Black ceramic as well as preparation method and application thereof

Abstract

The invention relates to the technical field of water purification materials, and provides black ceramic as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing clay, a pore-forming agent and water to obtain a wet material; and carrying out compression molding on the wet material, and calcining in an anoxic atmosphere to obtain the black ceramic. The black ceramic is prepared through calcination under the anoxic condition, the performance requirement of the filter ceramic can be met at the low temperature, the preparation energy consumption is remarkably reduced, the arsenic dissolution rate of the black ceramic can be effectively reduced, and the water purification performance of the black ceramic can be improved. The result of the embodiment shows that the black ceramic with performance equivalent to that of the black ceramic prepared by the traditional firing process (800-1100 DEG C) can be calcined at 700 DEG C, the removal rate of the obtained black ceramic to turbidity in water can reach 90%, and the arsenic dissolution rate is lt; and 0.4%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water purification materials, in particular to a black ceramic and a preparation method and application thereof. BACKGROUND

[0002] Water purification filter material is the core of water treatment technology, which removes pollutants (such as microorganisms, heavy metals, organic matter, residual chlorine, etc.) in water through physical interception, adsorption, biological action and other mechanisms, and is widely used in families, industries, environmental protection and special fields.

[0003] Ceramic water filters (CWFs) prepared by mixing clay and pore-forming agents (such as sustainable organic matter) and calcining can be applied to the purification of domestic drinking water. Through the dual action of micropore physical interception and surface antibacterial coating (such as silver plating), more than 99% removal rate of bacteria and protozoa can be achieved, which significantly improves the biological safety of drinking water.

[0004] However, there are still the following problems in the actual application of water purification ceramics: first, the preparation energy consumption is high. The current preparation process generally adopts high-temperature aerobic calcination, and the calcination temperature is as high as 1100℃, which has the problem of high energy consumption and increases the environmental burden; second, arsenic leaching risk. Studies have shown that during the high-temperature aerobic calcination process, the arsenic element naturally occurring in the water purification ceramic raw material will undergo a morphological transformation: the proportion of combined arsenic decreases significantly, and the content of exchangeable arsenic increases significantly. This morphological change significantly enhances the migration activity of arsenic elements, which may cause the water purification ceramic to become a secondary release carrier of arsenic pollution during long-term water purification, threatening the safety of drinking water.

[0005] In summary, there is an urgent need to provide a ceramic material with low preparation energy consumption, low arsenic leaching rate and good water purification effect. SUMMARY

[0006] Therefore, the present application provides a black ceramic and a preparation method and application thereof. The preparation method provided by the present application has low calcination temperature, and the obtained black ceramic has good water purification performance and low arsenic leaching rate.

[0007] In order to achieve the above-mentioned application purpose, the present application provides the following technical scheme: A preparation method of a black ceramic, comprising the following steps: Mixing clay, pore-forming agent and water to obtain wet material; Pressing the wet material to form a green body; Calcining the green body in an oxygen-deficient atmosphere to obtain a black ceramic; the calcination temperature is 700-950℃.

[0008] Preferably, the pore-forming agent is one or both of starch and rice bran.

[0009] Preferably, the starch is one or both of potato starch and wheat starch.

[0010] Preferably, the mass of the water is 10% to 15% of the total mass of the clay and the pore-forming agent; the mass of the pore-forming agent is 15% to 35% of the total mass of the clay and the pore-forming agent.

[0011] Preferably, the pressure of the press molding is 680 to 1000 psi.

[0012] Preferably, the anoxic atmosphere is a nitrogen atmosphere; the flow rate of the nitrogen is 1 to 6 L / min / m 3 .

[0013] Preferably, the calcination procedure comprises: (1) heating from room temperature to 105℃ at a rate of 1 to 6 ℃ / min and maintaining for 1 to 3 h; (2) increasing the temperature to 450℃ at a rate of 1 to 2 ℃ / min, maintaining for 0.5 to 1 h; (3) continuing to heat to the desired final temperature at a rate of 1 to 2 ℃ / min, and maintaining for 0 to 1 h; (4) naturally cooling to room temperature.

[0014] The application also provides the black ceramic prepared by the preparation method described in the above scheme.

