Study On Modified Activated Carbon Fiber Combined With Plasma For Removal Of Formaldehyde In The Air

Based on experimental research and related theory,methodologies of non-thermal plasma combined with modified ACF for formaldehyde removal are theoretically analyzed and examined preliminarily.Firstly,structural parameters have been obtained by systematically studying on differential electric discharge,waveform which effects on removal rate.Secondly,the optimization design could be concluded,including the factors of mass fraction,immersion time,soaking temperature through the comparative analysis between different ACF modified by various modifiers.Moreover,based on these experimental results above,Orthogonal Experiment has been utilized to optimize the formaldehyde-removal methodologies of modified activated carbon fibers combined with plasma.Finally,the effects of relevant modified activated carbon fiber characteristics,including surface morphology,structure and surface functional groups have been analyzed by utilization of SEM,XRD and FI-IR,and the main conclusions can be summarized as follows:1.Plasma of needle-plate and corona discharge can achieve to relatively efficient removal of formaldehyde.According to the experimental results,the removal rate of formaldehyde was 44%,under the circumstance of DC pulse for 60 min,and degradation rate 0.0020 mg/(m3,min).This rate could add to 44%when the power cycle of the AC waveform was attenuated wave within the degradation rate of 0.0024 mg/(m3.min).2.After structural optimization on parameters of needle-plate plasma device,the highest removal rate can achieve to 59%(60min),under condition of which the degradation rate was 0.0027 mg/(m3.min),within 4.5kV of supply voltage,14.5mm of the aperture,5mm of pitch hole,and 8mm of length.3.If the ACF is unmodified,the adsorption of formaldehyde would be weaker with only 18%of removal rate.However,modified ACF by KMnO4 can reach to a higher level.Because it could result in a diameter of 0.15?0.18?m particles or coating without any damage on the ACF's structure,by the procedure of which the ability of removal can increase to 63%.After 40 minutes,the proportion of formaldehyde can decrease to the formaldehyde national standard which is 0.1mg/m3.Moreover,the removal rate can reach to 84%with the degradation rate of 0.0073mg/(m3.min)when the amount of KMnO4 could increase to 3%,with 50min of immersion time,60 ? of soaking temperature.Under this circumstance,it would only need 20min to satisfy the national standard requirements.4.The highest removal rate of formaldehyde,which was 96%based on the experimental results,can be acquired by activated carbon fiber modified by KMnO4 combined with plasma within following characters:the KMnO4 mass fraction is 7%,50min immersion time,60? of soaking temperature and 50? of dry temperature.The various factors which effect on formaldehyde removal rate can be examined as follows:immersion time>soaking temperature>mass fraction>dry temperature.And the soaking temperature could be the most important elements.5.During the experiment on unmodified ACF example,two broad peaks near of 24 °,43 °could be discovered in the XRD patterns.The process of modification could broaden the diffraction peak and decrease the line intensity without any alternative change of d0002,d10,La,Lc.And the reason of which probably relates to the modification cause the appearance of-COOR,C=O,C-OH,H-O,C=CH2 and other functional groups on the surface of ACF.