Formaldehyde Removal by Activated Carbon Impregnated with KMnO4

{"news_id":8197,"is_preview":0,"news_info":{"id":8197,"company_id":176,"user_id":411,"author":"","website_id":781,"pub_date":"2023-10-09 11:35:06","urla":"formaldehyde-removal-by-activated-carbon-impregnated-with-kmno4","description":"This article compares the adsorption performance of activated carbon with different KMnO4 impregnation rates in removing formaldehyde in indoor air.","image_url":"https:\/\/oss.matchpages.cn\/matchpages\/common\/2023\/1016\/1590\/652ceab1b32cb\/Formaldehyde-Removal-by-Activated-Carbon-Impregnated-with-KMnO4.webp","image_alt":"Formaldehyde Removal by Activated Carbon Impregnated with KMnO4.webp","title":"Formaldehyde Removal by Activated Carbon Impregnated with KMnO4","content":"<h1 style=\"line-height: 1.75;\"><span style=\"color: #169179; font-size: 18pt;\"><strong>Formaldehyde Removal by Activated Carbon Impregnated with KMnO4<\/strong><\/span><\/h1>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Formaldehyde is a high toxicity pollutant listed as a Group 1 carcinogen. The formaldehyde in indoor air mainly comes from composite boards, adhesives, paints, disinfectants, and incomplete combustion of fuels of building decoration materials. Common methods to purify formaldehyde include ventilation, physical adsorption, chemical reaction, and photocatalytic oxidation. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Among these methods, the ventilation method is restricted by air quality and ventilation conditions; the chemical reaction method faces the safety problem of chemical reagents; the application of the photocatalytic oxidation method is restricted by low utilization efficiency of visible light and its destructive effect on furniture. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Meanwhile,&nbsp;<span style=\"text-decoration: underline; color: #169179;\"><strong><a style=\"color: #169179; text-decoration: underline;\" href=\"https:\/\/www.allcarbon.com.cn\/activated-carbon-adsorption\" target=\"_blank\" rel=\"noopener\" data-page_id=\"0\">activated carbon adsorption<\/a><\/strong><\/span>&nbsp;has become the most widely used air purification method because of its simplicity to use and low cost.<\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\"><span style=\"text-decoration: underline; color: #169179;\"><strong><a style=\"color: #169179; text-decoration: underline;\" href=\"activated-carbon-products\" target=\"_blank\" rel=\"noopener\" data-page_id=\"19700\" data-page_name=\"Activated Carbon Products \uff5c ACC\" data-page_type=\"menuPage\">Activated carbon<\/a><\/strong><\/span>&nbsp;has a large specific surface area due to its porosity and shows good performance in adsorbing formaldehyde. However, the adsorption of unmodified activated carbon is generally physical adsorption, and the adsorbed formaldehyde is often desorbed later. In order to strengthen the adsorption capacity and stability, the activated carbon is usually impregnated with other chemicals for modification to improve its chemical adsorption performance. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Potassium permanganate (KMnO<sub>4<\/sub>) is an ideal formaldehyde adsorbent that has strong oxidizing properties and can react with formaldehyde to generate carbon dioxide and water. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">For activated carbon impregnated with KMnO<sub>4<\/sub>, the main factors affecting its adsorption performance of formaldehyde are the changes in the activated carbon surface structure, such as surface area, pore size, pore volume. And because KMnO<sub>4<\/sub>&nbsp;directly reacts with formaldehyde, the impregnation rate of potassium permanganate is the main factor that influences the chemical adsorption of the modified activated carbon. Besides, it is found that relative humidity can also have an important effect on the adsorption of formaldehyde.<\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">From the perspective of environmental protection as well as cost reduction, after the activated carbon impregnated with KMnO<sub>4<\/sub>&nbsp;is saturated, in order to reduce the waste of a large amount of activated carbon, it can be re-impregnated with KMnO<sub>4<\/sub>&nbsp;for reuse in adsorbing formaldehyde.