[0015] The application also provides the application of the black ceramic described in the above scheme as a water purification material.

[0016] The application provides a preparation method of black ceramic, comprising the following steps: mixing clay, pore-forming agent and water to obtain wet material; pressing and forming the wet material to obtain a green body; calcining the green body in an oxygen-deficient atmosphere to obtain black ceramic; and the calcining temperature is 700-950 DEG C. The inventor finds through experimental research that the silicon-aluminum mineral generated in the oxygen-deficient calcination environment can improve the mechanical strength of the ceramic material, the performance requirements of the water purification ceramic can be realized at a lower temperature, and the preparation energy consumption is significantly reduced. Moreover, the iron-containing mineral phase generated by the oxygen-deficient calcination is mainly iron spinel and / or iron olivine, and the binding capacity of the iron-containing mineral phase to arsenic is stronger than that of the hematite crystal phase generated by the oxygen calcination, so that the dissolution of arsenic can be effectively inhibited. In addition, the water purification performance of the ceramic mainly depends on the interception of pollutants by the pores, the pores are formed by the combustion of the pore-forming agent, the smaller the pore size, the better the water purification efficiency, but the smaller the water permeation efficiency (flow rate), the black ceramic is calcined in the low-temperature oxygen-deficient environment, the pore-forming agent added is not burnt out to form carbon, the pore distribution in the water purification ceramic can be changed, the water purification performance of the black ceramic is enhanced, and the permeation efficiency of the black ceramic is ensured to be not significantly reduced. Further, in the preparation of the water purification ceramic by the traditional oxygen calcination, the amount of the pore-forming agent is usually less than 20% to ensure the mechanical strength and other performance requirements of the ceramic material, the oxygen-deficient calcination can be used to obtain the black ceramic with the required performance under the condition of a high amount of the pore-forming agent; the amount of the pore-forming agent can be increased to change the pore size distribution of the black ceramic, optimize the pore connectivity, significantly improve the permeability of the black ceramic, and improve the water treatment efficiency; and the oxygen-deficient calcination endows the black ceramic with higher mechanical strength, ensures that the structure of the black ceramic is stable under the condition of high porosity, improves the water treatment efficiency, ensures the efficient interception of pollutants, realizes the synchronous improvement of the treatment efficiency and the purification efficiency, and solves the contradiction between the permeability and the purification efficiency of the traditional water purification ceramic material.

[0017] The results of the examples show that under the condition that the amount of the pore-forming agent is 15-35%, the removal rate of the black ceramic prepared by the application to the turbidity in water can reach 90%, and the effluent turbidity can be reduced to below 1 NTU; the black ceramic with the performance equivalent to that prepared by the traditional firing process (800-1100 DEG C) can be calcined at 700 DEG C, and the calcination temperature is obviously reduced; and the arsenic dissolution rate of the black ceramic calcined under the oxygen-deficient condition is less than 0.4% without any additional modification treatment, and compared with the water purification ceramic prepared by the conventional oxygen calcination with the same formula, the arsenic dissolution rate is reduced by 19%-24%. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Potato starch is used as the pore-forming agent, and the effects of different amounts of the pore-forming agent on the permeability coefficient and the water purification efficiency of the ceramic under the calcination temperature of 950 DEG C, wherein (a) is the permeability coefficient, (b) is the water purification efficiency, the black ceramic is denoted as AnCWFs, and the water purification ceramic calcined by the traditional oxygen calcination is denoted as AeCWFs; Figure 2 Effect of different pore former contents on permeability coefficient and water purification efficiency of black ceramics with wheat starch as pore former at calcination temperature of 950℃, where (a) is permeability coefficient, (b) is water purification efficiency, black ceramics is recorded as AnCWFs, and traditional water purification ceramics calcined in oxygen is recorded as AeCWFs; Figure 3 Effect of different pore former contents on permeability coefficient and water purification efficiency of black ceramics with potato starch as pore former at calcination temperature of 700℃ or 950℃, where (a) is permeability coefficient, (b) is water purification efficiency; Figure 4 Effect of different nitrogen flow rates on arsenic leaching of black ceramics (pore former is rice bran, and calcination temperature is 950℃), where (a) is HN soil, (b) is HB soil, 2.6 L / min / m 3 Black ceramics calcined in nitrogen is recorded as AnCWFs-10, 5.2 L / min / m 3 Black ceramics calcined in nitrogen is recorded as AnCWFs-20, and traditional water purification ceramics calcined in oxygen is recorded as AeCWFs; Figure 5 Effect of different calcination temperatures on arsenic leaching of black ceramics; Figure 6 Effect of different pH values on arsenic leaching of ceramics calcined in oxygen and ceramics calcined in oxygen deficiency (pore former is rice bran, and calcination temperature is 950℃), where (a) is HN soil, (b) is HB soil, uncalcined clay is recorded as Clay, black ceramics is recorded as AnCWFs, and traditional water purification ceramics calcined in oxygen is recorded as AeCWFs; Figure 7 Effect of different pH values on arsenic leaching of black ceramics at different calcination temperatures; Figure 8 Effect of different coexisting ions on arsenic leaching of ceramics calcined in oxygen and ceramics calcined in oxygen deficiency (pore former is rice bran, and calcination temperature is 950℃), where (a) is HN soil, (b) is HB soil, uncalcined clay is recorded as Clay, black ceramics is recorded as AnCWFs, and traditional water purification ceramics calcined in oxygen is recorded as AeCWFs; Figure 9 Effect of different coexisting ions on arsenic leaching of black ceramics at different calcination temperatures; Figure 10 Mineral phase quantitative analysis results of black ceramics obtained by calcination in oxygen deficiency, where (a) is HN soil, and (b) is HB soil. DETAILED DESCRIPTION

