Adsorption Performance Of Formaldehyde Onto Activated Carbon Modified With Acid And Alkali

With the improvement of living standard,a large number of building materials appear in interior decoration,seriously endangers indoor air quality.Formaldehyde is a typical case of volatile organic gas.Long exposure to formaldehyde will affect physical function,eventurally will lead to cancer.Now,the treatment of formaldehyde is activated carbon adsorption.Therefore,exploring the adsorption performance of formaldehyde on activated carbon,especially improving the adsorption performance of modificated activated carbon is very important.This paper mainly studys from three parts,the first is the influence of modification by different acid and alkali on activated carbon's aperture characteristics,surface oxygen groups and surface morphology;the second is the influence of activated carbon's pore structure characteristics and surface oxygen groups on adsorption performance by molecular simulation;the third is the influence of adsorption performance of formaldehyde on modified activated carbon and unmodified activated carbon,and the influence of temperature on adsorption performance and modification performance.In order to explore the effect of different modification methods on activated carbon,activated carbon is modified with oxalic acid,nitric acid,and ammonia in this paper.To study the influence of organic acid,strong oxidizing acid and alkali modification on activated carbon's pore structure characteristics,oxygen functional groups and surface morphology,the physicochemical properties of modified activated carbon are characterized by surface area and pore distribution analyzer,Fourier transform infrared spectrometry,and scanning electron microscope.All of three modification methods could increase the percentage of micropore volume,and change the content of surface oxygen groups on activated carbon.The activated carbon modified by oxalic acid has largest increase on the percentage of micropore volume,up to 5%,it also improve the OH group on the surface of activated carbon.Nitric acid modification can make the surface of activated carbon rough.Ammonia modification has the least influence on the micropores surface area of activated carbon.To explore the impact of activated carbon pore structure and surface function groups on the adsorption performance,this paper builds formaldehyde model and activated carbon slit micropore model by Materials Studio,simulates the adsorption process by Grand Canonical Monte Carlo method(GCMC).The simulation results show that,the slit micropore of activated carbon and the OH group in the surface functional groups are favorable for the adsorption of formaldehyde.To study the difference of adsorption performance of formaldehyde between modified activated carbon and unmodified activated carbon,this paper tests four activated carbon sample by fixed bed adsorption experiments,analyses the adsorption curve,studys the adsorption energy,explores the adsorption kinetics property and adsorption performance.The experiments show that all of three modification methods will enhance the adsorption performance offormaldehyde on activated carbon.The activated carbon modified by oxalic acid can improve adsorption capacity about 16%at 303K,has the best adsorption performance.The increase of temperature will make the adsorption capacity decrease,but it will improve the modification effect of modified activated carbon.