Background,aim,and scope Owing to the rapid development of modernisation and urbanisation,living standards have gradually improved.However,the widespread use of high-energy-consuming indoor appliances and furniture ha...Background,aim,and scope Owing to the rapid development of modernisation and urbanisation,living standards have gradually improved.However,the widespread use of high-energy-consuming indoor appliances and furniture has made indoor environments a primary environmental problem affecting human health.Sick building syndrome(SBS)and building-related illness(BRI)have occurred,and indoor air conditions have been extensively studied.Common indoor pollutants include CO,CO_(2),volatile organic compounds(VOCs)(such as the formaldehyde and benzene series),NOx(NO and NO_(2)),and polycyclic aromatic hydrocarbons(PAHs).VOCs have replaced SO_(2)as the“The Fourteenth Five-Year Plan”urban air quality assessment new indicators.Indoor VOCs can cause diseases such as cataract,asthma,and lung cancer.To protect human health,researchers have proposed several indoor air purification technologies,including adsorption,filtration,electrostatic dust removal,ozonation,and plant purification.However,each technology has drawbacks,such as high operating costs,high energy consumption,and the generation of secondary waste or toxic substances.Plant degradation of VOCs as a bioremediation technology has the characteristics of low cost,high efficiency,and sustainability,thereby becoming a potential green solution for improving indoor air quality.This study introduces the research status and mechanism of plant removal of indoor VOCs and provides an experimental basis and scientific guidance for analysing the mechanism of plant degradation of pollutants.Materials and methods This study reviews studies on the harm caused by indoor pollutants to human health and related sources,mainly investigating the degradation of indoor formaldehyde,BTEX(benzene,toluene,ethylbenzene,and xylene)plant mechanisms,and research results.Results Plants can remove VOCs via stomatal and non-stomatal adsorption,interfoliar microbial,rhizosphere microbial,and growth media.Benzene,toluene,and xylene(BTX)are adsorbed by pores,hydroxylated into fumaric acid,and then removed into CO_(2) and H_(2)O by TCA.Formaldehyde enters plant leaves through the stomata and epidermal waxy substances and is adsorbed.After the two steps of enzymatic oxidation,formic acid and CO_(2) are generated.Finally,it enters the Calvin cycle and removes glucose and other nontoxic compounds.Discussion The non-stomatal degradation of VOCs can be divided into adsorption by cuticular wax and active adsorption by plant surface microorganisms.The leaf epidermal waxy matter content and the lipid composition of the epidermal membrane covering the plant surface play important roles in the non-stomatal adsorption of indoor air pollutants.The leaf margin of a plant is an ecological environment containing various microbial communities.The endophytic and inoculated microbiota in plant buds and leaves can remove VOCs(formaldehyde and BTEX).Formaldehyde can be directly absorbed by plant leaves and converted into organic acids,sugars,CO_(2) and H_(2)O by microbes.Bioremediation of indoor VOCs is usually inefficient,leading to plant toxicity or residual chemical substance volatilisation through leaves,followed by secondary pollution.Therefore,plants must be inoculated with microorganisms to improve the efficiency of plant degradation of VOCs.However,the effectiveness of interfoliar microbial removal remains largely unknown and several microorganisms are not culturable.Therefore,methods for collecting,identifying,and culturing microorganisms must be developed.As the leaf space is a relatively unstable environment,the degradation of VOCs by rhizosphere microorganisms is equally important,and formaldehyde is absorbed more by rhizosphere microorganisms at night.The inoculation of bacteria into the rhizosphere improves the efficiency of plants in degrading VOCs.However,most of these studies were conducted in simulation chambers.To ensure the authenticity of these conclusions,the ability of plants to remove indoor air pollutants must be further verified in real situations.Conclusions Plant purification is an economical,environment-friendly,and sustainable remediation technology.This review summarises the mechanisms of VOC plant degradation and presents its limitations.Simultaneously,it briefly puts forward a plant selection scheme according to different temperatures,light,and specific VOCs that can be absorbed to choose the appropriate plant species.However,some studies have denied the purification effect of plants and proposed that numerous plants are required to achieve indoor ventilation effects.Therefore,determining the ability of plants to remove indoor VOCs requires a combination of realistic and simulated scenarios.Recommendations and perspectives Plants and related microorganisms play an important role in improving indoor air quality,therefore,the effect of plants and the related microorganisms on improving indoor air quality must be studied further and the effect of plants on indoor VOCs will be the focus of future research.展开更多
The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atm...The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atmosphere due to the high activated energy of 88.7 k J/mol at the G3 level of theory. However, the computed results predict that the barrier for unimolecular decomposition of CF3OH is decreased to 25.1 kJ/mol from 188.7 k J/mol with the aid of NH3 at the G3 level of theory, which shows that the ammonia play a strong catalytic effect on the split of CF3OH. In addition, the calculated rate constants show that the decomposition of CF3OH by NH3 is faster than those of H2O and the water dimmer by 10^9 and 10^5 times respectively. The rate constants combined with the corresponding concentrations of these species demonstrate that the reaction CF3OH with NH3 via TS4 is of great importance for the decomposition of CF3OH in the atmosphere.展开更多