[0019] The application provides a preparation method of black ceramics, which comprises the following steps: The clay, pore former and water are mixed to obtain wet materials; The wet materials are pressed to obtain green bodies; firing the green body in an oxygen-deficient atmosphere to obtain black ceramic; the temperature of the firing is 700-950℃.

[0020] The clay, pore-forming agent and water are mixed to obtain wet material. The source of the clay is not particularly required in the present application, and natural clay can be used. The clay is preferably sieved before use. The mesh size of the sieve is preferably 200 mesh, and the undersize is used. The pore-forming agent is preferably one or more of starch and rice bran. The starch is preferably one or both of potato starch and wheat starch. In a specific embodiment of the present application, when the pore-forming agent is rice bran, the rice bran is preferably ground and sieved through 60 and 80 mesh sieves, and the material between the two sieves is used. The mass of the water is preferably 10-15% of the total mass of the clay and pore-forming agent. The mass of the pore-forming agent is preferably 15-35% of the total mass of the clay and pore-forming agent, and can be specifically 15%, 20%, 25%, 30% or 35%. The mass of the pore-forming agent is based on dry weight.

[0021] In the present application, the clay, pore-forming agent and water are mixed by first mixing the clay and pore-forming agent to obtain dry powder, and then mixing the dry powder with water.

[0022] After obtaining the wet material, the wet material is pressed to obtain a green body. In the present application, the pressure of the pressing is preferably 680-1000 psi, and the time of the pressing is preferably 1 min. The obtained green body is preferably naturally air-dried before being fired.

[0023] After obtaining the green body, the green body is fired in an oxygen-deficient atmosphere to obtain black ceramic. In the present application, the oxygen-deficient atmosphere is preferably a nitrogen atmosphere, and the flow rate of the nitrogen is preferably 1-6 L / min / m 3 , more preferably 2.6-5.2 L / min / m 3 .

[0024] In the present application, the temperature of the firing is preferably 700-950℃, and can be specifically 700℃, 800℃, 900℃ or 950℃, and is most preferably 700℃. The holding time of the firing is preferably 0-1 h, and more preferably 0.5-1 h. The firing procedure preferably comprises: (1) heating from room temperature to 105℃ at a rate of 1-6 ℃ / min (preferably 5 ℃ / min), and holding for 1-3 h (preferably 1 h); (2) heating to 450℃ at a rate of 1-2 ℃ / min (preferably 1.5 ℃ / min), and holding for 0.5-1 h (preferably 1 h); (3) continuing to heat to the desired final temperature at a rate of 1-2 ℃ / min (preferably 1.5 ℃ / min), and holding for 0-1 h (preferably 1 h); (4) naturally cooling to room temperature.