<\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\"><img src=\"https:\/\/oss.matchpages.cn\/matchpages\/common\/2023\/1009\/8234\/6523749c8ae86\/removing-formaldehyde-in-indoor-air.webp\" alt=\"activated carbon air filter.webp \" data-resolution=\"800*400\" \/><\/span><\/p>\n<h2 style=\"line-height: 1.75;\"><span style=\"font-size: 14pt;\"><strong><span id=\"Material-preparation-process\" style=\"color: #169179;\">Material preparation process<\/span><\/strong><\/span><\/h2>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Weigh a certain amount of&nbsp;<span style=\"text-decoration: underline;\"><strong><span style=\"color: #169179;\"><a style=\"color: #169179; text-decoration: underline;\" href=\"activated-carbon-products\" target=\"_blank\" rel=\"noopener\" data-page_id=\"19700\" data-page_name=\"Activated Carbon Products \uff5c ACC\" data-page_type=\"menuPage\">extruded activated carbon<\/a><\/span><\/strong><\/span>&nbsp;for pretreatment. Put the activated carbon in a container and put it in a drying cabinet with a temperature of about 90&deg;C. Dry for 8 hours until the quality of the activated carbon does not change. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Prepare 100 mL potassium permanganate solutions with different mass percentages (considering the consumption of potassium permanganate in the impregnation process, the actual concentration of the prepared solutions is slightly greater than the calculated concentration). Mix the activated carbon and solution evenly, then place the mixture in an ultrasonic vibrator and vibrate at 25&deg;C for 1-2 hours. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">After that, place the mixture in the drying cabinet with a temperature of 80-90&deg;C and dry for 8 hours to obtain modified activated carbon with different impregnation rates.<\/span><\/p>\n<h2 style=\"line-height: 1.75;\"><span style=\"font-size: 14pt;\"><strong><span id=\"Activated-carbon-surface-structure\" style=\"color: #169179;\">Activated carbon surface structure<\/span><\/strong><\/span><\/h2>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">The surface of activated carbon without KMnO<sub>4<\/sub>&nbsp;impregnated is relatively smooth, and its pore shapes are mostly elliptical. Whereas those of activated carbon with KMnO<sub>4<\/sub>&nbsp;impregnated are eroded, rough and uneven. As the impregnation rate increases, the surface area, average pore diameter, and pore volume of activated carbon all decrease to varying degrees. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Among these, the specific surface area, the average pore size and the total pore volume of activated carbon with a 20% impregnation rate are 11% less, 12.8% less, 22% less, respectively, than those with a 0% rate. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">This is because potassium permanganate is relatively fully loaded in the pore structure of activated carbon, blocking part of the structure. The pore volume of mesopores and micropores decreased significantly, indicating that the mesopores and micropores are the main impregnation sites of potassium permanganate in activated carbon.<\/span><\/p>\n<h2 style=\"line-height: 1.75;\"><span style=\"font-size: 14pt;\"><strong><span id=\"Effect-of-impregnation-rate-on-formaldehyde-adsorption\" style=\"color: #169179;\">Effect of impregnation rate on formaldehyde adsorption<\/span><\/strong><\/span><\/h2>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">The test results show that the adsorption capacity of activated carbon with potassium permanganate impregnation rates of 0%, 5%, 10%, and 20% for formaldehyde adsorption is 16.30 mg\/g, 18.56 mg\/g, 57.88 mg\/g, 73.94 mg\/g, and the time to reach saturation is 150 min, 190 min, 310 min, 360 min, respectively. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">The adsorption capacity of the four carbon materials all decreases with time. The maximum adsorption rates corresponding to the four materials are 27.6%, 31.2%, 46.0%, and 55.2%, respectively. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Compared with unmodified activated carbon, the average adsorption attenuation rates of those with 5%, 10%, and 20% rates are 1.9% less, 10.9% less, and 16.8% less, respectively. This shows that the adsorption continuity of carbon with 10% and 20% impregnation rates are relatively better. This conclusion can also be drawn from the saturation time of the four materials.<\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">Regarding activated carbon with an even higher impregnation rate, when the rate of KMnO<sub>4<\/sub>&nbsp;is 24%, the formaldehyde adsorption performance is the best, with formaldehyde adsorption capacity of 90.23 mg\/g. If the impregnation rate continues to increase, the adsorption capacity will gradually decrease. