is crushed and passed through a 100-mesh sieve, then washed and filtered with 1M HCl solution to obtain pretreated pyrolusite. 4g of the pretreated pyrolusite is weighed and placed in a ball mill jar, and a certain amount of small balls are added at a ball-to-material ratio of 20:1. The ball mill jar is then sealed, and the ball mill speed is set to 250 r / min. The ball milling times are set to 0, 15, 30, 60, 90, and 120 min, respectively. The ball mill is then started to begin ball milling. After the ball milling is completed, the mixture is removed, and the ball-milled activated pyrolusite adsorbent material is finally obtained.

[0030] like Figure 3 As shown, with the extension of ball milling time, the adsorption capacity of the prepared ball-milled activated pyrolusite adsorbent for gaseous arsenic first increases and then decreases, reaching a peak at 90 min (13.9 mg / g). This may be because, when the ball milling time is in the range of 30–90 min, the covalent nature of Mn and O in pyrolusite is enhanced under the action of mechanochemicals, thereby activating the lattice oxygen on the surface of pyrolusite and increasing the covalent nature of Mn and O in pyrolusite. 2+ +Mn 3+ ) / Mn 4+ The proportion of Mn on the surface of pyrolusite gradually increases; and as the ball milling time increases, the local reaction of pyrolusite becomes more intense, with oxygen in the air participating in the reaction, leading to an increase in the amount of Mn on the pyrolusite surface. 4+ The content increases. At the same time, the lattice oxygen content in pyrolusite also increases and then decreases with increasing ball milling time, reaching a peak at 90 min. Example 2

[0031] A method for preparing a mechanochemically activated pyrolusite adsorbent material comprises the following steps: pyrolusite is crushed and passed through a 100-mesh sieve, then washed and filtered with 1M HCl solution to obtain pretreated pyrolusite. 4g of the pretreated pyrolusite is weighed and placed in a ball mill jar, and a certain amount of small balls are added, with a ball-to-material ratio of 10:1, 20:1, 30:1 to 40:1. The ball mill jar is then sealed, and the ball mill speed is set to 250 r / min, with a milling time of 90 min. The ball mill is then started to begin milling. After milling is completed, the mixture is removed, and the milled activated pyrolusite adsorbent material is finally obtained.

[0032] like Figure 4 As shown, with the increase of the ball-to-material ratio, the adsorption capacity of the prepared ball-milled activated pyrolusite adsorbent material for gaseous arsenic first increases and then decreases, reaching a peak (13.9 mg / g) when the ball-to-material ratio is 20:1. Example 3

[0033] A method for preparing a mechanochemically activated pyrolusite adsorbent material comprises the following steps: pyrolusite is crushed and passed through a 100-mesh sieve, then washed and filtered with 1M HCl solution to obtain pretreated pyrolusite. 4g of the pretreated pyrolusite is weighed and placed in a ball mill jar, and a certain amount of small balls are added at a ball-to-material ratio of 20:1. The ball mill jar is then sealed, and the ball mill speed is set to 150r / min, 250r / min, 350r / min, and 450r / min, with a milling time of 90min. The ball mill is then started to begin milling. After milling is complete, the mixture is removed, and the milled activated pyrolusite adsorbent material is finally obtained.

[0034] like Figure 5 As shown, with increasing rotation speed, the adsorption capacity of the prepared ball-milled activated pyrolusite adsorbent material for gaseous arsenic first increases and then decreases, reaching a peak value (13.9 mg / g) at a rotation speed of 250 rpm.

[0035] In summary, under the conditions of a ball milling time of 90 min, a ball-to-material mass ratio of 20:1, and a ball milling speed of 250 r / min, the ball-milled activated pyrolusite adsorbent material with the best performance can be obtained. Under the action of mechanochemical processes, pyrolusite gradually loses its original crystal structure, such as... Figure 1 As shown, the crystallinity of pyrolusite first decreases and then increases with increasing ball milling time. And as... Figure 2 As shown, under the action of mechanochemistry, pyrolusite is further crushed and undergoes plastic deformation, which increases the specific surface area of ​​pyrolusite and is conducive to the adsorption of gaseous arsenic by pyrolusite. Example 4

[0036] An application of ball-milled activated manganese ore adsorbent as an adsorbent to capture gaseous arsenic in high-temperature industrial flue gas is disclosed. Specifically, the ball-milled activated manganese ore adsorbent adsorbs As2O3(g) in flue gas at high temperature, comprising the following steps: 0.1g of ball-milled activated manganese ore adsorbent prepared under optimal conditions is added to a specially designed fixed-bed reactor, spread evenly, and the reactor is placed in a reactor furnace; then, the concentration of As2O3(g) in the simulated flue gas is controlled to 60ppm by a hydride generator, and the gas composition of the simulated flue gas is configured by a gas distribution system; subsequently, the As2O3(g) in the flue gas is carried by the gas flow to the reactor furnace and captured by the prepared ball-milled activated manganese ore adsorbent. The reaction time is 60min, and the reaction tail gas is discharged after two stages of washing.

[0037] Furthermore, the reaction temperatures in the lower section of the tubular furnace are 200℃, 250℃, 300℃, 350℃, and 400℃, respectively.

[0038] The simulated flue gas composition was 95% argon + 5% oxygen, and the flue gas flow rate was 400 mL / min;

[0039] After the reaction was completed, the used adsorbent material was taken out, digested and diluted using a specific method, and a certain amount of the digest was filtered through a 0.45 μm filter membrane. The concentration of arsenic in the filtrate was determined using ICP-OES, and then the amount of gaseous arsenic adsorbed by the adsorbent material was calculated.

[0040] like Figure 6 As shown, the adsorption capacity of the ball-milled activated pyrolusite adsorbent material prepared under optimal conditions for gaseous arsenic in simulated flue gas increases with increasing temperature in the range of 200~400℃, and finally reaches a peak at 400℃ (17.5mg / g). Moreover, the adsorption capacity for gaseous arsenic under all temperature conditions is higher than that of unactivated pyrolusite.

[0041] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An application of a pyrolusite gaseous arsenic adsorbent material in adsorbing gaseous arsenic in flue gas containing gaseous arsenic; characterized in that, The preparation method of adsorbent material includes the following steps: The pretreated pyrolusite was placed in a ball mill jar with a ball-to-material mass ratio of 10-30:

1. The ball mill jar was then sealed, and the ball milling time was 90-120 min with a ball milling speed of 150-450 r / min. After the ball milling activation was completed, the pyrolusite gaseous arsenic adsorbent material was obtained. The gaseous arsenic in the gaseous arsenic flue gas includes at least one of gaseous As2O3 and gaseous AsH3; The adsorption temperature is 200~400℃; The pretreatment specifically involves crushing the pyrolusite through a 100-mesh sieve, then washing and filtering it with a 1M HCl solution to obtain the pretreated pyrolusite.

2. The application as described in claim 1, characterized in that, The gaseous arsenic-containing flue gas is either non-ferrous metal smelting flue gas or coal combustion flue gas.

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