[0025] The application further provides the black ceramic prepared by the preparation method. 3 .

[0026] The application further provides application of the black ceramic as water purification material.

[0027] The technical solutions in the application will be described clearly and completely below with reference to the embodiments in the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0028] The clay used in the following examples is two kinds, which are from Henan Province and Hebei Province, and are recorded as HN soil and HB soil. The main components of HN soil are kaolin and hematite, and the main components of HB soil are quartz and albite. The pore-forming agents used in the following examples are potato starch, wheat starch and rice bran. The rice bran is ground through a 60-80 mesh sieve, and the material between the two sieves is used.

[0029] Example 1 First, the clay (HN soil and HB soil) is passed through a 200 mesh sieve. The pore-forming agent is mixed with the clay at a ratio of 15%-35% of the total mass. Then, 10% of water is added to the mixed dry powder to obtain wet material. 15 g of wet material is weighed and pressed in a tablet press at a pressure of 700 psi for 1 min. The obtained green body is naturally air-dried and then placed in a tube furnace for calcination under anoxic atmosphere with continuous nitrogen flow (nitrogen flow is 2.6 L / min / m 3 or 5.2 L / min / m 3 ). The calcination program is as follows: (1) heated from room temperature to 105℃ at a rate of 5℃ / min and kept for 1 h; (2) heated to 450℃ at a rate of 1.5℃ / min and kept for 1 h; (3) continuously heated to the required final temperature (700℃, 800℃, 900℃, 950℃) and kept for 1 h; (4) naturally cooled to room temperature to obtain black ceramic.

[0030] Rice bran (15%) is used as a pore-forming agent, and the nitrogen flow is 2.6 L / min / m 3The carbon content in the black ceramics made from HN clay and HB clay is 15.7% and 10.0% respectively when the calcination temperature is 950℃, while the carbon content in the ceramics calcined in the presence of oxygen is not detected. The main mineral components of the black ceramics made from HN clay are fayalite, hercynite and mullite; the main mineral components of the black ceramics made from HB clay are quartz, fayalite and albite.

[0031] Wheat starch as the pore-forming agent (15%-35%), the nitrogen flow rate is 2.6 L / min / m 3 The carbon content in the black ceramics made from HN clay is 2.52%-8.88% when the calcination temperature is 950℃; potato starch as the pore-forming agent (15%-35%), the nitrogen flow rate is 2.6 L / min / m 3 The carbon content in the black ceramics made from HN clay is 5.19%-12.3% and 3.38%-15.3% when the calcination temperature is 700℃ and 950℃. The above results can show that there is carbon remaining in the black ceramics due to the incomplete combustion of the pore-forming agent, and the carbon content increases with the increase of the amount of the pore-forming agent.

[0032] The physical property parameters of the black ceramics obtained when rice bran and starch are used as the pore-forming agent are shown in Table 1 and Table 2.

[0033] Table 1 Physical property parameters of the black ceramics made from rice bran as the pore-forming agent

[0034] Table 2 Physical property parameters of the black ceramics made from starch as the pore-forming agent

[0035] Example 2 Potato starch and wheat starch are used as the pore-forming agent, the content of the pore-forming agent is changed, and the calcination is carried out at different temperatures. The obtained black ceramics are used for filtration experiment and the permeability coefficient is measured. The specific experimental process is as follows: 2.1 Effect of pore-forming agent on the filtration performance of black ceramics The clay used is HN clay, the pore-forming agent used is potato starch or wheat starch, and the amount of the pore-forming agent is 15%, 20%, 25%, 30% and 35% (w%); the calcination temperature is 950℃, the nitrogen flow rate is 2.6 L / min / m 3 , and the other conditions are the same as in Example 1.

[0036] As a comparison, the traditional aerobic calcination method (i.e. calcination with air) is used to prepare water purification ceramic materials, and the other conditions remain the same as in Example 1. When the proportion of the pore-forming agent is too high (the amount of potato starch is 30% and 35%, and the amount of wheat starch is 25%, 30% and 35%), the mechanical strength of the obtained samples is too low to be used.