文摘Background,aim,and scope Owing to the rapid development of modernisation and urbanisation,living standards have gradually improved.However,the widespread use of high-energy-consuming indoor appliances and furniture has made indoor environments a primary environmental problem affecting human health.Sick building syndrome(SBS)and building-related illness(BRI)have occurred,and indoor air conditions have been extensively studied.Common indoor pollutants include CO,CO_(2),volatile organic compounds(VOCs)(such as the formaldehyde and benzene series),NOx(NO and NO_(2)),and polycyclic aromatic hydrocarbons(PAHs).VOCs have replaced SO_(2)as the“The Fourteenth Five-Year Plan”urban air quality assessment new indicators.Indoor VOCs can cause diseases such as cataract,asthma,and lung cancer.To protect human health,researchers have proposed several indoor air purification technologies,including adsorption,filtration,electrostatic dust removal,ozonation,and plant purification.However,each technology has drawbacks,such as high operating costs,high energy consumption,and the generation of secondary waste or toxic substances.Plant degradation of VOCs as a bioremediation technology has the characteristics of low cost,high efficiency,and sustainability,thereby becoming a potential green solution for improving indoor air quality.This study introduces the research status and mechanism of plant removal of indoor VOCs and provides an experimental basis and scientific guidance for analysing the mechanism of plant degradation of pollutants.Materials and methods This study reviews studies on the harm caused by indoor pollutants to human health and related sources,mainly investigating the degradation of indoor formaldehyde,BTEX(benzene,toluene,ethylbenzene,and xylene)plant mechanisms,and research results.Results Plants can remove VOCs via stomatal and non-stomatal adsorption,interfoliar microbial,rhizosphere microbial,and growth media.Benzene,toluene,and xylene(BTX)are adsorbed by pores,hydroxylated into fumaric acid,and then removed into CO_(2) and H_(2)O by TCA.Formaldehyde enters plant leaves through the stomata and epidermal waxy substances and is adsorbed.After the two steps of enzymatic oxidation,formic acid and CO_(2) are generated.Finally,it enters the Calvin cycle and removes glucose and other nontoxic compounds.Discussion The non-stomatal degradation of VOCs can be divided into adsorption by cuticular wax and active adsorption by plant surface microorganisms.The leaf epidermal waxy matter content and the lipid composition of the epidermal membrane covering the plant surface play important roles in the non-stomatal adsorption of indoor air pollutants.The leaf margin of a plant is an ecological environment containing various microbial communities.The endophytic and inoculated microbiota in plant buds and leaves can remove VOCs(formaldehyde and BTEX).Formaldehyde can be directly absorbed by plant leaves and converted into organic acids,sugars,CO_(2) and H_(2)O by microbes.Bioremediation of indoor VOCs is usually inefficient,leading to plant toxicity or residual chemical substance volatilisation through leaves,followed by secondary pollution.Therefore,plants must be inoculated with microorganisms to improve the efficiency of plant degradation of VOCs.However,the effectiveness of interfoliar microbial removal remains largely unknown and several microorganisms are not culturable.Therefore,methods for collecting,identifying,and culturing microorganisms must be developed.As the leaf space is a relatively unstable environment,the degradation of VOCs by rhizosphere microorganisms is equally important,and formaldehyde is absorbed more by rhizosphere microorganisms at night.The inoculation of bacteria into the rhizosphere improves the efficiency of plants in degrading VOCs.However,most of these studies were conducted in simulation chambers.To ensure the authenticity of these conclusions,the ability of plants to remove indoor air pollutants must be further verified in real situations.Conclusions Plant purification is an economical,environment-friendly,and sustainable remediation technology.This review summarises the mechanisms of VOC plant degradation and presents its limitations.Simultaneously,it briefly puts forward a plant selection scheme according to different temperatures,light,and specific VOCs that can be absorbed to choose the appropriate plant species.However,some studies have denied the purification effect of plants and proposed that numerous plants are required to achieve indoor ventilation effects.Therefore,determining the ability of plants to remove indoor VOCs requires a combination of realistic and simulated scenarios.Recommendations and perspectives Plants and related microorganisms play an important role in improving indoor air quality,therefore,the effect of plants and the related microorganisms on improving indoor air quality must be studied further and the effect of plants on indoor VOCs will be the focus of future research.
基金This work was supported by the National Natural Science Foundation of China （No.10865003） and the Guizhou University for Nationalities （2010）. The authors thank professors W. T. Duncan, R. L. Bell, and T. N. Truong or providing the rate program through the internet.
文摘The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atmosphere due to the high activated energy of 88.7 k J/mol at the G3 level of theory. However, the computed results predict that the barrier for unimolecular decomposition of CF3OH is decreased to 25.1 kJ/mol from 188.7 k J/mol with the aid of NH3 at the G3 level of theory, which shows that the ammonia play a strong catalytic effect on the split of CF3OH. In addition, the calculated rate constants show that the decomposition of CF3OH by NH3 is faster than those of H2O and the water dimmer by 10^9 and 10^5 times respectively. The rate constants combined with the corresponding concentrations of these species demonstrate that the reaction CF3OH with NH3 via TS4 is of great importance for the decomposition of CF3OH in the atmosphere.
