Preparation Of Manganese Dioxide Supported On Activated Carbon And Its Formaldehyde Removal Performance

With the continuous improvement of people’s living standards,excessive indoor decoration has become a common phenomenon,and the accompanying indoor air pollution is inevitable.Volatile organic compounds（VOCs）,mainly formaldehyde（HCHO）,have attracted more and more attention because of their odor effect,sensory stimulation and chronic toxicity.Long term inhalation of such gases will lead to a variety of inflammatory reactions in human respiratory system,digestive system and circulatory system,It can even cause leukemia and other serious consequences.Therefore,indoor VOCs Pollution is an urgent problem related to the health of the whole people.Although a variety of remediation methods（such as adsorbent,filter and photocatalysis）can be used to treat or remove HCHO,it has been difficult to promote due to single adsorption or catalytic performance,high price,difficult production,economic constraints and other reasons.Among many metal catalysts,manganese dioxide catalyst has attracted much attention because of its following advantages:high degradation efficiency,strong regeneration ability,low price,simple preparation,no secondary pollution,etc.in this subject,it is combined with activated carbon materials with large specific surface area and large adsorption capacity to give full play to their advantages:adsorption catalysis at the same time or catalysis while adsorption,so as to produce a low-cost High efficiency and recycled composite catalyst to solve the problem of HCHO removal.The main research contents and results are as follows:（1）In order to prepare air purification materials with dual functions of adsorption and catalysis,AC@MnO₂ materials were synthesized by coprecipitation method.MnO₂ was grown in AC by the chemical reaction of KMnO₄ and Mn Cl₂.In the HCHO test experiment,the AC@MnO₂ material with the modification ratio of 1:10 showed the best adsorption performance:within 120 min,the HCHO removal rate was 95.3%.Within 120 min,the removal rate of HCHO was 95.3%.Combined with the experimental process,it could be found that the best adsorption amount of HCHO was just the instant fading of AC adding KMnO₄ solution.At this time,the mass ratio of KMnO₄ to AC was 1:10.After 5 cycle tests,the final HCHO removal rate was 81%,which still showed outstanding HCHO adsorption performance compared with pure AC and other mass ratio composites.（2）To solve the problem of dust pollution,ACF@MnO₂ material was prepared by immersion hydrothermal synthesis.In the HCHO adsorption test,the composite catalyst with0.05 mol/L KMnO₄ concentration and 180°C hydrothermal synthesis has the fastest HCHO removal effect at 5 minutes,and the HCHO removal rate is 98.66%at 120 minutes.After five repeated tests,t The HCHO adsorption performance of ACF@MnO₂material has always maintained the best catalytic activity,the adsorption speed is fast,and the final removal efficiency is 94.3%.Using ACF as carrier can not only solve the problem of dust,but also show the high-efficiency activity of manganese,which has the practical significance of market promotion.（3）In order to improve the firmness of MnO₂ on ACF surface and internal surface,ACF@MnO₂ ratio was prepared by C₆H₆O₇ and C₄H₆MnO₄ molar ratio.Only when n（C₆H₆O₇:C₄H₆MnO₄）=2:1,MnO₂ was successfully synthesized on the fiber.The morphology was hollow rod structure and the crystal form wasγCrystal form.From the HCHO test results,the HCHO concentration decreased to 0.65 mg/m³ in the first 5 min.After120 min,the HCHO removal rate was 95.6%.After 5 cycles,the formaldehyde removal rate was 92.67%.The firmness test showed that the f Abscission rate was 29.8%,which was 17.4%lower than that of the composites prepared in Chapter 3,and the bonding force between ACF and MnO₂ was effectively improved.