[0037] The obtained ceramic material was fixed on the filtering device. Surface water with turbidity of 5-15 NTU was used to carry out the filtration at a flow rate of 230 L / m - 1 h -1 After 110 mL of water sample was filtered, the turbidity of the water was measured. The permeability coefficient of the traditional water purification ceramic using 15% and 20% potato starch as the pore-forming agent was too low to carry out the filtration experiment.

[0038] The test results are shown in Figures 1-2 When potato starch was used as the pore-forming agent, the water purification efficiency of the black ceramic reached the maximum value when the dosage of the pore-forming agent was 30%, and was higher than the maximum water purification efficiency of the oxygen calcined ceramic material; when wheat starch was used as the pore-forming agent, the water purification efficiency of the black ceramic reached the maximum value when the dosage of the pore-forming agent was 30%, and was equivalent to the maximum water purification efficiency of the oxygen calcined ceramic material; at the same time, compared with the oxygen calcined water purification ceramic, the permeability coefficient of the black ceramic material was significantly improved, which was beneficial to improve the water treatment efficiency.

[0039] 2.2 Effect of calcination temperature on the filtration performance of black ceramic material The clay used HN soil, the pore-forming agent used potato starch, and the dosage of the pore-forming agent was 15%, 20%, 25%, 30%, and 35% of the total mass of the pore-forming agent and the clay, respectively; the calcination temperature was 700°C and 950°C, respectively, the nitrogen flow rate was 2.6 L / min / m 3 , and other conditions were the same as in Example 1.

[0040] The obtained black ceramic was fixed on the filtering device, and raw water with turbidity of 5-15 NTU was used to carry out the filtration at a flow rate of 230 L / m -1 h -1 After 110 mL of water sample was filtered, the turbidity of the water was measured.

[0041] The results are shown in Figure 3 When potato starch was used as the pore-forming agent, the water purification efficiency of the black ceramic reached the maximum value (see Figure 3 (b) in the middle), and the permeability coefficient under this condition was also high (see Figure 3 (a) in the middle).

[0042] From the results in 2.1 and 2.2, it can be seen that the water purification efficiency of black ceramics prepared by calcination at 700℃ under anoxic conditions with potato starch as the pore-forming agent and a proportion of 25%, 30%, and 35% is better than that of black ceramics prepared by calcination at 950℃, and the permeability coefficient does not fluctuate significantly with the change in the content of the pore-forming agent, indicating that a lower calcination temperature can be used for preparation. At the same time, the type of pore-forming agent has little effect on the water purification efficiency, but the content of the pore-forming agent has a significant effect on the water purification efficiency. It is worth noting that all the samples prepared under different conditions have good water purification function.

[0043] Example 3 This example studies the effects of nitrogen flow rate and calcination temperature on arsenic dissolution of black ceramics.

[0044] 3.1 Effect of nitrogen flow rate on arsenic dissolution The preparation conditions of black ceramics are as follows: clay is HN clay or HB clay, rice bran is used as the pore-forming agent, the amount of pore-forming agent is 15% of the total mass of pore-forming agent and clay; the calcination temperature is 950℃, the nitrogen flow rate is 2.6 L / min / m 3 or 5.2 L / min / m 3 , respectively, referred to as low nitrogen flow rate and high nitrogen flow rate, and other conditions are the same as in Example 1. At the same time, traditional oxygen calcination is used to prepare water purification ceramics at the same temperature, which is used as a control for the filtration experiment.

[0045] The obtained ceramic materials are fixed on the filtration device, and 100 mL of tap water is filtered at a flow rate of 275 Lm -2 h -1 . The outflow samples are collected at predetermined time intervals to obtain the relationship between the filtration volume and the arsenic concentration in the effluent, and the results are shown in Figure 4 , where (a) is HN clay and (b) is HB clay.