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">The main reason is that at an impregnation rate higher than 24%, the uniformity of the dispersion of potassium permanganate decreases, which reduces its contact with formaldehyde molecules and reduces chemical adsorption. In addition, too many potassium permanganate molecules block the pore structure of activated carbon, and the physical adsorption of activated carbon decreased significantly.<\/span><\/p>\n<h2 style=\"line-height: 1.75;\"><span style=\"font-size: 14pt;\"><strong><span id=\"Effect-of-relative-humidity-(RH)-on-formaldehyde-adsorption\" style=\"color: #169179;\">Effect of relative humidity (RH) on formaldehyde adsorption<\/span><\/strong><\/span><\/h2>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">The adsorption performance of activated carbon materials with a 10% KMnO<sub>4<\/sub>&nbsp;impregnation rate is tested with the relative humidity (RH) of 20%, 50%, and 80%. The result shows that when RH is 20%, the carbon material has the largest adsorption capacity, the longest adsorption saturation time, and the smallest average adsorption attenuation rate for formaldehyde. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">The formaldehyde adsorption performance of modified activated carbon decreasing as the relative humidity increases is because more and more water molecules are occupied on the surface of the modified activated carbon. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">At the same time, during the catalytic oxidation of formaldehyde with KMnO<sub>4<\/sub>, CO<sub>2<\/sub>&nbsp;and H<sub>2<\/sub>O are produced. Too many water molecules affect the cyclic adsorption process of formaldehyde molecules.<\/span><\/p>\n<h2 style=\"line-height: 1.75;\"><span style=\"font-size: 14pt;\"><strong><span id=\"Effect-of-repeated-impregnation-times-on-formaldehyde-adsorption\" style=\"color: #169179;\">Effect of repeated impregnation times on formaldehyde adsorption<\/span><\/strong><\/span><\/h2>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">The initial adsorption capacity and adsorption saturation time of activated carbon with a 10% impregnation rate of KMnO<sub>4<\/sub>&nbsp;for formaldehyde are 57.88 mg\/g and 310 min. Those of the first re-impregnated carbon are 50.20 mg\/g and 280 min, and those of the second re-impregnated carbon are 36.57 mg\/g and 210 min. <\/span><\/p>\n<p style=\"line-height: 1.75;\"><span style=\"color: #000000;\">From the data, it can be seen that the adsorption performance of the modified activated carbon material significantly decreases after the second re-impregnation. But it still shows a good adsorption capacity for formaldehyde compared with unmodified ones.<\/span><\/p>","discuss":0,"seo_title":"Formaldehyde Removal by Activated Carbon Impregnated with KMnO4","seo_keyword":"activated carbon air filter,activated carbon air purifier,activated carbon,","seo_describe":"This article compares the adsorption performance of activated carbon with different KMnO4 impregnation rates in removing formaldehyde in indoor air.","track_code":"","viewer":"","source_copy_id":0,"sort":71,"status":0,"data_time":"2023-12-29 16:26:02","create_time":"2023-10-09 11:30:52","update_time":"2025-04-02 09:56:43","type_items":[{"id":2083,"website_id":781,"name":"Activated Carbon","urla":""}],"tag_items":[]}}

<h1 style="line-height: 1.75;"><span style="color: #169179; font-size: 18pt;"><strong>Formaldehyde Removal by Activated Carbon Impregnated with KMnO4</strong></span></h1>
<p style="line-height: 1.75;"><span style="color: #000000;">Formaldehyde is a high toxicity pollutant listed as a Group 1 carcinogen. The formaldehyde in indoor air mainly comes from composite boards, adhesives, paints, disinfectants, and incomplete combustion of fuels of building decoration materials. Common methods to purify formaldehyde include ventilation, physical adsorption, chemical reaction, and photocatalytic oxidation. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">Among these methods, the ventilation method is restricted by air quality and ventilation conditions; the chemical reaction method faces the safety problem of chemical reagents; the application of the photocatalytic oxidation method is restricted by low utilization efficiency of visible light and its destructive effect on furniture. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">Meanwhile, <span style="text-decoration: underline; color: #169179;"><strong><a style="color: #169179; text-decoration: underline;" href="https://www.allcarbon.com.cn/activated-carbon-adsorption" target="_blank" rel="noopener" data-page_id="0">activated carbon adsorption</a></strong></span> has become the most widely used air purification method because of its simplicity to use and low cost.</span></p>
