| With the continuous acceleration of the modernization process,a variety of new materials are widely used in interior decoration,which brings us visual enjoyment as well as side effects such as exhaust emissions.Indoor decoration,including wall decoration coating,decorative floor,furniture and other articles,usually emits some volatile organic compounds,which will cause great damage to human health.The most important component of the compounds is formaldehyde.Long-term exposure in low concentration formaldehyde environment may cause cancer and damage human respiratory system.Activated carbon is one of the most widely used adsorbents,which has abundant pore structures and huge specific surface area,and can effectively adsorb formaldehyde in the air.However,the adsorption capacity of activated carbon on the market is limited,and it can not effectively decompose formaldehyde,which is easy to cause secondary pollution.Negative ion powder can produce negative oxygen ions in the air,which can effectively promote the decomposition of formaldehyde.Therefore,it is possible to improve the adsorption and removal of formaldehyde in the air by the composite modification of activated carbon and anion powder.In this paper,three kinds of activated carbon composites modified by anionic powder were prepared.The structure and morphology of the composites were characterized by FTIR,XRD,SEM and TGA.The formaldehyde concentration in the indoor environment was simulated and the formaldehyde adsorption and removal experiments were carried out in the closed environment.The adsorption time,the amount of adsorbent and the number of adsorption were studied can affect.It involves the following aspects:（1）Preparation of polyacrylic acid and anionic powder modified activated carbon composites for adsorption and removal of formaldehydePolyacrylic acid and anionic modified activated carbon composites（PAA/NG/AC）were prepared by graft polymerization of acrylic acid and crosslinking of glutaraldehyde with activated carbon and anionic powder.FTIR analysis showed that the target product was obtained.SEM analysis showed that the composites had fluted laminated structures loaded with particles of different sizes.The results of adsorption and removal for formaldehyde indicated that the products had high adsorption and removal capacity.When the used amount of adsorbent and contact time were 2.0 g and 10 h,the maximum removal of formaldehyde was achieved to 96.0%.The adsorption process accorded with pseudo second-order kinetic and Langmuir isotherm models.Adsorption was an endothermic and spontaneous chemical process.After five adsorption-desorption cycles,the removal of formaldehyde still kept over82.0%,and the content of negative ion radiated by the composites almost kept unchanged.（2）Preparation of titanium dioxide and anion powder modified activated carbon composites for adsorption and removal of formaldehydeActivated carbon and negative ion powder were used as the basic raw materials,and activated carbon loaded with titanium dioxide was obtained by solution gelation.After modification with acrylic acid and crosslinking with glutaraldehyde,titanium dioxide and negative ion powder modified activated carbon composites（Ti O2/NG/AC）were prepared.FTIR analysis showed that the target product was obtained.SEM analysis showed that particles of different sizes were loaded on the product surfaces.The results of adsorption and removal for formaldehyde indicated that the material had high adsorption and removal capacity.When the used amount of adsorbent and contact time were 2.0 g and 10 h,the maximum removal of formaldehyde was achieved to 98.0%.The adsorption process accorded with pseudo second-order kinetic and Langmuir isotherm models.Adsorption was an endothermic and spontaneous chemical process.The experimental results of five adsorption-desorption cycles showed that the regeneration performance of the adsorbent was good.After five adsorption-desorption cycles,the removal of formaldehyde still retained over 82.0%,and the content of negative ion radiated by the composites almost kept unchanged.（3）Preparation of chitosan and anionic powder modified activated carbon composites for adsorption and removal of formaldehydeThe modified activated carbon composites（CS/NG/AC）were prepared by impregnation method with activated carbon,negative ion powder and chitosan as the basic raw materials.Tetrethylenepentamine modified chitosan and negative ion powder and modified activated carbon were cross-linked with glutaraldehyde.FTIR analysis showed that the target product was obtained.SEM analysis showed that the products are activated carbon with different sizes of particles,which are manganese dioxide,anionic powder and modified chitosan.The results of adsorption and removal for formaldehyde indicated that the product has high adsorption and removal capacity.When the used amount of adsorbent and contact time were 0.5 g and 10h,the maximum removal for formaldehyde was achieved to 98.3%.The adsorption process accorded with the pseudo second-order kinetic and Langmuir isothermal models.The experimental results of adsorption-desorption cycles indicated that the regeneration performance of the adsorbent was good.After five adsorption-desorption cycles,the removal of formaldehyde was still over 83.2%,and the content of negative ion radiated by the composites almost kept unchanged.The above results signified that the three kinds of activated carbon composites modified by negative oxygen ions had high adsorption and removal capacity,good recycling ability and continuous adsorption capacity for indoor formaldehyde,and negative oxygen ions radiated after five adsorption-desorption cycles almost kept unchanged.Therefore,the adsorbent would be used for removal of indoor formaldehyde or VOCs in the air. |
