Removal Of Indoor Formaldehyde By Modified Bamboo Activated Carbon

It is well recognized that formaldehyde has always been one of the main indoor volatile gas pollutants with the popularity of interior decoration.The release of formaldehyde can cause harm to humans,and even cause cancer.Therefore,the removal of formaldehyde has been the focus of indoor environmental purification.The use of activated carbon,zeolite and other adsorbents to remove indoor formaldehyde has been widely used because of its low cost,easy to operate and other advantages.However,the adsorbent has some problems such as small adsorption capacity and easy saturation.In order to expand the adsorption capacity of biomass-based activated carbon adsorbent and prolong the service life of the adsorbent,bamboo activated carbon as raw materials was modified with different reagents.SEM,XRD,FT-IR,XPS and BET were employed to analyze the morphology,structure and functional groups of bamboo activated carbon before and after modification.The removal efficiency of modified bamboo activated carbon on indoor formaldehyde was analyzed,and the impact factor was also explored,so as to obtain the modified bamboo activated carbon with high efficiency and long-lasting for formaldehyde removal,and provide research ideas for the high value utilization of bamboo activated carbon.The main research results are as follows:（1）Bamboo activated carbon was treated by impregnation with 0.5mol/L of hydrogen peroxide,sodium hydroxide,oxalic acid and nitric acid.It was found that the surface roughness,the number of micropores and the oxygen-containing functional groups on the surface of the bamboo activated carbon were increased by acid-base treatment at low concentration compared with the unmodified activated carbon.Among them,carbonyl and ester groups play a key role in the removal of formaldehyde.Under different test conditions,the factors affecting the removal of formaldehyde by bamboo activated carbon are different.The main effect at static test is the micropore volume and pore size of bamboo activated carbon,while is the carbonyl and ester groups of bamboo activated carbon at dynamic test.Bamboo activated carbon modified by nitric acid and sodium hydroxide has better ability to remove formaldehyde.（2）Bamboo activated carbon was impregnated with HNO₃ and Na OH solutions of different concentrations（10%,20%,30%,40%,50%）.The results show that the concentration of HNO₃is 10%～40%,the micropore volume and micropore surface area of the modified bamboo activated carbon rise,and the contents of ester group and carboxyl group on the surface also increase.The pore structure of bamboo activated carbon modified by Na OH did not show obvious regularity.When the concentration of Na OH was lower than 30%,the contents of alcohol,ether,ester group and carboxyl group increased gradually.Compared with unmodified bamboo activated carbon,the formaldehyde removal efficiency was improved with different concentrations of HNO₃ and Na OH.As the concentration of HNO₃ is 40%and the concentration of Na OH is 30%,the most effective removal of formaldehyde are obtained.The content of ester group and carboxyl group on the surface of bamboo activated carbon is the decisive factor for formaldehyde removal.（3）Mn Ox/bamboo activated carbon composites with different loads were prepared by in-situ REDOX method of potassium permanganate.The results show that the Mn Ox loaded on the surface of bamboo activated carbon belongs to birnessite-type manganese dioxide.With the increase of loading,the morphology of Mn Ox gradually aggregates from nanorods to flocculation covering the surface of bamboo activated carbon,and the diffraction peak of Mn Ox becomes obvious.Compared with unsupported bamboo activated carbon（BAC）,the formaldehyde removal rate of bamboo activated carbon with different Mn Ox loads was improved.When the loading of Mn Ox was 3.5%,6%,8.5%and 11%,the removal time of formaldehyde was 2,5,6.5 and 8 times of that of BAC,respectively.The contents of Mn⁴⁺and lattice oxygen in Mn Ox/bamboo activated carbon are the main factors affecting the removal rate of formaldehyde.The Mn Ox supported bamboo activated carbon prepared by in-situ REDOX method has the best effect on formaldehyde removal and the longest service life,which is the synergistic result of adsorption and oxidation decomposition.