<p style="line-height: 1.75;"><span style="color: #000000;"><span style="text-decoration: underline; color: #169179;"><strong><a style="color: #169179; text-decoration: underline;" href="activated-carbon-products" target="_blank" rel="noopener" data-page_id="19700" data-page_name="Activated Carbon Products ｜ ACC" data-page_type="menuPage">Activated carbon</a></strong></span> has a large specific surface area due to its porosity and shows good performance in adsorbing formaldehyde. However, the adsorption of unmodified activated carbon is generally physical adsorption, and the adsorbed formaldehyde is often desorbed later. In order to strengthen the adsorption capacity and stability, the activated carbon is usually impregnated with other chemicals for modification to improve its chemical adsorption performance. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">Potassium permanganate (KMnO<sub>4</sub>) is an ideal formaldehyde adsorbent that has strong oxidizing properties and can react with formaldehyde to generate carbon dioxide and water. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">For activated carbon impregnated with KMnO<sub>4</sub>, the main factors affecting its adsorption performance of formaldehyde are the changes in the activated carbon surface structure, such as surface area, pore size, pore volume. And because KMnO<sub>4</sub> directly reacts with formaldehyde, the impregnation rate of potassium permanganate is the main factor that influences the chemical adsorption of the modified activated carbon. Besides, it is found that relative humidity can also have an important effect on the adsorption of formaldehyde.</span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">From the perspective of environmental protection as well as cost reduction, after the activated carbon impregnated with KMnO<sub>4</sub> is saturated, in order to reduce the waste of a large amount of activated carbon, it can be re-impregnated with KMnO<sub>4</sub> for reuse in adsorbing formaldehyde.</span></p>
<p style="line-height: 1.75;"><span style="color: #000000;"><img src="https://oss.matchpages.cn/matchpages/common/2023/1009/8234/6523749c8ae86/removing-formaldehyde-in-indoor-air.webp" alt="activated carbon air filter.webp " data-resolution="800*400" /></span></p>
<h2 style="line-height: 1.75;"><span style="font-size: 14pt;"><strong><span id="Material-preparation-process" style="color: #169179;">Material preparation process</span></strong></span></h2>
<p style="line-height: 1.75;"><span style="color: #000000;">Weigh a certain amount of <span style="text-decoration: underline;"><strong><span style="color: #169179;"><a style="color: #169179; text-decoration: underline;" href="activated-carbon-products" target="_blank" rel="noopener" data-page_id="19700" data-page_name="Activated Carbon Products ｜ ACC" data-page_type="menuPage">extruded activated carbon</a></span></strong></span> for pretreatment. Put the activated carbon in a container and put it in a drying cabinet with a temperature of about 90°C. Dry for 8 hours until the quality of the activated carbon does not change. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">Prepare 100 mL potassium permanganate solutions with different mass percentages (considering the consumption of potassium permanganate in the impregnation process, the actual concentration of the prepared solutions is slightly greater than the calculated concentration). Mix the activated carbon and solution evenly, then place the mixture in an ultrasonic vibrator and vibrate at 25°C for 1-2 hours. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">After that, place the mixture in the drying cabinet with a temperature of 80-90°C and dry for 8 hours to obtain modified activated carbon with different impregnation rates.</span></p>
<h2 style="line-height: 1.75;"><span style="font-size: 14pt;"><strong><span id="Activated-carbon-surface-structure" style="color: #169179;">Activated carbon surface structure</span></strong></span></h2>
<p style="line-height: 1.75;"><span style="color: #000000;">The surface of activated carbon without KMnO<sub>4</sub> impregnated is relatively smooth, and its pore shapes are mostly elliptical. Whereas those of activated carbon with KMnO<sub>4</sub> impregnated are eroded, rough and uneven. As the impregnation rate increases, the surface area, average pore diameter, and pore volume of activated carbon all decrease to varying degrees. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">Among these, the specific surface area, the average pore size and the total pore volume of activated carbon with a 20% impregnation rate are 11% less, 12.8% less, 22% less, respectively, than those with a 0% rate. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">This is because potassium permanganate is relatively fully loaded in the pore structure of activated carbon, blocking part of the structure. The pore volume of mesopores and micropores decreased significantly, indicating that the mesopores and micropores are the main impregnation sites of potassium permanganate in activated carbon.</span></p>