[0046] When rice bran is used as the pore-forming agent, the arsenic dissolution of HN clay black ceramics calcined at different nitrogen flow rates does not change much; however, the arsenic dissolution of HB clay black ceramics at low nitrogen flow rate is significantly lower than that at high nitrogen flow rate (when the outflow volume is 80 and 100 mL, the dissolution is even lower than the detection limit). Therefore, 2.6 L / min / m 3 is the best nitrogen flow rate. Through the analysis of Figure 4The total arsenic leaching during the filtration process can be obtained by integrating the arsenic leaching amount of the ceramics. Experimental data show that anaerobic calcination significantly inhibits arsenic leaching: the arsenic leaching amount of HN clay ceramics decreased from 3.54 μg / g under aerobic conditions to 0.066 μg / g, a reduction of 24.6%; while that of HB clay ceramics decreased from 3.05 μg / g to 0.0548 μg / g, a reduction of 19.4%. Meanwhile, both clays exhibited similar arsenic inhibition capabilities under anaerobic conditions, indicating that the type of clay has little impact on the arsenic leaching inhibition performance of black ceramics.

[0047] 3.2 Effect of calcination temperature on arsenic leaching The preparation conditions for black ceramics are as follows: HN clay is used as the clay, and potato starch is used as the pore-forming agent, with the addition amount being 25% of the total mass of the pore-forming agent and clay; the calcination temperatures are set at 700℃, 800℃, and 950℃, and the nitrogen flow rate is controlled at 2.6 L / min / m³. 3 All other conditions are the same as in Example 1.

[0048] The obtained ceramic material was fixed onto the filter device at 375 Lm. -2 h -1 110 mL of tap water was filtered at a flow rate of [unspecified]. Water samples were collected at pre-set time intervals, and the relationship between filtration volume and arsenic content in the effluent was measured.

[0049] Test results are as follows Figure 5 As shown (when the calcination temperature is 950℃ and the filtration volume is greater than 25 mL, the arsenic leaching amount is below the detection limit). According to... Figure 5 The results were calculated by integrating the total amount of arsenic leaching. The results showed that when the calcination temperature was 700℃ and 800℃, the amount of arsenic leaching from black ceramics was less than that from black ceramics calcined at 950℃, and the amount of arsenic leaching from black ceramics calcined at 800℃ was slightly lower than that from black ceramics calcined at 700℃.

[0050] Example 4 This embodiment investigates the arsenic leaching of black ceramics under different pH conditions.

[0051] The preparation conditions for black ceramics are as follows: HN clay or HB clay is used, and rice bran is used as the pore-forming agent, with an addition amount of 15% of the total mass of the pore-forming agent and clay; the calcination temperature is set at 950℃, and the nitrogen flow rate is 2.6 L / min / m³. 3 Other conditions are the same as in Example 1.

[0052] In addition, water purification ceramics prepared using the same raw material formula and at the same temperature through traditional aerobic calcination were used as a control.

[0053] The obtained black ceramic material was ground and passed through a 200-mesh sieve. The ceramic powder was mixed with water of different pH values ​​(6.5, 8) at a mass:volume ratio of 1 g:100 mL and shaken on a shaker for 24 h. The supernatant was collected, and the concentration of arsenic in the water sample was determined using ICP-MS. The same tests were performed on clay and traditional water purification ceramics.

[0054] Test results are as follows Figure 6 As shown, (a) is HN soil and (b) is HB soil.

[0055] according to Figure 6 The results show that, under pH conditions of 6.5 and 8, the arsenic leaching concentrations of black ceramics fired from both types of clay were lower than those of traditional water purification ceramics. This indicates that, under different pH conditions, calcination under anaerobic conditions inhibits arsenic leaching.

[0056] The clay used is HN clay, and the pore-forming agent is potato starch, with the amount of pore-forming agent being 15% of the total mass of pore-forming agent and clay; the calcination temperature is 700℃ or 950℃, and the nitrogen flow rate is 2.6 L / min / m³. 3 Other conditions were the same as in Example 1. The same method was used to test the arsenic leaching concentration of the obtained black ceramic material under different pH conditions.

[0057] Test results are as follows Figure 7 As shown, by Figure 7 It can be seen that, under the conditions of pH=6.5 and 8, the arsenic leaching amount of black ceramics calcined at 700℃ is lower than that of black ceramics calcined at 950℃.

[0058] Example 5 This embodiment investigates the effect of coexisting ions on the dissolution of arsenic in ceramics.

[0059] 5.1 Effects of coexisting ions on arsenic dissolution in ceramics calcined under different environments The clay used was HN clay or HB clay, and rice bran was used as a pore-forming agent to prepare black ceramic materials. The preparation method was the same as in Example 4.