<h2 style="line-height: 1.75;"><span style="font-size: 14pt;"><strong><span id="Effect-of-impregnation-rate-on-formaldehyde-adsorption" style="color: #169179;">Effect of impregnation rate on formaldehyde adsorption</span></strong></span></h2>
<p style="line-height: 1.75;"><span style="color: #000000;">The test results show that the adsorption capacity of activated carbon with potassium permanganate impregnation rates of 0%, 5%, 10%, and 20% for formaldehyde adsorption is 16.30 mg/g, 18.56 mg/g, 57.88 mg/g, 73.94 mg/g, and the time to reach saturation is 150 min, 190 min, 310 min, 360 min, respectively. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">The adsorption capacity of the four carbon materials all decreases with time. The maximum adsorption rates corresponding to the four materials are 27.6%, 31.2%, 46.0%, and 55.2%, respectively. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">Compared with unmodified activated carbon, the average adsorption attenuation rates of those with 5%, 10%, and 20% rates are 1.9% less, 10.9% less, and 16.8% less, respectively. This shows that the adsorption continuity of carbon with 10% and 20% impregnation rates are relatively better. This conclusion can also be drawn from the saturation time of the four materials.</span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">Regarding activated carbon with an even higher impregnation rate, when the rate of KMnO<sub>4</sub> is 24%, the formaldehyde adsorption performance is the best, with formaldehyde adsorption capacity of 90.23 mg/g. If the impregnation rate continues to increase, the adsorption capacity will gradually decrease. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">The main reason is that at an impregnation rate higher than 24%, the uniformity of the dispersion of potassium permanganate decreases, which reduces its contact with formaldehyde molecules and reduces chemical adsorption. In addition, too many potassium permanganate molecules block the pore structure of activated carbon, and the physical adsorption of activated carbon decreased significantly.</span></p>
<h2 style="line-height: 1.75;"><span style="font-size: 14pt;"><strong><span id="Effect-of-relative-humidity-(RH)-on-formaldehyde-adsorption" style="color: #169179;">Effect of relative humidity (RH) on formaldehyde adsorption</span></strong></span></h2>
<p style="line-height: 1.75;"><span style="color: #000000;">The adsorption performance of activated carbon materials with a 10% KMnO<sub>4</sub> impregnation rate is tested with the relative humidity (RH) of 20%, 50%, and 80%. The result shows that when RH is 20%, the carbon material has the largest adsorption capacity, the longest adsorption saturation time, and the smallest average adsorption attenuation rate for formaldehyde. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">The formaldehyde adsorption performance of modified activated carbon decreasing as the relative humidity increases is because more and more water molecules are occupied on the surface of the modified activated carbon. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">At the same time, during the catalytic oxidation of formaldehyde with KMnO<sub>4</sub>, CO<sub>2</sub> and H<sub>2</sub>O are produced. Too many water molecules affect the cyclic adsorption process of formaldehyde molecules.</span></p>
<h2 style="line-height: 1.75;"><span style="font-size: 14pt;"><strong><span id="Effect-of-repeated-impregnation-times-on-formaldehyde-adsorption" style="color: #169179;">Effect of repeated impregnation times on formaldehyde adsorption</span></strong></span></h2>
<p style="line-height: 1.75;"><span style="color: #000000;">The initial adsorption capacity and adsorption saturation time of activated carbon with a 10% impregnation rate of KMnO<sub>4</sub> for formaldehyde are 57.88 mg/g and 310 min. Those of the first re-impregnated carbon are 50.20 mg/g and 280 min, and those of the second re-impregnated carbon are 36.57 mg/g and 210 min. </span></p>
<p style="line-height: 1.75;"><span style="color: #000000;">From the data, it can be seen that the adsorption performance of the modified activated carbon material significantly decreases after the second re-impregnation. But it still shows a good adsorption capacity for formaldehyde compared with unmodified ones.</span></p>