[0060] Black ceramic powder was ground and passed through a 200-mesh sieve. Then, at a solid-liquid ratio of 1 g:100 mL, the ceramic powder was mixed with 5 mmol / L Na₂CO₃, NaH₂PO₄ / Na₂HPO₄, NaNO₃ buffer, and pure water, respectively, and shaken in a shaker for 24 h. The supernatant was collected, and the arsenic concentration was determined using ICP-MS. As a control, the same tests were performed on the clay raw material and traditional water purification ceramics (AeCWFs).

[0061] like Figure 8As shown, under different coexisting ion conditions, the arsenic leaching concentrations of black ceramics made from both types of clay were significantly lower than those of traditional water purification ceramics. This indicates that anaerobic calcination can effectively inhibit arsenic leaching in different chemical environments.

[0062] 5.2 Effect of coexisting ions on arsenic dissolution in black ceramics calcined at different temperatures The preparation conditions for black ceramics are as follows: HN clay is used as the clay, potato starch is used as the pore-forming agent, and the amount of pore-forming agent is 15% of the total mass of pore-forming agent and clay; the calcination temperature is 700℃ or 950℃, and the nitrogen flow rate is 2.6 L / min / m³. 3 Other conditions were the same as in Example 1. The test method for arsenic leaching concentration under different coexisting ions was consistent with that in 5.1.

[0063] Test results are as follows Figure 9 As shown, by Figure 9 It can be seen that, under the three different coexisting ion conditions, the arsenic leaching amount of black ceramics calcined at 700℃ is lower than that of black ceramics calcined at 950℃.

[0064] Example 6 This embodiment studies the mechanism by which black ceramics calcined under anaerobic conditions inhibit arsenic leaching.

[0065] The clay used was HN clay or HB clay, and rice bran was used as a pore-forming agent to prepare black ceramic materials. The preparation method was the same as in Example 4.

[0066] Phase and content analysis of HN clay and its fired black ceramics, and HB clay and its fired black ceramics were performed using XRD patterns combined with Rietveld refinement analysis.

[0067] Mineral phase analysis results ( Figure 10 The results show that before calcination, the original HN and HB soil samples contained hematite and chlorite, respectively; after nitrogen calcination, the former transformed into iron spinel and fayalite, while the latter transformed into fayalite. These newly formed iron-containing aluminum silicate minerals have a higher ability to fix arsenic than the hematite minerals formed by aerobic calcination. In addition, arsenic may enter the glass phase with the minerals, thus effectively inhibiting the dissolution of arsenic.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing black ceramics, characterized in that, Includes the following steps: Clay, pore-forming agent and water are mixed to obtain wet material; The wet material is pressed into a shape to obtain a blank; The green body is calcined in an oxygen-deficient atmosphere to obtain black ceramic; the calcination temperature is 700~950℃.

2. The preparation method according to claim 1, characterized in that, The pore-forming agent is one or both of starch and rice bran.

3. The preparation method according to claim 2, characterized in that, The starch is one or both of potato starch and wheat starch.

4. The preparation method according to claim 1, characterized in that, The mass of the water is 10% to 15% of the total mass of the clay and pore-forming agent.

5. The preparation method according to claim 1, characterized in that, The mass of the pore-forming agent accounts for 15% to 35% of the total mass of the clay and the pore-forming agent.

6. The preparation method according to claim 1, characterized in that, The compression molding pressure is 680~1000psi.

7. The preparation method according to claim 1, characterized in that, The oxygen-deficient atmosphere is a nitrogen atmosphere; the flow rate of the nitrogen is 1~6 L / min / m³. 3 .

8. The preparation method according to claim 1, characterized in that, The calcination process includes: heating from room temperature to 105°C at a rate of 1-6°C / min and holding at that temperature for 1-3 hours; then heating to 450°C at a rate of 1-2°C / min and holding at that temperature for 0.5-1 hour; continuing to heat to the calcination temperature at a rate of 1-2°C / min, holding at that temperature for 0-1 hours, and then naturally cooling to room temperature.

9. Black ceramic prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the black ceramic as a water purification material according to claim 9.

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